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If you’re like me, August is the most exciting month of the entire year. Football, soccer, volleyball, and cross country athletes are returning to campus for the pre-season camp. There’s always the mix of freshmen who are overwhelmed and walking around wide-eyed. The seniors, grizzled with their years of experience, are anxiously waiting to begin the countdown of their precious few remaining competitions. As all of these athletes come back to campus with their range of goals and hopes and dreams, their sport and strength coaches immediately have to wrestle with a tough question.

Should You Test Athletes at the Start of Pre-Season?

Believe it or not, this is a much bigger question than you might think. I’ve wrestled with both of sides of the argument and found the heart of the matter lies in a discussion about injuries. Those who oppose testing at the start of pre-season don’t want to see anyone injured in non-sport related activities. It’s a difficult opinion to argue against because I completely agree with it. After all, no one wants to see people get hurt, and it’s especially heart-wrenching to see someone go down before they even get to the first practice.

On the other hand, some coaches believe that if an athlete is going to get hurt in testing, that means they would get hurt within the first few practices anyway. I’m lucky because the head coaches I usually work with fall into the latter mindset, so they want to do some pre-season testing. With that said, let me ask you the big picture question: What’s the point of testing your athletes in the first place? Really, what information are you looking for after putting athletes through your testing battery?

In a previous post, I talked about the best conditioning test I know. With any performance test, there’s a lot of very helpful information to unpack once the athlete completes the test, so let’s move past the testing protocol and dissect what I do with the information.

When we get down to the nuts and bolts of performance testing, we’re conducting a mini experiment with our athletes. Think about it for a second. Both research subjects and our athletes complete a baseline test to see where they are with their skills. Then we expose them to a stimulus—be it a lifting program, supplement or placebo, sprint or agility program, or anything else. At the end of a set time period, the subjects and athletes come back and complete the same tests so we can compare their pre- and post-test results. We do all this work to answer the age-old question coaches and researchers wrestle with: Will doing this make any difference?

Know Your Own Athletes

There’s almost a century of research that gives us a solid foundation for the scientific principle and a baseline for determining appropriate training methods. While I’m certain that the General Adaptation Syndrome from Dr. Hans Selye or the Fitness-Fatigue Model credited to Dr. Mel Siff will fit almost every situation, there’s one glaring omission concerning all training programs—they were not designed using your athletes. It might be trite, but there are so many differences between what I’m able to do with my group of athletes and what another coach can do with their athletes. Is it a fair comparison to look at the results I get and automatically assume another coach will get the same?

There is a lot from the late Charlie Francis’s programs that I like and use, but there’s always an asterisk when looking at his athletes’ results. Many of his former athletes tested positive for performance-enhancing drugs, and we can all agree that these drugs help training a lot. So should I blindly follow the high-low training idea that Charlie Francis publicized? Of course not. He worked with the top sprinters in the world. I do not. Some of his athletes took drugs, none of mine (I hope) do. Surveying his work is a good start, but it can’t end there.

I look at the results from what my groups have done historically, compare those results to changes I’ve made with their programs, and then follow the advice of Bruce Lee: “Absorb what is useful, reject what is useless.” After doing this style of test-analyze-compare for years, I’m very confident that when someone goes through one of our 6- to 8-week long off-season training programs, I can predict their expected outcomes.

All of this information helps when having an honest conversation with everyone involved in your program. Having records of your past results is the only way to see if you’re helping athletes get better or if you need to try something different. This type of review is very helpful for all of us in the strength and conditioning profession who want to confirm that our mesocycles are working and that we’re getting an appropriate transfer of training.

But what about those people who don’t have our background and education, like sport coaches? Do they care about the incremental changes their athletes are getting, or do they care about how these changes impact the way their athletes can play the game? With team sports, isn’t this the real question we should be trying to answer?

From the Spreadsheet to the Playing Field

Don’t get me wrong, I have a track and field background and have competed in powerlifting, strongman, and weightlifting competitions, but these are different than team sports. With team sports, many factors that can’t be quantified come together to determine a winner. We’ve all seen it before; being the strongest, fastest, or most conditioned team does not necessarily mean you will win. You have a better chance, true, but it doesn’t mean the victory is in the bag. So you might be asking yourself, “Then what can I do to help out sport coaches?” I’m glad you asked.

How to Build a Player Comparison Tool

When it comes time to have hard conversations about keeping or cutting players from a team roster, I’m usually invited to attend the meetings. For years, I made the mistake of using too many terms that only strength coaches understand or charts that were too difficult to understand quickly. Well, that changed. Below is an example of one athletes’ profile and is typical of what I present to the coaches now.

• explosiveness (vertical jump)
• change of direction (5-10-5 pro agility)
• acceleration (10-yard sprint)
• top speed (10- to 20-yard split)
• stamina (220 fatigue resistance)
• power (power clean pull using GymAware)
• strength (back squat 1-rep max)
• body weight (a calibrated scale)
• body fat (three-site skinfold pinch)

Using some really basic statistical breakdowns, I made this chart which compares our current players to the historical average in their position group. Without going in depth with the equations, here is the basic idea.

1. Find the average for your category. It’s the sum of the results divided by the number of attempts.
2. Calculate the standard deviation. Excel is very helpful with this since you have to square and take the square root of each attempt subtracted from the average. You should do it longhand once or twice to get to know the equation, but when you’re doing this for more than four data sets, use Excel.
3. Now that you have your standard deviation and your average, you can define a range of scores that you would expect 68.2% of people to be within. The low number of the range is your “0” or worst score possible. The high number of the range is your “100” or best score possible.
4. Take your 100 score and subtract from it your zero score. This shows the range of acceptable scores for that test.
5. The next part is the one tricky point in the whole process. You have to subtract the athlete’s score from the 0 score, then divide it by the range. Finally multiply it by 100. Hang in there, I’ll show you an example in a second.
6. Now you have a number that is relative to their performance. Keep in mind that it is not the actual score but how it relates to their If they score a 50 in any category, that’s average, a 100 is very good, and a 0 is not.

Here is the actual data set from this player’s position group.

This player ranked 58 in their explosive quality. The equation is (33-31.4)/21.2 then multiply it by 100. This gives you 57.86 which becomes a score of 58 when rounded.

Let me be upfront, there’s a lot to do to set this up, and with Excel you can get a headache in a hurry chasing after an equation. Is it worth the time and energy? It is for me. In a brief instant, everyone can see how players’ skills rate. This player is pretty average for their position except in their stamina, and they’re slightly above average with their strength and body weight. In fact, they scored off the chart on their stamina. Now, I purposely cap the chart at 100 and zero even though I might have players score outside these boundaries, and that’s OK. Since this a comparison of how my current athletes compare to the historical average, I’m fine with having outliers.

In the example, the player has a ridiculously high score in stamina (137), but the chart is capped at 100. What’s important is that the player can do repeated bouts of high effort work and not fatigue as fast as some others in their group. With this in mind, if this athlete were to change positions or even play a different sport, their score would change to reflect the “average” for the new team and position group. Remember, we’re making a relative comparison of athletes in the same position group, not comparing them to a national average.

How to Use the Player Comparison Tool

Now that you’ve built this tool, how can you use it? As I mentioned, I am invited to the coaches meetings to talk about their prospects. By using this player profile, everyone can easily see if this person is athletic enough to keep up with the rest of the team. If I were at a school that offered athletic scholarships, I would push the head coaches to use this information for scholarship offers.

Think of it this way: If two recruits can play the game about equally, who will you offer a scholarship to? Tough one. What if we had their player profiles and one athlete didn’t score above a 50 in any category, and the other didn’t score worse than a 60. Would that information be helpful? It sure would.

If you’ve been keeping records on athletes for a while, you know who the all-stars or stand out players were. In that case, why don’t you use their information to build your data sets? This way, you’re comparing people to the best athletes you’ve worked with instead of the average from the best and weakest athletes you’ve worked with. Would this give you a better idea of what type of athletes are on a team? Now that I say this, I might want to make this change myself.

If you have sport coaches who are open to having open and honest conversations, this information becomes important in another way. It can help plan game strategy. Knowing each player’s weaknesses and strengths gives some insight on how to best use them to maximize their potential. For example, let’s say you have a star basketball player whose acceleration and change of direction ability rank very high, but their stamina and top speed ability scores are low. I would recommend to the coach that they have subs go in for this athlete often and suggest they change the team’s tempo on offense or defense.

Looking through these charts is also one of the ways I do in-house quality control of our programs. You saw the expected improvement ranges when players go through a 6-8 week off-season phase; looking at these graphs over time is a fast way to check if you’re helping your athletes improve.

It’s likely we’ve all worked with athletes who don’t improve at the expected rate, and all too often we blame the athletes. As coaches, we ask them if they’re recovering, eating right, or staying up too late. Or we blame their outside activities. Don’t get me wrong, there is a lot of truth in these questions, but it might not be completely on the athlete.

All athletes have different training ages, backgrounds, and abilities. Our freshmen workouts are three lifting days a week. What would you expect to see if an athlete comes in with a training background of four or five days a week? I would guess that their volume-load in a three-day program is actually their retaining or detraining load. This means they will either plateau or get worse. It’s not always, or completely, the athlete’s fault.

The Truth Is Out There

The real beauty of testing and building this tool is discovering the truth. The truth about your program. The truth about the players. The truth about realistic expectations. If you’re already testing your athletes regularly, you have this information and may need to spend some time upfront to format all of it. If you don’t test your athletes, this article has given you some points to think about. Either way, reach out when you need help. The truth is out there.

Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF

Caffeine is one of the most widely used—and abused—performance-enhancing drugs in the world. It enhances performance across a number of exercise types, including aerobic endurance, muscular endurance, repeated sprints, and maximum strength. Athletes know this, of course, which is why as many as 90% of them consume caffeine before or during competition, according to the research.

While researchers have examined how a pre-training or competition dose of caffeine directly impacts sporting performance, we need a wider conversation as to how caffeine fits into an athlete’s lifestyle and how this may impact athletic performance at the time when the athlete most needs a performance boost—in competition.

Regular Joe

Using caffeine as a performance enhancer isn’t only limited to those involved in sport. About 80% of the world’s population consumes some form of caffeine on a daily basis. In the UK, the average daily caffeine intake for adults is about 130 mg, which equals 2.5 espressos or 1.5 cans of Red Bull. Often, non-athletic adults consume caffeine for its positive effects on mental alertness and concentration, especially when sleep deprived. Caffeine also offers health benefits, primarily when consumed as coffee, with research suggesting it lowers overall mortality risk.

Traditionally, caffeine has been studied in two separate spheres: how it impacts athletic performance and how it impacts humans in their normal life. However—and this may surprise you—athletes are also normal people, and alongside consuming caffeine before a competition, they also tend to use caffeine in ways that mirror the general population.

Recent research has begun to explore this behavior, demonstrating how caffeine’s pain-reducing effects can help offset soreness associated with heavy training or reducing fatigue associated with travel or early morning training. Similarly, just like regular people, athletes consume caffeine by drinking coffee and tea socially.

Caffeine and High Performance

Our recent paper in Sports Medicine looked at how an athlete’s regular intake of caffeine, for sport and in general life, might impact their performance. We wanted to understand how athletes might become habituated to regular caffeine intake. We know that long-term exposure to some drugs requires more of that drug to exert the same effect. Caffeine is likely no different.

There are, however, surprisingly few studies exploring habituation and its effect on subsequent performance. The first study by Dodd and colleagues found no differences regarding time to exhaustion between habitual caffeine users and non-users. The researchers recruited non-habitual (average daily intake of 25 mg) and habitual (average intake >300 mg per day) caffeine users and had them undertake two incremental cycle tests with a pre-test caffeine dose of either 3 mg/kg or 5 mg/kg.

The opposite results were reported by Bell and McLellan, who found that habitual users (>300 mg/d) exhibited a smaller ergogenic effect from caffeine following a pre-cycle time to exhaustion dose of 5 mg/kg than did non-habitual users. These results were mirrored by a more recent, tightly controlled study by Beaumont and colleagues. In this study, participants took 3 mg/kg or a placebo every day for 28 days and then 3 mg/kg of caffeine before a performance test. The researchers found a smaller performance benefit compared to placebo in the caffeine supplemented group.

Finally, in a wonderfully provocatively titled study, “Dispelling the Myth that Habitual Caffeine Consumption Influences Performance Response to Acute Caffeine Supplementation,” Goncalves and colleagues reported no difference in performance enhancement following 6 mg/kg of caffeine in low, moderate, and high habitual caffeine users who ingested an average of 58 mg/d, 143 mg/d, and 351 mg/d, respectively.

Determining Caffeine Dosage

This leaves us in a delicate situation. Half of the studies suggest that habitual caffeine intake negatively affects caffeine’s subsequent performance benefits while the other half suggest no such thing. Which are we to believe?

In our recent paper, we proposed a theory that there has to be a substantial difference between the habitual and pre-competition caffeine doses for the negative effects of caffeine habituation not to occur. In the studies that supported a negative impact from caffeine habituation, there often was minimal difference between the habitual and pre-exercise caffeine doses. For example, in Beaumont’s study, both the habitual caffeine dose and pre-competition dose were 3 mg/kg.

Conversely, in the trials suggesting no negative effect from habituation, the pre-competition caffeine dose was much higher. In the Goncalves study, for example, the pre-trial caffeine dose was 6 mg/kg while the habitual dose in the high group was 350 mg/d (equivalent to about 4 mg/kg). This suggests that athletes can regularly consume caffeine, as long as the habitual dose is much less than their pre-competition dose.

That’s all well and good except that this prompts an obvious second question: How much caffeine should an athlete consume pre-competition? Very broadly, there is no right answer. Historically, the general recommendation is 3-9 mg/kg, with no additional benefits occurring above this amount.

Recent research, however, has suggested that doses lower than 3 mg/kg can also be ergogenic. I authored another paper that critically examined whether these guidelines applied to all athletes and found that they did not. As an example, variation in a gene called CYP1A2 may alter the optimal dose of caffeine. Recently, a group of researchers from Canada found that those with the CC version of the gene saw reduced sports performance with a 3 mg/kg caffeine dose while those with the AA version saw improved performance. These individuals may benefit from lower doses of caffeine or a longer period of time between ingestion and performance.

It’s very difficult to give a one-size fits all solution to the question of the optimal caffeine dose for an athlete pre-competition. I suggest that most people should experiment with consuming about 3 mg/kg 60 minutes before performance and then experiment with altering the dose and timing until the athlete arrives at an optimal strategy. For prolonged events, such as endurance running or team sports, there is a case for consuming caffeine later in the event, often with a lower dose.

Once we set the pre-competition caffeine dose, we can calculate the habitual dose—I recommend 50-75% of the pre-competition dose. If an athlete were to consume 3 mg/kg pre-competition, they could habitually consume 1.5-2 mg/kg on a daily basis. For an 80 kg person, this equals 120-160 mg of caffeine, which is roughly three cups of coffee or two small cans of energy drinks. This way, the athlete gets all the benefits of caffeine pre-competition as well as the benefits of regular use within training and can even consume caffeine socially.

Estimating caffeine intake is notoriously difficult, with many studies demonstrating a large range in caffeine concentrations between different drinks and brands; a coffee from Starbucks will have a different caffeine content as one from Pret. There also is a large range in caffeine concentration within the same caffeine source at different times; coffee from Starbucks will have different amounts of caffeine on different days.

Planned Caffeine Withdrawal

Another strategy often discussed is pre-competition caffeine withdrawal. Here, the athlete stops consuming caffeine for a period of time, often 7-28 days, before a competition to “re-sensitize” themselves to caffeine’s positive effects and gain a larger performance benefit. This strategy is also surprisingly poorly explored. A study examining the impact of a 4-day caffeine withdrawal found no effect on the performance benefits from a subsequent caffeine dose. It’s unclear whether a longer withdrawal period would have had a positive effect.

It’s also worth keeping in mind that caffeine withdrawal can be extremely unpleasant and can cause headaches, muscle pain, and sleep disturbances. While these side effects don’t last long, an athlete would not want to experience them before a competition. Given the lack of benefits from a pre-competition caffeine withdrawal period, along with the potential for negative side effects, I don’t recommend a withdrawal period.

Final Thoughts

So where does this leave us? There’s no reason why athletes cannot consume caffeine on a regular basis like normal humans in sporting and social contexts. Indeed, given caffeine’s positive effects on training performance, athletes should consume caffeine around training sessions. I suggest limiting their habitual caffeine dose to 50-75% of their regular pre-competition caffeine dose to limit any potential habituation effects.

Because there are apparently no positive effects from short-term caffeine withdrawal before a competition, I don’t recommend it. Finally, athletes should experiment with different caffeine doses and timing to better determine their optimal protocol, keeping in mind that the general advice may not be suitable for their own unique contexts.

Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF

The greatest part about coaching the sport you used to play is getting to help others experience the same feeling of accomplishment and camaraderie that you experienced, but on a larger scale. It’s extremely rewarding to be a part of that process. However, just because you’re a former athlete, that doesn’t mean you have all the answers—it’s still a long road full of mistakes.

We all start our coaching careers from different angles, and the entry point from which we start plays a role in the way those mistakes present themselves. Former athletes have an insight into the players’ experiences that may initially create rapport, but that background also comes with a unique set of challenges that we must overcome to efficiently transition from athlete to successful coach.

Below are four common mistakes young coaches make as they transition from competing to coaching. I have made all of these mistakes myself, and am in a constant battle to prevent myself from continuing to repeat them. Being self-aware of your shortcomings is the first step to correcting them, and ultimately becoming a better coach.

Copy-and-Pasting Your Program

“It’s what I did, and I got better.”

Probably the most common mistake athletes make as we transition to a coaching role is repeating what we did as an athlete in the hopes of passing that same success along to our athletes. Although done with the best intentions, your training was designed for athletes at your specific level, with your resources, on your schedule, and a methodology that was influenced by your coach’s philosophy, mentors, personality, work ethic, and biases, to name just a few factors. All of those variables will always be present in your decisions as a coach, but they do not manifest the same way for you as they did for your coach.

The ranking of KPIs (key performance indicators) such as acceleration, top speed, speed endurance, and work capacity—and the time spent at each—will differ greatly for athletes of different levels and genders, such as a male collegiate short sprinter and a female high school short sprinter. For a high school female, a bigger emphasis on speed endurance and work capacity is necessary due to lower training age, the need to achieve top speed earlier in the race, and less distance being covered while at that speed—meaning a larger percent of her race will be deceleration. The male collegiate sprinter, on the other hand, may get 70 meters into the 100m dash before deceleration occurs. Consequently, the density of speed endurance can be slightly deemphasized for the male.

The reverse can also be true. How efficiently are you spending your time training a male collegiate sprinter for the 100m dash doing intensive tempo intervals 3x a week, when the training adaptation from that stimulus constitutes 30% of your race? Copy-and-pasting will yield underperformance.

