Since the times of Ancient Greece, athletes have explored ways to get stronger, jump higher, and run faster. Each generation of new athletes have attempted to push the barrier and break previous records. It was with this quest in mind that Dr. Yuri Verkhoshansky stumbled upon and created “shock” training. In the Western world, this is known as the plyometric method. So what exactly is a plyometric? A plyometric exercise is one that utilizes the stretch-shortening cycle or myostatic stretch reflex.
The myostatic stretch reflex occurs when elastic energy is stored within the tendons and muscles following a rapid stretch, such as during an eccentric contraction. If a concentric contraction directly follows, as happens during a plyometric exercise, then the stored energy is released and it contributes to total force production.
If you’re having trouble visualizing this, think of it like stretching and launching a rubber band very quickly. The lengthening/stretching of the rubber band represents the eccentric portion, while the shortening/launching of the rubber band represents the concentric contraction.
While the topic of plyometrics is broad to say the least, this article will specifically cover how late intermediate and advanced lifters can use low intensity plyometric exercises during their warm-up, or within their training, to elicit maximal strength gains utilizing post-activation potentiation (PAP).
MAXIMAL STRENGTH & POWER: A PARTNERSHIP?
Strength is defined as the ability to produce force. You are able to display strength both isometrically and dynamically. When it comes to maximal strength, or limit strength, it is usually quantified as the greatest amount of force that a muscle or muscle group can exert in one maximal effort.
Power, on the other hand, is a combination of force and velocity:
P= Force x Velocity
In particular, power represents the exertion of force on an object and the object’s velocity in the direction which the force is exerted. As a result, alterations in force theoretically should create changes in power production.
Is that the case?
Yes! According to the literature, maximal strength is an important quality that affects power output and peak power production.
As noted by Schimidtbleicher, increased maximal strength allows for greater peak power production since it gives a person the ability to more easily accelerate submaximal loads. Moreover, people with higher levels of maximal strength tend to have a greater percentage of fast-twitch muscle fibers or type IIa/IIb fibers. As we know, type IIa/IIb muscles fibers most contribute to high power outputs.[1] These assertions are also supported by the research provided by Moss et al and Stone et al, which looked at the relationship of maximal strength and power.[2]
Side note: Don’t take this to mean that just boosting maximal strength will automatically increase power. That’s a quality you have to train. However, boosting maximal strength gives you the chance to be more powerful because you’re now working with a larger strength base.
Nevertheless, since the human body is complex it doesn’t end up being nearly that simple. Enter the central nervous system (CNS).
THE ROLE OF THE CENTRAL NERVOUS SYSTEM
Before moving on, lets have a quick recap.
1. Strength is the ability to produce force. Force = mass x acceleration.
2. Power is measured by taking the product of force and an object’s velocity in the direction that the force is exerted. Power = force x velocity
3. Higher levels of maximal strength tend to lead to higher levels of power according to the scientific literature.
Why isn’t it that simple?
When it comes to force generation one of the key component is the CNS. The CNS allows for coordinated muscular movements and force generation through innervation via motor units.
Motor units consist of a motor neuron and the skeletal muscle fibers innervated by the motor neuron’s axonal terminals.
As opposed to getting into muscle physiology, however, you just need to know that all motor units aren’t created equal, and that you have two main types:
- Low threshold motor units
These are smaller motor units that innervate type I muscle fibers, which generate low amounts of force, but are highly resistant to fatigue. These are the muscle fibers and motor units that allow us to do low intensity activities like writing this article, taking a walk, or getting a glass of water.
- High threshold motor units
These are larger motor units that innervate type IIa/IIb muscle fibers, which generate large amounts of force, but fatigue more easily, especially the IIb muscle fibers. These muscle fibers and motor units allow us to engage in explosive and powerful activities like lifting a maximal squat or performing a heavy clean & jerk.
So, in order to produce force quickly, one must be able to effectively utilize their high-threshold motor units. This is where plyometric exercises are useful. As noted by Bompa, the CNS controls muscle force by changing the activity of the muscle’s motor units; if a greater force generation is required, a greater number of motors units are recruited. This is known as Henneman’s size principle. Motor units are recruited from smallest to largest based on the force requirement needed.
