Acute:Chronic Workload & Our Research

Some research that myself and a few colleagues have worked on for the past year (and discussed for far longer than that) regarding our critiques of the acute-chronic workload model for sports injury have been recently published.

It was a pleasure to collaborate with this group of researchers and I learned a lot throughout the process and hopefully others will learn a lot when they read our work.

Below are the papers that I’ve been a part of:

  1. Bornn L, Ward P, Norman D. (2019). Training schedule confounds the relationship between Acute:Chronic Workload Ratio and Injury. A causal analysis in professional soccer and American football. Sloan Sports Analytics Conference Paper.
  2. Impellizzeri F, Woodcock S, McCall A, Ward P, Coutts AJ. (2020). The acute-crhonic workload ratio-injury figure and its ‘sweet spot’ are flawed. SportRxiv Preprints.
  3. Impellizzeri FM, Ward P, Coutts AJ, Bornn L, McCall A. (2020). Training Load and Injury Part 1: The devil is in the detail – Challenges to applying the current research in the training load and injury field. Journal of Orthopedic and Sports Physical Therapy, 50(10): 577-584.
  4. Impellizzeri FM, Ward P, Coutts AJ, Bornn L, McCall A. (2020). Training Load and Injury Part 2: Questionable research practices hijack the truth and mislead well-intentioned clinicians. Journal of Orthopedic and Sports Physical Therapy, 50(10): 577-584.
  5. Impellizzeri FM, McCall A, Ward P, Bornn L, Coutts AC. (2020). Training load and its role in injury prevention, Part 2: Conceptual and Methodologic Pitfalls. Journal of Athletic Training, 55(9). 893-901.

Many will argue and say, “Who cares? What’s the big deal if there are issues with this research? People are using it and it is making them think about training load and it is increasing the conversations about training load within sports teams.”

I understand this argument to a point. Having been in pro sport for 7 years now, I can say that anything which increase conversation about training loads, how players are (or are not) adapting, and the potential role this all plays in non-contact injury and game day performance is incredibly useful. That being said, to make decisions we need to have good/accurate measures. Simply doing something for the sake of increasing the potential for conversation is silly to me. It is the same argument that gets made for wellness questionnaires (which I have also found little utility for in the practical environment).

When we measure something it means we are assigning a level of value to it. There is some amount of weighting we apply to that measurement within our decision making process. Even if we are under the belief that collecting the metric is solely for the purpose of increasing the opportunity to have a conversation with a player or coach. In the back of our minds we are still thinking, “Jeez, but his acute-chronic workload ratio was 2.2 today” or “Gosh, I don’t know. He did put an 8 down (out of 10) for soreness this morning”.

Of course challenging these ideas doesn’t mean we sit on our hands and do nothing. Taking simple training load measures (GPS, Accelerometers, Heart Rate, etc.) and applying basic logic about reasonably safe training load increases from week-to-week, doing some basic analysis to understand injury risks and rates within your sport (how they differ by position, age, etc), and identifying players that might be at higher risk of injury to begin with (IE, higher than the baseline risk) and having a more conservative approach with their progression in training can go a long way. Doing something simple like that, doing well, and creating an easy way to report said information to the coach and player can help increase the chance for more meaningful conversation without using measures that might otherwise give a flawed sense of certainty around injury risk.

Regardless of our work, people will use what they want to use and what they are (or have been) most comfortable with in practice. However, that shouldn’t deter us from challenging our processes, critiquing methodologies, and trying to better understand sport, training, physiology, and athlete health and wellness.