Even variables like weather and location affected what your coach gave you as an athlete. Whether you realize it or not, your program’s training methodology was influenced by the weather and what you were able to do at any given time of the year. A change in location could completely derail your previous training if your program called for Block 60s in January, but the Northeast’s weather will prevent you from even glancing at the track until April, let alone spiking up.

Another example occurs in personality differences that influence coaching styles. The varying personality types from coach to coach may alter the effectiveness of certain methodologies: A very level, mellow demeanor may be contraindicating to administering a Tony Holler-esque “Feed the Cats” program, where creating an extremely high level of athlete arousal is needed to make that low volume dosage effective. It’s not impossible, by any means, but when you take a coach’s personality into consideration, you may realize that their way of leading and communicating with their athletes was an extension of their personality and not a chosen method.

The inability to step outside of your success and biases to seek new information can box you in. Like all things, there is a spectrum—once headed too far in the other direction, a different problem arises.

The Walking Textbook

This problem stems from the opposite playing experience of that mentioned above. When a former athlete feels they did not have a positive competing experience and could have achieved more if given the opportunity to train at a higher quality, we run into this archetype. The “walking textbook” effect comes into play when we place a higher emphasis on science than on people. Every coaching decision we make is determined by the latest research. We forget that we coach the people in front of us and not the parameters of the most recent studies; we think finding the perfect workout is more important than the athlete’s intent, so we spend more time writing and tweaking the program than on building an environment where the training is done with purpose.

After my first year of coaching the sprints, one example always stuck out to me. Pretty much every resource for information I used at the time (books, manuals, interviews, podcasts, etc.) said to do acceleration or absolute speed work on Monday. So, I did. Every single week. While I thought I was executing the perfect program, I missed the obvious reality right in front me: Some of my athletes weren’t ready to train the Monday after a meet. Had I been less attached to the prescription, I would have swapped Monday and Tuesday, done a general day on Monday, and then assessed whether athletes were ready to hit it on Tuesday.

Now, there are worse problems than being too reliant on the research, but where this mistake is really going to affect your program is the working relationship between you and your athletes. You’ll miss the opportunity to build the type of trust that comes from involving them in the training process and valuing their input. I won’t ever say that you can’t be effective being the textbook, but you’ll miss some crucial coaching moments.

Lack of Long-Term Vision

This mistake is extremely common in former athletes who start coaching without strong mentorship. Thinking back to our mindset as a young athlete, we all remember the feeling of needing to PR every meet despite our coach’s reassurance that the process would take care of itself over time. As we got older and we experienced bad practices, bad meets, and even bad seasons that turned out fine in the long run, we started to learn that performance can have up waves and down waves, all while ultimately trending upwards until the most important meets of the year. Essentially, when we’re young, we can’t see past the next meet. Over time, we learn to see the big picture.

When an athlete transitions into coaching, sometimes we must relearn that process from the coaching perspective. Where does an athlete need to be in November in order to lead to success in May or June? What does a 24.00 200m in May look like in the first few indoor competitions? A young coach’s gut feeling is a fear of failure, because their instinct isn’t based on any experience in long-term success.

We often panic after a bad performance the same way we used to as a young athlete—our gut instinct is to do more work, or even alter the program as a knee-jerk reaction to make KPI No. 1 the skill or quality our athlete just underperformed in this week. The long-term vision solution is to stay the course. Stay healthy, continue training your KPIs, and you’ll be right where you need to be four months from now, when it matters.

During my apprenticeship program at ALTIS, I remember Dan Pfaff commenting on young coaches and this remark of his will always stick with me: “Experienced coaches’ worst fear is doing too much, young coaches’ worst fear is not doing enough.” Resist the urge to panic, resist the urge to do those “where are they at” workouts in season, resist the knee-jerk reaction to a poor performance. Trust in your program and look long-term.

Cookbook Coaching: What, How, Why?

Everyone starts their coaching career enamored by the “what.” “What’s the best workout for a 200 runner who decelerates the last 50?” “What’s the ideal workout for a triple jumper with that horrible second step phase?” “What drill can help you get a faster start?” It’s why you can go to any coaching clinic or seminar, and most of the people just want to be given a workout.

When we athletes transition to coaches, we’ve known the “what” for the past 4-10 years but have very little experience understanding physiology, physics, and kinesiology to know why our coach gave us what they did. But we are still highly competitive after the transition, so to find success right away, we latch onto the “what” for quick results and disregard seeking the “why.”

Often, this problem is a continuation of the first mentioned problem above if not solved. Don’t get me wrong—there is value in trying to get experience using someone’s program and seeking success early—but if you don’t seek to understand the how and why behind the what, the odds are very unlikely that you will have a high success rate in any training group, and even fewer odds that the ones who do find success are performing at their potential. You may have the super stars at the top, but then there are 25% who have a moderate career and 25% who don’t get past their high school (thinking collegiately) PRs, while the other 25% is a mix between the athletes who lose their love for the sport and those who are out for the season.

Imagine printing off a Gordon Ramsay recipe and preparing that recipe 30 times in 30 different kitchens, all with slightly different variables. Some have convection ovens, some have standard ovens, some have burners that burn hotter than others, some have restaurant-grade frying pans and pots, some have just a microwave, etc. What are the odds that meal comes out Gordon Ramsay quality all 30 times just because you used a Gordon Ramsay’s recipe? Some may be restaurant quality, some may be passable, some may taste great but look awful, some may look great but taste awful, some may be completely inedible, and one time the kitchen may burn down before you even finish. Why? Because you didn’t understand the ingredients used in the recipe. You applied the exact same recipe to every situation without knowing how or what ingredients to manipulate in response to the slight variations to end up with the same quality meal.

The same goes for applying the “What, How, Why” to the training items on your menu. You can’t make changes to your program to account for the variability in people to yield the same results because you don’t understand what you’ve prescribed. How can you effectively train the 100m dash if you don’t truly know the KPIs of the event, let alone whether the workouts you’ve chosen efficiently change those KPIs? If you’re doing a workout and your “why” is to get strong or build a base, ask yourself how exactly do you define strength? Building a base in what? If you can’t answer these questions, you don’t understand the ingredients.

As we go through an athlete’s career, we WILL guess wrong and there will most likely be injuries that pop up here and there. When we guess wrong, our job is to problem-solve and find the ingredients responsible. And when an athlete gets injured, we must work with our physio staff to construct a Plan B that keeps in all the necessary ingredients to minimize the training gap while on the mend.

Good luck with either of those if you only know the “what.” We can’t reverse-engineer what we never engineered in the first place. Cookbook coaching may yield some superstars, but will ultimately fail in maximizing the potential of a roster.

The most important thing is to accept that failure is inevitable. Like Pfaff says: “The school of hard knocks is the best teacher!” The best we can do is put ourselves in a position to make the most educated guesses possible through education, experience, mentorship, and self-evaluation. The latter will always be the most difficult, as self-evaluation requires us to acknowledge our mistakes. But every mistake, including the four mentioned, presents an opportunity to grow and become a better coach.

Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF

A picture can speak a thousand words—and many of us are familiar with the picture of a blacksmith swinging his hammer. The paradox of the picture is that we focus on the variations of paths the hammer takes, but I haven’t heard anyone talk about the blacksmith’s wrist, elbow, or shoulder.

Anyone familiar with the picture of should know that it comes from the “OG” of studying movement, Russian neurophysiologist Nikolai Bernstein. Bernstein was concerned with the number of muscles and joints that need to coordinate when we move (striking, throwing, running, and jumping). How many limbs, muscles, and joints are involved? How are they involved, and where are they involved?

There many ways in which humans can move to achieve a goal: this is known as the Degrees of Freedom Problem. However, from the start to the end of a movement, humans need to control and organize the body in one or more planes of motion, (i.e., solve the Degrees of Freedom Problem/motor abundance). When accomplished, we call this coordination.

The blacksmith picture and Bernstein’s work regarding the Degrees of Freedom Problem led to the understanding that there is movement variability in the normal variations that occur in motor performance across multiple repetitions of a task. If a person tries to repeat the same movement twice, the two actions will never be identical because each repetition involves a unique motor pattern. Bernstein termed this “repetition without repetition.”

Movement sciences and coaches studying movement are doing a great job trying to understand how various constraints (environment, task, and individual) help to form movement on the field and court. And that movement isn’t always as clean and straightforward as we would like, as the picture of the blacksmith depicts. In the context of athletics, this has led coaches to believe that there is no such thing as a perfect technique, and we should not worry about working on technique. Instead, we should spend time on physical outputs and teaching movement variations.

But from one sports movement to the next, there is always variability in speed, fatigue, opponents, task, etc. A world-renowned Olympic sprints coach once told me that “In chess, you don’t need the biomechanical part.”

My return argument is: there are mechanical rules by which chess pieces must move. The Bishop moves in a straight line diagonally on the board. It can move as many squares as wanted until it meets the end of the board or another piece. The Rook moves in a straight line horizontally or vertically through any number of unoccupied squares until it reaches the end of the board or another piece blocks the Rook—you get where I’m going with this.

The path of the shoulder, elbow, and wrist are never fully the same, but that doesn’t mean the blacksmith doesn’t demonstrate shoulder rotation, elbow flexion and extension, and wrist supination. The velocities and ROM all differ with each swing, but the joint actions appear to be the same. My question to practitioners is this: Why are we only concerned with the path of the hammer and the variability it shows, rather than the joint actions and muscles that contribute to the hammer swing? In fact, this is something Bernstein contemplated, according to one of his former protégés.

