Mehmood Bhadra

Plyometrics is defined as the exercises that enable a muscle to reach maximum force in a short period of time. Plyometric training is a series of explosive body weight resistance exercises using the stretch-shortening cycle (SSC) of the muscle fiber to enhance physical capacity such as speed, strength, and power. It is a quick, powerful movement involving pre-stretching the muscle tendon unit followed by a subsequent stronger concentric contraction. This process of muscle lengthening followed by rapid shortening during the SSC is integral to plyometric exercise. The SSC process significantly enhances the ability of the muscle-tendon unit to produce maximal force in the shortest amount of time. These benefits have prompted the use of plyometric exercise as a bridge between pure strength and sport-related power and speed. Plyometric exercise is a popular form of training used to improve athletic performance.[1][2]

Initially known as “Stretch Shortening Cycle” or “Jump Training” described by Russian national jump coach, Mr. Yuri Verkhoshansky.[3]

The term “Plyometrics” was coined by former athlete and American track and field coach, Mr. Fred Wilt.[3]

It is derived from the Greek word “Pliometric”. “Plio/Plythine” meaning more/increase and “Metric” meaning measurement. Thus meaning “to increase the measurement.”[3]

In this model, elastic energy is created in the series elastic component (SEC) of the muscle and tendon and stored as a result of rapid stretch.

This stored energy is then released when the stretch is followed immediately by a concentric muscle action by the concentric component(CC)such as actin, myosin and cross-bridges of the muscle contributing to the force production.[2]

This model is based on the concept of stretch reflex.

Stretch reflex is the body’s involuntary response to and external stimulus that stretches the muscle and the stretch receptors such as muscle spindle and golgi tendon organ.

When muscle spindle at the musculotendinous junction are stimulated, stretch reflex is seen.[2]

The SSC is a combination of both the models previously mentioned i.e the mechanical model and the neurophysiological model and it forms the basis of Plyometrics. It incorporates both, the storage of energy in the Series Elastic Complex (SEC) and the stimulation of the stretch reflex to facilitate maximum recruitment of muscle units in a short amount of time.

Stretch-shortening cycle consists of three phases:[4]

Lower Extremities:

Upper Extremities:

These are appropriate for virtually any athlete and any sport. Eg: Football, Basketball, Rugby, etc. The direction may vary from sport to sport, but most of them require the athletes the produce quick and maximal vertical or horizontal movements

Examples of lower extremity plyometrics:

These exercises are best suitable for sports that involves more of upper body demand. Eg. Cricket, Badminton, Tennis, etc.

Examples of upper limb plyometrics:

The core often plays a double role; one involving dynamic movement (provided by the outer core muscles) and the other providing strong static stability (provided by the inner core muscles). Thus these muscle groups also have to be trained along with the upper and lower extremity.

Examples of trunk plyometrics:

It is important to combine movements to better prepare athletes for the demand of their sports. A typical athlete may run, change directions, jump and throw a ball in a matter of seconds thus it is necessary to train these combination of movements in an athlete. These combinations not only produces significant results but it also makes the training session enjoyable.

Some examples of combination:

Plyometric intensity refers to the amount of stress placed on the muscles, connective tissue and joints. Initially the intensity of the plyometric exercises should be low. Gradual progression should be made in the intensity, complexity and the difficulty of the exercises.[5]

Factors affecting the intensity

Plyometrics exercises place a high demand on the athletes body thus adequate rest must be provided for the body to recover from the excessive load. Typical recovery time is between 48 to 72 hours. Thus the frequency of plyometrics training is two to four sessions per week.Each session should last for one hour which includes 15 minutes of warm up, 20 to 30 minutes of plyometric training and 15 minutes of cool down.[5]

For lower body the volume is measured by the number of contacts per workout session.Whereas for upper body, volume is expressed in number of throws/catches per session. As the training progresses the volume must be increased.[5]

Plyometrics is a form of resistance training thus the progression should follow principle of progressive overload.

The progression must be:

Currently, most of the  basic plyometrics program range from 4 weeks to 6 weeks. Advanced plyometric exercises program can range from 12 weeks to 18 weeks. During the advance phase, progression and combination of plyometrics with other training form should be done.[5][6]

Selection of plyometric training equipment must be done based on the type of exercise and the intensity. Equipment should be modifiable to suit the needs of individual athletes as no two athletes are the same.[6]

Examples of equipment:

The choice of training environment has a major impact on the effects of plyometrics exercise both in training specificity and injury prevention. The hardness of the surface can affect the amortization phase by increasing or decreasing the ground-contact time i.e., softer training surface causes higher contact time. On a softer surface the body stiffens whereas on a harder surface the body softens the connective tissue to absorb the impact and prevent injury. For athletes, It is advised to train on a relatively softer surface for major part of the training season to prevent soft tissue injury and maintain peak health during high-volume preparatory period.[6]

Some examples of training surfaces:

The choice of appropriate footwear for any training program can be critical in both performance and health.[6]

Functions of a footwear:

A good footwear should consists of:

When transitioning form early preparatory phase to pre-competitive phase the training must be carried out in the shoes that will be used for the sport. Eg: spikes for track and field athletes, cleats for soccer, rugby baseball players, court shoes for racket sports, basketball and volleyball, etc.[6]

Criteria to begin plyometric training:

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The term refers to animals that have only been fed mother's milk. They have a low level of fat.

The meat of the cow or ox has been raised for at least six months before it is slaughtered.

They weigh around 135 kilo. It is known as a "suckling calf" if it still feeds on milk.

It is low in fat and tender. It is the most consumed in the house.

The animal is between one and two years old and is fed with feed and pasture. The meat is juicy and red, without excess fat, and it has a more intense flavor than beef.

Its consumption is widespread.

A young male is fed by feed and sometimes castrated.

The meat is red.

It is the meat of a male between two and four years old. It has a more appetizing meat than the previous ones.

The adult male animal is not gelded and is used for fighting or reproduction. Its meat has a stronger flavor.

Between two and four years is when the adult female of childbearing age devotes herself to reproduction. She can weigh over 600 kilo. It is less tender than veal or yearling and has more yellow fat than red meat.

Its flavor and juiciness are excellent. She is called an old cow when she is five years old.

The neutered male from the year of birth has already completed 48 months. It can weigh more than a ton.

The castrated meat has more fat in it. It has a red color and a fat that is very fat.

It is one of the most expensive on the market and has a special fame.

Ox meat is a claim on many restaurant menu. It does not taste good. Being an older meat, it has a more powerful flavor that sometimes catches the inexperienced customer by surprise.

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