Plyometrics play an important role in the development of any athlete. They're effective at turning strength into speed, which is critical in every sport. In a simple linear plan for training an athlete, plyometrics would fall between power generation and speed development. However, many coaches use them as a substitute for strength training exercises, or as a sport-specific developer of anaerobic capacity, which misses the point.
How They Work: Plyometrics (as defined by a rapid stretch-shortening cycle in muscle fibre) improve speed by increasing Rate of Force Development. This happens in three ways: by recruiting more muscle fibres with each movement; by recruiting muscle fibres in a more efficient pattern; and by turning each individual fibre on more rapidly. All three of these are limited by the nervous system, NOT muscular energy systems. That's absolutely critical to understand, if you're to use plyometric training appropriately.
How They're Meant To Be Used:
In very low-rep, high-rest-interval training blocks. Plyometrics are usually used in blocks of 1,3, or 5 reps. It's useful to have a knowledgeable trainer close by, because if form degrades, it's best to end the block early than to reinforce bad technique. Practice makes permanent!
Since they're primarily used to improve nervous system recruitment, rest intervals should be determined by the same. Your muscular metabolism will have the muscles prepared to move again BEFORE the neuromuscular aspect is ready, so force long rest intervals between blocks.
Plyometrics also take advantage of stored elastic energy in the muscle, which means a rapid turnover of force and a quick direction change, usually from down to up (with gravity to against gravity.)
When To Use Them:
If you really want to improve your speed and explosiveness, then plyometrics should follow a phase of solid strength training that includes some heavy movement in all planes. If you're too young, or injury prevents you from heavy movement, plyometrics can be used effectively after a few weeks of bodyweight strengthening exercises.
Do plyometrics first in your workout, ahead of strength exercises, and immediately following skill-based exercises. A solid warmup is required, so agility work is good beforehand, as long as it's not too intensive. 10 minutes or less is a good guideline. Be fresh, not tired, or you'll just reinforce bad motor patterns.
How To Use Them Best:
Plyometrics, by definition, begin with a rapid shortening of the muscle (a contraction,) followed by an explosive lengthening of the muscle. For example, dropping from a height, landing on two feet, sinking into a squat position, overcoming your downward momentum, and exploding upward into a jump is a plyometric maneuvre. Jumping from a static position onto a box is not, since there's no pre-loading of the CNS.
A good program would be put together this way:
1. Agility/Coordination as a warmup
2. Plyometrics – lower body
3. Plyometrics – upper body
4. Explosive, non-plyometric lifts: speed squats, cleans, jerks, speed deadlifts, speed bench
5. Rep work
Common Mistakes: many coaches simply do too many repetitions, or don't allow adequate rest for the nervous system to recover. Remember: the CNS recovers more slowly than the muscle does; increasing speed and power requires a longer rest interval, which has little correlation to heart rate. If your goals include increasing speed and power, high-rep plyometrics (more than 5) won't work. Best case, you're not improving; worst-case, you're reinforcing bad habits that will make you slower in the long run.
Occasionally, a coach will use a plyometric exercise (eg box jumps) to train anaerobic capacity. This works because plyometrics require the Valsalva maneuver – closing of the glottis to aid in spinal stability – and therefore a rapidly-increasing heart rate. That's fine, but increasing stamina and improving speed are two different things, and should be trained differently. Plyometrics are a very valuable tool, but like everything else, they're not a magic bullet that will improve all aspects of your game by themselves.
Our boxes: Pal, Pukey, and Pandora.