Bernstein’s Concept of Key-Movements

Bernstein wrote that an improvement in motor skill comes from establishing the pathway for achieving the needed goal (or the motor pattern), which is resistant to possible fluctuations under the influence of environmental conditions. Establishing a motor pattern occurs through the assimilation of the motor task’s essential parameters (motor determinants) with the gradual adaption of its nonessential parameters to the environmental conditions. “The organism tries to realize the essential variables by completely overcoming any difficulties and influences from the environment; as for the parameters of nonessential variables, the organism, on the contrary, is yieldingly adaptable.”

So not only is there variability within the blacksmith’s motor pattern swinging his hammer, but there are also essential parameters which allow him to swing the hammer (perform the motor pattern) consistently well. His hammer’s path may differ from swing to swing, but his arm’s joint actions don’t completely differ.

Relate this to an athlete’s technical preparation: their motor pattern, which must be established to acquire the motor skill, is the correct technique used to execute the competition exercise. The essential parameters of a motor pattern are the most important key-movements of competition exercise, which determine its correct execution as a whole.

A little-known fact in the physical preparation world is that Dr. Vladimir Zatsiorsky and Dr. Yuri Verkhoshansky were protégés of Bernstein. Dr. Verkhoshansky is one of the first coach/scientists to use the idea of finding out and establishing these “essential variables” (key-movements) to develop athletes.

In a conversation I had with his daughter, Dr. Natalia Verkhoshansky, she told me: “I have to say that nobody has used this term key-movements. It was necessary for me to introduce this term because in the articles of Bernstein, there is no definition of this term, also because his articles/books are totally scientific. It’s necessary to deliberate this information…In every kind of exercise there are key-movements…and that these key-movements have two characteristics: 1) they improve the whole complex movement. They are very important in motor learning, so if a person tries to improve the sports technique, it is very important to improve their ability/capacity to execute the key-movements correctly; 2) key-movements are important in increasing the magnitude of force-effort (power) employed while also decreasing the time (speed) that it takes to employ.”

I reached out to one of the world’s experts on Nikolai Bernstein and Motor Control, Professor Mark Latash, to see if he knew of more information on this topic. He told me, “In his book, Dexterity and Its Development, Bernstein did use a term similar to that (Key-movements), although he used it in a very fuzzy way. He was one of those geniuses that had such a deep understanding that he could use a fuzzy word and could still make it sound ok.” Professor Latash was kind enough to put me in contact with Dr. Vladimir Zatsiorsky, who was also a student under Bernstein and was one of the top biomechanists in the former Soviet Union. Dr. Zatsiorsky discussed with me a study he did in 1981, which looked at determining the most vulnerable muscle groups in sprinting (key-movements).

Dr. Zatsiorsky wrote and gave an example of a key-movement in his book, Science and Practice of Sports Training. It was a practical example for coaches on how to strengthen this key-movement, which he called the Principle of Accentuation; it is training strength through the range of the main sport movement, where the demand for high-force production is maximal. “In natural movements, at least on land, muscles are active over a relatively narrow range of motion. Usually maximal muscle activity occurs near the extreme points of angular motion.”

One of the many things that Dr. Verkhoshansky is well known for is his Principle of Dynamic Correspondence. It became one of the first well-known criteria for selecting special strength exercises. Dr. Verkhoshansky proposed applying the Principle of Dynamic Correspondence in training exercises with resistance in the key-movements of competition exercises. According to this principle, these movements must have the same:

• muscle groups involved in the exercise
• ROM and direction of movement
• accentuate the part of the movement amplitude
• character of the force-effort applying (the magnitude of force-effort and time of its applying)
• regime of muscle contraction

More on the practical application aspect in a bit.

Context and Results Are King

With much discussion among coaches about variability, I find myself coming back to several things: What is good and what is bad variability? How much and how little should we allow? And where are the results?

I get it; it can be hard sometimes to quantify improvements in movement quality. But there should still be some videos of before and after to demonstrate what we see, need to change, address, and improve upon. Biomechanics, motor control, motor learning, are all very difficult subjects of study. But what good is all of the knowledge if we can’t apply it to an athlete and see a result?

One of my biggest issues with any discussion, article, book, or podcast on motor learning and control is that context is often missing in the discussion. Gary Vaynerchuk said, “Content is key, but context is King.” I argue that context and results are king. What good is the information without results to back it up?

Context means who, what, and why as to the type of motor control and learning strategy and what it should be used for. For instance, movement variability is thrown about in many different ways with athletes—athletes running up steps with weights on their backs, athletes tossing water bags around, and athletes performing different types of cutting. What seems to be missing, however, is coaches giving context and reasons for the variability. For example, they are important to the task, caused by fatigue, due to physical limitations, normal noise in the motor action, or improve performance. This is something that should be trained.

Looking at a track and field sprinter, for example, we know that variability happens based on fatigue or arousal. But the underlying motor pattern should not have so much variability that the arms and legs are swinging every which way. The same is true for a baseball pitcher. There can be some subtle variability between pitch types and pitch locations, with the pitcher making a slight change to their arm slot. However, the key body actions of their weight shift and push off shouldn’t change from pitch to pitch.

Help Make the Understanding of Movement Simple, Not Simpler

When it comes to looking at movement and motor learning, I try to take a more simplistic approach. That’s not to say that understanding movement is an easy task or that I have it all figured out. I believe that simplifying it allows us to understand better which motor learning and control strategies we can best optimize.

Within the context of sport technique, we can break down complex motor skills into two types of skills that we should consider when trying to help a practitioner identify which motor control and motor learning strategy to use: hard skills and soft skills.

Hard Skills

Hard skills are the optimal mechanics in an ideal situation and the foundation of playing sports. For example, quarterbacks and baseball players have throwing mechanics with no perceptual stress in an ideal situation. Also consider a baseball player’s swing mechanics, a basketball player’s jump shot, a golfer’s swing mechanics, and an athlete’s linear running mechanics.

Hard skills are the general laws of physics and biomechanics as they pertain to the sporting action. These are where the key-movements are mastered within the motor skill. “Neurologists call this the ‘sled on a snowy hill’ phenomenon. The first repetitions are like the first sled tracks on fresh snow: On subsequent tries, your sled will tend to follow those grooves.”¹

We should build hard skills in a very precise and measured fashion, perfecting and repeating them before we move onto the next piece. Within the hard skill, two types of movements are important to understand, so a coach knows where to spend their time with the athlete: key-movements and secondary movements. As discussed above, key-movements are the force producing actions in the mechanics (for example, sprinting: paw back, ankle extension, knee drive).

The secondary movements help to transmit and stabilize the motor skill. They don’t contribute to the hard skill’s power production, but they can contribute to power and energy leaks. In sprinting, for example, the role of the shoulders and arms don’t necessarily contribute to the production of power, but if the shoulders aren’t moving in synchronization with the hips and legs and are swinging all over the place, they certainly can leak power.

I pay the most attention to hard skills, particularly with the key-movements, as this is where most of us in this industry can have a major effect. But if an athlete looks like garbage in an ideal situation, then throwing them in a blender (chaotic environment) is only going to make trash soup.

The difficult truth about building the hard skills is that it’s not very fun, as it takes deliberate practice to master them. Errors should not be allowed because hard skills are hard to break. If an error occurs in these hard skills—let’s say heel striking in sprinting—a top-down approach works best to correct the error as the athlete can only change this motor pattern if they are thinking about it. We can try to manipulate the environment or the task all we want, but I guarantee that if an athlete isn’t thinking about correcting the issue, they aren’t going to correct it. The error has to move from unconscious-incompetent to conscious-incompetent and then all the way to unconscious-competent. This is a daunting task, but it can be done.

Understanding the biomechanics and qualitative technique analysis of the hard skills is extremely important when determining where and what joint actions are effective. What are ineffective? Is the error due to poor technical learning? Is the error from poor technical application to a sport situation? Is the error due to physical limitations (strength, speed, mobility, stability, etc.)? Can the joint movement(s) involved in XYZ actions be improved with physical exercises or with technical exercises? Could the athlete’s actions lead to injury (technique plays a very large role in non-contact related injuries)?

Soft Skills

On the other hand, soft skills are how the hard skills are incorporated into a task and environmental situations. Soft skills are where you create a breadth of movement to learn how to adapt to the various changing situations of practice and sport.

“Soft skills are built by playing and exploring inside challenging, ever-changing environments. These are places where you encounter different obstacles and respond to them over and over, building the network of sensitive wiring you need to read, recognize, and react.”¹

Soft skills are the quarterback’s ability to throw with defenders at their feet, or on the run, with or without a hitch step, over the top of a corner, or through two linebackers. The baseball player bats against live pitching. The basketball player’s ability to shoot coming off of a pick, or with a hand in their face. A golfer swings on a slight hill through the ruff. A running back runs away from defenders.

This is where this movement about movement is focused. Perception and action. Repetition without repetition. How an athlete sprints, jumps, and changes direction will vary each time based on arousal, speed of movement, fatigue, goals, and the task of the situation.

However, this is where variability within a motor skill’s key-movements should not vary much per movement. In a quarterback’s throwing mechanics, the lower-body key-movements are the weight shift with the hip rotation separated from the shoulder rotation. The variability depends on whether they are standing tall in the pocket—as opposed to on the run—or throwing a route to their right (as a right-handed thrower) or to the left. Or if they’re in the shotgun formation and throwing a quick crossing route or rolling out to their left.

