Acute:Chronic Workload Ratio (ACWR)
This post is a little dense, so bear with me.
Background
Training volume is a frequently overlooked variable by athletes and even coaches. A big reason for this is just not having something in place to measure volume. That’s where acute:chronic workload ratio (ACRW) comes in. Dr. Tim Gabbett’s work illustrates how training volume is a major factor for injury prevention (more on this later).
Training Volume
Minimum Effective Volume (MEV) is the lowest volume that can be performed for athletes to improve. Maximum Recoverable Volume (MRV) is the highest volume that allows the athlete to recover to baseline. Constant training at the MRV can often lead to overuse injuries and poor performance. Maximum Adaptive Volume (MAV) is the volume that produces the greatest adaptation from training.
You want to shoot for training at your MAV.
Acute:Chronic Workload Ratio
ACWR is a relative comparison between fatigue (1-week acute workload) and fitness (4-week chronic average workload). The overall goal is to achieve greater fitness via a higher chronic workload in order to optimize performance and reduce risk of injury.
Measuring ACWR
To help simplify measuring ACWR, I recommend using a 1-10 Rating of Perceived Exertion (RPE) scale. Multiply the time of exercise by the overall self-reported RPE for that session.
For example, a 30-minute workout with a 7 on the RPE scale would be calculated as 210 units. Add up all the daily units for the week to get your acute workload. Add up your weekly units for 4 weeks to get your chronic workload. Your acute:chronic workload would be the acute workload (1 week) in units divided by the chronic workload (4 weeks) in units.
Sweet Spot
The “sweet spot” of 0.8-1.3 was found by Dr. Gabbett. The below image is from one of his studies. When ACWR is measured outside of this range, the risk of injury is increased. There is also a “danger zone” of 1.5+ with a much higher injury risk. Spikes up or down in training volume can negatively impact performance as well as put you at risk for injury.
What Should You Do About It?
If you are an athlete or a coach interested in monitoring training volume to prevent injuries, you should strongly consider using ACWR. Document the exercise duration and RPE (1-10) on a spreadsheet and continue to track the data.
When programming is pushing the limits of what the athlete is expected to handle, make the informed decision to change the volume weekly to stay in the MAV.
Maximum adaptable volume can and should improve as you progress. This just means that you are improving your fitness. Using ACWR, you can make sure that you are progressing at the appropriate intensity and duration to optimize performance as well as limit the chance of needing to take time from programming because of an injury or nagging pain. This may mean an extra day of rest or an active recovery day built into more intense weekly bouts.
I hope I didn’t lose you there.
Feel free to reach out with any questions.
Corey Hall, PT, DPT
