Cardiovascular responses to exercise as functions of absolute and relative work load

Abstract

The roles of absolute and relative oxygen uptake (VO2 and percent of muscle group specific VO2 max) as determinants of the cardiovascular and ventilatory responses to exercise over a wide range of active muscle mass have not previously been defined. Six healthy men performed four types of dynamic exercise--one-arm curl, one-arm cranking, and one- and two-leg cycling at four different relative work loads--25, 50, 75, and 100% of VO2 max for the corresponding muscle group. VO2 during maximal one-arm curl, one-arm cranking, and one-leg cycling averaged 20, 50, and 75%, respectively, of that for maximal two-leg cycling. Cardiac output was linearly related to VO2 with a similar slope and intercept for each type of exercise. Heart rate at a given %VO2 max was higher with larger active muscle mass. In relation to %VO2 max, systemic resistance was lower and plasma catecholamine levels were higher with larger active muscle mass. The cardiovascular responses to exercise are determined to a large extent by the active muscle mass and the absolute oxygen uptake, with the principal feature appearing to be the tight linkage between systemic oxygen transport and utilization.

Pressor Response to Static and Dynamic Knee Extensions at Equivalent Workload in Humans

“…This should be a natural result because VE is correlated with V . O 2, independent of exercising mode [30]. Moreover, it is possible that ventilation was not affected very much by metaboreflex as the cardiovascular system was [31].…”

Freqüência cardíaca máxima em idosas brasileiras: uma comparação entre valores medidos e previstos

“…This HR behavior during graded exercise is well-established in the literature, both in young and elderly subjects 15,16 . Some factors influence HR increase during physical exercise, which is indeed all-important for enhancing cardiac output to meet active muscle oxygen demand 20 . Exercise induces considerable acute autonomic adaptations, which greatly affect the cardiovascular system, including the chronotropic function 21,22 .…”

Comportamento da freqüência cardíaca e da sua variabilidade durante as diferentes fases do exercício físico progressivo máximo

“…Essa relação entre a FC e o consumo de oxigênio demonstram que o comportamento da FC durante o exercício depende, em grande parte, da demanda metabólica na musculatura ativa 27 .…”