Influence of slope and speed on spatio-temporal variability of recreational runners

Variability of spatio-temporal running parameters (STp) provides insights into the runner's self-organisation to the running environment. The aim of this study was to examine the influences of speed and slope on linear and non-linear measurements of variability for various STp (i.e. contact, flight, step times, step length, duty factor, leg and vertical stiffness). Twenty recreational runners (age 24.8 ± 6.3 years; height 1.8 ± 0.1 m; weight 64.0 ± 9.8 kg) completed 10-min randomized bouts of treadmill running at different conditions (80-120% of preferred running speed by 10% increments, ±2, 5 and 8% of slope). The influences of speed on the linear measurements of variability varied depending on the STp. As speed increased, there was no change in the linear measurement of step time variability, but a decrease for contact time variability. Negative slopes exhibited higher linear measurements of STp variability compared to flat or positive slopes, with results like those seen in slower speed conditions. Neither slope nor speed impacted non-linear measurements of STp variability, likely due to the use of moderate slope gradients and preferred running speed derived conditions. Future research should explore a wider range of conditions to gain a more comprehensive understanding of slope influence.