Abstract
ABSTRACT
Steady state exercise is widely used for psychophysiological studies in which a constant heart rate at a predetermined level is desired. We have developed a microcomputer servo‐controlled bicycle ergometer system that can be used for administering steady state exercise. Fourteen healthy male subjects, with a wide range of fitness levels (measured by Vo2max) were exercised to either a fixed workload (130 watts) or a predetermined heart rate level (servo‐heart rate) of 122 bpm (i.e., 65% of maximum calculated heart rate for the sample). Servo‐heart rate was implemented using a feedback loop that automatically adjusted workload to compensate for immediate variations in heart rate, resulting in a more consistent heart rate. Heart rate varied from the predetermined value by 17 bpm during fixed workload but only 3 bpm during servo‐heart rate (p<.05). Therefore, by using the microcomputer servo‐controlled bicycle ergometer, heart rate was maintained at a predetermined level regardless of the subject's fitness level. 2max and workload during servo‐heart rate were significantly correlated (r= .85, p<.05). Therefore, the workload necessary to maintain heart rate at a constant level may provide an approximate index of aerobic fitness level.
