The Relationship Between Workload and Non-Contact Musculoskeletal Injury in College Swimmers: A Prospective Cohort Study

Abstract

ABSTRACT Context: Swimmers are known for high training loads and overuse injuries, but few studies have investigated the relationship between the two at the college level. Objective: To determine the association between workload and non-contact musculoskeletal injury in college swimmers. We hypothesized (1) higher overall workload (kilometers swum throughout the season) would be associated with increased odds of injury and (2) the ratio of the current week's (acute) workload divided by the current month's (chronic) workload (i.e., the acute:chronic workload ratio (ACWR)) would be more strongly associated with odds of injury than acute or chronic workloads alone. Design: Prospective cohort study. Setting: College natatorium. Patients or Other Participants: Thirty-seven Division III college swimmers. Main Outcome Measures: Logistic regression using generalized estimating equations was used to calculate odds ratios (OR) with 95% confidence intervals (CI) for injury relative to high workloads and high ACWRs. Injury rates for several ranges of workloads and ACWRs were also calculated. Results: Eleven participants (29.7%) sustained 12 injuries, with seven injuries occurring during the participants' winter training trip. Injury was associated with high acute workloads (OR = 27.1 [95% CI = 8.2, 89.8]) and high ACWRs (OR = 25.1 [95% CI = 7.7, 81.4]) but not high chronic workloads (OR = 2.6 [95% CI = 0.3, 20.0]) or overall workloads (OR = 1.00 [95% CI = 0.99, 1.01]). High acute workloads (>37.2 km/week) and high ACWRs (>1.56) increased injury rate from ≤1% to 15% and 14%, respectively, compared to all lower acute workloads and ACWRs. Conclusions: College swimmers can tolerate high workloads spread out over the season. However, caution should be used when prescribing high acute workloads and high ACWRs (e.g., winter training trip) due to increased odds of injury.