Abstract

Anaerobic thresholds of five male subjects were determined invasively (ATi), from a marked increase in plasma lactate above resting levels (DeltaLa), and noninvasively (ATn), from a nonlinear increase in minute ventilation (VE) during incremental work (IW) leg cycling tests; work rate was increased 30 W every 2 min. Each subject also performed four constant-load work (CLW) tasks just above and just below their ATn and respiratory compensation threshold (RCT), i.e., the point expressed as 02 consumption (V02) or work rate, at which VE increases disproportionally to C02 output during IW. In four of the five subjects the ATn preceded the ATi during IW. Yet the ATn delineated the CLW in which marked lactate accumulation did or did not occur. During CLW just above the ATn in these same four subjects, VE/V02 and fractional expired 02 (FE02) peaked well before DeltaLa plateaued. These findings suggest that exercise hyperventilation is not necessarily proportional to increases in plasma lactate. Verf.-Referat