The tiny organelle hyped to be the missing link in performance is also the hardest to effectively measure and evaluate. Mitochondria are the powerhouses of our cells, but they are also the most difficult to research because of muscle biopsy requirements.
I wrote this article because everyone in conditioning should care about how mitochondria function and adapt to training. For about five years now, I have done more research on mitochondrial changes from training, including my own investigations and experiments. What I have found is exciting and a big opportunity, but only if you commit to doing the homework. Talk is cheap, meaning if you are chatting or tweeting about mitochondria but don’t know if you are making an adaptation, it’s a good idea to read through my position on why mitochondria matters.
The Mystery of Mitochondria and Training
Of all the adaptations, the most mysterious are changes at the cellular and molecular levels. Even now, we don’t understand how our genetics fully interact with the adaptation and proliferation of mitochondria. I have been very cautious and patient with training the aerobic system because we still are not fully confident we know what happens deep inside the body, and some evidence even points to some of the previous science possibly being myths.
Recently, Runner’s World posted a blog about maximizing mitochondria. It was very good, as always, since Alex Hutchinson, one of the best writers on running science, wrote it. What concerned me was that it left me less confident as to whether the science agrees on how adaptations to the aerobic system connect with both the number of mitochondria in our muscle cells, and the way they become more powerful. Two separate experts, Dr. Bishop and Dr. MacInnis, gave conflicting information on the reason mitochondrial adaptation occurs, based on their training recommendations. Bishop, as I interpreted, suggested a combination of volume and intensity, while MacInnis was more about interval options.
So, what do I believe? Volume and intensity are hard to separate, but after seeing the research and doing a few experiments invasively, the key is looking at how the winners train and what the research design replicates. Marathoners don’t run for 20 minutes broken down into five-minute chunks, and an NFL receiver frequently runs 40 sprints in a game. Soccer players seem to do an amazing number of repeated bursts, and run total distances that resemble a miler in training.
We can conclude that the research needs to focus on athletes, not ordinary individuals who are fitness or “healthy” subjects. The good news is that some great research is happening now, and we are likely to understand how fueling and training interact with the genetic research coming out of assorted prestigious universities.
Why You Should Care About Mitochondrial Function and Content
Winning is about specific fitness, a reduction in injuries, and the ability to recover between competitions. As conditioning levels decline, so do the opportunities for athletes to train. When we think of conditioning, most coaches focus on heart rate intensity. While that is a good proxy to perform some workouts, the heart rate response is not a perfect basis for prescribing training.
Adaptations to the heart walls and chambers, all the way down to the microscopic capillaries, are real adaptations from pushing the limits of conditioning. What we, as coaches, do with conditioning is sort of draconian—we suffocate an athlete safely and then use the internal adaptations to grow and nurture aerobic improvements. Some of those changes to the body are to the mitochondria in the muscle cells.
All the biology is fascinating, but if you do not see improvements in performance, you must evaluate the training to determine why. Conditioning is actually harder to test because fatigue and ability are nearly impossible to tease out without lab testing. An athlete performing stronger on a field test, such as a 30-15 shuttle test, may simply have more motivation or be less afraid of discomfort.
Sometimes just the opposite occurs: an athlete is a little sore or broken down with their legs and performs poorly, even if they made real changes to their conditioning abilities. When we train, some adaptations are not directly visible, although we can see their impact with the naked eye when athletes perform exceptionally well. Coaches should care about mitochondria because the amount of power they provide is a primary reason for the failure or success of conditioning programs.The amount of power mitochondria provide drives the success or failure of a conditioning program. Click To Tweet
One of the reasons that some coaches love mitochondrial science and others ignore it is that it’s difficult for anyone to know if it’s happening with their athletes or not. A guru can post long citations and sound like a genius; thus, the affinity to mitochondrial adaptations. Coaches who are practical and need to see simple changes in field tests just assume athletes are getting better somewhere at the microscopic level.
As non-invasive measures improve in both accuracy and precision, coaches can train with sharper focus and play less of a guessing game with training. Currently, no system can detect how the mitochondria in an athlete’s body are adapting, but we can see a strong “proxy with MOXY” if general production is trending. There is promising research from the University of Georgia with NIRS (Near-Infrared Spectroscopy) and mitochondrial changes are encouraging, but there need to be additional measures to have full confidence in the location of the likely changes.
