Biomechanical strategies to achieve faster running speeds on level ground, uphill and downhill grades

While the mechanical strategies for increasing running speed on level ground (LG) have been well described, those used to increase speed on uphill (UH) and downhill (DH) grades have not been fully elucidated. The purpose of this study was to determine if the mechanical strategies for increasing speed during UH and DH running are different from those used on LG. Twelve recreational runners ran on LG and a 7.5° incline and decline at three speeds individualized to their 5k race pace. Inverse dynamics were used to calculate sagittal plane joint work during stance and swing phase. Repeated measures ANOVAs were used to test for differences in speed-induced changes in spatiotemporal and joint work variables between conditions. Compared to LG, increasing UH speed was achieved by greater increases in step frequency, swing phase positive and negative hip work, and swing phase negative knee work. Increasing DH speed required a smaller increase in swing phase positive hip and negative knee work compared to LG. This study highlights the grade-dependent roles of the lower extremity muscle groups for increasing running speed, particularly during swing phase, providing perspective on training targets for runners who compete on hilly terrain.