Mechanical and physiological calibration of four cycle ergometers

Mechanical and physiological calibrations were performed on four research-grade cycle ergometers. Ten subjects rode each ergometer twice in a randomized testing order. The subjects pedaled at 60 rpm for 5 min at each of three power outputs, i.e., 49, 98, and 147 W. Heart rate, metabolic, and perceptual data were obtained each minute. Prior to and immediately following these test rides, mechanical calibrations were obtained in duplicate. From the mechanical calibrations, Ergometer A was approximately 10% below actual values at each power output. Ergometer B demonstrated a variable error, with the largest percentage and absolute errors occurring at the lower power outputs. Ergometers C and D generally demonstrated less than a +/- 3% error. Following the physiological calibration, Ergometer B exhibited a substantial drift in calibration, while Ergometers A, C, and D maintained their original calibration. The physiological data supported the mechanical calibration, and Ergometer B demonstrated a substantial drift between the first and second trials and produced substantially different results compared with the other three ergometers. Ergometers A, C, and D demonstrated acceptable consistency in results both within trials and among ergometers. These results demonstrate the importance of proper calibration and of understanding the calibration characteristics of ergometers selected for research purposes.