Intensity, duration and frequency of exercise as determinants of the response to a training regime

SummaryA group of 39 sedentary subjects were trained on the treadmill, using one of three graded intensities of effort (walking at 3.5 m.p.h., 0% slope, equivalent to 39% of their aerobic power; running at 5 m.p.h., 1% slope, equivalent to 75% of their aerobic power; running at 5 m.p.h., 6% slope, equivalent to 96% of their aerobic power). Exercise was undertaken one, three, or five times per week, and was maintained for 5, 10, or 20 min per session. The main factor influencing the extent of training achieved was the intensity of effort relative to the subject's initial aerobic power. However, training was also influenced by the frequency of exercise and (marginally) by its duration. Some training was achieved even at the lowest intensity of exercise, but the most effective regime involved the combination of maximum intensity, frequency, and duration of effort.