– Power can be defined as strength, divided by the time taken to perform the task.

– Power like all physical characteristics can be improved with training.

– Plyometrics can be used to develop power for sports conditioning & to add variety to any training program.

Formula for Power
Power =	Strength (Force x Distance) Time

Definition

Plyometric training involves a muscular contraction known as the "stretch shortening cycle" (SSC).

When the muscle lengthens under load (eccentric contraction) and followed by an immediate and powerful concentric contraction, a greater amount of muscular power is developed.

This is due to:

– The storage of elastic energy in the muscle, similar to a rubber band.

– The activation of the muscle spindles & golgi tendons when the muscle is on stretch. This causes the muscle to immediately contract as a safety mechanism.

According to the definition, any quick eccentric/concentric contraction that activates the stretch shortening cycle is plyometric.

Example one — Jumping:

Try to jump without bending the knees. Then try holding the bent knee position & then jumping.

Example two - Shoulder drop:

Perform the lowering phase of the shoulder press quickly. What happens?

Plyometric & skill performance

Many basic sporting skills are "plyometric" in some nature.

To perform these skills correctly some form of SSC will take place.

These skills also require vision & decision making to be successful & have a general & specific factor. (e.g jump shot)

Plyometric tasks are energy efficient, as they utilise a natural mechanical advantage, instead of energy utilisation.

For example, the SSC action of the soleus muscle will reduce the amount of energy required in running. The SSC action in the trunk will increase the power of a tennis serve without increasing energy output.

Sports Skills & Plyometrics

 

 

 

 

 

 

 

 

 

 

 

 

 

Contact Time

The SSC is more effective with quick movements, with minimum contact with the ground or throwing implement. Decreasing contact time will increase the power of the movement & the stored elastic energy will not be lost. Once the foot hits the ground/implement is caught/body twisted (depending on the exercise) the opposing action needs to be applied forcefully. Increased contact time is a sign of fatigue & the drill needs to be terminated or changed. This benefit will only come with prolonged training and is not achieved in the first few attempts. Technique must be developed correctly & gradually.

Example three - Chest throw:

Once the ball is caught with out stretched arms, in needs to be thrown back immediately, almost instantaneously. Try performing the drill with a pause between the catch & the throw.

Why use plyometric training?

There are many reasons for incorporating plyometrics into a conditioning program:

1. Minimal equipment is required
Only a few pieces of equipment may be required to perform plyometric exercises. Such as medicine balls, & boxes.

2. Large groups can be trained at one time
Any number of people can perform plyometric training.

3. Overload can be easily achieved
Overload can be achieved in a number of ways. Plyometrics can be divided into the following categories, low, medium, high and very high intensity. Overload can also be achieved by increasing repetitions, reducing rest period, increasing speed of movement or increasing distance.

4. Variety of different movements
Plyometric movements are sports specific. Some examples include jumping drills for basketball and volleyball, bounding drills for sprinting and medicine ball drills for tennis.

5. Utilisation of a natural human movement
Plyometric exercises utilise a natural human movement and develop this movement to increase it's potential in athletic performance.

Plyometrics & the personal trainer

The case against plyometrics

It should be pointed out that there is a school of thought that believes plyometrics are not a valid form of training for sport or general fitness.

This view is based on the following:

Safety considerations

Plyometric training is a very effective form of training when performed correctly. If performed incorrectly, there is a certain risk of injury. The following guidelines will help ensure the athlete/client is less likely to be injured while performing plyometrics.

1. Adequate warm up
A warm up should be performed to prepare the muscles for the strenuous activity that will take place. If the muscles are not fully warmed up they will not receive as effective stretch. Due to the impact involved in plyometric exercises, cold muscles can tear easily. Activities such as short sprints and small jumps can provide a more specific warm up.

2. Stretching
Athletes should ensure that they always perform adequate stretching before and after training, to reduce the risk of injury. Dynamic mobility exercises are very important in the warm up. Stretching exercises should also be performed between sets.

3. Perform on a soft surface
Plyometric training should be performed on a relatively soft surface. Grass or synthetic tracks are good surfaces on which to perform plyometrics. Lower impact drills can be performed on carpet, matting or sprung aerobics floors.

4. Wear correct footwear
Footwear that is stable and has adequate cushioning must be worn.

5. Proficiency & technique
The athlete/client must be proficient in the basics before attempting more intense plyometric exercises.

6. Recovery
Allow at least 48-72 hours between sessions to ensure full recovery. Beginners may need even longer recovery periods. An athlete/client should never perform plyometrics if they are sore from a previous session.

