Managing the individual in a team sport environment is one of the greatest challenges but one of the most crucial aspects to the collective success of the team. Training and performance share a complex relationship, which is based on several factors, many of which are unique to the specific individual and the performance task. Therefore, athlete monitoring has become a popular trend among strength and conditioning coaches1.
Monitoring training loads is one of the simplest ways to determine the athlete’s response to the training stress over a period of a time. By monitoring what an athlete has performed in a week (Acute workload) compared to what he has been prepared for (Chronic workload), the strength and conditioning coach can begin to build trends in predicting injury risk. Predicting and ultimately preventing injury is the “Holy Grail” in athlete performance. The Chronic workload can be determined as an athlete’s state of fitness, whereas the acute workload can be determined as the athlete’s state of fatigue2. The difference between the positive function of fitness and the negative function of fatigue produces either a positive (where the chronic workload is above the acute workload) or a negative (where the chronic workload is below the acute workload) training-stress balance. The assumption is that physical preparedness grows as chronic workload outweighs acute workload2 – suggesting that as fitness improves and fatigue is reduced, the performance of the athlete should improve. However, if acute workload outweighs chronic workload, the athlete is at an increased risk of injury – especially in the week following a negative training-stress balance.
The above graph shows an example of a training phase depicting chronic workload, acute workload and daily workload. This is indicative of a positive training-stress balance as the athlete’s chronic workload outweighs the acute workload over a period of time.
It is important to note that a sudden spike in daily training load will increase the athlete’s acute workload while decreasing the chronic workload2, potentially leading to a negative training-stress balance and increased risk of injury in the 1 week following.
A more recent calculation in the form of a ratio provides defined thresholds with quick and easy feedback. The acute:chronic workload ratio indicates that a player is less resistant to injury when subjected to spikes in acute workload, which equates to very-high acute:chronic ratios ~ 1.53.
THE CHRONIC:ACUTE TRAINING LOAD RATIO
In the current week, a very high acute:chronic workload (>2.11) in combination with a very high acute workload is associated with an increased risk of injury by up to 6.9 times as well as demonstrating a 10 fold increase in injury risk in the subsequent week3.
The acute:chronic workload ratio needs to be analysed in combination. A high chronic workload combined with moderate, and moderate – high workload ratios had a smaller risk of injury than a low chronic workload combined with several acute:chronic workload ratios3. (Additional Reading recommended; Training injury paradox: should athletes be training smarter or harder?; Gabbett, T; BJSM)
It is suggested that monitoring acute:chronic workloads be mainstream practice in elite sport in order to better predict the onset of injury and therefore prevent rather than react. For the most practical application, it is best to monitor the acute to chronic workload ratio during the current week and as an average over two weeks relative to either a high or low chronic workload.
- Joyce D, Lewindon D. High Performance Training for Sports. Human Kinetics; 2014.
- Hulin BT, Gabbett TJ, Blanch P, Chapman P, Bailey D, Orchard JW. Spikes in acute workload are associated with increased injury risk in elite cricket fast bowlers. Br J Sports Med. 2014;48(8):708-12.
- Hulin BT, Gabbett TJ, Lawson DW, Caputi P, Sampson J a. The acute:chronic workload ratio predicts injury: high chronic workload may decrease injury risk in elite rugby league players. Br J Sports Med. 2015;33:1-7.