This study set out to ascertain the incidence of a heel strike transient (HST) and to verify whether modifications of muscle activation time could be correlated with the presence and the characteristic of a HST. Lower limb kinematics, kinetics and surface electromyography (SEMG) of normal subjects were examined during barefoot walking. A short-lived sharp HST was present in 76% of the trials while a smooth HST, of longer duration was seen in 13.3% of the trials. The transient phenomenon was absent in the remaining 10.7% of trials. The SEMG showed that alteration in the activation timing of muscles correlated with the presence of a HST.