Activation analysis of the lower limb muscles of cyclists during pedaling

Abstract

It is important to elucidate the lower limb motion based on the activation of lower limb muscles during pedaling to improve pedaling performance of cyclists. In previous studies, although the activation of these lower limb muscles has been investigated by a surface electromyogram (EMG), the evaluation of muscle contraction during pedaling has not been conducted. Muscle contraction refers to the muscle activation state accompanying a change (stretching / shortening) of the muscle length, and the exerted muscle strength and the status of muscle fatigue have complicated relationships that are difficult to be clarified. The purpose of this study is to propose a novel method to evaluate the muscle contraction during pedaling. Muscle contraction characteristics were analyzed to elucidate the pedaling motion based on relationships between muscle length variation (stretching / shortening) and contraction velocity and the strength of muscles. In the experiments, cyclists were instructed to perform their pedaling technique at two pedaling rates (cadence: 80–90 and 110–120 rpm). EMG signals were recorded from rectus femoris (RF), biceps femoris (HAM) and gastrocnemius (GAS). Pedal force was measured by a power meter (Pioneer Inc.). Furthermore, the lower limb motion during pedaling was measured using a 3D motion capture system. In addition, the muscle length model of the lower limb was constructed based on the Hill–Stroevo model to identify the lower limb muscle length during pedaling. The experimental results show that the proposed system evaluates the muscle activation and contraction during pedaling as well as the pedaling skill based on the muscle contraction. The analysis results of the muscle contraction show the importance of the hamstrings activation state during the pedaling motion.