What is Plyometrics?
Plyometrics is a method of developing explosive power. It is an important component of most athletic performances. Plyometrics have been integrated into overall training programs in many sports and it has made a significant factor in planning the scope of athletic development. Power is the combination of strength and speed, is the application of force through a range of motion within a unit of time, and is essential in performing most sport skills.
What does Plyometrics do?
Eccentric muscle contraction is the central type of contraction used in plyometric training. Eccentric muscle contraction allows a muscle to sustain greater tension that it can develop in an isometric position. Because the load applied to the muscle causes it to work by lengthening, it is called negative work. When muscles contract eccentrically, they lengthen and produce force simultaneously. The energy cost of the negative work is less than that of positive work. The body requires less motor-unit activation and consumes less oxygen in eccentric contractions and exercise, compared with concentric contractions. There is a higher mechanical efficiency in eccentric than in concentric exercise because the body generates a higher tension at the point of the muscle’s insertion producing more force in the muscle. Eccentric muscle contraction allows for the stretch response which involves parallel muscle fibers exerting maximal tension at stretch lengths slightly greater than resting length. An important component accompanying strength is the muscle’s elasticity, its ability to lengthen and increase in tension, which resides in the contractile elements of skeletal muscle. The range of elasticity is directly proportionate to the ability of the tissue to resist forces and return to its original shape upon releasing a load; it is this elastic property that plyometric training plays on.
Eccentric and concentric muscle actions usually occur simultaneously in combinations of muscle function known as the stretch-shortening cycle (SSC). Defining the principles of the stretch-shortening cycle will help us understand not only what is occurring within training and performing but also how to apply these principles; which is useful in planning plyometric training. The basis of voluntary and involuntary motor processes involved in the stretch-shortening cycle is the so-called stretch reflex. This stretch reflex and spindle apparatus are vital components of the nervous system’s overall control of body movement. When executing most movement skills, the muscles receive a load and the rapid stretching (loading) of these muscles activates the muscle spindle reflex, which sends a message through the spinal cord to the muscles. This message causes the muscles to contract powerfully. The stretch-shortening cycle combines an eccentric contraction, in which the involved muscles undergo tension through lengthening or stretching (negative work) and a concentric contraction, in which the muscles shorten (positive work).
Progressive Overloads:
Exercises that use the stretch-shortening cycle, or plyometrics, stimulate the neuromuscular system, enhancing the ability of the muscle groups to respond more quickly and powerfully to changes in muscle length. Plyometrics allows you to formulate exercises that isolate various sections of the body for training. Exercises that are involved includes jumps, bounds, hops; flexions, extensions, trunk rotations; and tossing, throwing, or passing. Plyometrics use different types of overloads to develop strength, power, and endurance: Resistive Overload, Spatial Overload, and Temporal Overload.
|
Resistive Overload
|
Spatial Overload
|
Temporal Overload
|
|
|
|
|
|
|
- Sagittal, transverse, frontal
|
|
|
|
|
|
|
This overload takes the form of rapidly stretching a limb or the entire body in an eccentric contraction.
|
This overload is accomplished by increasing the range, within the desired plane of movement, or increasing the range of motion.
|
This overload is accomplished by executing the movement as rapidly and as intensely as possible.
|
Evaluate Your Athletes:
- Age
· Age is an important consideration for plyometric training. Youngsters who have not reached puberty should not participate in plyometrics, especially at the intense levels. It is recommended that 12- to 14-year olds use plyometric training as preparation for future strength training. As age increases, the ability of the nervous system, muscle and joint pliability and energy production decrease, which makes plyometric training less attractive to older athletes.
- Flexibility
· Flexibility is a key issue when considering a plyometric workout. Look to see if flexibility exists, or fails to exist, in the ankles and calf muscles for proper foot mechanics. Also, look at the flexibility in the shoulders, hips, and spine for proper hip set and segmental cushioning.
- Posture
· Posture is also an element that is very critical in plyometric training. Notice the proper use of the torso mechanics; pelvic tilt; and positioning in cervical, thoracic, and lumbar spine. Look for balance in equilibrium, torso tilt, and each appendage’s joint alignment. Assess the stability of the foot as it is in contact with the ground, the firmness of stance, joint tension, and coordinated control.
- Past Injuries
· Past injuries could be a limiting factor in a plyometric workout. Because of joint or muscle instability, past injuries could hinder the ability to perform the high intensity and high impact of plyometrics. Lack of range of motion from back and spine problems can also be problematic for this type of training.
Selecting Equipment:
Facility:
· Natural grass is preferred for eccentric-style training
· Cushioned hardwood floor
· Do not use any surface with more cushion than a wrestling mat
· Concrete, cement-hard grass surface, and muddy grass are not recommended
Equipment:
· Angle Box- can be aluminum, wood, or metal
· Angle Board- can be aluminum, wood, or metal
· Bars- can range from a dowel rod to Olympic size
· Boxes- usually wooden with rubber top
· Cones
· Dumbbells
· Heavy Bags
· Hurdles- six inch to track size
· Landing Pits
· Medicine Balls- all weights and sizes
· Stair Steps
· Tubing or Bands- different resistive colors/types