Generally, there should always be these key-movements, but the ROM and velocity of their actions will vary. The variability will differ for a baseball pitcher, whose body actions should not change while their arm slot should—elbow and wrist actions are based on the type of pitch and the location they are trying to throw.

Closing Thoughts

In the Central Virginia Sports Performance Manual Vol. 3, I go into details of the three key-movements of sprinting. One of these is knee drive, which may vary for a soccer player based on the speed of motion and the direction of movement. But the mechanical law of the knee drive (creating a short lever) should not vary far regardless of the situation. That leg has to fold up from behind to quickly move to the front of the body.

How to tear an ACL is pretty well documented—have your knee go in and forward and rotate with an extreme amount of force. Change of direction mechanics will vary depending on the task and the perceived situation. However, the key laws of where and how to stop and slow down should not vary.

If you Google change of direction, you will likely see more commonalities than not. The athlete should stop or slow down in the fewest amount of steps as possible. The plant leg (depending on which direction the athlete is coming from and going) should be outside the width of the athlete’s hips on the outside leg with as little or no weight on the inside leg. The variability of change of direction occurs when the athlete reacts to getting to an open space, following an opponent, with a ball, or running away from an opponent.

The paradox of the hammer is that we get caught like a bug staring at the light, watching the variation of the hammer. The Degrees of Freedom Problem has shown that human movement is not clean cut. Variability of movement is essential because we are not robots, and the human body is a complex system with many degrees of freedom, which it must try and coordinate with various constraints to perform motor skills. This is what allows us to adapt our movements; it serves a functional role.

On the other side of the coin, however, there are mechanical laws by which we are allowed to move. These mechanical laws are similar from person to person, although they may not all be identical and can vary in ranges of motion, velocities, effects of physical and mental stress, etc. Certain joint actions and sequences are better suited as power developers and force absorbers, while some are not. There are mechanical laws according to which athletes must move, but then there is bandwidth we can move within. A coach’s intuition for knowing which is which—and how one thing can affect the other—is where our industry is missing pieces to this puzzle.

Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF

References

1. Coyle, D. The Talent Code: Greatness Isn’t Born. It’s Grown. Here’s How. A Bantam Book 2009.

At Exceed Sports Performance and Fitness in Westborough, MA, we train more than 150 athletes each month, and receive dozens more in monthly visits, including drop-ins by performance coaches from other facilities looking to gain insight on the ExceedSPF method. The most common questions we receive from performance coaches center around our training methodology and the types of equipment we employ to train our athletes. In answering these questions, we recommend only what we believe to be the best techniques and technologies available.

From our perspective, the kBox flywheel system by Exxentric is one of the most valuable pieces of equipment at our facility. Not only does the kBox distinguish itself through its incredible versatility, but more importantly, our athletes love using it!

Exceed’s kBox Story

In early 2017, we installed our first kBox and quickly began the task of incorporating it into our existing training programs. At first, I was skeptical about whether the kBox actually offered substantive value as a training tool, or was simply another flash-in-the-pan piece of equipment that looked great on social media but then quickly collected dust in the corner of the gym. My doubts were quickly laid to rest.

The kBox represents a quantum leap in flywheel training technology, combining sturdy construction and versatile operation to allow an athlete to train almost any movement imaginable with concentric and eccentric loads. Today, Exceed has incorporated the kBox into the training programs of athletes at all levels, from the elite NFL professional to the casual weekend warrior.

Here are my top 10 reasons why your gym should buy a kBox:

Results

Athletes have options with training, now more than ever. Results are one of the criteria that athletes use to determine where to go, so as a private sector coach with competition all around me, I pride myself on getting athletes better. Massachusetts is better known for producing hockey athletes than football players, but over the last few years Exceed has had a nice streak of producing NFL players. We know that when athletes head to play at the collegiate level, they talk to other athletes about training for the Combine after their NCAA career finishes.

We have a lot of college kids come back to us because they remember who helped them get there. The only difference is athletes need to trust that we can make them better at the pro level, not just during high school and the summers of their college career. Now, they remember the kBox and other investments we made to help them get every inch in jumping or every tenth in sprinting. If flywheel training didn’t work, we wouldn’t waste our time and money. Any piece of equipment can get athletes into the gym once or twice, but the right tool keeps them here.

Lately, we have seen local linemen from our area get signed by teams in the NFL. We know that part of that is us, since many of those Massachusetts athletes train at our facility. A growing interest of ours is adding muscle quickly because we plan to work with even more linemen, and based on our research, adding mass from flywheel training is a powerful approach that we need. The science supporting flywheel training appears to be locked in, so we are going to put more and more effort into this type of training. If flywheels help with strength, power, and speed, it is nearly a perfect tool because it helps with muscle hypertrophy as well.

Safety

Ironically, the use of flywheels is very safe, but eccentric training usually gets a bad rap because the overload is usually foolish. On average, an athlete who has a few months of solid training can jump into flywheels instantly and begin the process. The reason athletes are safe with flywheels is that the speed and rebound load are highly autoregulated by their concentric abilities. Some athletes have poor eccentric abilities, but the likelihood of an athlete having extremely poor eccentric abilities after months of conventional training is slim to none. Performing traditional exercises with the kBox or kPulley is very safe, and all you have to do is demonstrate a few reps and the athlete is ready to go.

The use of the hip belt is also great for those who are not tolerant of spinal loading. It’s not that hip squatting is a perfect solution, but it’s a much better solution compared to alternatives like partial reps. Most of the time, we like performing kBox squats with the belt versus a harness because we know that an athlete can only handle so much wear and tear.

Portability

Another value point I will mention right away is the size of the system. If you are a small gym, every inch matters. We are large compared to most private facilities, but when the space is large, so are the operational costs and the need to get athletes serviced effectively. If we have to move the kBox out of the way for another activity we can do it instantly, and if we had more systems we could stack them if needed. Some high schools don’t even have a weight room, and the ability to take the kBox system out on the field for soccer training or the court for volleyball or basketball is huge for some coaches.

We do appreciate the general population market, as it often consists of former athletes who need to be trained long after their career in sport finishes. Some great coaches do work with average joes from all walks of life and need to travel with their equipment. Instead of being limited to bands and dumbbells, the kBox is perhaps the best personal training tool in the business. It only needs a duffle bag for the flywheels and accessory handles and harnesses, which is a very attractive proposition for those on the move. Every generation of kBox gets lighter, and if you are hard-pressed for portability, the system’s lite version is the size of a large skateboard and weighs only about 50 pounds.

Versatility

Any piece of equipment that can do more than one exercise is important to us. We have plenty of single-exercise options in our gym, as they are specialized and important for specific needs, but equipment that can do more is helpful. However, we don’t want a piece of equipment that can do dozens of exercises poorly—we need each exercise to be as good or better than the barbell equivalent. Doing exercises on flywheel platforms must be effective, not just possible. We know that by using the kBox, we can get in a dozen exercises we feel help athletes make progress, and we are sure other coaches can do even more than our selected exercises.

In addition to the sheer number of exercises, the loading of flywheels at different speeds and the types of contractions is exciting for us. We don’t spend too much time with isometric combinations or other methods such as potentiation with the device, but it’s nice to know that if we do need those techniques, the system can provide them. Additionally, the system allows for different types of harnesses and grip handles, such as bars and single arm attachments. We like the quality of the equipment provided in the kits, as cheap accessories are never good in the long run.

Workflow

Flywheel training doesn’t compromise efficiency or effectiveness. We don’t rush kids in and out of workouts like we’re a fast food joint. We do know that study time and sleep matter, so we have to get a workout done in an efficient manner. Using the kBox is efficient with time constraints, and you can get a lot of work done quickly because of short rest periods. Flywheels are also efficient with swapping out athletes during sets, because using waist harnesses or sharing bars is quick.

Switching plates doesn’t matter in group environments with heavy training because you have to rest anyway, but not having to do so makes a kBox more efficient than a squat rack. The prime benefit with flywheels is they are about athletes producing the resistance, not placing more lead on the bar. Not being reliant on plates in the weight room is not only a value financially, but not having to clean up and put back weights is a nice bonus also.

Obviously, the more stations or kBoxes you have, the more you can do. Down the road, we plan to increase the number of flywheel machines we have, mainly because they’re fast and easy to set up and put away. Not only do we care about the athletes getting home to have dinner or go to bed, but we are human as well and can’t spend all evening rearranging things in the gym.

Science

One area I want to mention is the research behind flywheel training. The kBox is relatively new, but the technology has been around for decades, so plenty of scientific studies are available for coaches. We share a Dropbox of the latest studies internally so that we all have access to flywheel training developments when a new paper comes out.

Parents want to know more than ever why we do things at our facility, and having fresh research really does a nice job if a parent asks. It’s fine to share something that is years old as well, because nobody wants to feel like a guinea pig, but parents also want to know you are current in your training. The kBox isn’t the only system available, but the key is having a community of coaches on SimpliFaster sharing the scientific approaches to learn from.

Justifying training means more than uniforms or shirts on the wall and bragging about athletes you work with; it’s having the evidence to say with confidence it was more than just good genetics that got them there. We know the coaching is great at our facility, but having the science to back up our approaches is important to us and should be important to you.

