Avoiding injuries – the Nerdy detail!

By Peter Horobin and Neil Smith - Specialist running injury clinicians at Pure Sports Medicine.

In our last article, we gave some general advice for avoiding injury as you build up your mileage in preparation for Run for Love. In this article, we will expand on some key areas of injury prevention theory and briefly outline some of the evidence for adopting such strategies. During our recent talk at Tribe HQ three main topics came up; 1) is strength training useful 2) how helpful is stretching and 3) how do you safely build up your mileage? Let’s take these three subjects one at a time:

Strength training – not got enough time for the weights?

From a performance perspective, it is useful - from an injury preventative perspective, it is essential. An excellent study by Lauersen et al (a 2013 systematic review and meta-analysis of randomised controlled trials) looked at how effective various injury preventative interventions were over 25 trials with a total of 26, 610 participants. Take it from us, this is a very powerful study! The authors concluded that strength training reduced overuse injuries by almost 50%. They also found some benefit to balance training but interestingly no benefit to stretching - more on this later.

So, if you don’t have strength training in your weekly plan, why not? A common worry among keen amateur endurance athletes is the fear of bulking up, “but won’t it make me slow?”, they might say. This is a common misconception which has been disproved by the literature. A paper by Ronnestad and Mujika analysed the effects of heavy and explosive strength training on endurance performance and found evidence for multiple benefits – namely an improvement in exercise economy, anaerobic capacity, lactate threshold, delayed fatigue, improved rate of force development… the list goes on. Importantly, they observed no increase in overall athlete body mass.

Yamamoto et al looked at whether strength training could improve performance and they found an average increase in running economy of 4.9% and a 2.9% increase in participant’s performance.

So, ask yourself again – if you don’t strength train, why not? The evidence points to a 50% reduction in injuries and a small, but significant, improvement in performance. Ideally you would have a progressive programme personalised to your needs set by a good Strength and Conditioning coach, but at the very least, we advocate strengthening exercises for the main muscle groups – calfs, legs, glutes and some trunk muscle exercises. So, incorporate calf raises, squats and lunges into your weekly plan as a bare minimum.

Stretching – is it a waste of time?

As already mentioned, the large study that assessed thousands of endurance athletes found no injury preventative benefit from stretching. Those that stretched had statistically just as many injures as those that didn’t. So, is it just wasting time? This point divides a lot of opinions, particularly as some authors have suggested that performing static stretching before an event slightly increases your risk of injury. Due to such findings, static stretching before exercise has gone out of fashion and been replaced by more dynamic exercises that have been found to result in small increases of range of motion with no negative effects.

For many years, people have religiously carried out static stretching post-exercise in the belief that they will reduce delayed onset muscle soreness (DOMS) and improve range of motion. The traditional belief, that is still held by some, was outlined in a paper in 19615, the authors stated how stretching increases blood flow to the muscle and thereby reduces soreness and improves recovery.

This concept has since been challenged with studies demonstrating a reduced blood flow during stretching and a barely significant reduction in muscle soreness which in part prompted the search for additional recovery methods such as ice bathing and foam rolling which we will leave to another day but is equally as divisive.

Another reason why people carry out static stretching is to increase their flexibility. Weeks of static stretching interventions have successfully demonstrated an improvement in range of motion however, this is likely due to an increased stretch tolerance (the ability to withstand the stretching force) rather than an actual increase in muscle-tendon length. If, for example, you have tight hamstrings that you like to stretch on odd occasion, you might be wasting your time as studies suggest that you must stretch A LOT to increase their length – and even then, you probably aren’t actually lengthening the muscle but rather just teaching your nervous system to be less sensitive when you take the muscle towards it’s end range. For such people that want to increase muscle length, the literature is starting to provide more evidence for the effectiveness of eccentric strengthening exercises. This is an exercise where a muscle actively resists a slow and steady lengthening of that muscle. This process potentially promotes the addition of more muscle filaments along the course of the muscle by a process called sarcomerogenesis. Picture it like this; static stretching is quite like stretching a spring – you might lengthen it a bit but it will quickly recoil back to its original length once the stretching force is removed. Eccentric exercises lengthen the spring but also add more coils to either end resulting in a longer spring after a while.

To the best of our knowledge, no studies have looked at the psychological effects of stretching on pain and performance. A pre and post competition stretching routine may help an athlete to prepare and recover mentally from an event. Perhaps the routine of a stretching ritual carried out before a 10km race will help to settle some nerves and a good cool down afterwards will allow for reflection of the task helping performance in other ways. Either way, we both feel that, if you are going out for a long, steady run this weekend, there is no benefit to carrying out lots of static stretches. But if you think it helps you, go for it.

The ‘10% rule’ – how to increase your mileage safely.

The 10% rule comes from the excellent work by Tim Gabbett. His paper called “The training-injury prevention paradox: should athletes be training smarter and harder?” is open access and should be read by all coaches and high level athletes. In it, he discusses the ‘sweet spot’ which should be all athletes target. It is sufficient training volume that enables good performance but comes with a low injury risk since higher training loads may result in good fitness and performance but come at an increased risk of injury. Athletes can be at particular risk if they greatly increase their weekly training loads beyond that of their current tissues capacity. As illustrated in the graph below, there is a relatively low risk of injury with weekly increases of 10% or less. Anything greater comes with an increased injury risk – this lead to the 10% rule. If you are looking to safely increase your mileage, then it is advisable to take your current weekly mileage and increase it by no more than 10% for the following week.

Running injuries can result from a variety of factors with training error being one of the most common causes. In clinic, we often come across runner’s knee’s, IT band problems and achilles pains that can be traced back to a time when there was a sudden unaccustomed increase in training levels. So, train smarter to avoid the services of someone like us!

Neil Smith Physiotherapist, BSc - neil.smith@puresportsmed.com

Peter Horobin, Osteopath BSc, DO MSc - peter.horobin@puresportsmed.com

Pure Sports Medicine - A team of world-class sport and exercise medicine specialists will work with you to prevent, diagnose, treat and manage your injury, ensuring you’re at your best, every day.

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