Davis & Gruber 2019, Quantifying exposure to running for injury research

Viewpoint in BMJ Open Sport & Exercise Medicine. Argues weekly mileage is a poor measure of running exposure, because two runners covering the same distance experience different stress depending on pace and fitness; injury research should combine external load (distance, duration, step count, pace) with internal load (heart rate, RPE). Notes that self-reported single-session distance can deviate from −28% to +40% against objective measurement, that GPS error reaches ≤6.2% in urban or forested conditions, and that wrist heart-rate error during running is 3.3–6.2%. Makes the case that step count is a more biomechanically meaningful exposure metric than distance. Open access.