The Association Between Noncontact Injuries and the Acute-Chronic Workload Ratio in Elite-Level Athletes: A Critically Appraised Topic.

Clinical Scenario: Workload monitoring and management of an athlete is viewed by many as an essential training component to determine if an athlete is adapting to a training program and to minimize injury risk. Although training workload may be measured a variety of different ways, session rate of perceived exertion (sRPE) is often used in the literature due to its clinical ease. In recent years, sports scientists have been investigating sRPE as a measure of internal workload and its relationship to injury in elite-level athletes using a metric known as the acute:chronic workload ratio (ACWR). This critically appraised topic was conducted to determine if internal workload using the ACWR is associated with injury. Focused Clinical Question: In elite-level athletes, is there an association between the ACWR for sRPE and noncontact injuries? Summary of Search, Best Evidence Appraised, and Key Findings: The literature was searched for studies investigating the association between noncontact injuries and the sRPE ACWR in elite athletes. Three prospective cohort studies were included. Two studies found that high ACWR led to 2.0 to 4.5 times greater injury risk compared with a more balanced ACWR. One study found that low chronic workloads coupled with a low ACWR were associated with injury. Clinical Bottom Line: The majority of evidence suggests that when the acute workload exceeds the chronic workload, there is an increase in injury risk. The evidence also supports that a low chronic workload with a low ACWR should be considered as an injury risk factor. Strength of Recommendation: Based on the American Family Physician's Strength of Recommendation Taxonomy, there is level A evidence to support the sRPE ACWR as a risk factor for noncontract injuries in elite athletes.

The Acute: Chronic Workload Ratio Is Associated with Injury in Junior Tennis Players.

PURPOSE: Session RPE (sRPE) is used to track internal training/competition load in athletes using a metric known as the acute to chronic workload ratio (ACWR). Research that reported on team sports has determined that if the acute load is higher than the chronic load, athletes are likely to sustain injury. No studies, however, have attempted to investigate internal load and injury in a tennis population despite the rigorous training loads. Therefore, the purpose of this study was to investigate if sRPE ACWR is associated with injury in junior tennis players over a 7-month time period. METHODS: Forty-two junior tennis players were recruited to participate, 26 were included in the final analysis. Players provided a rating of RPE as an estimate of training intensity every day after training/match sessions. sRPE, a measure of internal and external training load was calculated by multiplying the training/match sRPE by the session duration in minutes. Players self-reported all injuries. The ACWR was the primary independent variable. Acute load was determined as the total sRPE for 1 wk, whereas a 4-wk rolling average sRPE represented chronic load. RESULTS: Seventeen players sustained injuries. The model indicated that ACWR from the previous week (P < 0.001) and previous injury history (P = 0.003) were significant predictors of injury the following week. In the week preceding injury, the average ACWR was 1.57 (SD, 0.90). CONCLUSION: Injured players had on average 1.5 times more training load in the past week compared with the previous 4 wk. A majority of players who went on to sustain an injury were not prepared for the load endured. These results were similar to previous studies investigating ACWR where an acute increase in load was associated with increased injury risk.