It’s important for coaches and athletes in high-intensity sports to consider exercises for strength, power, RFD, and impulse when planning a training regimen.
It’s also important to have a guiding philosophy. To begin developing a philosophy, a logical set of questions to ask are:
- What am I trying to do?
- How am I going to do it?
- Why am I doing it this way?
Keep the philosophy simple, so the training plan does not become overly complicated and ineffective.
During any discussion regarding resistance training for sports performance, it’s important to bear in mind the SAID principle (Specific Adaptation to Imposed Demands). While coaches often use the term, not all think critically about what qualifies as specific and what does not.
We may have a conceptual idea of one method, position, speed, or movement sequence as being specific, but in reality, we may be wrong. Still, it’s important to push the boundaries of thought and strive toward sport specific training. A lot of research shows that the way in which we train has a direct and specific effect on training outcomes.
This is what we mean by specificity:
- How fast or slow we actually lift a load
- How fast or slow we intend to lift a load
- The force vectors in which we direct training loads
- How we move throughout the duration of an exercise
- Eccentric, isometric, and concentric demands
- Joint positions and muscle activation sequences
Because training adaptations are specific, it’s wise to consider both the context of training transfer as well as the need for variation. Avoid getting hooked on one specific exercise or one way of performing an exercise. Instead, use a variety of exercises or exercise subsets that contribute to the sports performance outcome. Use different bars, stances, tempos, and loads to create a holistically developed athlete. Our goal as athletes and coaches is to prepare for sport, not to prepare for a single lift in the weight room.Use different bars, stances, tempos, and loads to create a holistically developed athlete. Click To Tweet
Before we dive any deeper, here are terms you ought to know.
- Force: defined as mass multiplied by acceleration. Any time we attempt to move ourselves or an object, we exert some amount of muscular force.
- Strength: the skill and ability to produce force.
- Rate of Force Development (RFD): the rate at which we produce increasing amounts of force during an effort. RFD is measured in Newtons per second.
- Ground Reaction Force (GRF): the exchange of forces that occurs when an object is in contact with the ground. The direction and magnitude of force that goes into the ground and is then exerted back onto the athlete is the GRF.
- Impulse: the application of force over a period of time which causes a change in momentum. Force multiplied by time is equal to its impulse.
As enthusiasts and professionals in the world of sport, we want to develop the high-intensity qualities of strength, power, RFD, and impulse. Why are these factors important?
- Strength is the underlying quality of all movement. An explosive athlete must have a requisite level of strength to be competitive and avoid injury.
- Power is the quality that determines how much work we can do in how little time. Running fast and jumping high require a large amount of work in a small amount of time, and developing power is a logical practice to undertake.
- RFD capabilities allow us to produce more force at an earlier point in a muscle contraction. Our power output is related to RFD because producing more force at an earlier point in time allows us to do more work in less time.
- Impulse directly causes the amount of movement we produce in an explosive action. It can be manipulated by changing either the force exerted or the amount of time in which to exert it. In the blocks, impulse can be adjusted by block placement. If we create a more flexed hip position on the front leg of the blocks, we can push on the front block for a longer time and create a larger impulse and starting velocity upon block clearance.
Knowing these qualities is great, but how do we develop them? As is the case in other areas of life, there are many ways to do this and even more opinions on which are best. It’s important to optimize training by looking at these qualities and determining how they reflect the demands of the athlete’s given sport. Develop programs with these factors in mind.
The following section will give ideas of where to begin and how to structure a training program to develop high-intensity capabilities.
From a programming perspective, building basic levels of strength is not complicated. Until we reach the elite levels of lifting, the basic approach to getting strong is to lift heavy objects with proper form while targeting joint movements and muscle groups that are used in sport. While nearly any challenging lift will make us stronger in some regard, we must always try to get the best bang for our buck.
When selecting exercises for strength development, I prefer movements that activate large amounts of tissue and don’t require the athlete to move around or leave the ground in a very significant way.
For the sake of this article, I’ll refer to these movements as being static. The athlete stays in place while doing the movement and does not leave the ground or move across the ground for the duration of the set.
Why? If we truly challenge ourselves in an exercise such as the squat or deadlift, the load used to produce strength gains should be heavy enough to prevent dynamic movement. From a safety perspective, it’s safer to lift heavy with static movements than to try and overload a dynamic movement.
