EMG RESPONSE PATTERNS AND MOTIVATIONAL STYLES AS PREDICTORS OF PERFORMANCE AND DISCONTINUATION IN EXPLOSIVE AND ENDURANCE SPORTS AMONG TALENTED TEENAGE ATHLETES

Talented teenage athletes of both sexes performing explosive and endur ance sports were studied twice (age 15-16 yr: N = 65; and age 17-18 yr : N = 48) to predict excellence and discontinuation in sport at age 18 -19 from scores on motivational style and task-related electromyograph ic (EMG) changes. They all performed a car-racing video task in the la boratory where the preferred hand operated a joy-stick. Surface electr odes recorded EMG activity from both legs (gastrocnemius) and forearms (flexor carpi radialis). Psychological predictors included scores on (a) motivational styles (the Sport Orientation Questionnaire, the shor t Sensation Seeking Scale, the Life Orientation Test, a new scale on s o-called social reactivity named the Negativism Dominance Scale (react ive and proactive negativism), the Telic Dominance Scale and questions about the importance of friendship and of physical competence in spor t), (b) type of sport and (c) self-reports on task-related motivationa l state in the laboratory. Information about excellence in sport and d iscontinuation was collected from the sport administration, and subjec ts who discontinued from their sport were contacted at age 18-19 yr fo r registration of discontinuation motives. Skilled explosive sport per formers at age 18-19 were characterized by low tonic EMG gradients in the 'passive' forearm at age 17-18, attributed relatively high signifi cance to physical competence in sport and scored high on goal orientat ion and proactive negativism at age 15-16. In contrast, skilled endura nce sport performers, scored high on tonic EMG gradients in the 'passi ve' forearm and attributed relatively high significance to friendly re lations among sport mates. Subjects discontinued from competitive spor ts within the age of 18-19 were mainly moderate explosive sport perfor mers at age 15-16. Negative experiences in sport were most frequently reported as discontinuation motives. However, 80% of the discontinued subjects were still practising physical activities without taking part in competitions.