The effect of various levels of strenuous to exhaustive exercise on reaction time.

Reaction times and heart rates of 10 subjects walking and running on a motor-driven treadmill were recorded. The exercise consisted of four 3-min stages: Stage 1, 2.5 mph at 12% grade; Stage 2, 3.4 mpg at 14% grade; Stage 3, 4.2 mph at 16% grade; Stage 4 5.0 mph at 18% grade. Subjects were given three separate tests at 1-week intervals. There was an increase in reaction time with increased exercise, but this effect diminished significantly over days. Also, when heart rate was 80% of maximum during the post-test, reaction time was not significantly different from the pre-test. Optimum reaction time was obtained at approximately 40% of maximum heart rate.