Useful exercises for strength development:
- Squat Variations: Back squat, front squat, box squat, goblet squat, safety bar squat, cambered bar squat, dumbbell front squat, rear leg elevated split squat, and hex bar squat.
- Deadlift Variations: Straight bar deadlift, hex bar deadlift, block pull, rack pull, and heavy kettlebell deadlift.
- Hip Thrust Variations: Barbell hip thrust, single leg hip thrust, standing band hip thrust, heavy band hip thrust, and heavy band pull through.
- Press Variations: Straight bar bench, floor press, dumbbell bench press, bench with a block, incline bench press, and shoulder press.
- Hyper/Extension Variations: 45-degree hyper, reverse hyper, bent leg hyper, and semi-bent leg hyper.
These exercises recruit large amounts of tissue over various regions of the body. Given that the body responds proportionally to the stress applied, large movements that activate large amounts of tissue will lead to a proportionally large response from the body. This response includes acute and chronic hormonal, structural, and neural changes.
Less experienced and weaker athletes will see improvements with lower intensities, such as lifting 60-70% of their 1-rep maximum with slightly higher rep ranges (such as 5-8 reps). As athletes become stronger and more proficient in their lifting skills, intensities can increase and the reps can decrease, allowing for long-term development through intensification over time.
A 14-year-old kid who weighs 140 pounds doesn’t need to max out to get stronger but a 300-pound rookie in the NFL might. At a certain point in an athlete’s career, it may be wise to shift toward maintaining absolute strength levels. In this case, intensities or volumes of absolute strength work can be reduced to prevent fatigue and risk of injury.A 140-lb teen doesn't need to max out to get stronger but a 300-lb NFL rookie might. Click To Tweet
Developing power should be high on the priority list for athletes who need to run fast, jump high, jump far, or hit hard.
From a physics standpoint, power = work/time. In sports, a more understandable definition is power = force x velocity. Therefore, training for power requires two basic components: large forces and relatively high velocities. Many people instantly think of bar velocity, but we also need to consider limb and whole body velocities when programming for power development.When programming for power development, coaches should consider limb and whole body velocities. Click To Tweet
As with strength, we want to use exercises that stimulate large amounts of tissue. In contrast to strength development, power development requires exercises that are more dynamic where athletes move through space as they complete a movement. These movements include leaving the ground vertically, translocation horizontally, or otherwise.
While we can develop power with a static lift like a squat or bench press, basing a power development program on static lifts will sell our athletes short in the long run. The same goes for solely using Olympic lifts for maximal strength development; this won’t optimize an athlete’s strength development.
Depending on the individual, loads for power development should be chosen based on their scientifically proven efficacy, their relation to the demands of the athlete’s sport, and the athlete’s level of strength and power development (Stone et al. 2003).
For example, when using the back squat for power development, studies have shown that loads in the 40-60% range produce power outputs similar to loads around 90%. The take-home point is that speed athletes can use the lower loads, while load bearing athletes, such as offensive linemen, can use the higher loads. Both are working in power production zones that are optimized for the demands of their sport.
Useful exercises for power development:
- Olympic Lifts: Power clean, power snatch, hang clean, and mid-thigh clean pull.
- Load the hang cleans at 70-90% to emphasize force characteristics of power (Bevan et al. 2010).
- Load the mid-thigh clean pulls at 40% of 1-RM power clean to emphasize velocity components of power (Comfort et al. 2012).
- Jump Squats
- 42% back squat 1-RM to maximize hip power, 0% to maximize knee and ankle power (Moir et al. 2012).
- Slightly lighter loads emphasize force while slightly heavier loads emphasize velocity.
- Weaker athletes should use loads that are relatively lighter while stronger athletes can use loads which are relatively heavier (Stone et al. 2003).
- Kettlebell swings
- Kettlebell swings from 16kg-32kg and jump squats from 0-60% of 1-RM can outperform back squats in peak power and mean power outputs (Lake, Lauder 2012).
- I prefer to add a band, encouraging a faster eccentric movement and a greater need for creating a large horizontal impulse.
- Squats at either 40-60% or at 90% of 1-RM (Zink et al. 2006).
- Speed athletes can benefit from the 40-60% range due to the same power output at a higher velocity; load bearing athletes, such as a football lineman, will benefit from the 90% load due to their need to express power in a loaded situation.
