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 running-related injuries exists between the 2 running schedules focused on progression in either running intensity or volume.
Level of evidence: Etiology, level 1b. J Orthop Sports Phys Ther 2018;48(10):740-748. Epub 12 Jun 2018. doi:10.2519/jospt.2018.8062.
Keywords: injury diagnoses; running; running-related injury; training variables.