Every year we come across new or established training methods. Each method, as you know, brings its own specific adaptations. In this column, we will look at plyometric training.
Plyometrics involves the transition from an eccentric muscle contraction (muscle stretching) to a concentric contraction (muscle shortening). Some experts note that the transition between the two contraction phases must take fewer than 0.5 seconds.
The basic theory behind plyometrics can be explained as follows:
Physiological adaptations of plyometric training
The main adaptation of plyometric training is in muscle fibre recruitment, with increased intramuscular/intermuscular coordination and better motor unit recruitment. This type of training improves power. There is virtually no change in body composition and very little muscle hypertrophy.
Prescribing plyometric training
Plyometric exercises are intended for experienced clients, such as those with more than a year of regular gym training or high-performance athletes. Note that a person who wants to train using the plyometric method must be able to perform a squat lift of 1.5 times their body weight. It is important to start this type of training at a low intensity and progress gradually, as there is an increased risk of injury due to the high intensity (height of jumps, hardness of the floor, number of reps, etc.).
Plyometric training sessions should be performed once or twice a week. Keep in mind that this training should last only four to ten weeks. The recovery period is considerably longer for plyometric training—approximately four to seven days—than for conventional concentric/eccentric muscle workouts, which mostly involve a recovery period of between 12 and 72 hours.
When you prescribe plyometric training, you must consider a range of training variables to achieve the client’s objectives.
Here are some guidelines:
Reps (number of jumps)
As mentioned earlier, plyometrics improves power. For optimal results, periods of effort must last under 10 seconds. It is therefore important to keep the number of reps to between four and eight jumps per set (about 0.5 seconds per jump). This total muscle activation time targets IIB fibres and results in increased power.
The number of prescribed sets is based on the client’s physical condition. It’s better to start off training with two sets per exercise and up this to four toward the fourth week.
We don’t all have the same explosive power, so the idea is to adjust the height of the jumps to suit each person’s physical ability. Here’s a tip: place two blocks at the same height and jump from the first block to the second. The transition time between the two blocks must be under 0.5 seconds. Repeat this test, increasing the height of the blocks each time until you have trouble reaching the top of the second block (the height of both blocks, in this case, remains the same). You’ll then have found the ideal jumping height.
Rest between sets
Plyometric training causes muscle and neuromuscular (peripheral nervous system) fatigue. To allow adequate recovery (ATP resynthesis), the suggested rest period is three to five minutes. A shorter rest period than this will hinder your performance.
Plyometric training is a great way to develop your muscle contraction speed, leading to improved performance in your sport.
Be warned: your muscles will probably be sore after your first training session.
Have a great workout!
Jean-Denis Thomson, B.Sc.
Training Department Director
References: Steven J. Fleck, William J. Kraemer (1997), Designing Resistance Training Programs, 2nd ed., Champaign, IL: Human Kinetics.