Muscle recruitment pattern in cycling: A review

Studies have indicated that the muscles work in a systematic and coordinated way to generate and direct power from the human body to the crank during cycling. Understanding of the muscle involvement or recruitment pattern during cycling will be useful for developing specific and effective muscle training and rehabilitation programs for cyclists. Moreover, it will also facilitate the use of the cycling ergometer for therapeutic purpose. This paper reviews the current literature on muscle recruitment pattern during cycling and the effects of muscle fatigue, cadence, riding posture and seat height on this recruitment pattern. In the power phase or 'downstroke', the hip, knee and ankle joints extend simultaneously for the pushing action, whilst in the recovery phase or 'upstroke', they flex together to pull the pedal back to the top dead center of the crank cycle. Recent studies have indicated that in this repeated sequence, the mono-articular muscles are mainly involved in the generation of positive work whereas the biarticular muscles are responsible for regulating force transmission. Some muscles co-activate during cycling to provide synergistic actions and other functional needs. Muscle fatigue is an important factor affecting cycling performance. It has been reported that muscle fatigue in the lower body would alter the cycling motion and muscle activation pattern. Therefore, studying the change of muscle activation pattern during cycling at the fatigued level may shed light on the sequel of local muscle fatigue. A muscle training program specifically for cycling can then be designed accordingly. Additionally, the change of cadence during cycling will affect the muscle recruitment pattern. There is a unique cadence that minimizes the muscle activation level at a specific level of power output. This cadence will increase as the power output increases. The change of riding posture from sitting to standing renders the pelvis unsupported and the body weight will assist the power phase of pedalling. Similarly, changes to the seat height will alter the posture which will affect the directions of muscle actions to the crank, thus changing the muscle recruitment pattern.