Gait Stability and Structure During 30-Minute Treadmill Running: Implications for Protocol Duration and Shoe Familiarity

Many peer-reviewed studies report spatiotemporal or kinetic parameters of running gait without considering their stability, temporal structure, or relationship to typical run durations. This study investigated the stability and temporal structure of key spatiotemporal and kinetic parameters during a 30-minute easy-paced treadmill run (13 km∙h-1) while participants wore familiar and unfamiliar every day running shoes. Step-level data were analysed across the full time series and in sequential 1-minute epochs to determine how long each parameter takes to reach practical stability and whether this differs between shoe conditions. Approximately, 2,450 steps were analysed per condition. Within-participant variability was low (CV< 2.5%) for all parameters and conditions except for peak impact force (CV=6.9-7.0%) and average loading rate (CV=8.4-8.7%). DFA-α indicated persistent temporal structure for stride duration, swing time, and active peak force, whereas loading-phase kinetics showed weak long-range dependence. No significant differences were observed between shoe conditions for variability or temporal structure, although ground contact time was slightly longer in the unfamiliar shoe. Practical windows of stability relative to each participant’s 30-minute mean ranged from 11 to 17 minutes for spatiotemporal variables, 9-17 minutes for active peak force, and within the first minute for impact related parameters and impulse. These findings indicate that studies examining spatiotemporal and kinetic parameters during easy-paced treadmill running require 11-17 minutes of continuous data to obtain 1-minute epoch estimates that are practically stable relative to 30-minute averages, regardless of footwear familiarity.