7. Age
Younger athletes/clients must only attempt low intensity exercises. Similarly, older athletes/clients must not attempt higher intensity exercises, until they have mastered lower intensity ones.

8. Preparation
Any persons undertaking plyometrics should have an adequate level of strength, fitness, balance & stability. They should also be free from injury or any other condition that may effect performance.

Example four

Warm Up steps for circuit with plyometrics

Walk > Jog > stretch > run throughs >mobility drills (leg swings, arm swings, bum kicks, rotator cuff) > low intensity drills >higher intensity drills.

Training guidelines

Plyometric training has specific guidelines, which need to be followed closely to ensure a successful program. The following guidelines also outline how to conduct each session.

Program Guidelines

Take 10 minutes to perform warm up activities before each session, such as running, forward, sideways & backwards. Small jumps should also be undertaken to prepare the muscles for work.

Example five - Court sport athlete:

Low intensity, quick step drills performed no more than twice a week. 2 or 3 exercises per session performed just after the warm up. Include one medium intensity drill after 6 weeks of training.

Example six - Fit PT client:

Medicine ball drills as part of circuit training, once a week. Low/medium intensity drills as part of boxing session (10 punches-2 tuck jumps for 10 sets)

Example seven - Weight trainer:

Use short response plyometric drills as a superset with weight exercises (drop push ups with bench press, box jumps with leg press etc)

Plyometric exercises

The exercises are divided into four categories, according to their level of intensity. Beginners should start on low intensity exercises and move onto higher intensities as they mature and master basic techniques.

Low intensity

Training Guidelines

 

Ankle Hops

The client stands with the feet parallel and shoulder width apart. He/she jumps as high as possible, pushing off the toes and keeping the legs straight.

Ski Jumps

The client stands on one foot. The other leg is bent at 90 degrees, with the foot behind the body. They jump to the side, landing on the other foot.

Low Lateral Jumps

A small obstacle, such as a dome marker or a line, is required for this drill. The client stands to the side of the obstacle, with feet parallel and ankles close together. Keeping the ankles close together, he/she jump up and over the obstacle, i.e. side to side.

Chest Throws (medicine ball)

Two clients sit opposite each other, with the soles of the feet touching. One holds the ball to their chest, then throws it to his/her partner, similar to a basketball pass. The other catches the ball and immediately throws it back.

Side Ball Throw

The clients stands side on with the ball out in front. They throw the ball to one another by twisting the trunk. The ball is caught & returned as quickly as possible.

Medium intensity

It is important to have mastered correct technique before moving to medium intensity exercises.

Training should be kept to only a few exercises per session, no more than once a week.

Training Guidelines

Tuck Jumps

The client stands erect with feet parallel and shoulder width apart. He/she jumps as high into the air as possible, bringing the knees up to the chest. The arms are held across the chest throughout the drill. A small jump between reps may help beginners develop the correct technique.

Squat Jumps

The client stands erect with feet parallel and shoulder width apart & the hands behind the head. He/she jumps as high into the air as possible, keeping the legs relatively straight.

Split Jumps

The client starts with one leg in front of the body, the other leg behind. Both legs are bent slightly at the knee. They jump into the air as high as possible. While in the air the legs change positions.

Lateral Jumps

This exercise is performed the same as low lateral jumps, however a higher obstacle is used, e.g a witch’s hat or small hurdle.

Double Leg Jump

The client starts with feet parallel and shoulder width apart.

He/she jumps forward swinging the arms, trying to gain as much distance as possible.

When the client lands, he/she should spring into the next jump as quickly as possible.

Overhead Throw (medicine ball)

Two clients go down on one knee, facing each other. One of them holds the ball above the head in two hands and throws it to their partner, similar to a soccer throw in. The other catches the ball and throws it back as quickly as possible.

Ball Wall Throw

The client stands opposite a wall, hloding the ball to one side. They throw the ball across the body, catching it on the other side.

Twist & Throw

Two client stand side by side, approximately one metre apart. One holds the ball out in front. He/she throws the ball out in front of their partner, using a powerful rotation of the trunk. The partner catches throws the ball back the same way.

Lateral Hops

The client stands with feet together and legs slightly bent. They jump directly to the side as far as possible, keeping the feet together.

Box Jumps

The client stands facing a box, 30-50cm in height. He/she jump onto the box, making sure the whole foot lands on the box, then steps off and repeat the exercise.

High intensity

At least six months to a year of strength & medium intensity plyometric training is required before attempting high intensity exercises. Remember to keep the training load low as the training intensity increases.

Training Guidelines