Estimating force in the rectus femoris and vastus intermedius via ultrasound during gait at different speeds

We investigated if ultrasound image (US) brightness could be used as a surrogate measure of force in 2 quadricep muscles during gait. We hypothesized that higher speeds would have higher correlations between brightness and ground reaction force (GRF). We found that the preferred speed (PS) had the lowest correlation in the rectus femoris (RF) muscle during both loading and propulsion phases of gait.