During my recent University Studies as part of continuing my education in the Master of Sports Medicine Degree at The University of Melbourne I came across some very useful research regarding load management. As there is a large amount of high-quality research on this topic it is probably easiest to focus on what is most easily useful to the everyday sportsperson. More specifically this is called the acute:chronic workload ratio.
If you are reading this blog you have probably commenced training for that goal that you set a few months ago. Whether it is completing a triathlon or running the Melbourne marathon there is a lot more to it than just running as many kilometres as you can. Ideally your training needs to be measured in ‘load’ and you need to ensure you are not over training or under training to avoid sustaining an injury along your journey.
Firstly, what is Load?
It is important to measure load with both internal (how you are feeling) and external (what you did) measures. For example:
- External Load – eg kilometres, repeated sprints/jumps, distance covered
- Internal Load – eg Rate of Perceived Exertion (RPE), heart rate (HR), and other wellbeing protocols
This can be measured across both competition and training days.
An easy example of this is to use “Sessional RPE”. This is when you use training time (minutes) x intensity (RPE). i.e 30 minutes training session of 6/10 RPE = 180 units if you had 5 sessions like that in one week your weekly training load would be 900 units. Please see below an example of an RPE scale:
Another example of measuring load is to use a GPS tracker or an average heart rate. These seem to be fitted in lots of smart watches or smart phones now.
Once you have these measures, we need to estimate acute load allowing us to calculate our chronic load.
Acute load = sum of the load over a 7-day period. E.g 5 days of exercise x 180 units per session = 900 units
Chronic load = average of the acute load over a 4-week period e.g week 1 (900), week 2 (1000), week 3 (950), week 4 (1050)/ 4 weeks = 3,900 units/ 4 weeks = a chronic load of 975 units.
Therefore your Acute:Chronic load ratio is calculated as acute load/chronic load = 900/975 = 0.92
Why is this important to calculate?
Research has found that athletes have much less chance of injury if they train in their “sweet spot”. Which is between 80% to 130% of their Acute:Chronic Load Ratio (Or 0.8 – 1.3)
So it is also important to note that under training (less than 80% of your chronic load) can be just as detrimental as over training (greater than 130% of your chronic load). For up to 4 weeks after the variation in training load (John W et al., 2015)
It is important to minimise large week-to-week fluctuations (Hulin, Gabbett, Lawson, Caputi, & Sampson, 2016; Orchard, James, Portus, Kountouris, & Dennis, 2009). By calculating the chronic load, we are able to calculate a floor (80% of chronic load) and a ceiling (130% of chronic load) for load as you train. This is demonstrated in the graph below:
(Charlton et al. 2015)
The following graph represents a large variation of training loads. The dark purple line is above the ceiling and the light purple are below the floor. Each variation will pose an increased risk for injury over the coming weeks.
(Charlton et al. 2015)
The correct training loads in the “sweet spot” will protect you from an increase in injury (Billy T, Tim J, Daniel W, Peter, & John A, 2016; Dennis, Farhart, Goumas, & Orchard, 2003)
(Cross, Williams, Trewartha, Kemp, & Stokes, 2016)
(Drew & Finch, 2016)
By calculating the “sweet spot” you will be able avoid injury. So remember:
- Establish and maintain adequate training loads
- Avoid large spikes and troughs in your load
- Have an increased awareness of latent periods following an increase or decrease in load.
Billy T, H., Tim J, G., Daniel W, L., Peter, C., & John A, S. (2016). The acute: chronic workload ratio predicts injury: high chronic workload may decrease injury risk in elite rugby league players. British Journal of Sports Medicine(4), 231. doi:10.1136/bjsports-2015-094817
Charlton P, Drew MK. Can we think about training loads differently? Canberra, Australia: Australian Institute of Sport; 2015.
Cross, M. J., Williams, S., Trewartha, G., Kemp, S. P. T., & Stokes, K. A. (2016). The Influence of In-Season Training Loads on Injury Risk in Professional Rugby Union. International Journal of Sports Physiology & Performance, 11(3), 350-355.
Dennis, R., Farhart, R., Goumas, C., & Orchard, J. (2003). Bowling workload and the risk of injury in elite cricket fast bowlers. Journal of Science and Medicine in Sport, 6(3), 359-367. doi:https://doi.org/10.1016/S1440-2440(03)80031-2
Drew, M. K., & Finch, C. F. (2016). The Relationship Between Training Load and Injury, Illness and Soreness: A Systematic and Literature Review. Sports Medicine (Auckland, N.Z.), 46(6), 861-883. doi:10.1007/s40279-015-0459-8
Hulin, B. T., Gabbett, T. J., Lawson, D. W., Caputi, P., & Sampson, J. A. (2016). The acute:chronic workload ratio predicts injury: high chronic workload may decrease injury risk in elite rugby league players, 231.
John W, O., Peter, B., Justin, P., Alex, K., Kevin, S., Jessica J, O., & Peter, B. (2015). Cricket fast bowling workload patterns as risk factors for tendon, muscle, bone and joint injuries. British Journal of Sports Medicine(16), 1064. doi:10.1136/bjsports-2014-093683
Orchard, J. W., James, T., Portus, M., Kountouris, A., & Dennis, R. (2009). Fast Bowlers in Cricket Demonstrate Up to 3-to 4-Week Delay Between High Workloads and Increased Risk of Injury. In (Vol. 37, pp. 1186-1192).