Both static and dynamic exercises influence the cardiovascular system and its functioning. During static exercises, compensatory changes are made, not immediately but progressively, until the optimal circulatory and respiratory conditions prevail. Unless the dynamic exercise is too strenuous, the compensation is adequate. During dynamic exercise, the demands placed upon the circulatory system exceed the possibility of adequate change, and the balance is temporarily run as oxygen debt.
The minute output of the heart clearly shows the minute volume of blood flow through the general circulation, and the minute output must be similar for both ventricles. The heart’s output during static activity has been analyzed by different investigators using various tools ranging from four to nine liters of blood per minute. The output is significantly increased during the dynamic activity, ranging from 29 to 35 or more liters per minute. Within physiological limits, the minute volume output of the heart is usually stipulated by the minute volume of blood returning to the heart from the great systemic veins. So the heart cannot pump more blood into the arteries than it receives (Dishman, 1988). In pulmonary circulation, little blood pooling is possible so that, within some limits, as much blood is returned to the left heart as is pumped from the right heart. In the systemic circulation, the condition differs. During dynamic exercise, more and more of the tissues become active with accompanying vascular changes (vasodilatation) and with a tendency toward pooling the blood.
During the static exercise, the contractions of the skeletal muscles press on the capillaries, venules, and thin-walled veins within and between them and other rigid structures, resulting in the blood being forced forward in the direction of the greater veins and right heart. Also, this process on the veins is due to the exchange pressing and releasing issue of the contracting and relaxing muscles, which varies considerably in static and dynamic exercise intensities but differs markedly in character. This fact is correlated undoubtedly with the relative amounts of muscle employed, the position of the muscles relative to that of the main venous channels, and the relative frequency of the contractions and relaxations. When we consider two almost equally exhaustive sports, like running and rowing, the movements in the latter are never very rapid. At the same time, in the former, they are not only rapid but rhythmical (Cox, 2000).
Data results on the oxygen consumption per kilo body weight per minute indicate that running, owing to its greater ease and the higher frequency of its movements, induces a considerably greater circulation rate of the blood than rowing of about equal intensity. Because of this, the heart of the runner is subjected to less strain than that of the oarsman. Maintained static contractions of the muscles not only do not aid in pumping the blood forward but may even hinder the venous return and, although, make such exercises exhausting out of all amount to the total energy expended (Department of Health 1994). During dynamic exercises, venous pressure rises. This is in part due to the auxiliary pumping action of the muscles and of respiration, probably also to other factors. It has been pointed out by Henderson and his coworkers that the venous return seems to be in some method correlated with the oxygen requirement (Bowling, 1995).
For the first few seconds, at least, the acceleration of the pulse is due largely to a shortened diastole, but after a short period of dynamic activity, the systolic period is shortened, allowing more beats per minute and thus indicating activity of the accelerator mechanism. He noted that when the pulse rate reaches 135 per minute, systole and diastole are usually equal in length, but above 185 diastoles becomes shorter in duration than systole. The latent period of the human heart in response to psychical activity is about one heart cycle (Berlin & Colditz 1990). That the heart rate is accelerated during physical exercise and work is a matter of common knowledge. It is influenced by both the type and intensity of the exercise. A person whose normal resting pulse rate is 70-75 minutes has a heart rate of 160 or even 180 for the same interval during intensive exercise. Assuming that the volume of blood expelled at each stroke output remained the same as during rest, his heart output would be augmented only about two and one-half times. This is about the limits of the maximum reserve in possession of the heart by virtue of a change in the rate of a beat alone (Bennett & Murphy, 2000).
Physical activity is closely connected with the increased oxygen requirement of the active tissues. During static exercise, this is affected primarily by mechanical factors which serve as support to the heart in maintaining circulation. The increased blood flow from the veins into the heart cannot be effected promptly but requires a brief interval for a complete change to be made to the new conditions incurred by the onset of the activity. When the blood has passed through the capillaries from the arteries and heart, the driving force of the heart has been lost, so the blood would return slowly through the veins. The erect position normally assumed by man imposes additional opposition to the venous return from all parts of the body situated below the level of the heart due to the effects of gravity and the hydrostatic factor. Only a relatively small part of the total circulation is affected favorably by this factor, namely, in the head and neck regions (Hunt 2005). During physical executives, static and dynamic, vascular changes are made at the onset of physical exercise, but they are equally rapid and effective at its cessation.
References
Bennett, P., & Murphy, S. (2000). Psychology and health promotion. Buckingham: Open University Press.
Berlin J.A., & Colditz, G.A. (1990). A meta-analysis of physical activity in the prevention of coronary heart disease. American Journal of Epidemiology, 132, 612-628.
Bowling, A. (1995). Measuring health: A review of quality of life measurement scales. Buckingham: Open University Press.
Cox, R.H. (2000). Sport psychology: Concepts and applications. Dubuque, IA: W.C. Brown.
Department of Health (1994). More people, more active, more often. London: Department of Health.
Dishman, R.K. (Ed.) (1988). Exercise adherence: Its impact on public health. Champaign, IL: Human Kinetics.
Hunt, S.M., McEwan, J., & McKenna, S.P. (2006). Measuring health status. London: Croom Helm.