CARDIOVASCULAR STRESS ASSOCIATED WITH SUBMAXIMAL ISOKINETIC EXERCISE IN YOUNG AND OLDER ADULTS

Abstract

1989 We compared heart rate (HR), mean arterial blood pressure (MAP) and rate-pressure product (RPP) responses to submaximal isokinetic concentric (CON) and eccentric (ECC) knee extension exercise at the same absolute torque output in 20 young (M&SD=23.2&1.7yr) and 20 older (M=75.2&4.6yr)adults. After determination of peak CON and ECC torques, subjects performed separate, randomly ordered, two-minute bouts of CON and ECC exercise at 90 degrees/s (exercise intensity = 50% of CON peak torque). Peak torques were higher (p<0.001) in ECC exercise, and were also higher (p<0.001) in younger vs. older adults for both CON and ECC exercise. HR, MAP, and RPP increased (p<.001) throughout the exercise bouts for both age groups. CON exercise elicited a greater HR, MAP, and RPP response than ECC exercise (p<0.001) for both age groups. There was no difference in peak HR or RPP between young and older adults for either type of contraction, however, peak MAP was higher in the older adults. Thus, at the same absolute torque output, isokinetic CON knee extension exercise elicited a significantly greater level of cardiovascular stress than ECC exercise in both young and old adults. These results have implications for determining appropriate fitness and rehabilitation programs for older adults. Supported by the Natural Sciences and Engineering Research Council