Influence of blood donation on the incidence of plateau at VO2max

The purpose of this study was to examine the effects of reductions in blood volume and associated oxygen-carrying capacity on the incidence of plateau at (2max). Fifteen well-trained athletes (age 23.3 +/- A 4.5; mass 77.4 +/- A 13.1 kg, height 180.1 +/- A 6.0 cm) completed three incremental cycle tests to volitional exhaustion, of which the first was defined as familiarisation, with the remaining two trials forming the experimental conditions of pre- (UBL) and post-(BLE) blood donation (similar to 450 cm(3)). The work rate for the incremental tests commenced at 100 W for 60 s followed by a ramp of 0.42 W s(-1), with cadence being held constant at 80 rpm. Throughout all trials, (2) was determined on a breath-by-breath basis using a pre-calibrated metabolic cart. The criteria for plateau determination was a a dagger (2) a parts per thousand currency sign 50 ml min(-1) over the final two consecutive 30 s sampling periods. Despite a significant (P = 0.0028) 9.4 % reduction in haemoglobin concentration and 10.8 % (P = 0.016) reduction in erythrocyte count between UBL and BLE, there was no change in plateau incidence. However, significant differences were observed for both (2max) (P = 0.0059) 51.3 +/- A 7.6 (UBL) 48.4 +/- A 7.9 ml kg(-1) min(-1) (BLE) and gas exchange threshold arrival time 383.4 +/- A 85.2 s (UBL) 349.2 +/- A 71.4 s (BLE) (P = 0.0028). These data suggest that plateau at (2max) is unaffected by O-2 availability lending support to the notion of the plateau being dependent on the anaerobic capacity and the classically orientated concept of (2max).