Abstract

The purpose of this investigation was to determine the effect of intensity and duration of exercise on energy expenditure during both the exercise and post-exercise periods. In Part A, three male and three female volunteer subjects cycled at an intensity of 70 VO2 max for 30 minutes (Day 1) and 15 minutes (Day 5). In Part B, six males cycled at 70 VO2 max for 30 minutes (Day 7) and at 50 VO2 max (Day 11) until the total work was the same as Day 7. On Days 3 and 9 no exercise was performed. During the preexercise, exercise and post-exercise rests, 30-second recordings were made of respiratory exchange ratio (R) and oxygen consumption (VO2). In Part A, gross, net (gross - rest) and total (exercise + post-exercise) oxygen cost for the 30-minute exercise and the post-exercise period were significantly greater (p<0.01) than for the 15-minute duration. In part B, the oxygen cost at 50 VO2 max and 70 VO2 max was not significantly different during the exercise but during the post-exercise period both the gross and net oxygen cost were greater (p<0.01) following the 50 VO2 max effort. Also the total net oxygen cost (net exercise + net post-exercise) was higher for the 50 VO2 max effort. These data suggest that the duration of activity is a primary stimulus to elevated post-exercise oxygen consumption. Verf.-Referat