Plyometrics – By Barry Rudd
Plyometrics – Why, What, How and When?
Why?
It is the goal of every athlete to achieve their best; whether they are weekend warriors or professional sportsmen/sportswomen. So in sports where it is advantageous to produce rapid, powerful movements there is a lot of interest in Polymeric Training. So what is Plyometric Training and how and when do we do it?
What?
Plyometrics is defined as – ‘a type of exercise training designed to produce fast, powerful movements, and improve the functions of the nervous system, generally for the purpose of improving performance in a specific sport.’
It can refer to muscles of the lower and upper body.
During Plyometric movements the muscle is loaded with an eccentric (lengthening) action, followed immediately by a concentric (shortening) action. Studies have shown that when compared to normal muscle contractions, a muscle that is stretched before a concentric contraction, will contract more forcefully and more rapidly.
A great example of this is a crouch before a vertical jump. Crouching before the jump allows the athlete to jump higher. The muscles are stretched during the crouch just before they are contracted when jumping.
Every plyometric action is broken into 3 phases, which when joined together are referred to as the stretch-shortening cycle.
Pre-Stretch – The eccentric contraction (lengthening) of the muscle.
Amortization – The brief period of time between the stretching and contraction (the shorter the better).
Contraction – The desired movement created.
There are two main reasons for the increase in power production during a Plyometric movement – The natural elastic recoil of the muscles and tendons of the body; as well as a neurological response. This neurological response is called the stretch-reflex – when a muscle is stretched quickly an involuntary response used to prevent injury and over stretching occurs. This response increases activity in the muscle; causing a rapid breaking action and potential for a strong concentric muscles contraction.
According to numerous studies if the concentric contraction does not immediately follow the eccentric (lengthening) contraction then the potential for increased force production is lost.
How and When?
Polymeric training in conjunction with a good strength training program has been shown to increase performance in powerful activities such as jumping and sprinting. But how and when do we complete plyometric training -
As little as 1-2 polymeric exercises completed 1-3 times per week over a 6-12 week program has been shown to produce results. The volume of this training can also be quite low; with 2-4 sets of 10 repetitions being shown to be affective. Some classic plyometric exercises include counter-movement jumps, bounding, hopping and medicine ball throws.
Although there is no data specifically relating Plyometrics and injury, there are a few recommendations, made to reduce this risk, as well as to maximise results -
It is recommended that heavy weight training and plyometric training not be completed on the same day; technique should be perfect; and a landing surface with suitable shock absorption properties should be used such as grass or rubber mats (concrete or hardwood is to firm).
So if you think that increasing your power output will improve your performance, don’t wait any longer! Consult your Exercise Physiologist for a tailor made Plyometric Training program designed to help you reach new heights.