Spontaneous mechanical activity in musculature (SMAM) can be observed from time to time in diffusion-weighted images (DWI) of the human lower leg. In DWI, motion sensitivity is usually restricted to a time window between diffusion-sensitizing dephasing and rephrasing gradients. Capabilities to detect SMAM occurring outside this time window by DWI are expected to be clearly reduced. The temporal sensitivity of diffusion-weighted sequences to SMAM is evaluated by varying diffusion-sensitizing time. In addition, concurrent surface electromyography (sEMG) measurements were performed in order to reveal the temporal correlation of the events in both modalities.