Twelve trained trail runners participated in a study to understand changes in running form over time. They ran on a treadmill for over three and a half hours, with each session divided into three blocks. The study aimed to measure changes in stride mechanics at the same speed.

Throughout the steady running, most metrics like cadence and energy cost remained stable. However, the duty factor, or the time spent in contact with the ground, increased slightly. This shift from 71.3% to 72.7% suggests a subtle change in running mechanics over time, even at constant speed. Read more culture coverage.

The study recommends monitoring duty factor during long runs to identify potential fatigue patterns. While the change was small, it provides insight into how running form can alter during extended periods of steady running. Related: Blood Profiles of Faster Runners: What We Know.

This original Runner World brief is based on reporting from Marathon Handbook. Visit the source for its complete reporting, context and any later corrections.