Leg Compression Tights Reduce Muscle Activation by Altering Ski Turning Technique

Abstract

PURPOSE: To determine the influence of leg compression tights on the kinematic and neuromuscular performance of alpine ski turns. METHODS: Wireless inertial measurement units (IMUs) and surface electromyography (EMG) electrodes captured bilateral segmental orientations and unilateral vastus lateralis (VL), rectus femoris (RF), biceps femoris (BF) and gluteus medius (GM) muscle activations during slalom race simulations from 9 collegiate alpine ski racers. Average ankle, knee and hip positions and turn durations were calculated from the downhill leg during 18 turns (9 right; 9 left) while wearing either directional compression (DCP) or standard compression (SCP) tights. Average VL, RF, BF and GM EMG amplitudes from the right leg were measured during 9 turns. The order of DCP and SCP conditions was balanced. A 3-way mixed factor, repeated measures ANOVA compared the effects of turn direction and compression type across the 18 turns and one-way repeated measures ANOVA compared the effect of compression type on EMG amplitudes. RESULTS: Average turn duration was 4% longer for the left leg (right, .94 ± .02; left, .980 ± .021 s; p=.039). Average knee position was 3% more flexed during the DCP condition (DCP, 117.1 ± 1.4 deg; SCP, 120.8 ± 1.3 deg; p=.010) and the right leg was 4% more flexed (right, 116.5 ± 1.5 deg; left, 121.3 ± 1.1 deg; p=.020). Average hip position was 5% more flexed during the DCP condition (DCP, 145.4 ± 1.5 deg; SCP, 153.5 ± 1.2 deg; p<.001) and the right leg was 3% more flexed (right, 147.6 ± 1.3 deg; left, 151.3 ± 1.2 deg; p=.012). Average GM, RF and VL activations were 26%, 17% and 17% lower for the DCP condition, respectively (GM: DCP, 2.7 ± 1.9 mV; SCP, 3.7 ± 2.6 mV; p<.001; RF: DCP, 3.0 ± 2.0 mV; SCP, 3.6 ± 2.7 mV; p=.020; VL: DCP, 2.4 ± 1.5 mV; SCP, 2.9 ± 2.1 mV; p=.020). CONCLUSION: The DCP tights demonstrated an alpine skiing turn technique with greater hip and knee flexion and reduced VL, RF and GM muscle activations, which may indicate a mechanism of reduced fatigue for these muscles.