In order to further compare shod versus barefoot running, 35 subjects ran two bouts of 4 minutes at 3.33 m · s-1 on a treadmill dynamometer. Parameters were measured on about 60 consecutive steps. Barefoot showed mainly lower contact and flight time (p < 0.05), lower passive peak (1.48 versus 1.70 body weight, p < 0.05), higher braking and pushing impulses (p < 0.05), and higher pre-activation of triceps surae muscles (p < 0.05) than shod. It was concluded that when performed on a sufficient number of steps, barefoot running leads to a reduction of impact peak in order to reduce the high mechanical stress occurring during repetitive steps. This neural-mechanical adaptation could also enhance the storage and restitution of elastic energy at ankle extensors level. 1 The work was undertaken at the Laboratoire de Physiologie - GIP E2S, Pavillon 12, Hôpital St Jean Bonnefonds, 42055 Saint-Etienne Cedex 2, France