Abstract

Aim of this study was to provide electromyographic feedback for 1) pedagogical advice in motor learning, 2) ergonomics of materials choice and 3) competition. (1) EMG data were collected for the Stem Christie, the Stem Turn and the Parallel Christie and verified for the complexity of patterns; (2) integrated EMG and linear envelopes were analysed from standardized positions, motions and slopes using compact, soft and competition skis; (3) in a 'parallel special slalom', muscular activity pattern and intensity of excavated and flat snow conditions were compared. EMG data from the 3 studies were collected in the French Alps (Tignes). In the 3 studies and for all subjects, we found a high level of co-contractions in the lower limb extensors and flexors, especially during the extension phase of the ski movement. Stem Christie and Parallel Christie showed higher levels of rhythmic movement (92 and 84%). The second initiation movement of the Stem Turn produced 74% repetitive rhythmic patterns. In addition, its coordination pattern was more complex. Systematic differences were noted between the racing, soft and compact skis. Data suggest that 1) the Stem Turn demands a higher level of neuromuscular ability than the other 2 drills and should therefore only be introduced in the training of more advanced skiers; 2) on average and for the slope inclinations investigated (11 and 27 deg), soft skis showed the least EMG activity indicating a better control of the overall ski movements, 3) excavated snow condition was not a disadvantage. Verf.-Ref.