The influence of a directional compression garment on muscle activity and performance in recreational alpine skiers
Snyder, Cory James
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Recent studies reported reduced muscle activity in competitive alpine skiers using directional compression (DC). It is not known whether the effects of DC are limited to competitive skiers, or if similar changes would be observed in recreational skiers during a full day of skiing. The purpose of this study was to examine changes in hip and leg muscle EMG patterns in recreational alpine skiers when skiing with and without a lower body DC garment. METHODS 11 intermediate and expert skiers volunteered for this study. Subjects completed 2 randomized trials, one in a DC garment, and one in a non-compressive (NC) base layer. EMG of the gluteus medius (GMED), gluteus maximus (GMAX), rectus femoris (RF), adductor longus (ADL), and vastus lateralis (VL) were recorded using EMG during three measurement runs with standardized turns on each visit. Standardized turns were used to compare EMG response between conditions and measurement runs. Subjects also completed self-paced skiing bouts (SP) between measurement runs. Skiing performance (heart rate, velocity, and skiing load (vertical/runs) were measured during the SP bouts. 2x3 repeated measures ANOVA's was used to compare kinematic and EMG changes during measurement runs, as well as performance during self-paced skiing between (p < or = 0.05). RESULTS Subjects skied more runs (DC 18.60 + or = 0.98, NC 13.55 + or = 1.06, p=0.001) and vertical (DC 4805.31 + or = 304.31 m, NC 2373.56 + or = 219.60 m, p=0.001) during free skiing with DC than NC. Heart rate and ski velocity were not different between SP bouts. Peak edge angle was lower in the DC treatment (DC 55.06 + or = 10.70°, NC 57.90 + or = 9.10°, p=0.008). Absolute muscle activity was lower in the DC condition for all muscles (p < or = 0.05), although no differences were observed in relative muscle activity. CONCLUSIONS No differences in relative muscle activity were detected, absolute muscle activity was lower in the DC condition. Subjects improved their self-paced skiing performance in the DC condition. There was also a trend towards lower RMS for all muscles in the DC treatment. Further research should investigate the influence of DC garments on repeated bouts of recreational alpine skiing on consecutive days.