Plyo-Power – The Science Behind Plyometric Training Techniques

 

Kevin Foster-Wiltshire is a Level 4 Specialist Exercise Instructor and has a lengthy C.V that includes training Olympic medallists, coaching strength and conditioning for professional boxers to reach title fights, advising on exercise referral for Arsenal Football Club and managing the fitness of several elite marathon runners and triathletes.  Kevin has his own successful business, Next Level Fitness based in Manchester, and is also a lecturer for Drummond Education on Advanced Resistance and Metabolic Programming.  He also writes as an expert contributor for Men’s Fitness Magazine.

 

 

Rationale

Plyometrics is not a new thing.  The science behind this form of training developed through the 1950s with landmark research undertaken in Russia and other European countries.  This form of training uses the ‘Stretch-shortening cycle’ and allows us to train the elastic properties of muscle to develop explosive power. When done correctly they are an effective sport specific form of exercise. With so many variations and movements the ethos of a true plyometric movement seems to have been lost in translation and is quite often performed with poor methodology.  It seems everyone from novices to PT’s are misusing the term plyometric by confusing it with power movements used in general fitness training rather than specific work for the enhancement of explosive pwer.

So what is the problem with that?

With any exercise you should always ask why? What is the purpose behind this movement.  If you’re looking to increase explosive power or speed and agility then confusing power movements with plyometrics could be slowing you down

The Science

So, let’s start by defining plyometrics. Put simply it’s ‘explosive-reaction training’. To get more in-depth, plyometric exercises involve the rapid stretching and immediate successive contracting of muscles leading to the training outcome of increased muscle power with improvement to the functions of the nervous system, thus enhancing and fine-tuning the relationship of the neuromuscular system.

It is the activation of ‘the myotatic reflex’ commonly known as the stretch reflex’ which causes the given muscle to contract. These are neurons called stretch sensory receptors which promote a reflex action built into the deep intra-fusial fibres of muscle as a mechanism to tell the muscle to contract if over stretched. For example, when the feet hit the floor from landing from a jump the quadriceps will stretch, a message instantly gets sent to your central nervous system that causes a reflex contraction of the same muscle that is being stretched.

Plyometrics also uses the key concept in exercise physiology  This is muscle contraction that lasts the least amount of time.  The least amount of time a muscle contracts produces more energy than a slower contraction or release regardless of the size or bulk of the muscle.

Another key element of plyometrics is the ‘concentric contraction coil up’.  For a muscle to act it first must ‘coil up’ which is actually stretching it to a maximum pre-action length where it loads and is held in this state and energy is stored on the myosin head.  This should last a second or less only for maximum storage and therefore maximum use in the concentric phase.

In summary there are three phases of a plyometric muscle contraction.  The first is the ‘eccentric phase’ to initially lengthen and load.  Next is the ‘amortisation phase’ the split second holding period which builds the energy power.  Finally the ‘concentric phase’ in which muscles ‘coil’ and use that trapped energy to create the explosive muscle shortening movement.

This counteractive contraction can be powerful and correct cultivation of its benefits give increased performance.

There is also a neurological component which can train the brain’s hardwiring to train the neurons to learn that in some situations i.e. sports,that quick, precise muscle contractions with singular surge of energy production rather than pausing in contraction and losing the stored energy.

An excellent way to demonstrate this is to stand facing a wall and jump as high as you can reach – you may load first then jump – repeat this now with a little jump before, then see how high you can reach – you will be able to get higher with a pre-jump than in a stationary position. This is a form of plyometrics.

Importance

By implementing a chosen plyometric exercise into your routine you can increase your capabilities for a targeted movement pattern. This now leads us into the realms of sport specific strength training. By thinking out of the box you can improve your golf swing, your tennis serve, how hard you punch or kick, how far you can throw, jump… the list goes on.

Plyometrics are key for anyone looking to increase their strength and power without a decrease in speed, agility, reactions etc. They’re especially important with athletes who need to perform with ‘dynamic strength’ which is a combination of speed and power in certain movement patterns i.e. punching, kicking, throwing, running, jumping or any other sports specific movement.

Most people aiming for this training outcome often unwittingly use heavy strength training in isolated exercises at the wrong stage of a training program to gain power. Heavy weight training has its benefits and is useful – particularly as a pre-curser to plyometrics, however, training this way may lead to ‘stiffening-up’ and can make you feel slow and sluggish in the movement pattern essential for the given sport. This is where plyometrics become ideal, by combining speed and power with movement and momentum – more importantly, movement and momentum specific to your individual wants or sports specific needs – you can become stronger, more powerful, whilst at the same time maintaining and often improving motor skills such as speed and agility.

It is important that plyometrics is used with periodisation and that it follows a period of anatomical stabilization training (as ligament stress is high in these exercises) and muscular strength training as a pre-curser.  It is also important not to use too close to tapering for competition as to gain the full benefits time is needed for full adaptation to take place.

Education

Examples of power movements that are often confused with plyometric movements.

•  Squat jumps (where the eccentric phase is absorbed or held too long)
•  Hand clap press ups (where the eccentric phase is absorbed)

Plyometric basic examples that can translate to a number of common sporting movements.

•  Depth jumps onto a bench – drop down onto floor, landing eccentrically, (coiling) upon instant contact with floor (less than one second amortisation phase), jump up to opposing bench (concentric phase, increases leg power and strength using the trapped energy)

•  Quick pass chest press– partner passes the medicine ball at chest height, (catching coiling phase) the ball is thrown back on instant contact (less than one second amortisation phase into concentric phase increases arms and chest power and strength)

 

By Kevin Wiltshire

Edited by Gill Cummings-Bell