Relations between heart rate, reaction speed, and subjective effort at different work loads on a bicycle ergometer.

The hypothesis concerning an inverted-U relationship between activation and performance was examined by comparing the performance of 25 subjects in a choice-reaction task at five different work loads on a bicycle ergometer. Heart rate was used as an index of activation. The results were in full agreement with the hypothesis, performance being more efficient at a medium activation level than at high and low levels.