The increase in performance generally is related to the achievement of adaptive changes in the organism. Adaptive changes can be achieved by repeated application of Exercise load. The way to achieve adaptive changes in the organism is a systematic repetition of Exercise load. Repeated loads refer to as adaptation stimulus. The principle of adaptive changes is the axis: homeostasis → adaptation stimulus (load) → adaptation.
If adaptation stimuli are applied properly, training can be expected to have accumulative effect. If motor activity is carried out in such a way that it evokes desirable current change of human functional activity, and consequently long-term, structural and psycho-social changes, it can be referred to as load.
Example : If I run every other night in the park without much planning and adherence to the principles of sports training, sooner or later pass the same track may be quicker, but also feeling more relaxed, which is a simplified functional change. Psychosocial changes in this case represent my daily effort and responsibility run out every night out.
Metabolic specificity of exercise and training is based on an understanding of the transfer of energy in biological systems. Efficient and productive training program can be designed through an understanding of the process of energy repletion for muscle work of various inensity and duration of load.
Adenosine triphosphate allows the transfer of energy from exergonic to endergonic reactions. Without an adequate supply of ATP, muscular activity and growth would not be possible.
Indicators of exercse load provide information on the condition of organism during training activity. They are sensitive to changes in the size of load. Among the indicators, there are:
The ability to resist external resistance with muscle contraction represents a basic principle of developing the complex of strength ability. Muscle contraction is conditioned by many factors. If there is no visible movements of body segments during muscle contraction, this is referred to as static strength (e.g. holding tim in squat when thighs are held horizontally to the ground). On the other hand, if muscle contraction causes a visible movement of body segments by stretching (excentric muscle contraction) or by shortening the muscle (concentric muscle contraction), it is referred to as dynamic strength (e.g. mutual movement of forearm and upper arm during benchpress exercise). The dynamic strength can further be divided into partial manifestations of dynamic strength:
Maximal strength is manifested by overcoming high or even limit external resistance at a slow speed with a specific muscle group usually in one repetition (e.g. in benchpress).
Explosive strength is manifested by overcoming low external resistance or weight of own body with maximal acceleration in single (acyclic) movement of participating segments (e.g. in throws, or take-offs).