How Science Measures the Changes to Mitochondria
Due to the size of the mitochondria, very powerful microscopes are necessary, and under those lenses are muscle biopsies; samples of fibers that originate from the subjects researched. The process is very demanding and not something you will see done with underclassmen, but as the technology improves and becomes more available, we may see some high schools with access to some seriously expensive instrumentation within the next decade.We should appreciate scientists discovering what our workouts are doing, unseen by the naked eye. Click To Tweet
When researchers look for evidence or clues of change, they look at the enzymes, status of the fibers (nutritional), fiber composition, specific protein content, and the mitochondrial respiration and ROS production details. Most of the science isn’t easy for coaches to value, but because of the sheer difficulty and work entailed, we should appreciate the scientists helping us discover what exactly our workouts are doing that is invisible to the naked eye.
Evaluating muscle biopsies isn’t easy work and the studies take years to really penetrate the coaching circles. When you add in what is happening at the molecular level, things get very complicated, especially in the age of at-home DNA tests. The reason scientists don’t just look at the mitochondria in isolation is that they want to know what exactly triggers the changes, or as best as they can discover. What happens at both the cellular and molecular levels creates a cause and effect, and less speculation on simple pre and post changes to the structure and activity of only one organelle.
Besides observing the changes that happen with muscle cell mitochondria—both the content (amount) and function (efficiency)—scientists look at the way the athlete fuels and repairs. Low glycogen stores throttle up biogenesis or create more mitochondria, and some nutrients also, paradoxically, blunt the signaling. With knowledge of the conditional factors of nutrition, as well as the fiber type distribution, it’s possible to model a theoretical plan. When you add in the sequence and structure of workouts, the timing of the resistance training and conditioning adds another variable that you must consider. Researchers are doing a spectacular job factoring in these contextual elements in their studies.
Before We Dive into Specific Workouts
Many readers will skip right to this point, the meat and potatoes of the article—the workouts. When we think mitochondria, most old school coaches will think aerobic workouts, such as continuous long distance running or similar. Some coaches are familiar with HIIT, or High Intensity Interval Training, but it’s not really as simple as volume and/or intensity. If it was, we wouldn’t see so many conflicting opinions on what maximizes capacity to form efficient mitochondria. Throw in weight training, and even the timing and sequence of nutrition, and the variables all lead to a mixed bag of questions and answers.
When the science is murky, turn to close observation of those that win continuously with specific training programs. It may even be deceiving to follow a coach, since programs sometimes work because of talented athletes, thus making solid training decisions hard to figure out. A coach with some extra cash, a desperate athlete or two, and touched with a bit of curiosity can get lab testing done if they search and network right. I am not sure if it’s illegal to bypass the red tape, but I am fairly confident that the privatization of science is fine if you sign the right paperwork.
Just to make sure coaches and athletes reading this article don’t google “mitochondrial lab testing,” disease screening is a different process and will not provide you with training adaptations. Any baseball fan will remember Rocco Baldelli—specifically how his mitochondrial disease was mistakenly attributed to laziness. Years ago, I met one of Rocco’s former strength coaches, who had misinterpreted his fatigue from the disease as a sign of not being a hard worker because he didn’t “look sick” or have signs of a typical illness. This is important because healthy athletes are sometimes gifted with type II muscle fiber, and simply seem sloth-like because they really don’t have as much slow-burn energy as the workhorse athlete with more aerobic traits.
Polarized Training to the Rescue?
Research on polarized training, or going hard and easy at the same time for conditioning, is growing in popularity because of HRV monitoring and some cool research on its effect on mitochondria. Training is a little more complicated than alternating between speed sessions and low-intensity volume work; it includes progressing and tapering, as well as selective changes to modalities and recovery techniques. Periodized training is not extinct, but due to modern competitive schedules, the traditional model of putting in work before competing is starting to become an endangered species.
Based on the latest information on what constitutes true polarized training, we do know that most of the success in international competition comes from traditional base work—hard enough to create changes long-term, but not so hard that recovery isn’t possible. One very simple example with cycling used a polarized program and compared it to a threshold program. The polarized group did exactly 80% of the work at below-threshold pace and 20% at higher-than-threshold pace. The results were clear that polarized training made better improvements, but the effect was a little shaky and unclear with what happened at the mitochondrial level. Most likely, the issue was that the study was too short to really see how and why adaptations resulted outside the lab performance testing.
