Evaluating A Training Program
Using Acute on Chronic Workloads VS The 10% Rule
The most common way for someone to get injured is a spike in training volume. We see this ALL of the time in the clinic. The tricky thing is, it’s hard for someone to evaluate ‘am I doing too much?!’
One method to assess, the 10% rule, has long been used (especially for runners): don’t increase your running volume (mileage) by more than 10% each week. It’s a little too black and white and doesn’t account for someone’s overall activity tolerance and baseline. There is a more nuanced, but favorable approach to analyze activity/training volume called the Acute to Chronic Workload Ratio.
Let’s dig in…
When it comes to designing a training program, the primary goal is to optimize performance while minimizing the risk of injury. Duh, that’s what all athletes want! Give me results, spare me the injury. Traditionally, athletes and coaches have relied on the "10 Percent Rule", as mentioned above, to guide training progression. This simplistic guideline often falls short, especially for more seasoned athletes, those recovering from an injury or starting fresh after a long break. Imagine you run just 5 miles per week, want to increase your running volume, and strictly follow the rule; it would take over two months to reach 10 miles per week, which can be frustratingly slow for most runners.
Enter the acute-to-chronic workload ratio (ACWR), a more nuanced and effective method for managing training volume. Now, ACWR isn’t exactly a new method,it was introduced to sports science literature in 2014, and hasn’t caught the fame like the 10% Rule. This formula calculates the ratio of your most recent weekly mileage (or other training load measures - weight, reps, etc) to the average of the past four weeks'. For instance, if your last four weeks of running mileage were 80, 70, 90, and 100 miles, your ACWR would be 100 / 85 = 1.18. This number will make more sense as you keep reading.
Comparing the 10% Rule to ACWR
The 10 Percent Rule:
The 10 Percent Rule is a simple and intuitive guideline that advises increasing your training load by no more than 10 percent per week. For example, if you ran 10 miles this week, you should aim to run no more than 11 miles the following week. This rule is designed to prevent overtraining and reduce the risk of injury by ensuring gradual progression.
Benefits:
Simplicity: Easy to understand and apply, making it accessible for beginners.
Consistency: Encourages steady and predictable increases in training load.
Limitations:
Overly Conservative: For advanced athletes, the 10 percent increment might be too slow to induce significant performance improvements.
Context-Independent: Doesn't account for the variability in individual responses to training, such as how different athletes recover or adapt to training loads.
Why ACWR Over the 10 Percent Rule?
The ACWR offers a dynamic and more individualized approach. The International Olympic Committee's consensus statement on sports injuries recommends an ACWR "sweet spot" between 0.8 and 1.3, which minimizes injury risk. ACWRs above 1.5, however, substantially increase injury risk.
Benefits:
Individualized Approach: This method considers both recent (acute) and longer-term (chronic) workloads, allowing for a more personalized training plan.
Injury Prevention: By monitoring the ratio of acute to chronic workloads, athletes can avoid sudden spikes in training that increase injury risk.
Performance Optimization: Helps in balancing workload to ensure optimal performance and recovery.
Limitations:
Complexity: Requires detailed tracking and analysis of training loads, which can be time-consuming and may need specialized tools.
Data Dependence: Accurate implementation relies on consistent and precise data collection, which can be challenging.
Practical Application in Training
Building a Solid Foundation
Chronic workload acts like a savings account, buffering against sudden spikes in training demands. Low to moderate increases in workload are ideal for fostering favorable adaptations while minimizing injury risk. Here’s a breakdown of how different ACWR categories affect training:
<0.8 = Detraining Zone: Reducing training load too much can lead to detraining.
0.8-1 = Deloading Zone: Useful for recovery phases.
1.1-1.3 = Adaptation Zone: Optimal for positive adaptations.
1.3-1.5 = Mild Risk Zone: Should be limited to short periods.
>1.5 = Very High Risk Zone: Avoid, especially with higher chronic workloads.
Early Training Plans
When starting a new training regimen, athletes may see high ACWRs due to a lack of chronic workload. Initially, this might not indicate a high injury risk if they aren’t returning from injury. Increasing workload by 10 to 20 percent weekly until a solid chronic workload is established is prudent. Post this period, monitor the ACWR closely to avoid exposing yourself to unnecessary risks.
Making the Choice: Which Method is Right for You?
Both the 10 Percent Rule and ACWR have their merits, but their applicability depends on your specific needs, goals, and resources.
Beginners: The 10 Percent Rule is a great starting point due to its simplicity and ease of application. As you become more experienced and data-savvy, transitioning to ACWR could offer more refined control over your training.
Advanced Athletes: For those with access to detailed training data and the ability to analyze it, ACWR provides a more nuanced approach to managing training loads and optimizing performance.
Injury-Prone Athletes: If you have a history of injuries, the ACWR's emphasis on balancing training and recovery will help you train more safely and effectively.
Conclusion
While the 10 Percent Rule remains a valuable guideline for many, the Acute on Chronic Workload Ratio offers a modern, data-driven approach that can lead to better performance outcomes and reduced injury risk. By monitoring and adjusting ACWR, athletes can optimize their training for performance gains while minimizing injury risk!
SOURCES
Buist, I., Bredeweg, S. W., van Mechelen, W., Lemmink, K. A., Pepping, G.-J., & Diercks, R. L. (2007). No effect of a graded training program on the number of running-related injuries in novice runners. The American Journal of Sports Medicine, 36(1), 33–39. https://doi.org/10.1177/0363546507307505
Carey, D. L., Blanch, P., Ong, K.-L., Crossley, K. M., Crow, J., & Morris, M. E. (2016). Training loads and injury risk in Australian football—differing acute: Chronic workload ratios influence match injury risk. British Journal of Sports Medicine, 51(16), 1215–1220. https://doi.org/10.1136/bjsports-2016-096309
Hulin, B. T., Gabbett, T. J., Lawson, D. W., Caputi, P., & Sampson, J. A. (2015). The acute:chronic workload ratio predicts injury: High chronic workload may decrease injury risk in elite rugby league players. British Journal of Sports Medicine, 50(4), 231–236. https://doi.org/10.1136/bjsports-2015-094817
Maupin, D., Schram, B., Canetti, E., & Orr, R. (2020). <p>the relationship between acute: Chronic workload ratios and injury risk in sports: A systematic review</p>. Open Access Journal of Sports Medicine, Volume 11, 51–75. https://doi.org/10.2147/oajsm.s231405
Ramskov, D., Rasmussen, S., Sørensen, H., Parner, E. T., Lind, M., & Nielsen, R. O. (2018). Run clever – no difference in risk of injury when comparing progression in running volume and running intensity in recreational runners: A randomized trial. BMJ Open Sport & Exercise Medicine, 4(1). https://doi.org/10.1136/bmjsem-2017-000333