Progression in Running Intensity or Running Volume and the Development of Specific Injuries in Recreational Runners: Run Clever, a Randomized Trial Using Competing Risks

BACKGROUND: It has been proposed that training intensity and training volume are associated with specific running‐related injuries. If such an association exists, secondary preventive measures could be initiated by clinicians, based on symptoms of a specific injury diagnosis. OBJECTIVES: To test the following hypotheses: (1) a running schedule focusing on running intensity (S‐I) would increase the risk of sustaining Achilles tendinopathy, gastrocnemius injuries, and plantar fasciitis compared with hypothesized volume‐related injuries; and (2) a running schedule focusing on running volume (S‐V) would increase the risk of sustaining patellofemoral pain syndrome, iliotibial band syndrome, and patellar tendinopathy compared with hypothesized intensity‐related injuries. METHODS: In this randomized clinical trial and etiology study, healthy recreational runners were included in a 24‐week follow‐up, divided into 8‐week preconditioning and 16‐week specific‐focus training periods. Participants were randomized to 1 of 2 running schedules: S‐I or S‐V. The S‐I group progressed the amount of high‐intensity running (88% maximal oxygen consumption [VO2max] or greater) each week, and the S‐V group progressed total weekly running volume. A global positioning system watch or smartphone collected data on running. Running‐related injuries were diagnosed based on a clinical examination. Estimates were reported as risk difference and 95% confidence interval (CI). RESULTS: Of 447 runners, a total of 80 sustained an injury (S‐I, n = 36; S‐V, n = 44). Risk differences (95% CIs) of intensity injuries in the S‐I group were ‐ 0.8% (‐5.0%, 3.4%) at 2 weeks, ‐0.8% (‐6.7%, 5.1%) at 4 weeks, ‐2.0% (‐9.2%, 5.2%) at 8 weeks, and ‐5.1% (‐16.5%, 6.3%) at 16 weeks. Risk differences (95% CIs) of volume injuries in the S‐V group were ‐0.9% (‐5.0%, 3.2%) at 2 weeks, ‐2.0% (‐7.5%, 3.5%) at 4 weeks, ‐3.2% (‐9.1%, 2.7%) at 8 weeks, and ‐3.4% (‐13.2%, 6.2%) at 16 weeks. CONCLUSION: No difference in risk of hypothesized intensity‐ and volume‐specific runningrelated injuries exists between the 2 running schedules focused on progression in either running intensity or volume. LEVEL OF EVIDENCE: Etiology, level 1b.