So far, there is no evidence of polarized training being superior for mitochondrial adaptations, but based on studies looking at both volume and intensity, polarized training has promise. Coaches should worry more about how the progression of training loads affects joint health over theoretical volume standards or frequency of sprints. On the other hand, it’s still a reality that overload requires knowledge of the thresholds required to change an athlete for the better, and record-keeping in conjunction with physiological testing is a sound check and balance.
Concurrent Training Contradictions
A few studies indicated that endurance running after resistance training is different than performing weight sessions followed by running. Some studies find that it doesn’t matter, while other studies show that resistance training amplifies mitochondrial changes. Other key variables are the length of a time window between sessions and the specific type of volume and mode of each option.
Interference will occur eventually, as no marathoner will ever be able to win the shot put. Nor will linear improvement to strength and conditioning continue indefinitely as athletes hit impressive outputs. It’s safe to say that, early on, nothing matters with neophyte or lower-level athletes, but as training becomes more advanced, the small decisions—like sequence of training—may likely be a decisive factor in winning when chronic commitment to cell signaling is practiced.
Periodization is again on trial, with a plea from proponents of more contemporary ways of scheduling and planning training throughout the year. The issue isn’t so much that periodization is dead, it’s that science struggles to connect with practice in regard to long-term training research. If the possibility of an advantage exists with training structure, no coach wants half their athletes being the control. As the athletes reaches their genetic ceiling, they require exponentially more effort to get diminishing returns with improvement. Focusing on complementing training with smarter pairings of modalities can deepen the training effect.
A few authors—mainly pop science writers—have claimed that the last mode of exercise will signal or turn on the switch to the adaptations. Lifting after aerobic training will not create an interference effect, and swapping the order isn’t going to make or break a program, especially when there is enough time between sessions. It’s more important to have the entire macro view or big picture of all the training, as practical demands of sequence of training and distribution of resources play a more vital role to training than “activating genes” alone.
Low Glycogen Training Debates
One of the current trends and controversial topics is the effectiveness of low glycogen training with biogenesis of mitochondria. Similar to altitude training, training high or low now has a new meaning. In theory, and supported by some research, low fueling of the glycogen stores sends a signal to create more powerhouses of the cell. Training with low glycogen stores challenges the body and drives deep adaptations that are great on paper, but taking a cycling study out of context is very dangerous unless the plan makes sense logically. Given the fact most sports are team or speed and power events, when would you employ such techniques when athletes are doing explosive work instead of threshold-type endurance activities?
The most compelling aspect of low glycogen training is the immediate expression of PGC-1α from one session at low intensity, roughly 60-70% of an athlete’s VO2 max. But the fault with this training is that team sports can’t do polarized training or easy aerobic work day after day. The fueling science isn’t new: Interval sprints on low glycogen are older than the athletes we are likely working with. What is new, though, is the publication of more contemporary studies on training programs or something similar to real-life workouts. Coaches don’t care about idle research studies unless the training resembles what they do with their athletes or it’s something they would do if the results are really there.
There is a current debate on the anabolism requirements of repair and how low glycogen stores can create an interference with myofibril (muscle) regeneration. So far, the research has plenty of conflicting reports on protein synthesis and what state of feeding or fasting conditioning really makes a difference that matters. The example of post-workout nutrition is the best lesson, as the athletes just need to have calories within the ballpark of the day, not within 30 minutes or similar. Other questions must be investigated, such as which nutrients may or may not influence mitochondrial changes, as other signaling pathways exist outside of substrate levels in the body.
Periodization of nutrition is growing from the merging of different dietary plans instead of the typical segregation of beliefs. Current experimentation, ranging from intermittent fasting to re-feeding strategies, tends to have early promise, but later proves less impactful as we learn of the tradeoffs that occur when the pendulum swings in any direction. It is fair to conclude that nutrient timing matters, but only for very specific and narrow purposes, and that caloric intake is usually a stronger influence than smaller nuances.
Workouts That Work: Classic Training That Still Produces Results
I have more than three workouts, but I use the following themes to program daily. Conditioning simply extends output based on a percentage or pace, so if a marathoner is slow and can hold 90% of their speed, a faster runner that holds 85% of their speed might be a better performer. Endurance is a description of absolute abilities, and coaches want to see both how much output an athlete can produce and how much output they can sustain. Repeat speed qualities start with the ability to produce speed first, and the decay of output is usually not as important if the overall picture looks like an advantage. Most games and sports have breaks built in or provided for medical purposes, so passive recovery will happen, like it or not.
