August 29, 2019 by ACE Physical Therapy and Sports Medicine Institute  
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Tid Bits of Info

  • The term plyometric exercise was first used in 1964.
  • The use of plyometric exercises uses the stretch-shortening cycle of muscle contraction to develop a more forceful contraction.
  • Plyometric exercises involve all three types of muscle contractions : eccentric, isometric and concentric.
  • Every forceful movement is preceded by an eccentric contraction.
  • Prior to beginning a plyometric exercise routine, seek the advice of a knowledgeable healthcare professional.

For many athletes, plyometric training has proved to be an effective conditioning program that helps develop power and strength. Though it’s been around since the 1960s, people often ask, “What is it?” In short, plyometric training involves three types muscle contraction exercises that lead to more forceful contractions. These exercises can have amazing results, but it is important that training be guided and individualized to get the best results and avoid an injury.

Plyometric exercises have been used in training of athletes since the 60s.  These exercises utilize reflexive responses to muscle tissue stretching to illicit a response.  The actual neurological phenomenon that occurs during this type of training is too complicated to describe in detail for this blog, but the exercise routine produces contraction of muscles via a reflex response in the muscle.

The actual exercise includes three types of muscle contraction, eccentric, isometric and concentric.  During the first phase of these exercises the muscle tissue lengthens while being under a great deal of tension.  This is the eccentric portion of the exercise.  During this phase there is a portion of the muscle (the spindle) that reacts to the stretch and sends a reflex signal to the spinal cord. Within the cord, this reflex signal stimulates a response that illicit the muscle tissue to contract concentrically and helps to relax or inhibit the antagonist (muscle that opposes the motion of the contracting muscle).  Lastly the contracting muscle has one more protective mechanism that responds to excessive tension in the contracting muscle tissue.  Should the tension become too great, the Golgi Tendon Organ (GTO) inhibits the muscle contraction and reduces the tension within the contracting muscle to prevent trauma to the muscle.

The second phase of muscle contraction during these exercises is the isometric phase.  This phase occurs when the eccentric (elongation) of the muscle cells is completed and the concentric or shortening phase has not begun. This phase is known is as the amoritization phase.  When this phase is shortened the amount of power and force increases during the concentric phase.

The last phase is the concentric phase or shortening muscle contraction.  The amount of force production in this muscle contraction is increased when the previous phases have produced a great deal of stored energy due to the stretch of elastic tissue in the muscle cell (similarly to stretching a rubber band to its maximum and then releasing it).

The different phases can be trained and help to produce a more powerful/forceful  muscle contraction.  Every forceful action that the human body produces is preceded by the eccentric loading of the muscle.  This is known as the stretch-shortening cycle (SSC) of muscle contraction.  The SSC, produces the stretch of the elastic properties of the muscle tissue and “stores” the energy.  When the muscle begins to shorten and concentrically contract, the “stored” energy is utilized to help produce a more forceful contraction.

The benefits of plyometric exercises are numerous.  By training the muscle to respond more efficiently and powerfully the utilization of energy is improved and the power output of a muscle mass is enhanced.  This enables someone to produce more forceful muscle contractions with less energy consumption.  When the power is enhanced the velocity of the muscle contraction improves.  This usually leads to more speed, quicker changes of direction, better control to stop and start and increase the height that someone can jump.

The use of plyometric exercises has to be individualized to every patient or athlete.  The age, injury history, pertinent medical history and basic foundational strength of the individual has to be taken into consideration. No one should begin a plyometric workout routine if they have not been involved in a basic foundational strengthening program.  This type of program should continue and the plyometric routine should be a part of it and not the other way around.

The plyometric exercise routine can cause muscle damage that is needed to develop more strength and power.  The over-load principle of strength training must be followed and the load management must take place to avoid excessive muscle tissue damage.  In most instances, the muscle strength and power will improve but the size of the muscle does not change during the initial 6-8 weeks of training.  The neural adaptation that occurs produces the improvement in power and strength.  There must be a gradual progression in the number of plyometric exercises that are performed during a workout and several days’ rest should be included to allow for adequate recovery.

Seeking proper guidance regarding what specific exercises should be included in a plyometric routine is highly recommended.  There are numerous healthcare professionals that can help you with the specifics and doing the wrong the exercises or too many of the correct exercises can lead to a significant injury.

Developing power and strength is the goal of nearly any strength training program.  The individualized training program can include some form of plyometric exercises.  Anyone that is interested in developing strength and power whether it is to enhance athletic skills or simply to make everyday life easier can benefit from plyometric exercises.

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