The key to utilizing stored elastic energy involved in the SSC is the ability to minimize the conversion time between the ending of the eccentric and beginning of the concentric phase of the movement. The attachment time between myosin and actin strands is brief, usually 15 to 120 milliseconds.
A long delay between the stretching and contacting phase of the movement results in increasing detachment of the myofilaments which negates the potential to utilize the elastic energy stored in the muscle (Siff 2000). There are two main factors involved with the stretch shortening cycle.
The Factors Include:
- Muscle and tendon elasticity
- As well as neural factors.
When a tendon or muscle is stretched, elastic energy is stored within its structure. The elastic energy is recoiled and used to increase the efficiency of the concentric phase of movement. The level of stored energy is proportional to the applied force and speed of the stretch. The magnitude of the stretch is a function of muscle and tendon stiffness (Zatsiorsky 1995).
The stiffness of a muscle is variable and depends on the forces applied while tendon stiffness is constant. The higher the tension in a muscle, the harder it is to stretch. Studies show that elite athletes experience a higher level of stiffness in their muscles than in tendons, thus elastic energy in elite athletes is primarily stored in the tendons (Zatsiorsky 1995).
The neural mechanisms most prominent in the SSC are the myotatic stretch reflex and Golgi tendon organ. The myotatic reflex receptors (muscle spindles) are specialized muscle fibers which detect length change within the muscle. The primary role of the muscle spindles is to set the muscle to a preset length. When the muscles are stretched the muscle spindles are also stretched.
This causes muscle spindle discharge, which results in alpha motoneuron release, which results in reflex contraction of the stretched muscle. This reflex enables the muscle to return to its present length.
The Golgi tendon organ is located in the muscle-tendinous junction and senses change in the tension of muscle. The primary role of the Golgi tendon organ is to prevent potentially injurious muscle tension. When this organ senses forces are excessive, muscular contraction is inhibited.
Golgi Tendon Organ.
One of the primary training goals for enhancing the SSC is to maximize the positive effects of the myotatic stretch reflex while minimizing the negative effects of the golgi tendon organ. This type of training could involve accelerative movements with or without weights.
Accelerative training, in this case, would refer to rapid stretching followed by accelerative contraction. Training with heavy weights at slow speeds can also be used to inhibit the golgi tendon organ.
Muscles and tendons are connected in a series. To visualize the stretch shortening cycle picture two springs connected. The first spring (tendon) has properties that do not change under the influence of movement. The second spring (muscle) has properties that vary depending on muscle stimulation (Zatsiorsky 1995).
The level of muscle tension is not constant during movement. When an athlete is attempting to exert maximal muscular contraction, subconscious as well as conscious mechanisms are at work. The two neural mechanisms we spoke about are displayed simultaneously.
The goal is to maximize the benefits of the stretch reflex and minimize the actions of the golgi tendon organ.
Plyometrics is a popular method used to enhance reactive strength. When used properly these drills have proven to be effective. The problem is these movements have been widely mis-used. Below I have provided an overview of the history and evolution of plyometric training.
Plyometric training was developed by Yuri Verkhoshansky as a means to enhance speed strength. What is now referred to as plyometrics was originally called the shock method. The original meaning of the word plyometric (originally spelled pliometric) was intended to mean concentric contraction.
Plyometrics became popular in the USA in the 70s according to most authorities. Soviet sprinters were displaying impressive sprint times so U.S. coaches decided to travel to the Soviet Union to figure out what was going on. The Americans saw an athlete step off a box, jump up in the air and the rest, as hey say, is history.
On their return to the United States, they spread the work of the magic training method. Needless to say they never took into consideration the planning and conditioning that existed in addition to this type of magic training. In the Soviet Union the shock method was used in a cyclic nature which involved varying intensity levels and conditioning methods.
Today every coach and fitness instructor in the world is probably using some type of supposed plyometrics. As an example, a coach might have an athlete jump ten minutes with no regard to times spent on the ground or quality. According to the founder of shock method training, if you spend an excess of 0.2 of a second on the ground after landing this does not constitute true plyometric activity.
The ultimate goal in shock method training is to maximize the benefits of the stretch shortening cycle as discussed earlier. The athletes need sufficient strength in the musculoskeletal system before adhering to this type of training. A great deal of force is produced in the joints when performing any type of jumping or falling.
Concentrate on quality training when using plyometrics. This should not be a fatiguing endeavor; remember the goal is speed strength.
In general, terminate high intensity plyos 7-14 days before competition.
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Tune in for Part 9 when I discuss particular strength training exercises and programs I incorporate with my MMA athletes.
About Coach Hale
Coach Hale is the owner of Total Body Fitness, Winchester Golden Gloves Boxing and MaxCondition Sports Conditioning. He designs comprehensive training programs for coaches and athletes worldwide. He is the author of Optimum Physique and contributor to numerous exercise and sports publications. Coach Hale is an official member of The World Martial Arts Hall of Fame in recognition of his strength and conditioning work with martial artists. He also serves as vice-chairman for the World Martial Arts Hall of Fame. To learn more about coach Hale visit his website at www.maxcondition.com.
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