One of the benefits of plyometric training is the increased activation of the fast-twitch motor units. [3] Plyometric drills allow for an individual to improve their efficiency of utilizing their high-threshold motor units.
This is important since both max force production needed to move maximal weight and peak power production needed to move a weight explosively both rely on the high threshold motor units to innervate fast twitch muscle fibers.
Since we know that both peak power and max force production are directly correlated to high threshold motor unit recruitment, we can then utilize plyometric drills directly before a heavy resistance set to take advantage of the phenomenon known as PAP.
POST-ACTIVATION POTENTIATION (PAP)
If you are unfamiliar with the term PAP, it refers to a phenomenon by which acute muscle force output is enhanced transiently (between 5 to 30 minutes) as a result of contractile history of the muscle fibers and nervous system stimulation.[4] This is typically accomplished by completing a set of a heavy resistance exercises prior to an explosive exercise that uses the same movement pattern.
Why does this phenomenon occur?
The truth is that the exact cause is unknown, but there are two proposed theories.
1. The first theory involves the Hoffmann Reflex (H-Reflex). The H-Reflex is an excitation of a spinal reflex elicited by specialized nerves that conduct impulses to muscle. The theory is that PAP comes from an enhancement of the H-Reflex, which increases the efficiency and rate of nerve impulses to the muscle.[5]
2. The second theory involves phosphorylation (addition of a phosphate for production of ATP). The idea is that a max contraction makes actin and myosin more responsive to the calcium ions released, thus triggering events that lead to enhanced force production.[6]
Traditionally, PAP has been used to promote increases in power production rather than maximal force production. In other words, heavy sets of squats have been used to produce more power during box jumps or sprinting.
Yet, we know that both peak power production and maximal strength are directly correlated to high threshold motor unit recruitment. So what prevents us from switching the order? Well, nothing at all.
In fact, I’ve seen athletes blow through plateaus time and time again by performing a low intensity plyometric exercise prior to a maximal strength exercise.
So now that you understand the science and rationale behind my methods, it is time to get to the programming.
SAMPLE PROGRAMMING
Prior to moving on, a word of caution: these techniques are for individuals that have a substantial strength base and training age. If you have not been training for several years, then focus on getting stronger before using advanced techniques.
When it comes to integrating low intensity plyometric exercises to benefit from the PAP phenomenon, I like to do it in two ways:
The first includes the plyometrics during the warm-up phase, which works great for people that are quite powerful and explosive, but tend to fatigue quite easily. The second uses contrast training, which works well for people that have great work capacity, but are not as powerful and explosive.
LOW INTENSITY PLYOMETRIC DURING YOUR WARM-UP
The general purpose of a warm-up is to increase core temperature, activate dormant muscles, prepare the body for movement, and stimulate the CNS. The latter can be done using low intensity plyometric exercises after you’ve finished your breathing drills, soft tissue work, and dynamic mobility drills.
The low intensity plyometric exercises should be the last drill that you perform during the warm-up phase prior to performing your first main compound movement of the day (i.e. a bench press, deadlift, or squat variation). This is because PAP lasts anywhere between 5 to 30 minutes in length.[7]
Generally speaking, the plyometric exercises during the warm-up for lower body days are one-leg and two-leg bounding, power skips, lateral skips, and repeated jumps. During upper body days, I will use plyo push-ups and some medicine ball ballistic exercises since true plyometric exercises are limited when it comes to the upper body.
SAMPLE LOWER BODY WARM-UP
SQUAT VARIATION MAX STRENGTH DAY
A) Lateral High Knee Skips or High Knee Skips – 2 X 20 ground contacts (10 right and 10 left)
Rest 30 – 45 seconds, then perform B
B) Hurdle or Dumbbell Jumps – 2 X 6
Rest 2 minutes and go back to A. After last set completed, then start to pyramid up to your working set for your main squat variation for the day.
C) Squat Variation (Main Movement)
DEADLIFT VARIATION MAX STRENGTH DAY
A) Lateral Bounding or Forward Bounding – 2 X 14 ground contacts (7 right and 7 left)
Rest 30 – 45 seconds, then perform B
B) Repeated Jumps (back and forth) – 2 X 6
Rest 2 minutes and go back to A. After last set completed, then start to pyramid up to your working set for your main squat variation for the day.
