Determination of Anaerobic Threshold by the Ventilation Equivalent in Normal Individuals

Abstract

In 131 untrained healthy volunteers unsteady-state upright bicycle ergometryt was carried out by computer-assisted on-line ergospirometry. In 11 males and 4 females capillary lactate and blood gas analyses sampled simultaneously at 1 min intervals revealed that it is possible to determine the anaerobic threshold (AT) and a threshold of decompensated metabolic acidosis (TDMA) from the respiratory gas exchange by controlling the ventilation equivalent for O2 (VEO2 = .ovrhdot.VE/.ovrhdot.VO2) [expiratory ventilation rate/expiratory ventilation rate for O2] and CO2 (VECO2 = .ovrhdot.VE/.ovrhdot.VCO2). Invasive measurements are unnecessary. Solely ergospirometrical tests in 66 males and 50 females, aged 20-65 yr, showed the expected higher work load levels and .ovrhdot.VO2 at AT and TDMA in males. There was a significant negative correlation to age. There are no sex differences in AT and TDMA for weight-corrected work rates. In the age group 20-39 yr, AT is at about 1 W/ kg [work] body wt, TDMA at about 2 W/kg body wt. The larger maximum exercise capacity wt corrected for males (3 W/kg) compared to females (2.6 W/kg) was dependent on a greater capability in the range of maximum exertion and not on a different level of AT and TDMA.