Feedback

The kMeter lets us get feedback to the athlete every rep. We used another flywheel device in the past that was very nice, but without the quantification it was like blindly adding weights to the bar and prescribing sets and reps. It was fine for accessory work at the end of training, but it was not going to move us forward much when we wanted to take flywheels to the next level. The need to quantify loads is everything in the weight room, and the feedback drives competition within the group and with the athlete’s own performance if training on their own. Athletes who are not normally motivated are curious about what they can do, as traditional barbells seem to be great for rewarding maximal strength, but those with a good power and average strength level can also benefit greatly.

The kMeter is a great option for those looking for feedback, and it’s not just for displaying force or power. The kMeter is a live dashboard that provides audio feedback to coaches. If you have flat screens in your gym then you are in for a treat, because you can use an Apple TV to display the scores or outputs. After the session is completed, the data can be exported quickly and easily, and we now use the information for better programming.

Simple to Use

We don’t ever like to compare ourselves to other facilities, but we do have to put our foot down and point out that we do most, if not all, of the training ourselves. We do provide internships, but our business model never interferes with our training model. We realize that everyone has to make a living, but if we were planning to water down training for the sake of exploiting college kids, we wouldn’t have opened up our doors in the first place.

Instead of dumbing down training or making it cookie cutter, we individualize training as much as possible. Yet, we do know that foundational work matters and we have programs that teach the fundamentals before advanced methods. The flywheels are simple to use, so if an athlete is familiar with training, they can jump right into flywheel training if properly supervised.

We love teaching and instructing athletes to be more coordinated and skilled, but only so much verbal coaching is absorbed by student athletes who are always under fire. For us, we want the optimal amount of teaching time, and too much exchange and correction is overwhelming at any level.

Fun to Use

Flywheel training is tough work, and anyone that tries it will quickly learn that it’s harder than it looks. A good flywheel system properly loaded can go head to head with a complete set of barbells with loading, but the system is also a welcome part of our program as it is fun to use. Anything that is different than gravity is new and exciting to athletes, and this experience doesn’t wear off like other equipment. Even after months of using it, the athletes still enjoy the resistance it delivers, and we like using it ourselves.

If you train athletes in the private sector, you know that you have to juggle a lot to make it work. Being the best in the area with results isn’t good enough anymore, as plenty of talent trains everywhere these days. To be successful, results and caring coaches aren’t enough—you have to make sure the experience is a rewarding one.

Flywheels are part of a program that gives athletes the right training benefits, but sports are supposed to be fun, so training for them can’t be a pain. Our training is a lot of hard work, but it’s also fun. Adding in flywheels is a mature way to add a little sweetener without going too far. Any system that can make training that is effective and demanding fun is rare, and the kBox does add some enjoyment into training during the season.

Value

As a business owner, I have to always weigh the results of the training against the cost of getting training done in a gym. We think about heating during the winter and air conditioning during the summer, the cost of replacing equipment, and even our indoor turf wearing down. We never buy on price; we invest in the value because smart investing is felt later rather than immediately.

The kBox is affordable, but due to the machine also being versatile and effective, we know it’s a piece of equipment that others will find valuable as well. Also, the price of a kMeter is a huge value, since collecting power and eccentric readings with a force plate is much more expensive, even with PASCO or other entry-point products. As mentioned earlier, not having to spend more money on weight plates is important to us, because we need to keep our overhead reasonable, and with all of our racks in our gym, added equipment becomes a big expense.

I have seen a lot of homemade equipment on the internet, and I commend anyone trying to find a way to implement flywheels on a budget. But don’t think about the cost of making a device—think about the value of knowing that if anything goes wrong, a FedEx package can solve those problems. The cost of maintenance matters, and the forces through a flywheel platform will break down one that’s homemade. We were tempted to create our own system and were glad we didn’t because we would be negligent if anything were to happen to somebody using it.

Invest in kBox Training Education

Coaches can get a lot of value from just doing squats on a kBox, but actually reading coaching blogs and research from sport scientists can help you get more out the machine. We started slow and added more and more exercises, as well as the new Pulley device this year, and love our results with it. Most of our training is with barbells and dumbbells, but a growing number of our training programs incorporate the eccentric benefits of flywheels. We don’t provide many testimonials as we are boxed in by what we endorse, but the kBox is worth the investment if you want to leverage both the art and science of training.

If you are dedicated to making your athletes better, there is strong evidence that flywheel training works, so using the kBox machine will give your team or facility an advantage.

Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF

An individual’s dietary and supplement strategies greatly influence sport performance. This holds true for all ages, ethnicities, and levels of skill, regardless of whether the goal is optimizing physical activity for health and fitness or training for high performance sport. An individually tailored sports nutrition and supplement plan is key, as highlighted in the most recent “Nutrition and Athletic Performance” joint position statement by the American College of Sports Medicine, the Academy of Nutrition and Dietetics, and Dietitians of Canada, which states that “Nutrition plans need to be personalized to the individual athlete… and take into account specificity and uniqueness of responses to various strategies.”¹

These strategies encompass overall dietary patterns, macronutrient ratios, micronutrient requirements, eating behaviors (e.g., nutrient timing), food sensitives and intolerances, and the potential benefits or harms of using supplements (e.g., vitamin, minerals, protein powders) and ergogenic aids (e.g., caffeine, creatine, buffers). A shift away from our standard, one-size-fits-all team approach toward tailored nutrition and a focus on individual needs is what nutrigenomics, from science to practice, aims to address.

It’s in Your Genes

Personalized nutrition, based on an individual’s genotype, is not new, and there are several examples of rare (e.g., phenylketonuria) and common (e.g., lactose intolerance, celiac disease) genetic disorders, where specific dietary recommendations are implemented to manage metabolic deficiencies². For commonly seen conditions such as lactose intolerance and celiac disease, the avoidance of dairy and gluten, respectively, is part of the personalized dietary plan. And if you either embrace your daily cup of java or completely avoid it because of the way it makes you feel (e.g., awake and energized or perhaps anxious and jittery), this is also due to genetic variation.

Many athletes aren’t sure if caffeine is helpful or harmful. Genetic testing for rate of caffeine metabolism (more on this later) may help to reinforce their suspicions or motivate them to experiment with and without caffeine during exercise rather than assuming it works, or never trying it and missing out on its benefit. Although genetic testing is well-established in the clinical setting to help manage diseases and conditions, the growth in nutrigenomics research has created opportunities to improve health, wellness, and sport performance in athletes through nutrition-focused genetic testing. As the sporting world battles with risky supplements and unprecedented occurrences of doping violations, the sport science community is embracing new ways to help athletes safely and legally reach their peak performance.

Following the right diet for you is the hallmark of what nutrigenomics is aimed at, but those working with athletes often seek information beyond the performance diet (i.e., advice on the use of supplements and ergogenic aids), and for which athletes and at what times. Even if we have evidence that a supplement is effective, it may not be so for all athletes. For example, there is evidence that nitrates (beetroot), creatine, and caffeine appear to have wide variability in their erogenicity, and in some cases, may be ergolytic. In the case of caffeine, there are dozens of studies reporting wide variability in the effects of caffeine on performance, and nutrigenomics, in part, may explain the source of these differences. A detailed discussion on caffeine and genetics is highlighted below.

While it has long been suspected that genetics play an important role in determining how we respond to foods and nutrients, the surge in nutrigenomics research over the past decade has demonstrated this scientifically. Our genetic makeup affects the way we absorb, metabolize, and utilize nutrients, and these gene-by-diet interactions translate into differences that are relevant to both health and sports performance. A practical application of nutrigenomics is the use of personal genetic testing, which can provide information that will guide recommendations for dietary and supplement (if needed) choices that are more effective at the individual level than current dietary advice. This advice has been set out by governments and other health and sport organizations, and is geared, for the most part, toward the general “active” population. You are not a population.

The Rise of Genetic Testing

The demand for genetic testing for personalized nutrition and fitness, by athletes and active individuals, is growing, and there is an increased need for dietitian-nutritionists, fitness professionals, coaches, and other sports medicine practitioners to understand the current evidence in this developing field. The sport environment is dynamic, progressive, innovative, and extremely competitive. Providing athletes with individually tailored dietary and other performance-related information based on their unique DNA is a novel competitive edge embraced by both practitioners and scientists working in the world of sport.

Those working with athletes seek a better understanding of the practical applications and actionable measures that they can take to improve athletic performance based on genetic information, which includes how genetic testing is performed, what it measures, and how to effectively interpret the results. The growing body of science in nutrigenomics in sport is the foundational building block by which we can help athletes reach their genetic potential through implementation of dietary and supplement strategies that are aligned to their genome.

A Deeper Dive into the Science: Caffeine

In the field of nutrigenomics, caffeine is the most well-studied compound with regard to trials that investigate direct impacts of gene-nutrient interactions on athletic performance. Caffeine has widespread use in athletics in the form of coffee, tablets, energy drinks, gels and chews, and “pre-workouts,” based on the belief that athletes can train harder or compete more successfully after ingesting caffeine³. However, it appears that caffeine does not benefit all athletes equally, and may in fact impair performance in some. Recently published results by the author highlight the importance of considering CYP1A2 genotype in the development of personalized sport nutrition and sport supplement protocols⁴.

Numerous studies have investigated the effect of supplemental caffeine on exercise performance, but there is considerable inter-individual variability as to the magnitude of these effects^5-7or lack of an effect^8,9when compared to placebo. The large variation in individual response to caffeine is often overlooked in caffeine performance studies, and due to infrequent reporting of individual data, it is difficult to determine the extent to which variation in responses may be occurring. The performance of some individuals is often in stark contrast to the average findings reported, which may conclude beneficial, detrimental, or no effect of caffeine on performance. Some of these inter-individual differences appear to be due to variations in genes such as CYP1A2, which is associated with caffeine metabolism and caffeine response¹⁰.