- Unilateral horizontal drop jump distance is the best predictor of sprint distances up to 20m, except for 5m sprint time which is best predicted by unilateral vertical drop jump rebound height (Schuster, Jones 2016).
- A short-term program of hurdle hops & depth drops increases absolute power, relative power, and maximal pedaling velocity (Chelly et al. 2010).
- Horizontal jump tests have stronger correlations with acceleration performance due to the horizontally oriented force application of sprint acceleration.
- Vertical jump tests correlate to maximal velocity sprint performance, likely due to the vertical nature of force application at top speed.
Rate of Force Development
As an athletic quality, RFD determines how quickly we can produce a given amount of force. Two athletes may be able to apply the same amount of absolute force to an object (such as a bar), but the athlete who reaches that level of force production sooner (for example, at 250ms vs. 500ms) is the more explosive athlete.Faster athletes will spend less time on the ground compared to slower athletes. Click To Tweet
In a race involving athletes with a range of skill levels, the faster athletes will spend less time on the ground compared to the slower athletes. This is due to their superior RFD capabilities (as well as their ground contact mechanics). Training enhanced RFD can result from shifts in fiber type, changes in muscle-tendon unit stiffness, increased early phase neural drive (50ms into an explosive effort), and changes in muscle fascicle length (Shoenfeld 2016).
When training to enhance RFD, it’s good to start with heavy loads and relatively fast velocities. Also, have the intent to go from zero force production to maximal force production in the shortest time possible. If an athlete lifts in a very controlled manner, they won’t spur much development in their RFD. In fact, they might experience negative effects on their RFD capabilities.If athletes lift in a very controlled manner, they won’t spur much development in their RFD. Click To Tweet
Useful exercises for training RFD:
- Mid-thigh clean pulls done at 120-140% of 1-RM power clean load (Comfort et al. 2012).
- Mid-thigh hang cleans between 30-90% (Suchomel et al. 2014); some studies report peak numbers at 30%, 60%, and 90%. Keep in mind the demands of each athlete when determining load.
- Sled pulls weighted on the heavier end of the spectrum will have a sprint specific impact on RFD, noted in one study as 20% of body mass (Martínez-Valencia et al. 2015).
- As a side note, heavier sled loads have more effect on early acceleration where force characteristics are more important. Lighter sled loads have a greater impact on late acceleration due to the speed demands of late acceleration.
Impulse causes the change in an object’s momentum; for example, when a shot put is launched or when an athlete’s body is projected with each step of an acceleration sprint.
Expressed mathematically as force x time, impulse is influenced by the amount of force produced as well as the time over which that force is exerted. The reason quick athletes with high frequencies during early acceleration are not very fast is that they don’t produce enough impulse. They raise their foot off the ground without applying force for a long enough time period.
Sprint acceleration performance and mean speed over 40m is strongly correlated with horizontal propulsive impulse while vertical propulsive impulse is not. Athletes and coaches in sports that rely on acceleration need to bear this connection in mind because improving horizontal propulsive impulse will likely improve acceleration sprint times.Improving horizontal propulsive impulse will improve acceleration sprint times. Click To Tweet
Though sparse, there is some research available regarding various exercises and impulse. Horizontal propulsive impulse should be of particular interest to sprint athletes and coaches.
Useful exercises for developing impulse capabilities:
- Sled sprints, depending upon the harness placement.
- Attaching the harness at the waist produces greater net horizontal impulse, net horizontal mean force, propulsive impulse, and propulsive force compared to using a shoulder harness (Bentley et al. 2016).
- 20% body mass loads have greater ground reaction impulse compared to 10% load conditions (Cottle et al. 2014).
- Kettlebell swings produce a greater impulse than back squats and jump squats (Lake, Lauder 2012).
- Hip hinge kettlebell swings can develop horizontal impulses.
- Attaching a band at a certain height can shift the force vector according to preference because the angle of the band influences the force vector throughout the movement.
There are many considerations when it comes to exercise selection for high-intensity training.
Consider force vectors, which are the direction and magnitude in which a load is directed. Does the athlete need to develop axial qualities or anteroposterior qualities?
Consider the demands of an athlete’s sport, and choose relative loads accordingly. If a sprinter produces the same power output using a 40% load and a 90% load, maybe they should stick to the lighter, faster loads.
By optimizing training to the needs of the athlete, time and energy can be directed and utilized in an optimal fashion.
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