Effect of speed on kinematic, kinetic, electromyographic and energetic reference values during treadmill walking

Evaluation of normal and pathological gait on the level ground has drawbacks that could be overcome by walking on a treadmill. The present work was designed to assess the feasibility of extended gait analysis on a treadmill allowing multiple steps recording at a constant speed in young healthy subjects. It also aimed to provide speed-specific kinematic, kinetic, electromyographic and energetic reference values.

Twelve healthy volunteers (23 +/- two years) walked on a force measuring treadmill at six speeds (1-6 k mh(-1)). Kinematics and kinetics were analysed at the hip, knee and ankle. Electromyographic muscle activity timing of quadriceps femoris, biceps femoris, tibialis anterior and lateral gastrocnemius was recorded. The energy cost was computed from oxygen consumption measurement.

All variables were speed-dependent. Kinematics and kinetics peaks amplitude increased and occurred earlier during the walking cycle with increasing walking speed. Muscle activity timing also changed with speed, although the number of bursts remained constant. The energetic cost presented a U-shaped curve, with minimal values around 4 km h(-1). Data were compared to overground walking data obtained by several authors: all results, except kinetic ones, were similar, turning down the thought that biomechanics of treadmill and overground walking could be different.

This study provides reference values for normal and pathological walking on treadmill and allows speed-dependent comparison between subjects.