The effects of non-contingent feedback on the incidence of plateau at [??][O.sub.2max]

The purpose of this study was to examine the effects of non-contingent feedback in the form of heart rate (HR) on the incidence of plateau at V O2max. Ten physically active males (age 24.8 yrs [+ or -] 4.2; mass 81.4 [+ or -] 9.0 kg; stature 1.80 [+ or -] 0.11 m, V O 2max 53.2 [+ or -] 5.8 ml x [kg.sup.-1] x [min.sup.-1]) who were [??][O.sub.2max] testing naive but were cognisant as to the heart rate responses to exercise completed four incremental tests to volitional exhaustion, separated by ~72 h for the determination of [??][O.sub.2max] and gas exchange threshold. The first trial served as a familiarisation with the remaining three being experimental conditions where HR was presented in a screen projection as either the actual response (HR-A) or 10 b.min-1 higher than recorded (HR-H) or 10 b x [min.sup.-1] lower (HR-L). Throughout all trials [??][O.sub.2] was recorded on a breath-by-breath basis with plateau criteria of [less than or equal to] 50 ml x [min.sup.-1]. RESULTS: A significant difference was observed for [DELTA][??][O.sub.2] over the final two consecutive 30s sampling periods between HR-A, both HR-L and HR-H (p = 0.049) and for the incidence of plateau response between condition (p = 0.021). An additional significant difference was observed for sub-maximal [DELTA][??][O.sub.2] responses between HR-A and HR-H (p = 0.049) and HR-A and HR-L (p = 0.006). Non-significant differences were observed for all other criteria. These data indicate that when presented with non-contingent feedback in the form of HR, that the perceptually orientated pacing schema becomes disrupted promoting a sparing of the finite anaerobic capacity to compensate for the imbalance between the afferent signal and perception of effort. Key words: Pacing, incremental exercise, [??][O.sub.2max], [??][O.sub.2]-plateau