Abstract

The anaerobic threshold (AT) is defined as the VO2 at which blood lactate concentration lactate begins to systematically increase (lactate break point) during incremental exercise. Numerous studies have shown that gas exchange break points at the anaerobic treshold correlate highly with the lactate break point. Recently, it has been suggested that the anaerobic threshold occurs at a fixed lactate of 2 mM or 4 mM. We therefore compared the gas exchange AT to the three lactate criteria (break point, 2 mM, and 4 mM) for AT estimation. Fourteen subjects performed an incremental cycle ergometer test. Ventilation and gas exchange were computed every 30 s. During the same 20-s intervals, venous blood was sampled for lactate. Four criteria were used for AT determination: (1) systematic increase in VE/VO2, without a concomitant increase in VE/VCO2; (2) lactate break point; (3) 2 mM lactate; and (4) 4 mM lactate. Relative to the gas exchange criterion, AT was higher by 44, 280, and 1028 ml/min for the three lactate criteria, respectively; the last two being significantly different. Thus, the anaerobic threshold discerned from gas exchange or the lactate break point does not correspond with a fixed, absolute lactate of 2 mM or 4 mM. Verf.-Referat