Electromyographic activity of triceps surae muscles during human locomotion at various slopes

Several studies have reported data for human walking at various slope angles (Tohuhiro et al., 1985; Redfern et al, 1997), but few present data at steeper slope conditions both up and down. In experiments using animal models, for example, having cats walk at slope conditions between 100% upslope and 100% downslope, it was reported that ankle extensor muscles displayed different behaviors during up and down slope compared to level walking (Gregor et al, 1999). These results might be explained, in part, as a response to increased intensity of movement (Herzog et al, 1993), or, in part, as a force feedback response to increased force produced by biarticular muscles (Nichols, 1994). We hypothesized that the human triceps surae muscle would also display unique behaviors during upand downslope conditions, especially at slopes greater than 30 %. The purpose of the present study was to investigate, through the use of electromyography (EMG), changes in triceps surae muscles while walking on a level surface and at varying slope angles.