Competition effects on physiological responses to exercise: performance, cardiorespiratory and hormonal factors

The purpose of this study was to explore the mechanisms for increased exercise performance in conditions of competition. Endurance trained subjects (n=14) performed incremental treadmill running to exhaustion in control laboratory conditions (non-competition) and in conditions of simulated competition to assess performance (running duration). Heart rate and respiration gases were monitored continuously through each exercise condition. Blood lactate, cortisol, growth hormone and testosterone concentrations were also determined at pre- (rest) and postexercise in each condition. Results indicated competition exercise performance was significantly increased 4.2% (+49 sec; p<0.05) as was peak VO2 response 4.4% (+2.5 ml O2 x kg(-1) x min(-1); p<0.05) versus non-competition. No significant differences were found in peak measurements of minute ventilation, respiratory exchange ratio, ventilation threshold, post-exercise lactate, heart rate, or the ventilation equivalent for O 2 between the exercise conditions. In both conditions growth hormone and testosterone concentrations increased significantly in response to exercise (p<0.001), whereas cortisol responses post-exercise were significantly elevated in the competition (p<0.05) but not in the control condition (p>0.05). These findings support that in competitive situations the affective state (motivation) experienced by athletes can enhance performance in exercise events, and lead to an increased peak oxygen uptake. The magnitude of the improvement is of a substantial nature and of a level seen with some training programs. Competitive conditions also augment the cortisol response to exercise, suggesting that enhanced sympatho-adrenal system activation occur in such situations which may be one of the key "driving forces" to performance improvement.