Physiology of Concept 10 10 Training

of Concept 10 10 Training

An objective of Concept 10 10 resistance training is to create more tension in a muscle for a given workload. This is accomplished by decreasing the speed of movement. The amount of force or tension a muscle can develop during a muscle action is substantially affected by the rate of muscle shortening (concentric phase) or lengthening (eccentric phase) (Smith, Weiss, and Lehmkuhl, 1995). The amount of tension generated in a muscle is related to the number of contracting fibers. Each muscle fiber (or muscle cell) contains up to several hundred to several thousand myofibrils, which are composed of myosin (thick) and actin (thin) protein filaments (Guyton and Hall, 1996). The repeating units of thick and thin filaments within each myofibril comprise the basic contractile unit, the sarcomere. In a muscle fiber, the slower the rate at which the actin and myosin filaments slide past each other, the greater the number of links or cross-bridges that can be formed between the filaments (Smith, Weiss, and Lehmkuhl, 1995). The more cross-bridges there are per unit of time, the more tension created. Thus at slow muscle action speeds, a higher number of cross-bridges can be formed, which leads to a  maximum amount of tension for a given workload.

The tension in a muscle is related to the number of motor units firing and to the frequency with which impulses are conveyed to the motor neurons (Berger, 1982). Physiologically, using a slower speed protocol requires the activation of more muscle fibers and an increase in the frequency of firing in order to maintain a force necessary to lift a given workload (Smith, Weiss, and Lehmkuhl, 1995). This provides stimulation for muscle strength development. The initial strength development involves neurological adaptations (stimulation of muscle fibers through increased firing and recruitment) followed by muscle hypertrophy (Enoka, 1986). In muscle hypertrophy, an increase in protein synthesis results in a multiplication of myofibrils within muscle fibers leading to an enlargement of the cross-sectional area of the muscle (Berger, 1982). There is also a corresponding increase in the number of actin and myosin
filaments, which subsequently increases the capacity for cross-bridge formation (Guyton and Hall, 1996).