3301 Board #62 May 30, 8

Abstract

Cycling shoe orthotic insoles, an intervention used to correct pedaling mechanics in riders, have received little attention in the literature. Arch supports, if correctly fitted, may have the potential to improve muscle firing patterns and the transfer of force from the rider to the bicycle thereby improving efficiency and performance. PURPOSE: This study tested the hypothesis that the use of orthotic insoles in cycling shoes would alter the muscle activity and submaximal efficiency of healthy, experienced, male cyclists. Additionally, it was hypothesized that the insole that allowed the lowest level of lateral knee movement (greatest stabilizing effect) would produce the greatest improvements in these variables, and be related to the rider’s arch height. METHODS: Nine cyclists were evaluated during four VO2max tests, using four different insole conditions (flat [no insole], low, medium, and high arch support) in a random order. Wireless electromyography was used to measure muscle activity, and telemetry-based gas analysis was used to determine cycling efficiency. VO2max tests were performed at least 48 hours apart to reduce the impact of fatigue. RESULTS: For the dominant (D) and non-dominant (ND) legs, heart rate at anaerobic threshold (HRAT) differed by insole (p=.014; p=.017, respectively). For the D leg, pairwise comparisons showed that the best fit insole (152.8±4.4 bpm) did not differ from any other condition. For ND leg, the best fit insole (153.0±4.63bpm) produced a lower HRAT than baseline (157.4±4.6bpm; p=.044). D leg hamstrings ratios (HSRATIO) differed by pedal types (p=.007). With non-centering float pedals, the best fit insole condition (.74±.27) produced a significantly lower HSRATIO than the medium condition (1.51±.28; p=.005), shifting muscle activation levels toward the lateral side. With centering float pedals, the best fit insoles (1.1±.25) showed a significantly higher ratio than the medium insole (.30±.32; p=.021), shifting activity towards the medial side. CONCLUSION: Orthotic insoles may be effective in altering hamstrings activation ratios about the knee, but their impact on cardiovascular performance remains undetermined.