C) Deadlift Variation (Main Movement)
SAMPLE UPPER BODY DAYS
BENCH VARIATION MAX STRENGTH DAY
A) Medicine Ball Overhead Slam or Rotational Medicine Ball Slam – 2 X 8 (per side for rotational slam)
Rest 30 – 45 seconds, then perform B
B) Plyo Push-up – 2 X 6
Rest 2 minutes and go back to A. After last set completed, then start to pyramid up to your working set for your main bench variation for the day.
C) Bench Variation (Main Movement)
CONTRAST TRAINING
The contrast sets should only be used for the main movement of the day and not during warm-up sets for the main movement. You only pair the plyometric movement with your working sets.
BENCH PRESS VARIATION DAY
1a. Choose 1: (3-5 sets X 4–6 reps)
Explosive Pushup
Medicine Ball Chest Pass to Floor
Supine Medicine Ball Chest Throw
Rest Period: 75 to 90 seconds before primary lift set
1b. Bench Press Variation for Max Strength
SQUAT VARIATION DAY
1a. Choose 1: (3-5 sets X 16-20 ground contacts)
Lateral Bounding
Forward Bounding
High Knee Skips3-5 X 16-20 ground contacts
Rest Period: 75 to 90 seconds before primary lift set
1b. Squat Variation for Max Strength
DEADLIFT VARIATION DAY
1a. Choose 1: (3-5 sets X 4-6 reps)
Repeated Jumps
Hurdle Jumps
1 Leg Lateral Hop (per side for reps)
Rest Period: 75 to 90 seconds before primary lift set
1b. Deadlift Variation
CLOSING THOUGHTS
By utilizing these methods, you will not only find yourself busting through your current plateau, but you may find that your bar speed increases during your submaximal effort days or dynamic days.
Just remember to properly use the rest periods between your plyometric exercise and heavy sets because if not fatigue will negate the effects of PAP.
Now go out there and time to hit some new PRs at the gym!
IMG_6087_small
ABOUT THE AUTHOR
James Darley is the founder of Historic Performance, and specializes in making busy office professionals strong, jacked, and athletic. He has formerly interned at LIU-Brooklyn and Benfield Sports Performance, and has worked with a variety of individuals ranging from financial executives to Division I athletes. Outside of fitness, James enjoys reading history books, fishing, and hiking. Check out his Twitter and Facebook to get daily goodies!
RESOURCES
[1] SCHIMIDTBLEICHER, D (1992). Training for power events. In: Strength and Power in Sports. P.V. Komi, ed. London: Blackwell Scientific Publications, pp. 381–395.
[2] MOSS, B.M. P.E. REFNES, A. ABILGAARD, K. NICOLAYSEN, AND J. JENSEN (1997). Effects of maximal effort strength training with different loads on dynamic strength, cross-sectional area, loadpower and load-velocity relationships. Eur. J. Appl. Physiol. 75: 193–199.
STONE, M.H., H.S. O’BRYANT, L. MCCOY, R. COGLIANESE, M. LEHMKUHL, AND B. SCHILLING (2003). Power and maximum strength relationships during performance of dynamic and static weighted jumps. J. Strength Cond. Res. 17:140–147.
[3] BOMPA, TUDOR AND CARRERA, MICHAEL (2005). Periodization Training for Sports, 2nd edition, 199.
[4] ROBBINS, D.W (2005). Postactivation potentiation and its practical applicability: a brief review. J Strength Cond Res., 19(2): 453-458.
[5] HODGSON, M., DOCHERTY, D., & ROBBINS, D. (2005). Post-activation potentiation underlying physiology and implications for motor performance. Sports Medicine, 25 (7), 385-395.
[6] HAMADA, T., SALE, D.G., MACDOUGALL, J.D., & TARNOPOLSKY, M.A. (2000a). Postactivation potentiation, muscle fiber type, and twitch contraction time in human knee extensor muscles. Journal of Applied Physiology, 88, 2131-2137.
[7] CHIU, L.Z., FRY, A.C., WEISS, L.W., SCHILLING, B.K., BROWN, L.E., & SMITH, S.L. (2003). Postactivation potentiation response in athletic and recreationally trained individuals. Journal of Strength and Conditioning Research. 17(4), 671-677.
