Following a strength training program a muscle enlarges itself (Morpurgo, 1897), or hypertrophies as a result of the following factors:
- the number of myofibrils (the slender threads of a muscle fiber) per muscle Tiber increases (hypertrophy),
- an increased capillary density per muscle fiber,
- an increased amount of protein,
- and an increased total number of muscle fibers.
Zatsyorski (1968) considers that strength magnitude is a function of the following three factors:
- Intermuscular co-ordination, or the interaction of various muscular groups during performance. In a physical activity which requires strength there has to be an adequate co-ordination between the muscle groups which take part in the action. Often the muscles are involved in a certain sequence. For instance in clean and jerk (weight lifting), at the start and during the early part of the lift the trapezius muscle has to be relaxed. This muscle, however, should take part in the jerking phase. Very often though, even some elite athletes contract the trapezius from the beginning of the lift. This lack of co-ordination results in an alteration of the technical pattern of the lift, and consequently in an ineffective performance. Similarly, in sprinting events often the contraction of shoulder muscles has a negative effect upon the sprinter’s performance. Therefore, it seems that the consequence of inadequate intermuscular co-ordination is a performance below one’s potential, and both the coach and athlete should pay attention to it. Relaxation techniques seem to lead to an improvement in the coordination of muscular contractions.
- Intramuscular co-ordination; an athlete’s force output depends also on the neuromuscular, units which simultaneously take part in the task. According to Baroga (1978) if during an arm curl the muscle biceps brachii has a maximum force output of 25 kg, electrical stimulation of the same muscle may result in an elevation of the muscle’s force capacity by 10 kg. It is therefore apparent that the athlete often is not capable of involving all of the muscle fibers in any particular activity. This phenomenon is called by Kuznetsov (1975) the “force deficit” and may be improved by the employment of maximum load or other training methods (forthcoming in this chapter) which result in the recruitment of more neuromuscular units.
- The force with which the muscle reacts to a nervous impulse. A muscle reacts to a training stimulus with only about 30% of its potential (Kuznetsov, 1975). The employment in training of the same methods or loads only leads to a proportional training adaptation. In order to elevate or bring about a superior threshold of adaptation higher intensity stimuli have to be used since maximum stimuli results in maximum effect. Therefore, one of the consequences of a systematic training is the progressive improvement of the nervous impulses synchronization, and the intensive activity of the antagonistic muscle (a muscle that acts in opposition to the action of another muscle) with the agonistic muscle (prime mover). A training program will also enable muscle fiber groups to alternate so that when one group of muscle fibers exhaust, another group will start to contract, thus resulting in strength improvement