The biggest risk factor for acquiring an injury during sport is having previously had that injury whilst playing. This is the same for any muscle/tendon/ligament/bone injuries. For example, having rolled an ankle playing basketball makes you significantly more likely to roll it again when playing basketball. Another common example is the runner who experiences pain at the front of the knee; they are more likely to get this same pain again when running in the future.
Often the occasion where the athlete is most vulnerable is on returning to sport after time off due to injury. This is for a number of reasons including strength and general fitness, the degree of healing in the injured area, mental confidence in regards to utilising the previously painful or injured area, as well co-ordination and balance changes.
The decision to return to play can be difficult. If the athlete returns too early they may experience a recurrence. But if you delay return to sport unnecessarily, then the athlete may experience negative changes (physical and mental) as a result of withdrawing from the physical activity and exercise they enjoy.
Training is an important aspect of sport. The weight applied to healing muscles/tendons/ligaments/bones during training is a vital component of tissue healing, with ‘appropriate’ loading of the athlete resulting in significantly quicker return to sport time frames. The trick is to know how much to load an athlete and when a physio can help with this.
An informative review by Blanch and Gabbet (2015) combined return play data from three different sports – cricket, football and rugby league – to create an injury prediction table (see below):
This table compared the acute load (training performed in the past week) to the athletes chronic load (training that was performed per week on average over the last four weeks). Load may be kilometres run in a long distance runner, balls bowled in a cricketer, or even changes of direction in a soccer player.
Now this is where it gets a little tricky. You will need your calculator for the next part. By dividing the acute load by the chronic load, a % risk of injury over the next week can be determined. Two examples of how this table can be used are provided below:
- A middle distance runner training for the Burnie 10 typically runs ten kilometres a week (his normal average). He strains his left foot three weeks out from the race. His chronic load drops to three kilometres due to rehabilitation and a reduced ability to run. If the runner tries to perform the Burnie 10, his acute load (100%) will significantly exceed his chronic load (30%) and he’ll have a 61.4% chance of suffering an injury.
- A female football player strains her thigh when sprinting for the ball. She normally trains and plays soccer for about 120 minutes a week (her normal average), but due to her injury has averaged only 60 minutes per week over the last four weeks (her chronic average is 50% of normal). She has the grand final on the weekend and wants to know what her chances are of hurting herself if she played 90 minutes of the game. Her acute load would be 75% of her normal load, whilst her chronic load is 50% of her normal load, resulting in a 5-8% chance of re-injury.
This table is not perfect. Other factors can affect the likelihood of re-injury such as sleep, fatigue, strength, balance and so on. This can be quite confusing but your local Physiotas can help you to determine if it is safe to return to sport. Training is vital in the injured athlete’s journey to return to play. The longer someone has been injured, the longer they will need to train to ensure adequate rehabilitation of their injury. Have you trained enough to return to play?
Blanch, P., & Gabbett, T. (2015) Has the athlete trained enough to return to play safely? The acute:chronic workload ratio permits clinicians to quantify a player’s risk of subsequent injury, British Journal of Sports Medicine, 50, 471-5. doi:10.1136/bjsports-2015-095445
About the Author:
Zac is currently in the final stages of a Masters in Sports Physiotherapy through La Trobe University. As well as working at Physiotas, Zac is the State Strength and Conditioning Manager and Physiotherapist for the AFL Tasmanian Football Academy.
Zac’s main clinical interest is in the application of strength and conditioning to the rehabilitating athlete, whether that be at the elite level or the weekend warrior. Other areas of interest include chronic and acute low back pain, and shoulder pain.
Zac’s personal interests include football, strength training and riding horses.