Footstep analysis at different slopes and speeds in elite race walking

Abstract In order to investigate the effects of speed and slope on kinematic parameters, we studied the step parameters of twelve elite race-walkers on a treadmill at different speeds (3.61, 3.89 and 4.17 m·s) and slopes (0, 2 and 7%). A high-speed digital camera (210 Hz) was used to record motion, 2D data were analyzed with Dartfish 5.5Pro. The parameters studied were step length (SL), step frequency (SF) and contact time (CT). The results showed that the increases in SL were linearly related to increases in speed: r = 0.37 with p < 0.01 while decreases in SL were elicited with an increase in slope r = -0.56, p < 0.0001 [(0-2% = -3.5%, p < 0.02), (0-7% = -7.5%, p < 0.01)]. SF was positively correlated with increases in speed r = 0.56, p 0.0001 and slopes r = 0.50, p < 0.0001 [(0-2% = 3.6% n.s.), (0-7% = 8.5%, p < 0.01)]. Conversely CT was negatively correlated with increases of both speed; r = -0.57, p < 0.0001 and slope r = -0.50, p < 0.0001 [(0-2% = -3.4%, n.s.), (0-7% = -7.7%, p < 0.01)]. These results suggest that using slopes higher than 7% could considerably alter the neuromechanical behaviour of athletes, whereas slopes around 2% could positively influence the performance of the elite race walkers without altering race-walking technique.