Plyometrics
Power is the ability to produce maximal muscular forces very rapidly, and is therefore very important in the game of rugby. Plyometrics are specialist exercises that enable a muscle to reach maximal strength in a short space of time. This works by stretching a muscle and then relying on its elastic properties to produce greater forces than are normally possible in the reflex contraction (as the muscle returns to it's resting length). In order to achieve this greater muscular force, the muscle must contract within the shortest possible time following lengthening. The following drills use dynamic movements to achieve such a stretch-shortening in a muscle, thus causing a faster concentric (reflex) contraction of the muscle. You need to ensure that your body is suitably developed and well trained before attempting such exercises. Technique is very important. If possible, try to spend some time with a coach who is experienced in such techniques as you begin to use them. Individuals with a history of stress-induced injuries to the feet, ankle, shin, knees, hips or lower back should not perform plyometric activities without consulting a chartered physiotherapist.
Classification of Plyometric exercises:
Jumps: Begin and ends with one or both feet. Usually performed in sets of 8-12 repetitions. These form the lowest intensity of plyometric exercises.
Hops: Begins and ends with one or both feet, and associated with a component of maximum horizontal distance. Training volume is usually measured by sets of 4-10 reps, or by distance (i.e. covering 40-60m in a set). These are low-medium intensity exercises.
Bounds: The alternate movement associated with take-off from 1 foot and landing with the other in repetitive sequence, usually with the aim of covering as much distance between each ground contact as possible. These are classified as medium intensity exercises, and are usually undertaken in sets of 4-10 reps, or by covering a distance (for example 60-80m).
Shock: Very high intensity plyometrics, which will place significant stress on the neuro-muscular system and connective tissues. These usually constitute an element of depth jumping (jumping down from a raised platform, for example a box 40cm in height), and will have either a vertical component (i.e. Jump down and then up) or a horizontal component (i.e. Jump down and then out). An experienced performer, who is sufficiently well trained to cope with the high stresses associated with shock training, should only undertake training of this nature. The platform height will vary according to the age, weight, training status and experience of the performer. You should not undertake shock plyometrics if you are under 16, do not have a high current strength level and you are not in excellent physical condition prior to commencing the programme. As guidelines, athletes over 100kg in weight should not perform depth jumps from heights exceeding 50cm. Similarly, depth jumps should not be performed until a player can perform a freeweight squat exercise with a mass that is 1.5 times his bodyweight.
You can reduce the intensity of a plyometric exercise by lowering the centre of mass in a jump (i.e. starting from a bent over position), or by increasing the surface area of a contact, for example by landing on 2 feet rather than 1.
Progression:
You should progress your plyometrics training from exercises of low intensity to medium to high intensity, following the principle of progressive overload.
This should apply over a number of weeks, but also within individual sessions. Some low intensity plyometric exercises, for example single-leg hopping on the spot with the eyes closed, are excellent to incorporate into the warm-up routine, in order to activate the bodies internal sensory (proprioceptive) systems and stimulate the muscles around the ankle and foot joints.
Plyometric activities are ideal for pre-season training, following the period of strength development. Shock and higher intensity plyometrics should not be used during periods when the playing or training volume is high, due to the recovery time that the body needs after each session.
Plyometrics take a relatively longer time period to recover from than other training methods. Recommended frequencies therefore range from 1 session per week (low intensity work with beginners) to 3 low intensity sessions per week in an experienced performer. Very high intensity sessions may take up to 10 days to fully recover from.
Training volume:
Beginners should start of with no more than 70 foot contacts per session, and gradually progress up to 100. Intermediate players (or advanced players with large body masses) should utilise 100-120 foot contacts per session. Advanced players should work between 120-140 foot-contacts in one session. You should not exceed these totals.
Complex training:
Although plyometric training should not normally be undertaken on the same day as strength training, due to the fatigue induced in such sessions, experienced individuals may wish to combine these activities. For example, a squat followed by a cycled spit-squat jump, or a bench press followed by an explosive chest pass with a medicine ball.
Such a movement utilises the muscles involved in maximal strength exercise, and trains them in a powerful and explosive movement, therefore maximising the training effect.
Key points to consider when undertaking plyometric training
- Warm up thoroughly.
- If you experience muscular or joint problems, stop immediately.
- Wear quality footwear, which provides ankle support and has adequate, but not too much, cushioning in the sole.
- Use a flat landing surface that has good shock-absorbing properties. Surfaces such as sprung-loaded floors are not appropriate (they interfere with the elastic properties of the muscle as it operates in a plyometric), nor are heavily cushioning surfaces, such as a crash mat (they absorb too much energy and ruin the stretch-shortening mechanism of the exercise). The best surface is a grass field or tartan athletics track.
- If boxes or benches are used, make sure they are sturdy, and have a non-slip surface.
- Make sure you have an adequate area for your training. Do not put yourself at risk from obstacles (or others) that may encroach onto your activity.
- The work should be quality, therefore ensure that you are adequately rested between sets.
- Technique is very important: If in doubt, seek appropriate coaching. As with sprinting, you should land on the balls of the feet and use this area of the foot to apply force to the floor in order to accelerate the body off the ground. The contact pattern should therefore be ball-heel-ball.
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