Anaerobic threshold and maximal aerobic power for three modes of exercise

Abstract
Alterations in selected respiratory gas exchange parameters were proposed as sensitive, noninvasive indices of the onset of metabolic acidosis (anaerobic threshold (AT)) during incremental exercise. Routine laboratory measures of gas exchange, i.e., nonlinear increases in .ovrhdot.VE [expiratory ventilatory rate] and .ovrhdot.VCO2 [total body CO2 consumption] and abrupt increases in FEO2 were used to investigate the feasibility of AT detection. The comparability of the AT and .ovrhdot.VO2 max [total maximae body oxygen consumption] were examined among 3 modes of exercise (arm cranking, leg cycling and treadmill walk-running) with double determinations obtained from 30 college-age, male volunteer subjects. The AT for arm cranking, leg cycling and treadmill walk-running occurred at 46.5 .+-. 8.9 (mean .+-. SD), 63.8 .+-. 9.0 and 58.6 .+-. 5.8% of .ovrhdot.VO2 max, respectively. No significant difference was found between the leg exercise modes (cycling and walk-running) for the AT while all pairwise arm vs. leg comparisons were significantly different. Using nine additional subjects performing leg cycling tests, a significant correlation of r = 0.95 was found between gas exchange AT measurements (expressed as % .ovrhdot.VO2 max and venous blood lactate AT measurements (% .ovrhdot.VO2 max). The gas exchange AT is a valid and valuable indirect method for the detection of the development of lactic acidosis during incremental exercise.

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