Muscle activity in slalom and giant slalom skiing.

The purpose of this study was to document and compare the muscular activity patterns observed in seven competitive racers during slalom (SL) and giant slalom (GS) skiing using quantitative parameters of EMG and qualitative video recordings. Twelve muscles of the leg and trunk were monitored using surface electrodes and telemetry. EMG activity was related to phases of movement determined from the video. SL was partitioned into two phases (initiation and turning) and a third phase (completion) was distinguished for GS. The majority of muscles were active at a moderate to high level for the whole turn, with average amplitudes (AA) between 58% and 112% maximum voluntary contraction. Large peak amplitudes (PA) were attributed to the substantial components of centrifugal and gravitational force that the skier must resist in the latter part of the turn. The similarity in muscle activity between SL and GS was surprising. The only significant differences were increases of 11.8% in AA for the AT in SL and 8.8% in PA for the EO in GS. There was ample evidence of co-contraction, suggesting a quasistatic component to skiing.