Orthotic Insoles Show no Acute Effects on Knee Kinematics during Pedaling in Experienced Cyclists

Abstract

Orthotic insoles have the potential to change knee kinematics in cyclists by modifying the angle at which force is transferred from the rider’s foot to the pedal. Adjusting knee kinematics may positively affect pain and performance in road cyclists; however, there is a paucity of controlled research examining this question. PURPOSE: To determine if the use of orthotic insoles in cycling shoes would alter the pedaling mechanics of nine healthy, experienced, male cyclists (age: 32±6.3 y; height: 1.78±0.06 m; weight: 83.6±11.9kg) and to examine if the insole that allowed the lowest level of lateral knee movement would be related to the rider’s arch height and would produce the greatest improvements in knee kinematics. METHODS: The 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. High-definition video recordings were used to measure lateral knee movement. Tests were performed at least 48 hours apart to control the levels of fatigue. RESULTS: The non-flat insole that resulted in the lowest level of lateral knee movement was identified for each leg. Spearman rank-order correlations showed no relationship between arch height and this “best fit” insole. Because the best fit insole was not the same between feet for most participants, general linear mixed models were run two ways, with the best insole for the dominant leg and non-dominant leg identified as the overall “best fit” insoles. For the dominant leg, best fit insoles produced significantly less knee movement (5.23±.34cm) than high (6.04±.36cm; p=.015) or medium (6.54±.39cm; p=.001) levels of arch support. CONCLUSION: These findings imply that orthotic insoles may alter pedaling mechanics, but appear to offer no benefit over riding without insoles and may actually be detrimental at greater insole heights.