Task-induced tonic and phasic EMG response patterns and psychological predictors in elite performers of endurance and...

Highly skilled performers of endurance and explosive sports as well as 'mixed' sports (total n = 26) were recruited to perform perceptual-motor tasks in the laboratory. These subjects represented 'models' for testing of motivational and affective moderators of task-related tonic and phasic electromyographic (EMG) changes. They all performed a car-racing video task with their preferred hand operating the joy-stick. Surface electrodes recorded EMG activity from both legs and forearms. Psychological predictors included type of sport and self-reports on involvement during performance in the laboratory. Tonic EMG changes in the legs were not strongly related to predictor variables, whereas 'passive' forearm EMG elevations were high in the endurance sport subjects (25% of variance explained). Stepwise multiple regression analyses stated that 70% of the variance in phasic increases of active forearm EMG power was explained by four predictor variables: marked increases occurred in (1) performers of endurance sports, those who (2) felt relatively low levels of 'arousal', (3) enjoyed the task, and (4) reported being 'stressed' while performing the task. In these subjects, therefore, psychological variables related more strongly to EMG reflecting pyramidal than extrapyramidal discharges.