Is the Relationship Between Stride Length, Frequency, and Velocity Influenced by Running on a Treadmill or Overground?

The purpose of the study was to compare the relationship between stride length (SL), stride frequency (SF), and velocity while running on a treadmill and overground. Participants (n=10; 22.3±2.6 yrs; 1.71±.08 m; 71.4±15.5 kg) completed a total of 14 runs (7 treadmill, 7 overground) with each run at a different velocity. SL, SF, and velocity data were recorded using wearable technology (Garmin, Fenix2). The outdoor trials occurred first. The treadmill velocities were selected to match the range of velocities used overgroud. SL vs. velocity plots were generated for treadmill and overground data for each participant and fit with a 2(nd) order polynomial in the form of SL=Av(2)+Bv+C. Each equation coefficient (i.e., A, B, C) was averaged across participants and compared between treadmill and overground using paired t-tests. The A coefficient (v(2) term) was different treadmill vs. overground (p=0.031). Neither B (p=0.136) nor C (p=0.260) coefficients were different treadmill vs. overground. It was concluded that the A coefficient (v(2) term) for SL vs. velocity was larger during overground vs. treadmill running. This is an indication that the strategy of changing SL across velocities was different when on the treadmill vs. overground. Specifically, while running on a treadmill, SL continued to increase in a more linear manner than when running overground.