Biological Effects of Physical Activity

• Main Author: Williams, R. Sanders (Author)
• Other Authors: Williams, R. Sanders 1948- Robert Sanders, Wallace, Andrew G. 1935-
• Format: Unknown
• Language: English
• Published: Champaign, Ill. Human Kinetics Books 1989; ©1989
• Series: HKP sport science monograph series v. 2
• Subjects: Physical fitness > Congresses; Exercise > Physiological aspects > Congresses; Physical Fitness > Congresses; Exercise > Congresses
• Online Access: Click Here to View Status and Holdings.
• Item Description: "Proceedings of the First Biennial PepsiCo Foundation Conference on Fitness and Health, held at Duke University, Durham, North Carolina, May 9-10, 1988"--T.p. verso
• Physical Description: vii, 180 pages illustrations 23 cm
• Bibliography: Includes bibliographies
• ISBN: 0873222180
• ISSN: 0894-4229

A knowledge about the capacity of the various links in the circulatory system in the human or any species would aid in understanding the principles for control of the cardiovascular system when under load, such as during exercise. If the heart of a species has the capacity to supply blood flow and maintain blood pressure when most vascular beds of the body are maximally dilated, then control principles are likely to be dif ferent than if the conductance of the periphery vastly surpasses the central circulatory capacity. (In humans it has been established that the various links of the circulatory system are closely interrelated; i.e., correlation coefficients are around .9 or above when the amount of hemoglobin, blood volume, heart volume, and stroke volume as well as muscle capillary density and muscle mass are related to each other or to maximal values for cardiac output or oxygen uptake (Holmgren & Åstrand, 1966). The conclusion then is that there is a good balance and match between central and peripheral capacities. During exercise a maximal vasodilation of muscle can thus be allowed (Indeed, recently it has been proposed that the blood flow to muscles is excessive during maximal whole body exercise. This notion was based on observations of some oxygen remaining in the venous blood returning from contracting muscles during exhaustive exercise at sea level and various altitudes (Wagner, 1988; Wagner et al., 1986).) (Also, the opposite view has been voiced; that is, the heart and the cardiac output are insufficient for the huge potential for a flow of the skeletal muscle (Rowell, Saltin, Kiens, & Christensen, 1986).) In this ar ticle the evidence to support this latter view will be presented.