Abstract
Background
The acute: chronic workload ratio (ACWR) is an index of the acute workload relative to the cumulative chronic workloads. The monitoring of physical workloads using the ACWR has emerged and been hypothesized as a useful tool for coaches and athletes to optimize performance while aiming to reduce the risk of potentially preventable load-driven injuries.
Objectives
Our goal was to describe characteristics of the ACWR and investigate the association of the ACWR with the risk of time-loss injuries in adult elite team sport athletes.
Data sources
PubMed, EMBASE and grey literature databases; inception to May 2019.
Eligibility criteria
Longitudinal studies that assess the relationship of the ACWR and time-loss injury risk in adult professional or elite team sports.
Methods
We summarized the population characteristics, workload metrics and ACWR calculation methods. For each workload metric, we plotted the risk estimates for the ACWR in isolation, or when combined with chronic workloads. Methodological quality was assessed using a modified version of the Downs and Black scale.
Results
Twenty studies comprising 2375 injuries from 1234 athletes (all males and mean age of 24 years) from different sports were included. Internal (65%) and external loads (70%) were collected in more than half of the studies and the session-rating of perceived exertion and total distance were the most commonly collected metrics. The ACWR was commonly calculated using the coupled method (95%), 1:4 weekly blocks (95%) and subsequent week injury lag (80%). There were 14 different binning methods with almost none of the studies using the same binning categories.
Conclusion
The majority of studies suggest that athletes are at greater risk of sustaining a time-loss injury when the ACWR is higher relative to a lower or moderate ACWR. The heterogenous methodological approaches not only reflect the wide range of sports studied and the differing demands of these activities, but also limit the strength of recommendations.
PROSPERO registration number
CRD42017067585.
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Data Availability
Additional data can be provided by reasonable request to authors.
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Acknowledgements
The authors would like thank Dr. for their courtesy in authorizing the use and implementation of the ColorADD® colour system for our figures. The authors would also like to thank Cristina Valente for her valuable help in building and finetuning all the figures in this article.
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RA and ARM performed the database searches. RA and EHW performed the data extraction, methodological quality assessment and initial interpretation of results. TG provided advice throughout the interpretation of data and manuscript drafting. RA was responsible for initial drafting of the article, which was reviewed and edited by all authors. All authors were involved in the conception, design and interpretation of data. All authors read and reviewed the manuscript critically for important intellectual content and approved the final version to be submitted.
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Tim Gabbett works as a consultant to several high-performance organisations, including sporting teams, industry, military and higher education institutions. He also conducts training load workshops for health practitioners—in these workshops, among other topics, the strengths and limitations of the acute:chronic workload ratio are discussed. Peter Blanch is currently employed by a sporting organization which has been involved in the production of ACWR research. Renato Andrade, Eirik Halvorsen Wik, Alexandre Rebelo-Marques, Rodney Whiteley and João Espregueira-Mendes declare that they have no conflicts of interest relevant to the content of this review.
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Andrade, R., Wik, E.H., Rebelo-Marques, A. et al. Is the Acute: Chronic Workload Ratio (ACWR) Associated with Risk of Time-Loss Injury in Professional Team Sports? A Systematic Review of Methodology, Variables and Injury Risk in Practical Situations. Sports Med 50, 1613–1635 (2020). https://doi.org/10.1007/s40279-020-01308-6
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DOI: https://doi.org/10.1007/s40279-020-01308-6