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Injury Prevention & Training Load

In this month’s blog we examine the science behind training load and injury risk.

It was long thought that higher training loads were associated with a greater risk of injury. But perhaps happily for some, increasingly the research suggests that training harder is actually a key factor in reducing the risk of injury.

Numerous studies have investigated the influence of training volume, intensity and frequency on fitness and performance sports in sports ranging from running to cricket and football.

In general, physical performance improves with increases in training load; it’s on this basis the concept of training for performance is founded. In the last 30 years, injury surveillance data has enabled sports scientists to evaluate the amount of training that could increase the risk of injury. Injuries can largely be put into one of two categories; traumatic injuries or those relating to repetitive strain on ligaments, muscles and bones. An example of a repetitive strain injury in an endurance runner might be a stress fracture in the foot related resulting from the repetitive impact forces from running long distances. It is this just this type of injury resulting from repetitive training loads that are the most controllable and also those that are most impacted by training loads.

Training harder – with greater volumes and working harder in sessions increases muscle strength, fitness and sports specific conditioning – all of which protect the body from injury. But the same increases in training also produce fatigue and this fatigue which is likely to increase the injury risk, so this presents an interesting paradox: training hard is beneficial but how much is too much?

Acute and Chronic training loads

To better understand the amount of training that could increase your risk of injury it’s helpful to consider the concept of acute and chronic training loads. Acute training load is the training accumulated over a short period of time; normally a week, whilst chronic training load is amount of training completed over a longer period of at least 6-8 weeks. Research suggests that high chronic training loads improve physical strength and fitness over time. And so long as these ‘chronic’ training loads are progressed steadily, then they can help reduce injury risk. I’m sure you can think of athletes who have performed consistently over a long period of time without long lay-offs who continue to thrive despite high demands of their support. Consistency of training and performance demands is often the magic ingredient here.

However, if the acute or short-term load is very high then the risk of soft tissue injury is increased. For example, if you’re training for an event and your average weekly training has been around 45km a week , your acute load in a week shouldn’t exceed your chronic load by more than a ratio of 0.8-1.3 (studies vary on this hence the range in the recommended ratios). Here’s an example in a runner training for a half marathon:

Total training load over the last week (acute load) = 62km

Average weekly training kilometres over the last 6 weeks (chronic load) = 45km

Load ratio= 1.4 – too high!

What does this all mean for my training?

In simple terms, sudden increases or ‘spikes’ in training in the amount of training are a risk factor for soft tissue injuries. To minimise injury risk ensure your weekly increase in training is gradual. You may have come across the ‘10%’ rule, often used in running, meaning you shouldn’t increase your training by more than 10% week on week. Recent studies suggest this to be on the conservative side, but it is a good rule of thumb, particularly if you’re relatively new to running.

This idea of acute and chronic training focuses on the volume/amount of training but doesn’t take into consideration other elements of your training such as training intensity or the frequency of sessions. Sudden increases in the training intensity (e.g: amount of weight or speed) could also be a risk factor for injury. Also be mindful of building your training gradually after you have a lay off from training or exercise for any reason – whether it be a two week holiday or period of illness; if you have more than two weeks off training ensure you build back in gradually rather than continuing where you left off.

Can high training loads protect me from injury?

Low training loads have actually been found to be associated with a greater risk of soft tissue injury. Training loads ensure the body has the best physical qualities in place -and it’s these qualities that protect from injury. So, the greater the training load the more of these protective qualities can be developed. If your training loads are low you never achieve these qualities which in turn increases risk of injury. So don’t be afraid of building to train at higher volumes but do it gradually and your training should be carefully planned with adequate recovery blocks in place to optimise the training effect. Always listen to your body; juggling the other demands in life such as work and family can increase your fatigue levels, so it’s not only your sporting demands when you plan your training.

What else do I need to consider to reduce my risk of injury?

Injury risk is multifactorial and we can’t ignore the numerous contributing factors that can increase our risk level. Aside from managing training loads, ensuring you have the best strength and mobility qualities for your sport is essential. Strengthening hamstrings for sprinting might benefit from some additional focussed training in the gym or shoulder conditioning could help improve both mobility and muscle activation to improve your shoulder joint function in the pool.

Other factors to consider are optimal nutrition and hydration, particularly important for bone health, and well managed preparation and recovery (warm up’s and cool downs). It’s also important to ensure any injury niggles receive the right treatment and rehabilitation to ensure they fully resolve, unfortunately your history of injury is a big predictor that you will have further problems in the future so it is well worth getting those niggles sorted.

Get in touch today if you need further input on injury prevention and management!


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