What is Plyometric Training?
Plyometric training began in Russia and was first introduced by a well-known track and field coach, Verkhoshanski, referred to it then as shock training or jump training. Many years later in 1975 Fred Wilt, a Purdue women’s track coach, was credited with coining the term Plyometrics. The word is derived from the Greek words plythein (or plyo), which means to increase and metric, which means to measure. Traditionally, programs to increase jump height have focused narrowly on plyometrics and disregarded other training methods. This program combines plyometrics, weight lifting, and body mechanics, completing a full shockwave effect to maximize energy transfer and jump height.
Attentional focus is just one factor of the Shockwave Method, but it yields great results in little time. In vertical jumping and reaching, using a VertecTM measurement device, subjects that focused externally on the rungs of the device jumped higher than when they focused internally on their fingertips. This small change increased jump height by an average of 16.3%, alone.
This significant difference is due in part to the constraints an internal focus imparts on the motor system; this can include co-contractions and inefficient contractions. Co-contractions are activation of the muscles on both sides of the leg for stabilization. This is much needed when landing to prevent injury, but if the hamstrings are firing in the upward phase of a jump they are counteracting the force developed by the quads and effectively decrease jump height. This conscious control constrains the motor system, but can be removed under an external focus. Without constrains on the motor system movements become more automatic and can be learned faster.
When attention is focused externally on the outcome of the action (ball going into the goal), as compared to an internal focus on body movement (the act of kicking the ball) this results in greater movement effectiveness and efficiency. As it relates directly to jumping, with an external focus athletes have been shown to jump with greater peak forces, impulses, and joint moments with less muscular activity as compared to an internal focus. This means their muscles worked more efficiently to complete the movement.
Jumping Physiology and Mechanics
The descent phase of jumping is when the subject bends their knees and lowers themselves closer to the ground before exploding upward. The transition between the descent phase (eccentric contraction) and the ascent phase (concentric contraction) is called the amoritization phase, and it is crucial to jump performance. As the time for this phase decreases, the stored energy is used more efficiently in the transition, thus increasing the speed and power of the movement in the ascent phase. If the amoritization phase is too long, the energy stored is lost as heat, the stretch reflex is not activated, and the work done in the ascent phase is less effective. The rapid deceleration-acceleration of the amoritization phase is what produces the explosive reaction that’s responsible for increasing the speed and power of the movement.
The force production of muscles is strongest in eccentric contraction, followed by isometric contraction, then concentric contraction. Concentric is the weakest form of muscle contraction, but in plyometrics it is able to produce the greatest amount of power, due to an efficient transfer of energy. This is why a short amoritization phase is so critical in power development of muscles. To give you an idea of how short the amoritization phase needs to be in order to efficiently transfer force for an explosive jump, if the phase lasts any longer than 0.25 seconds it is considered a slow plyometric movement, these include countermovement and squat jumps. Fast plyometric movements occur in less than 0.25 seconds, drop jumps would be a prime example.
Each movement pattern involved in jumping should be practiced in isolation, early in training. These smaller components can then be integrated into the full movement pattern. The reason for this is to establish proper mechanics that can be carried over into practice. If a muscle cannot function correctly in isolation, then it cannot function properly in jumping when the full sequence is combined.
In sub-maximal intensity efforts, slow twitch muscle fibers are recruited. As exercise intensity increases to 30-80% of maximal effort fast twitch IIa fibers are recruited. IIa and IIb fibers are then recruited at 70-80% of maximal effort. Given there are only 3 ways to increase fast twitch muscle fibers: 1) maximum intensity effort, 2) electrical stimulation, and 3) plyometric exercise, it is critical that high intensity efforts greater than 80% are made to ensure recruitment of fast twitch fibers for power development. At this effort intensity plyometric training can increase jump height up to 26%.
Following an 8 week plyometric program, significant improvement can be seen in 10 meter sprint time by 22.1% and agility test time by 29.6%. Explosive athletes are also seen to have improved performance in cycling, weightlifting, and golf swing performance. The use of unilateral and bilateral jump drills has been shown to be more advantageous in increasing jump height and sprinting speed. As shown, the benefits of plyometric training extend beyond jump height. To ensure continued improvement and training participation, it is essential not to overtrain.
To avoid injury when performing plyometrics it is important to note when fatigue sets in. This can be recognized when quality of movement deteriorates and the movement is not able to be performed with proper mechanics, this is the time to end the plyometric session. 48-72 hrs of rest is recommended between plyometric training sessions.
Delayed Onset Muscle Soreness Treatment
Because jumping includes eccentric muscle contraction, delayed onset muscle soreness (DOMS) is likely in the untrained individual. This will last 7-10 days and is self-limiting. See our article on DOMS for the fastest methods of recovery.
In order to have the proper coordination and motor control to perform plyometrics, foundational strength must be built prior to beginning such a program. This should be a priority for athletes below 1-1.5 x body weight squat. Until this benchmark is achieved, it would be sensible for athletes to avoid high intensity plyometric exercise. Other contraindications include, but are not limited to: pain, inflammation, acute or sub-acute sprains, joint instability, and soft tissue limitations from post-operative conditions. Beyond preparation for plyometrics, weight training will also increase jump height.
In most cases weight training has improved vertical jumping performance by 1-3 inches (or by 5-15%). Studies have shown that the combination of plyometric training and weight training is more beneficial than plyometric training on its own. Those who do plyometrics in combination with weight training spend less time in the amoritization phase than those who do either form of training separately.
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Wulf, G. Dufek, JS, Lozano L, Pettigrew C. Increased Jump Height and Reduced EMG Activity with an External Focus. Journal of Human Movement Science. 2010; 29: 440-448.
Wulf G, Dufek S. Increased Jump Height with an External Focus Due to Enhanced Lower Extremity Joint Kinetics. Journal of Motor Behavior. 2009; 41(5): 401-409.
Wulf G, Zachry T, Granados C, Dufek J. Increase in Jump-and-Reach Height Through an External Focus of Attention. International Journal of Sports Science & Coaching. 2007; 2(3): 275-284.
Fatoutos I, Jamurtas A, et al. Evaluation of Plyometric Exercise Training, Weight Training, and Their Combination on Vertical Jumping Performance and Leg Strength. Journal of Strength and Conditioning Research. 2000; 14(4): 470-476.
Davies G, Riemann B, Manske R. Current Concepts of Plyometric Exercise. International of Sports Physical Therapy. 2015; 10(6): 760-786.
Ozmen T, Aydogmus M. Effect of Plyometric Training on Jumping Performance and Agility in Adolescent Badminton Players. Turkish Journal of Sport and Exercise. 2017; 19(2): 222-227.
Bremec D. Practical Applications of an Optimized Plyometric Training – an Overview. The Swedish School of Sport and Health Sciences. Thesis. 2017.
Slimani M, Chamari K, Miarka B, Del Vecchio F, Cheour F. Effects of Plyometric Training on Physical Fitness in Team Sport Athletes: A Systematic Review. Journal of Human Kinetics. 20016; 53: 231-247.