A framework for the Acute: Chronic Workload Ratio (ACWR)-
It is important, as coaches that we have a concept of what appropriate an workload for our athletes is. There are several theoretical concepts in practice and a large amount of misinformation out there.
Rest is not always the answer and on the flip side, it is not always appropriate to do more.
There are several proposed models that serve to provide a framework to help coaches plan and execute training/competition blocks. One such framework is the Acute:Chronic Workload Ratio (ACWR).
Now, remember that it is just that, a framework. It is by no means definitive, it is not predictive (eg, cannot predict injury) and it is certainly not the only piece of information coaches should use to make decisions. But it does serve to help guide our planning and drive conversations you have with your athletes.
The introduction to the ACWR below will outline the theoretical concepts, definitions and physiological reasoning behind using such a metric.
The ACWR helps coaches assess and monitor training-load and gain an insight in to an athletes previous and current level of fitness. Thus the relationship between what has been done vs what they are now equipped to do can be understood using ACWR.
Acute workload is the current week and is usually 1-week (7 days). This workload can include all training and match loads (including if the athlete completed multiple sessions in a single day). As a coach, there is value in understanding the acute load for every athlete on your squad.
Chronic workload is usually classed as 4-week (28 day) rolling average of an athletes acute workload. The chronic value gives coaches an insight in to an athletes typical weekly workload.
What metrics should we consider to use for ACWR?
Hard Running Efforts
2D & 3D Load
Ideal implementation of the ACWR requires coaches to review data each day, for all athletes.
To get an idea of what values constitute too much work or not enough, see the table below:
When using any training load metric, coaches MUST understand that they are by no means definitive. Training load and injury risk carry a high level of complexity and variability. It is inappropriate to assume that a ratio or single metric will tell a complete story. All sports, athlete demographics and populations will have different injury risks, so it is important to consider many streams of information when making informed decisions.
The relationship between ACWR and injury risk (%) [Gabbett 2016].
Other important factors to consider when interpreting the training load picture:
Level of Sport Played
Training-Load Spikes and Injury
There is a growing body of evidence that shows a strong relationship between spikes in training load and non-contact injuries. As coaches it is your job to appropriately plan training and competition weeks to avoid excessive increases in athlete training loads.
Plans should factor in weekly changes (+/-) in training-load with the aim of decreasing injury risk. Currently the research around training load and injury risk suggests a weekly limit of no more than 10% increase or decrease in training loads.
Developing Robust and Physically Fit Athletes
The ACWR should not be a metric that coaches are afraid of, as well as being a monitoring tool the, it also has the potential to be used effectively to plan long term (and safe) increases in load. As coaches develop athlete over time and accumulate large volumes of appropriate training, this will serve to protect against potential injury risk.
In practice, this means that if coaches appreciate planning and monitoring of athlete loads, they will be able to deliver well thought out training programs that both prepare athletes for competition and protect against injury.
Soligard, T., Schwellnus, M., Alonso, J., Bahr, R., Clarsen, B., Dijkstra, H., Gabbett, T., Gleeson, M., Hägglund, M., Hutchinson, M., Janse van Rensburg, C., Khan, K., Meeusen, R., Orchard, J., Pluim, B., Raftery, M., Budgett, R. and Engebretsen, L., 2016. How much is too much? (Part 1) International Olympic Committee consensus statement on load in sport and risk of injury.British Journal of Sports Medicine, 50(17), pp.1030-1041. http://bjsm.bmj.com/content/50/17/1030
Bourdon, P., Cardinale, M., Murray, A., Gastin, P., Kellmann, M., Varley, M., Gabbett, T., Coutts, A., Burgess, D., Gregson, W. and Cable, N., 2017. Monitoring Athlete Training Loads: Consensus Statement. International Journal of Sports Physiology and Performance, 12, pp. S2-161-S2-170. http://journals.humankinetics.com/doi/abs/10.1123/IJSPP.2017-0208
Gabbett, T., 2016. The training—injury prevention paradox: should athletes be training smarter and harder?.British Journal of Sports Medicine, 50(5), pp.273-280. http://bjsm.bmj.com/content/early/2016/01/12/bjsports-2015-095788?__hstc=196135283.0bb2ae1552d2dda845881b6516c33848.1481673600081.1481673600082.14816736000