Absolute Output: Maximal velocity and acceleration rates create the roadmap for loading submaximal speeds, provided that eccentric qualities are sufficient to handle stressors of impact. A short sprint, usually time to peak velocity, can provide both maximal speed and enough acceleration capacity that repeat work and sustained work are easy to calculate. The actual repeated sprints, even with longer rest periods, are more than sufficient to promote enhancement to the existing mitochondria.
Interval-Based Running: Speeds faster than threshold with abbreviated rest periods create a stimulatory signal from the combination of total volume and an intensity higher than LSD (Long Slow Distance). The reason I like interval work that is slower than typical HIIT is that the contractions are fast, but the speed is easy enough to maintain. Also, intervals are easy to monitor and easy to do with groups. Heart rate recovery techniques—those that use the slope pattern of beats per minute to determine when to go—are unnecessarily difficult to manage in real time. Using the right rest of either 30-60 seconds or in a 1:1 ratio are excellent options.
Continuous Velocity Saturation: For the most part, the typical jog kills conditioning because it uses a sloppy stride to get the “work done.” Instead of starting long and building speed or reducing rest, starting with intervals and extending longer is the best progression. I have taken poorly running soccer athletes (under 80 kilos) and extended their tempo running from 200m to nearly four continuous minutes. Most athletes who can do repeated three to four minutes of running can do a long field test with no problem, whether it’s a distance run for time or shuttle test for total length. I use saturation as a term because of the Moxy Monitor—a way to get non-invasive cellular data—really helps with continuous workouts.
Countless options and permutations exist with modalities, but running, on average, usually transfers better and is easier to compare between training sessions. The best way to keep pushing aerobic adaptations is with frequency and volume of training, and durability means allowing for enough recovery of hard and connective tissues. Contrasting impact loads of running with slightly unloaded forces from pool and bike routines may be the right balance, so monitoring both physiological status and mechanical load will prevent much of the stoppage of training. It’s better to have a great program done 100% of the time than a perfect program on paper done with multiple weeks of rehabilitation and detraining.
Does Genetics Tell How Well Athletes Adapt to Training?
Many of the emails I get are indirect requests to suggest an at-home genetics test, and I will not do it. Genetics testing is a Pandora’s Box I don’t want to open, but genetics doesn’t have to about swabs and predictions. Instead, simple sport testing can evaluate it, as well as honesty about what you have and don’t have for talent. Genetics is a heavy science, but some information we know from field testing can help determine which workouts may create responses that mean something down the road. Coaches know that talent isn’t about who is better equipped to perform in short or long events; it’s usually about a combination of things in conjunction with an athlete’s genetic makeup.
Genetics connects to how and if an athlete responds to training inputs. A coach with experience and a good feel for the research can deduce what “type” of athlete they are working with, usually without lab equipment. Nothing beats performances in games or competition, but with training, simple responses or lack of change are a strong indication of what an athlete is born to do. Outside of recruiting talent, coaching is about making who you have better with the right information, and the best data is a clear evaluation of transferable workouts and/or tests.
Two key trains of thought exist with talent evaluation: what the athlete can do without training and how they respond to training inputs. Some athletes come into sport as nearly finished products, demonstrating how the blessed are gifted by a combination of parental DNA and some randomness of hereditary. Other athletes come into the sport with talent, improve rapidly and consistently with training, and win by maximizing what they have.
In summary, coaches need to ask these two important questions:
- How much potential does this athlete have in their respective sport or event?
- How well does this athlete respond to training inputs, including nutritional interventions?
With just good record keeping and data collection, coaches can conclude if it’s the training, the environment, or the athlete themselves holding the athlete back. Almost too many times, the problem is not a “bad talent DNA” issue from the parents; it’s the athlete’s character and the way they were raised. Not everything that matters is measurable, but when the variables that are measureable don’t reveal anything, always think about the tough areas of evaluation as the reason for stagnation in performance.
Start Field Testing with Confidence
The goal of this article was not to mesmerize with cool technology and penetrating science, but to empower a coach with a better understanding of the relevance of mitochondria and how they should influence athlete preparation. With the new science and without much equipment, coaches can start building aerobic adaptations through more simplified training, and see improvements with what they already do in field testing.Coaches can’t evaluate mitochondria with a stopwatch, but can understand their effect on training. Click To Tweet
We can’t evaluate mitochondria with a stopwatch, but we can see the effects on training over time and make sound conclusions. A wealth of different scientifically supported options in training are now available for use by coaches, and harnessing them can make a difference in an athlete’s career.
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