Over 95% of caffeine is metabolized by the CYP1A2 enzyme, which is encoded by a gene of the same name: the CYP1A2 gene¹¹. A genetic variation or single nucleotide polymorphism (SNP) in this gene has been shown to alter CYP1A2 enzyme activity^12,13, and has been used to categorize individuals as “fast” or “slow” metabolizers of caffeine. Individuals with the AC or CC genotype (slow metabolizers) have an elevated risk of myocardial infarction¹⁴, hypertension^15,16, and pre-diabetes¹⁷, with increasing caffeinated coffee consumption, whereas those with the AA genotype show no such risk. Additionally, regular physical activity appears to attenuate the increase in blood pressure induced by caffeine ingestion but only in individuals with the AA genotype, providing further evidence that genetics can act as a confounding variable when trying to establish the effects of caffeine across entire populations¹⁶.

In the largest caffeine-exercise study to date, Guest et al.examined the effects of caffeine and CYP1A2 genotype, on 10km cycling time trial (TT) performance in competitive male athletes after ingestion of caffeine at 0 mg, 2 mg (low), or 4 mg (moderate) per kg body mass⁴. There was a 3% improvement in TT time in the moderate dose in all 101 subjects, which is consistent with previous studies using similar doses^5,18. However, there was a significant caffeine-gene interaction where improvements in performance were seen at both caffeine doses, but only in those with the AA genotype who are “fast metabolizers” of caffeine. In that group, the 6.8% improvement in cycling time at 4 mg/kg was greater than the 2-4% mean improvement seen in several other cycling TTs studies, using similar doses^5,18-23. Among those with the CC genotype, the “slow metabolizers,” 4 mg/kg of caffeine impaired performance by 13.7%, and in those who have the AC genotype there was no effect of either dose⁴.

The findings are consistent with a previous study by Womack et al., who observed a caffeine-gene interaction and improved TT cycling performance with caffeine only in those with the AA genotype²⁴. In contrast, previous studies either did not observe any impact of the CYP1A2 gene on caffeine-exercise studies^25,26, or reported benefits only in slow metabolizers²⁷. There are several reasons that may explain discrepancies in study outcomes, including smaller samples sizes that cause very low numbers and/or no subjects in one genotype^26-28,and shorter distance or different type (power versus endurance) of performance test²⁷than those of Guest et al.⁴and Womack et al.²⁴.

The unmasking of the effects of genotype on performance may occur during exercise of longer duration or where an accumulation of fatigue is occurring (aerobic or muscular endurance), where caffeine often provides its greatest benefits, and where the adverse effects to slow metabolizers are more likely to manifest²⁹. Indeed, in a study of basketball performance in elite players, caffeine improved repeated jumps (muscular endurance) but only in those with the AA genotype; however, there was no genotype effect in in the other two performance components of the basketball simulation³⁰. Similarly, in a crossover design of 30 resistance-trained men, caffeine ingestion resulted in a higher number of repetitions in repeated sets of three different exercises, and for total reps in all resistance exercises combined, which resulted in a greater volume of work compared to placebo conditions, but only in those with the CYP1A2 AA genotype³¹.

Taken together, the weight of the evidence buttresses that variants in the CYP1A2 gene likely play an important role when trying to determine which athletes are most likely to benefit from caffeine ingestion during aerobic or muscular endurance-type exercise. Trials that include performance outcomes are very valuable to nutrigenomics research as it applies to athletic performance, and these results highlight the importance of considering genetics when deciding whether athletes should use caffeine or other ergogenic aids to improve performance.

The Practical Side

What Will a Genetic Test Tell You?

Different versions of a gene or genetic variations (called single-nucleotide polymorphisms or “SNPs”) can cause us to have different responses to certain components of food. For example, the symptoms felt by individuals who react to lactose and caffeine in their diet (i.e., lactose intolerance and caffeine sensitivity) are caused by certain genetic variations. While general dietary recommendations might be prudent to follow, the one-size-fits-all approach to nutritional advice could limit some individuals from reaching their full potential—their full “genetic potential.”

How Would My Diet Change?

Nutrigenomics testing includes several micronutrients that have modified requirements due to genetic variation, such as vitamins A, B12, C, D, and E, calcium, iron, choline, and bioactives such as caffeine. Here are some examples of what information is gained: A genetic test can tell you if you are inefficient at converting beta-carotene into the active form of vitamin A based on the BCMO1 gene³²or if your conversion is normal/efficient, based on a gene that modifies the activity (normal/slow) of the enzyme responsible for this conversion.

The good news is, you can take action and resolve it easily by consuming more beta-carotene foods or foods that already contain pre-formed vitamin A. In athletes, vitamin A is important for its antioxidant roles, the immune system, and eye heath, which is a critical asset in most sports (e.g., hand-eye coordination). A similar situation occurs for vitamin D, which is key for immunity, muscle recovery, and bone health. Do you convert vitamin D normally into its active form, and do you transport it efficiently throughout your body? Again, a gene that controls an enzyme is involved here, but we also have a transporter (of vitamin D) that is controlled by another gene. Therefore, two genes, the GC and CYP2R1 gene, are analyzed to determine your risk of vitamin D deficiency³³.

This situation is easily remedied through vitamin D supplements (good dietary sources are few). In addition, nutrigenomics testing addresses ideal macronutrient ratios, which can also tell you if your ideal body composition would be more easily achieved and maintained with a lower fat diet or a higher protein diet depending on your genotype^34,35. You will also find out if caffeine (CYP1A2 gene) is good for your heart¹⁴, if it’s likely to improve your endurance performance⁴, or if are you better off limiting this substance for better health and to optimize your endurance.

To date, the science supports the use of roughly 50 genetic markers to guide recommendations for personalized nutrition and supplementation. This is an important fact, as many genetic testing companies use (and sell) hundreds of genetic markers that are based on the weak evidence of associations studies, which do not provide enough evidence to create recommendations that are both accurate and actionable. This may do more harm than good, as more is not always better.

It’s important to research the companies that interest you and ensure their science team is made up of individuals with doctorate degrees in the areas of both genetics and nutrition, preferably who are actively researching in the field, and who can properly interpret study findings. With the surge in research groups worldwide conducting nutrigenomics studies, the science is progressing rapidly, and the number of valid genetic markers will likely double over the next few years.

Lastly, along with improvements in dietary precision, nutrigenomics testing has also been shown to enhance motivation and behavior change, where disclosure of genetic information has been associated with adherence to favorable dietary changes^36-40.  This aspect of personalized nutrition is certainly welcomed, because even in our highly motivated athletes⁴¹, nutrition professionals still encounter significant barriers to behavioral change when trying to convince athletes to adopt healthier nutrition practices.

Sport Nutrigenomics vs. Talent ID and Exercise Prescription

Although there is much overlap in how we design diets and create training programs for our athletes, to achieve specific sport goals it is important to underscore the distinction between the strength of evidence supporting DNA-based advice for personalized nutrition versus that for exercise and training protocols.

There is keen interest in using genetic testing to improve athletic performance^42,43; however, it is important to acknowledge the lack of evidence surrounding the ability to identify future (athlete) talent and predict the likelihood of creating the next Serena Williams or Usain Bolt⁴⁴. Using genetics to determine a training program based on your personal genotypes is in its early stages and is not currently supported as a scientifically sound approach, although it is likely to be a viably employed training tool in the next decade⁴⁵. Many of the outcomes in athletic talent or athlete phenotypes (e.g., VO₂max, power) are complex traits determined by potentially thousands of genes, and therefore not easily tested for in a way that would make the information useful or “actionable,” which is necessary when you get back to the gym.

In contrast, nutrigenomics works by identifying genetic variations that can help to determine individual nutritional requirements, the presence of food intolerances and sensitivities, and optimal dietary patterns that will help to improve health, body composition, and sports performance. These usually involve only a few specific genes as opposed to hundreds or thousands that are associated with a naturally high VO₂max (since this is primarily genetic and not as trainable as muscle mass increases, for example). Several micro- and macronutrients impacting athletic performance have been studied in nutrigenomics research and can be applied to nutritional counseling in athletes.

One or a few SNPs can identify an individual dietary-related modification that aims to improve precision for nutritional recommendations, requirements, or optimal intakes, and provide information that will help to tailor supplement protocols. Therefore, coaches and other sport professionals should be cautious and diligent when entering the marketplace in search of genetic tests to improve athletic performance, beyond nutrition and some basic performance measures, as they may also include invalid and unreliable training or exercise advice.

A Step-by-Step Guide to Genetic Testing

*Note this info pertains to the company the author uses in practice. Each company has different standards for their security/privacy and time to get results (wide range: 3-12 weeks), and not all lab testing is of the same quality, so do your research.

1. Ask your health care provider, nutritionist, or other sports professional to order the genetic testing kit for you.
2. The saliva collection kits include a tube in which you provide a saliva sample (approx. ¼ teaspoon), which is then mixed with a preservative, sealed, and sent back to the lab for analysis. This takes 30-60 seconds.
3. Your results are encrypted and sent to a secure server that is only accessible to the person who ordered the test (dietitian, coach, etc.) through their account on the company website.
4. Two to three weeks later, you will receive your personalized “Nutrigenomics and Sport Performance Profile” report. The report will identify what genotype you are for each SNP that has been tested (each company has a different number of SNPs that they test for).

