Fig. 1. (A) Myoelectric signal from the biceps femoris for one stride of running at 4.5 m s^–1. Heel-strikes occurred at times of 0 and 750 ms. (B) The mean myoelectric intensity for 20 consecutive strides is shown as a function of time and frequency, with high intensities denoted by dark shading. The 20 time-windows that divide the stride are indicated by the vertical grey lines. (C) The myoelectric intensity spectra for each of the 20 time-windows shown in B.