Finding Your Optimal Training Load: Reaching Peak Performance and Minimising Injury Risk
The Acute on Chronic Workload Ratio
The relationship between training load, fitness and injury is critical to athletes and sports science practitioners. We all seek to find that optimal level where training programmes are well designed and difficult enough to reach peak performance and at the same time reduces risk of injury. These injuries are those which are commonly deemed preventable, because they are the result of errors in training load (commonly termed overuse injuries). Let’s explore some of the key factors surrounding the training-performance-injury paradigm to help you find your training ‘sweet spot.’ The place where you maximise performance and minimise possible negative consequences of training (injury, illness fatigue and overtraining) (1, 2).
Measuring Training Load
Training load isn’t simply the amount of kilometres ran or the amount of weight lifted. It is the total amount of physical work completed (external load) and the body’s physiological and perceived response to it (internal load). Therefore even identical training programmes will result in a different total training load, depending on the individual athletes characteristics (age, training experience, injury history, physical capacity, sleep quality, strength). We need to consider not only the objective load but how the body responds to it and this will vary to the individual. External load can be quite easily tracked with GPS trackers or smart watches, fitbits that quantify distances traveled or with inertial sensors for hopping and jumping sports. A simple internal training load tool is rating of perceived exertion (RPE); a 1-10 rating system of how intense a training session was. This is often multiplied by session duration for an estimate unit of total training load.
The Relationship Between Training Loads and Injury
Training loads are commonly monitored in high level sports. A study on a professional rugby league player who performed greater amounts of very high-speed running per session were 2.7 times more likely to sustain a non-contact soft tissue injury (3). Across codes in the AFL higher 3-week running distance and 3 week sprint distance were associated with greater risk of injury (4). Similar findings have been observed in cricket players, with fast bowlers who bowled greater than 50 overs in a match or 188 deliveries in a week at greater risk of injury. Interestingly those who bowled less than 123 deliveries also had an increased risk of injury (5). The findings from a study monitoring internal workload in Rugby League players suggest the harder players train the more injuries they will sustain and that high strength and power loads may contribute to on field injuries (6). Therefore it is is important to monitor training loads and carefully schedule gym sessions to avoid residual fatigue and minimise risk of training related injuries.
Gabbett over a 2 year period tracked training loads (RPE x minutes) in elite Rugby League players. This enabled the development of a Load-Injury prediction model which identified players were 50-80% more likely to sustain a preseason training injury at a weekly load of 3000-5000 units (using session RPE x minutes). Looking deeper at weekly training load increases of 5-10% had small <10% chance of injury, whereas increases greater than 50% see escalation of injury risk to between 20-50%. This information identifies that higher absolute weekly training loads are associated with greater injury risk.
So Stop Training Hard?
The evidence presented paints a negative light against high training load and training hard. Training hard however is a key factor to help athletes develop adaptations and physical qualities that ultimately improve performance. There is evidence that shows training in fact has a protective effect against injury, particularly with high chronic workloads (3-6 week volume, acute – 1 week). It is intuitive that although very high speed running carries the greatest injury risk it is also necessary to train to allow players to perform these under stress conditions of a match. In Preseason team sports who performed a greater than 18 weeks training prior to initial soft tissue injury had reduced risk of subsequent injury (7). Additionally low training loads have also been linked to increased injury risk in sports such as as cricket, baseball and rugby union. So collectively we find that although high absolute loads increase injury risk a low load approach may not in fact be best to improve physical qualities and reduce injury risk.
Finding That ‘Sweet Spot’
So we wish to train hard for reaching peak performance at the same time wish to reduce risk of injury. It’s not so much the amount of training load we are doing but the ratio of the acute to chronic workload that can give you best information on your training ‘sweet spot’. Acute workload could be as little as a single session however is generally considered over the course of a week, whereas chronic ratio is the average of the most recent 3-6 weeks training. In this respect if the acute to chronic ratio is low, the athlete is in a state of minimal fatigue and has developed fitness. Research indicates a 0.8-1.3 ratio is best and that injury risk increases after reaching a 1.5 ratio. So if you’re trying to get serious with your training and wish to reduce injury risk this is a good place to start. For practicality here’s a few helpful tips:
- Record 0-10 RPE (exertion) after each exercise session and multiple by session duration (these are your base units)
- Sum together to form your weekly average
- Compare this week (acute), with an average of the previous month (chronic) and compare to find your acute:chronic which should aim to be <1.5
- Week to week training load increases should be less than 10% as well
- What get’s measured gets improved, so you may consider also documenting quality of sleep, mood, stress level, nutrition or feelings of soreness.
Lewis Craig (APAM)
Masters of Physiotherapy
- Gabbet TJ. 2016. The training-injury prevention paradox: should athletes be training smarter and harder, Br J Sports Med; 50:273-280
- Banister EW, Calvert TW, Savage MV, et A systems model of training for athletic performance. Aust J Sports Med 1975;7:57-61
- Gabbett TJ, Ullah S. Relationship between running loads and soft-tissue injury in elite team sport athletes. J Strength Cond Res 2012;26:953-60
- Colby MJ, Dawson B, Heasman J, et Accelerometer and GPS-derived running loads and injury risk in elite Australian footballers. J Strength Cond Res 2014;28:2244-52
- Dennis R, Farhart P, Goumas C, et Bowling workload and the risk of injury in elite cricket fast bowlers. J Sci Med Sport 2003;6:359–67
- Gabbett TJ, Jenkins DG. Relationship between training load and injury in professional rugby league players. J Sci Med Sport 2011;14:204
- Gabbett TJ, Domrow N. Risk factors for injury in sub-elite rugby league players. Am J Sports Med 2005;33:428–34.