In-Season Load mangement with ACWR

In-Season Preparation typically involves an extended duration of uninterrupted training.  This time of year allows for coaches to provide a consistent training stimulus in conjunction with the competition schedule.  It is vitally important for this training phase to maintain and drive physiological change to make sure players are injury free and in peak performance late in the season.

One way to monitor this stimulus over the course of the season is through acute and chronic loads along with measuring the ratio of the two (acute to chronic workload ratio ACWR).  With regards to acute load, it is measured over a 7 day period and it is calculated by taking the average load over a 7 day period.  The chronic load is measured over a 21 day period and it is calculated by taking the average workload over a 21 day period. Acute to Chronic Workload Ratio (ACWR) compares the acute load (last 7 days) to the chronic load (21 days prior). The calculation takes the average load over the last 7 days divided by the average load over the 21 days before that. It is worth noting that there is an ongoing debate about the best method for calculating  and interpreting ACWR.

Gabbet and colleagues in 2010 used sRPE to model the relationship between training loads and the likelihood of non-contact and soft tissue injury in elite Rugby League players. Within this study they found that players who exceeded the weekly training load threshold (cumulative sRPE) were 70 times more likely to test positive for non-contact or soft tissue injuries - while players who did not exceed the weekly training load were injured one tenth as often. Again in 2016, Gabbet and colleagues created some foundational work around ACWR ratios and a potential 'sweet spot' to minimize the chance of non contact and soft tissue injury risk. Gabbet and colleagues demonstrated a lower risk of injury when athletes fell between .8 and 1.3 for ACWR.

Acute:Chronic Workload Ratio (Gabbet, 2016)

Along with Gabbet, quite a few other practitioners have conducted studies on the recommended ACWR 'sweet spot'.  When reviewing multiple studies (Maupin 2020, Gabbet 2016, Bowen 2020, Griffin 2020), all practioners generally suggest that higher ACWRs are associated with increased injury risk. It should be noted that there is some variation in the specific ranges and findings across different sports and populations. With that said, it is important to take these considerations into account when utilizing ACWR when monitoring training loads.

When conducting training sessions over the course of the season, there will likely be times where there are spikes in ACWR for players and for the entire team.  If your team and players are dealing with spikes in ACWR, there are quite a few ways to mitigate extended spikes over the course of the in-season training phase.

1. Reduce acute workload: Since a high ACWR indicates that the acute workload is significantly higher than the chronic workload, the most immediate intervention would be to reduce the acute workload (i.e., the training load in the most recent week).

2. Gradual load progression: Ensure that training loads are increased gradually over time to build chronic workload capacity. This helps prevent sudden spikes in acute workload relative to chronic workload.

3. Monitor and adjust: Continuously monitor ACWR and adjust training loads accordingly to maintain the ratio within the suggested "sweet spot" of 0.8 to 1.3, which is associated with lower injury risk.

4. Individualization: Tailor interventions to each athlete's specific needs, fitness levels, and sport requirements.

5. Recovery strategies: Implement appropriate recovery techniques to help manage fatigue associated with high acute workloads.

6. Periodization: Incorporate proper periodization in training plans to balance workload and recovery over time.

7. Education: Educate athletes and coaches about the importance of workload management and the potential risks associated with high ACWRs.

Development and Application of an Injury Prediction Model (Gabbett 2010)

Monitoring and regulating training loads, acute and chronic, are critical to ensure that players receive a progressively overloaded periodized training program and are given adequate recovery between high volume and high intensity sessions (Gabbet 2010). While there is a relationship between acute high training loads and potential injury risk it is important for practitioners to understand how to manipulate the training response in order to minimize these spikes in acute load. Coaches can use historical data, Internal load, External load, along with subjective surveys to mitigate large spikes in Acute loads. One thing to also remember is athletes need to build Chronic load to potentially mitigate the chance of injury - so, the relationship between large spikes in acute load along with building chronic load are vitally important. Using ACWR will allow you to make sure that each month the training stimulus is adequate and athletes are not being undertrained or overtrained.

Reference:

Gabbett TJ. The training—injury prevention paradox: should athletes be training smarter and harder? Br J Sports Med. 2016;50(5):273-280.

Gabbett TJ. The development and application of an injury prediction model for non-contact, soft-tissue injuries in elite collision sport athletes. J Strength Con Res. 2010;(24):2593–603

Gabbett, TJ. Influence of training and match intensity on injuries in rugby league. Journal of Sports Sciences. 2004; 22(5), 409-417.

Maupin D, Schram B, Canetti E, Orr R. The Relationship Between Acute: Chronic Workload Ratios and Injury Risk in Sports: A Systematic Review. Open Access J Sports Med. 2020;11:51-75.

Bowen L, Gross AS, Gimpel M, Bruce-Low S, Li FX. Spikes in acute:chronic workload ratio (ACWR) associated with a 5-7 times greater injury rate in English Premier League football players: a comprehensive 3-year study. Br J Sports Med. 2020;54(12):731-738.

Griffin A, Kenny IC, Comyns TM, Lyons M. The Association Between the Acute:Chronic Workload Ratio and Injury and Its Application in Team Sports: A Systematic Review. Sports Med. 2020;50(3):561-580.