Training Loads and Injury Risk

Training Loads and Injury Risk – Finding the Sweet Spot

Regular participation in sport and exercise is one of the best things we can do to optimise our health and well-being. The benefits of regular physical activity are numerous and well-established. Some of these include: reduced risk of cardiovascular and metabolic health complications, improved weight management, improved mental health, and a shorter recovery and less severe outcomes if you become sick. This is not to mention the multitude of other social and psychological benefits associated with team sports and group exercise.

Around this time of year – where new year’s resolutions are being set and the summer sun is inviting us to soak in its splendour outdoors – people are starting to ramp up their exercise. Great! With more and more people beginning to increase their training, this time each year we start to see the same pattern pop up: people go too hard, overdo it, and get injured. So why do we reliably get injured when we exercise more, when our more athletic friends seem to get away with training year-round injury-free?

It’s all about Risk

Injuries happen. Look at any professional sporting team – even with the best doctors, physiotherapists, and allied health staff working around the clock to keep their athletes in top condition – you’ll see injuries popping up every single week. While we’ve made great strides in reducing rates of certain types of injury in sport using modern warm-up and strengthening protocols (such as the FIFA11+ protocol for professional football, or the KNEE program for netball), injuries are a part of life and something we will never get rid of completely.

Sport, exercise, and all forms of physical activity inherently come with a certain risk of injury. Though many sporting injuries are the result of physical contact, slips, and traumas, the majority of injuries we see are considered overuse injuries – something we’re a lot better at predicting and preventing. 

Training Load & Supercompensation

Overuse injuries occur when repetitive loading of a tissue, joint, or other structure within the body exceed the body’s ability to recover from the damage associated with that load. These include common conditions such as; patellofemoral pain, shin splints, bursitis, tendinopathies, and at the extreme end can include stress fractures and muscle tears.

High levels of training load results in minor damage to bones, joints, and muscles, which our body responds to by repairing that damage and making the tissue stronger and more durable for next time. This is usually called supercompensation. This process occurs with rest, and takes time. For muscles, we’re looking at days for this regeneration to occur, and for bones, joints, and other tissues, we’re looking at weeks. 

Simply put, training load can be thought of as the total amount of exercise performed multiplied by the difficulty of that exercise. In professional sporting contexts, this can be quantified a number of different ways, for example by calculating the total weight lifted in a workout, the total distance ran during competition, or the number of minutes spent exercising above a certain heart rate. A simple method of quantifying training load for recreational athletes involves rating a workout’s difficulty using the Rate of Perceived Exertion (RPE) – a simple scale of 1-10 where 1 feels like minimal exercise and 10 feels like maximal exercise.

So as we begin to ramp up our training loads in preparation for beach cricket or this year’s Christmas pudding, we run the risk of overloading our bodies without allowing adequate time for rest and recovery – eventually leading to injury. However, we know from the research that progressively overloading the body is a key variable in improving our our strength, fitness, and sports performance (that is, gradually increasing workout difficulty, duration, or intensity from week to week). So how do we achieve supercompensation and reach our fitness goals without increasing our risk of injury?

Optimal Training Loads and the Acute:Chronic Workload Ratio

When looking to significantly increase training loads, we need to consider the speed at which we begin to ramp things up. Multiple studies have been conducted looking at training loads and injury risk, and conclusions have always been fairly consistent. This chart from the British Journal of Sports Medicine shows the likelihood of injury in multiple Aussie sports represented using an acute:chronic workload ratio. Here, the acute workload represents the total training volume of the past week, and the chronic workload represents the average total weekly training volume of the previous 3-6 weeks.

Gabbett TJ. The training—injury prevention paradox: should athletes be training smarter and harder? British Journal of Sports Medicine 2016;50:273-280. 

What this chart shows is that the timing of any changes to our training volume is incredibly important in predicting our risk of injury. As the author of the above study notes, there seems to be a ‘sweet spot’ where injury risk is lowest when acute:chronic workload ratios sit between 0.8-1.3. 

It should now come as no surprise that any significant increases to training load over a 3-6 week period drastically increase our risk of getting injured. This means that going from running 2-times a week to running 5-times a week without allowing your body the time to adapt to that volume is likely to end in pain or injury. In the same way, increasing from a 50kg to 100kg bench press over the course of 4 weeks also carries an increased risk of injury than increasing to, say, 70kgs.

What may be a more interesting finding is that any significant decrease in training load over the same period is also associated with an increased risk of injury. In much the same way that we lose strength and fitness after any significant time away from training, our bodies lose their capacity to handle load with significant periods of rest. A sudden decrease in training load is likely associated with a decrease in body strength and robustness, leading to a higher chance of injury when exercise is performed.

Practical Tips & Take Home Messages

Our bodies are strong and resilient, and can handle most of whatever we choose to throw at them. With that said, sudden increases or decreases in current exercise volumes can lead to an increased risk of injury. In order to enjoy your summer and reduce your chance of needing to see us, here are some general tips to avoid injury:

• Establish an exercise routine and stick to it. This will avoid any sudden spikes in training load due to inconsistent training scheduling.
• Avoid sudden spikes in training load – this includes sudden increases or decreases.
• Slowly get stronger. Regular gym work and strength and conditioning has been shown to significantly reduce your likelihood of many common injuries, and will probably help your sport performance too!
• Optimise your recovery. Ensuring that rest, nutrition, and stress levels are well managed is vital to recovery from exercise and creating a supercompensation response. This includes aiming for 7-9 hours of good quality sleep per night.

Unsure where to start? Speak to a professional!

Here at MyoActive, our team of Myotherapists, Physiotherapists, and Osteopaths are all trained in exercise prescription and modern injury prevention protocols. To find an available appointment, simply call 0422 580 035 or book online via https://myoactive.cliniko.com/bookings. 

By David – MyoActive Sports Physiotherapist