Why Plyometrics?

Plyometric excercises include Jumps in place, squat jumps, split squat jumps, standing jumps, pike jumps, barrier hops, skips, bounds, alternate leg bounds, box drills, box jumps, depth jumps, and so on.

Athletes train using Plyometrics (Plyo) to build  speed and power.  As a bi-product of being fast and powerful, athletes tend to look and feel good.   So how does this work for a training regimen in the average individual, and why?  I’ll first explain simply.  To understand Plyo more scientifically, scroll down further and read under “How Plyometric Exercises Work”.

Plyometrics exercises are highly anaerobic.  This is just perfect.  Remember, training anaerobically has numerous benefits – 1. you are burning almost purely fat

2. oxygen deficit spurs bone growth 3.we are increasing power and hence workout volume 4. we are creating physiological changes such as increasing stored glycogen and creatine levels in skeletal muscle 5. we are building type 2 muscle fibers,  which are exponentially larger than the type 1 fibers used in aerobics, hence inducing very rapid changes in our physique and body composition through increased muscle mass.  Think back on the 2012 Olympic games – jumpers, male and female ARE among the most fit people on this earth.

For cardio exercise, I like to use plyo to increase one’s Anaerobic Threshold (AT). The AT varies from person to person, and, within a given individual, sport to sport. Untrained individuals have a low AT (approximately 55 % of VO2 max), and elite endurance athletes, a high AT (approx. 80 – 90% of VO2 max).

Further reading below:

What our muscles do during Plyometric exercises

A muscle that is stretched before a concentric contraction, will contract more forcefully and more rapidly (4,5). A classic example is a dip” just prior to a vertical jump. By lowering the center of gravity quickly, the muscles involved in the jump are momentarily stretched producing a more powerful movement. But why does this occur? Notice the counter-movement Two models have been proposed to explain this phenomenon. The first is the

Mechanical Model
In this model, elastic energy is created in the muscles and tendons and stored as a result of a rapid stretch (6,7,8). This stored energy is then released when the stretch is followed immediately by a concentric muscle action. According to Hill (9) the effect is like that of stretching a spring, which wants to return to its natural length. The spring is this case a component of the muscles and tendons called the series elastic component. The second model is the

Neurophysical Model
When a quick stretch is detected in the muscles, an involuntary, protective response occurs to prevent overstretching and injury. This response is known as the stretch reflex. The stretch reflex increases the activity in the muscles undergoing the stretch or eccentric muscle action, allowing it to act much more forcefully. The result is a powerful braking effect and the potential for a powerful concentric muscle action (10,11,12).

If the concentric muscle action does not occur immediately after the pre-stretch, the potential energy produced by the stretch reflex response is lost. (i.e. if there is a delay between dipping down and then jumping up, the effect of the counter-dip is lost).

It is thought that both the mechanical model (series elastic component) and the neurophysical model (stretch reflex) increase the rate of force production during plyometrics exercises (6,7,8,10,11,12).

The Stretch-Shortening Cycle

All plyometric movements involve three phases. The first phase is the pre-stretch or eccentric muscle action. Here, elastic energy is generated and stored.

The second phase is the time between the end of the pre-stretch and the start of the concentric muscle action. This brief transition period from stretching to contracting is known as the amortization phase. The shorter this phase is, the more powerful the subsequent muscle contraction will be.

The third and final phase is the actual muscle contraction. In practice, this is the movement the athlete desires the powerful jump or throw.

This sequence of three phases is called the stretch-shortening cycle. In fact, plyometrics could also be called stretch-shortening cycle exercises (1).

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