Foot Strike Patterns During a Continuous 1600 m Outdoor Run in Recreational Female Runners

Foot strike pattern is typically classified from a single observation, which may not capture how it changes during a continuous run. This study examined how the proportion of heel strikes changed across a continuous 1600 m outdoor track run, completed at a self-selected maximal effort by 20 recreational female runners, and its associations with running speed, heart rate, cadence and contact time. Vertical ground reaction force was recorded from the right foot with a force-sensing insole sampling at 200 Hz. Every stride was classified as a heel, midfoot or forefoot strike from the morphology of the vertical force-time curve. Odds of heel relative to midfoot striking were estimated with binary logistic mixed-effects models and expressed as odds ratios (OR). The proportion of heel strikes did not change systematically across the four laps. Longer contact time was associated with lower odds of heel striking (OR 0.988), whereas higher heart rate relative to a runner's own mean (OR 1.047) and faster running speed (OR 1.277) were associated with greater odds (all p < 0.001). Cadence was not associated with foot strike. Differences between runners accounted for most of the explained variance (marginal R² = 0.18, conditional R² = 0.81). A single observation may therefore not represent the foot strike pattern used across a whole run.