Rugby fitness training – Plyometrics
There are two components to strength, maximum strength and fast speed
strength (power). Your power is crucial to on field performance.
One major contributor of power is the ability to use the stretch
shortening cycle as it provides a significant amount of energy to
any fast paced movement.
Stretch Shortening Cycle (SSC).
The SSC occurs when ever a muscle undergoes a rapid slight stretch followed
by an immediate contraction from the stretched muscle. The cycle
occurs in three stages:
- Stretch phase- The muscles undergo a quick slight stretch.
- Pause phase – The time between the end of the stretch (phase 1) and the beginning of the contraction phase (phase 3).
- Contraction phase – The muscle undergoes a concentric contraction with more force than would be expected due to the SSC contribution.
During the stretch phase, the rapid slight stretch in the muscle(s) produces two responses. It invokes the stretch reflex of the body, a signal that tells the
muscle to forcefully contract to protect itself from injury. This
can be seen in the knee jerk reaction where the knee suddenly moves
from a slight tap just below the knee cap.
Secondly, during stretching energy is stored which then contributes to recoiling the muscle back to resting lengths, e.g. the muscle acts like a
spring being stretched. The two events results in additional energy
contributing to the contraction and therefore producing more force.
The effect of the Stretch shortening cycle can be seen by doing two vertical jump tests. In the first jump, squat down so that the thighs are parallel
to the ground, then without moving any lower jump upwards as high
as possible. In the 2nd jump, squat down to parallel, but before
jumping upwards, quickly drop the thighs slightly below parallel
then immediately jump.
The second jump produces a greater height, this is from the muscles in the thighs and buttocks invoking the SSC during the movement. This resulted
in energy being stored then used and the stretch reflex making those
muscles contract more forcefully, therefore producing a higher jump.
To develop and enhance the bodies ability to store energy during the
stretch shortening cycle you can perform exercises that are called
plyometrics. These involve short, fast and explosive movements that
will over time improve your ability to store energy in a stretched
muscle and use it for more powerful and explosive movements.
A testament to the power of plyometrics is the fact every professional sprinter and track and field athlete uses them extensively in their training
to improve power.
Types of exercise and their use during the year
There are many different plyometric exercises and they are classified
on how much stress they cause to the body, low, medium or high intensity.
The key to using these exercise is the way they are varied during
the year and how they fit in with the other training methods. This
is all covered by the laws of periodization.
Combining the techniques
Plyometrics are just one of the different training areas any serious rugby player should focus upon.
The mains areas to focus upon are agility, sprint training, plyometrics, resistance training, aerobic fitness, core and flexibility.
The combination of these based upon your specific needs will produce