High-G environment and responses to graded exercise

Effects of acceleration in the Gz axis on human cardiopulmonary responses to exercise

“…A signal proportional to the power was recorded continuously. The crank axis was at the level of the seat (Bjurstedt et al 1968). The subject had both a tachometer and a metronome to indicate the pedalling rate.…”

“…The evolution of space stations in the past 20 years and the installation of equipment, including cycle ergometers and respiratory monitoring systems, have allowed acquisition of some data in microgravity, parts of which have been published (Buderer et al 1976;Levine et al 1996;Michel et al 1977;Shykoff et al 1996;Girardis et al 1999). At high a g , although a few papers reporting metabolic data during exercise in a spinning human centrifuge can be found (Bjurstedt et al 1968;Nunneley and Shindell 1975;Nunneley 1976;Bonjour et al 2010), very little is known of the cardiovascular response to exercise. Bjurstedt et al (1968) and Bonjour et al (2010) reported only heart rate (f H ) values during exercise at high a g .…”

“…At high a g , although a few papers reporting metabolic data during exercise in a spinning human centrifuge can be found (Bjurstedt et al 1968;Nunneley and Shindell 1975;Nunneley 1976;Bonjour et al 2010), very little is known of the cardiovascular response to exercise. Bjurstedt et al (1968) and Bonjour et al (2010) reported only heart rate (f H ) values during exercise at high a g . Cardiac output ( _ Q) during increased a g was reported by Rosenhamer (1967), Bjurstedt et al (1974) and Pendergast et al (1987), but the first two of these studies might have had technical limitations, the second presents data at one relative work load only (50% of maximal aerobic power at 1 g, without accounting for possible negative effects of a g on maximal aerobic power), and the last is a partial preliminary report in a book chapter.…”

Gravitational Force and the Cardiovascular System1

“…To this end, studying normal subjects in an increased G z environment may provide insight into the feedback mechanisms involved in the prevention of or tolerance to orthostatic hypotension. Many studies of G z tolerance have been conducted; however, relatively few have measured cardiovascular variables during steady state adjustment to increased G z [6,13,20,23,25]. Data from these studies are combined with data from our studies in table II.…”

“…In early studies [6,23], it was suggested that low levels of exercise supported the cardiovascular system during increased G z ; it was already well known that straining maneuvers assist G z tolerance [2,10,17]. No studies, however, follow the cardiovascular variables over a period of constant G z .…”