Johansen et al. 2025, High-risk running sessions in a 5200-person cohort

Prospective cohort of 5,205 runners across 588,071 sessions. A single-session distance more than 10% longer than the longest run of the prior 30 days raised overuse injury rate: small spike (>10-30%) hazard rate ratio 1.64, moderate (>30-100%) 1.52, large (>100%) 2.28. Week-to-week mileage change and the acute:chronic workload ratio showed no positive association, and large ACWR spikes were if anything protective. Moderate to strong (very large sample, observational design).