Mechanical and neural stretch responses of the human soleus muscle at different walking speeds

During human walking, a sudden trip may elicit a Ia afferent fibre mediated short latency stretch reflex. The aim of this study was to investigate soleus (SOL) muscle mechanical behaviour in response to dorsiflexion perturbations, and to relate this behaviour to short latency stretch reflex responses. Twelve healthy subjects walked on a treadmill with the left leg attached to an actuator capable of rapidly dorsiflexing the ankle joint. Ultrasound was used to measure fascicle lengths in SOL during walking, and surface electromyography (EMG) was used to record muscle activation. Dorsiflexion perturbations of 6 deg were applied during mid-stance at walking speeds of 3, 4 and 5 km h(-1). At eac…

Achilles tendon length changes during walking in long-term diabetes patients

Diabetes leads to numerous side effects, including an increased density of collagen fibrils and thickening of the Achilles tendon. This may increase tissue stiffness and could affect stretch distribution between muscle and tendinous tissues during walking. The primary aim of this study was to examine stretch distribution between muscle and tendinous tissues in the medial gastrocnemius muscle-tendon unit in long-term diabetes patients and control subjects during walking.Achilles tendon length changes were investigated in 13 non-neuropathic diabetes patients and 12 controls, whilst walking at a self selected speed across a 10 m force platform. Electromyographic activity was recorded in the me…

Effects of prolonged walking on neural and mechanical components of stretch responses in the human soleus muscle

After repeated passive stretching, tendinous tissue compliance increases in the human soleus (SOL) muscle–tendon unit. During movement, such changes would have important consequences for neural and mechanical stretch responses. This study examined the existence of such effects in response to a 75 min walking intervention. Eleven healthy subjects walked on a treadmill at 4 km h−1 with a robotic stretch device attached to the left leg. Ultrasonography was used to measure SOL fascicle lengths, and surface EMG activity was recorded in the SOL and tibialis anterior (TA) muscles. Perturbations of 6 deg were imposed at three different measurement intervals: Pre (immediately before the walking inte…

Muscle fascicle stretch velocity in relation to stretch reflex activation at different contraction levels in human triceps surae