Nutrigenomics: A Future Competitive Edge

It is becoming increasingly clear that, among other performance parameters, our genes determine our specific and unique nutritional needs when it comes to health and performance. Providing athletes with individually tailored dietary and other performance-related information based on their unique DNA is a novel competitive edge embraced by both practitioners and scientists working in the world of sport. The growing body of science in nutrigenomics in sport is the foundational building block by which we can help athletes reach their genetic potential through implementation of dietary and supplement strategies, such as caffeine use, that are aligned to their genome. When it comes to sports nutrition, this emerging science is the nutritional competitive edge of our future.

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References

1. Thomas, D.T., K.A. Erdman, and L.M. Burke. “American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance.” Med Sci Sports Exerc, 2016. 48(3): p. 543-68.
2. Gorman, U., et al. “Do we know enough? A scientific and ethical analysis of the basis for genetic-based personalized nutrition.” Genes Nutr, 2013. 8(4): p. 373-81.
3. Wickham, K.A. and L.L. Spriet. “Administration of Caffeine in Alternate Forms.” Sports Med, 2018. 48(Suppl 1): p. 79-91.
4. Guest, N., et al. “Caffeine, CYP1A2 Genotype, and Endurance Performance in Athletes.” Med Sci Sports Exerc, 2018. 50(8): p. 1570-1578.
5. Ganio, M.S., et al. “Effect of caffeine on sport-specific endurance performance: a systematic review.” J Strength Cond Res, 2009. 23(1): p. 315-24.
6. Higgins, S., C.R. Straight, and R.D. Lewis. “The Effects of Preexercise Caffeinated Coffee Ingestion on Endurance Performance: An Evidence-Based Review.” Int J Sport Nutr Exerc Metab, 2016. 26(3): p. 221-39.
7. Graham, T.E. and L.L. Spriet. “Performance and metabolic responses to a high caffeine dose during prolonged exercise.” J Appl Physiol(1985), 1991. 71(6): p. 2292-8.
8. Hunter, A.M., et al. “Caffeine ingestion does not alter performance during a 100-km cycling time-trial performance.” Int J Sport Nutr Exerc Metab, 2002. 12(4): p. 438-52.
9. Roelands, B., et al. “No effect of caffeine on exercise performance in high ambient temperature.” Eur J Appl Physiol, 2011. 111(12): p. 3089-95.
10. Yang, A., A.A. Palmer, and H. de Wit. Genetics of caffeine consumption and responses to caffeine.” Psychopharmacology(Berl), 2010. 211(3): p. 245-57.
11. Begas, E., et al. “In vivo evaluation of CYP1A2, CYP2A6, NAT-2 and xanthine oxidase activities in a Greek population sample by the RP-HPLC monitoring of caffeine metabolic ratios.” Biomed Chromatogr, 2007. 21(2): p. 190-200.
12. Ghotbi, R., et al. “Comparisons of CYP1A2 genetic polymorphisms, enzyme activity and the genotype-phenotype relationship in Swedes and Koreans.” Eur J Clin Pharmacol, 2007. 63(6): p. 537-46.
13. Djordjevic, N., et al. “Induction of CYP1A2 by heavy coffee consumption in Serbs and Swedes.” Eur J Clin Pharmacol, 2008. 64(4): p. 381-5.
14. Cornelis, M.C., et al. “Coffee, CYP1A2 genotype, and risk of myocardial infarction.” JAMA, 2006. 295(10): p. 1135-41.
15. Palatini, P., et al. “CYP1A2 genotype modifies the association between coffee intake and the risk of hypertension.” J Hypertens, 2009. 27(8): p. 1594-601.
16. Soares, R.N., et al. “The influence of CYP1A2 genotype in the blood pressure response to caffeine ingestion is affected by physical activity status and caffeine consumption level.” Vascul Pharmacol, 2018.
17. Palatini, P., et al. “Association of coffee consumption and CYP1A2 polymorphism with risk of impaired fasting glucose in hypertensive patients.” Eur J Epidemiol, 2015. 30(3): p. 209-17.
18. Desbrow, B., et al. “The effects of different doses of caffeine on endurance cycling time trial performance.” J Sports Sci, 2012. 30(2): p. 115-20.
19. Skinner, T.L., et al. “Coinciding exercise with peak serum caffeine does not improve cycling performance.” J Sci Med Sport, 2013. 16(1): p. 54-9.
20. Saunders, B., et al. “Placebo in sports nutrition: a proof-of-principle study involving caffeine supplementation.” Scand J Med Sci Sports, 2016.
21. Jenkins, N.T., et al. “Ergogenic effects of low doses of caffeine on cycling performance.” Int J Sport Nutr Exerc Metab, 2008. 18(3): p. 328-42
22. Graham-Paulson, T., C. Perret, and V. Goosey-Tolfrey. “Improvements in Cycling but Not Handcycling 10 km Time Trial Performance in Habitual Caffeine Users.” Nutrients, 2016. 8(7)
23. Bortolotti, H., et al. “Performance during a 20-km cycling time-trial after caffeine ingestion.” J Int Soc Sports Nutr, 2014. 11: p. 45.
24. Womack, C.J., et al. “The influence of a CYP1A2 polymorphism on the ergogenic effects of caffeine.” J Int Soc Sports Nutr, 2012. 9(1): p. 7.
25. Algrain Haya A., T.R.M., Carrillo Andres E., Ryan Emily J., Kim Chul-Ho, Lettan Robert B. II, and Ryan Edward J. “The Effects of a Polymorphism in the Cytochrome P450 CYP1A2 Gene on Performance Enhancement with Caffeine in Recreational Cyclists.” Journal of Caffeine Research, 2016. 6(1): p. 34-39.
26. Salinero, J.J., et al. “CYP1A2 Genotype Variations Do Not Modify the Benefits and Drawbacks of Caffeine during Exercise: A Pilot Study.” Nutrients, 2017. 9(3)
27. Pataky, M.W., et al. “Caffeine and 3-km cycling performance: Effects of mouth rinsing, genotype, and time of day.” Scand J Med Sci Sports, 2016. 26(6): p. 613-9.
28. Joy, E., et al. “2014 female athlete triad coalition consensus statement on treatment and return to play of the female athlete triad.” Curr Sports Med Rep, 2014. 13(4): p. 219-32.
29. Doherty, M. and P.M. Smith. “Effects of caffeine ingestion on exercise testing: a meta-analysis.” Int J Sport Nutr Exerc Metab, 2004. 14(6): p. 626-46.
30. Puente, C., et al. “The CYP1A2 -163C>A polymorphism does not alter the effects of caffeine on basketball performance.” PLoS One, 2018. 13(4): p. e0195943.
31. Rahimi, R. “The effect of CYP1A2 genotype on the ergogenic properties of caffeine during resistance exercise: a randomized, double-blind, placebo-controlled, crossover study.” Ir J Med Sci,2018.
32. Ferrucci, L., et al. “Common variation in the beta-carotene 15,15′-monooxygenase 1 gene affects circulating levels of carotenoids: a genome-wide association study.” Am J Hum Genet, 2009. 84(2): p. 123-33.
33. Slater, N.A., et al. “Genetic Variation in CYP2R1 and GC Genes Associated With Vitamin D Deficiency Status.” J Pharm Pract, 2015.
34. Zhang, X., et al. “FTO genotype and 2-year change in body composition and fat distribution in response to weight-loss diets: the POUNDS LOST Trial.” Diabetes, 2012. 61(11): p. 3005-11.
35. Phillips, C.M., et al. “High dietary saturated fat intake accentuates obesity risk associated with the fat mass and obesity-associated gene in adults.” J Nutr, 2012. 142(5): p. 824-31.
36. Nielsen, D.E. and A. El-Sohemy. “Disclosure of genetic information and change in dietary intake: a randomized controlled trial.” PLoS One, 2014. 9(11): p. e112665.
37. Hietaranta-Luoma, H.L., et al. “An intervention study of individual, apoE genotype-based dietary and physical-activity advice: impact on health behavior.” J Nutrigenet Nutrigenomics, 2014. 7(3): p. 161-74.
38. Livingstone, K.M., et al. “Effect of an Internet-based, personalized nutrition randomized trial on dietary changes associated with the Mediterranean diet: the Food4Me Study.” Am J Clin Nutr, 2016. 104(2): p. 288-97.
39. Celis-Morales, C., et al. “Can genetic-based advice help you lose weight? Findings from the Food4Me European randomized controlled trial.” Am J Clin Nutr, 2017. 105(5): p. 1204-1213
40. El-Sohemy, A. “Only DNA-based dietary advice improved adherence to the Mediterranean diet score.” Am J Clin Nutr, 2017. 105(3): p. 770.
41. Keegan, R.H., C; Spray, C, et al. “A qualitative investigation of the motivational climate in elite sport.” Psychology of Sport and Exercise, 2014. 15(1).
42. Guth, L.M. and S.M. Roth. “Genetic influence on athletic performance.” Curr Opin Pediatr, 2013. 25(6): p. 653-8.
43. Mattsson, C.M., et al. “Sports genetics moving forward: lessons learned from medical research.” Physiol Genomics, 2016. 48(3): p. 175-82.
44. Webborn, N., et al. “Direct-to-consumer genetic testing for predicting sports performance and talent identification: Consensus statement.” Br J Sports Med, 2015. 49(23): p. 1486-91.
45. Pitsiladis, Y.P., et al. “Athlome Project Consortium: a concerted effort to discover genomic and other “omic” markers of athletic performance.” Physiol Genomics, 2016. 48(3): p. 183-90.