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Jun

Preventing the Preventable – Hamstrings and Calves

Wouldn’t it be fantastic if we could completely stamp out running muscle injuries? Of course that can never happen, but there are steps you can take to minimise your risk and potentially give you an advantage over the opposition. The following article will outline what the scientific evidence has to say about preventing muscle injuries, starting with the hamstrings.

Hamstring strains are the most common muscle injuries in sport. Last year AFL clubs lost an average of 21 missed games per year due to hamstring tears. To make matters worse hamstring injuries have a high recurrence rate. Therefore, it is obvious that anyone who tears a hamstring has work to do to prevent recurrence. But what about someone who has never torn their hamstring? How do you know if you or your fellow runners are vulnerable?

The simple answer is that anyone doing high speed running is vulnerable. Thankfully though, there is an excellent way to reduce your chances of tearing. A huge and scientifically rigorous study performed on elite, sub-elite and amateur Danish soccer players showed that by intervening with one exercise, the Nordic hamstring exercise (Google Nordic hamstring exercise if you have not seen it before), the chance of a hamstring tear was reduced by 70%. The results of the study were so strong that it would almost be considered negligent not to be doing Nordics (or an equivalent eccentric exercise) if you are a high speed athlete. I have included below a table with the recommended dosage for the Nordic hamstring exercise that was used in the study to decrease the amount of soreness an athlete will go through.

Recommended training protocol – from Petersen et al. (2011)

One potential problem with the Nordic hamstring exercise is that it is a bilateral exercise. It has been shown in Aussie rules players that if they have hamstring strength asymmetry of greater than 8% between sides (or >15% in soccer players) they have increased odds of hamstring injury. Therefore, if you have one side stronger than the other, doing a bilateral exercise may selectively recruit more effort from the stronger side and increase the strength deficit between sides. Thankfully, asymmetrical strength is a risk factor that is quite modifiable.

You can get an idea of any asymmetry from a simple hamstring bridge capacity test (the first Google image if you search for hamstring bridge capacity test). Do as many lifts of your trunk as you can on each side and compare the result for each side. Remember that differences might be quite subtle based on your strength, perhaps just one repetition could be a 10% difference. Target any asymmetry you find by doing more sets of hamstring bridges on your weaker side. Certainly, don’t neglect your stronger side or the Nordic hamstring exercise, just sort out your imbalance at the same time. A large study performed on elite soccer players showed a significant reduction in hamstring injuries for the players who corrected their strength imbalances.

So it should be clear so far that strength is a huge factor in preventing hamstring injuries. But what else can be done? Stretching is a common warm-up practice to help prevent injury. To date unfortunately there has not been any evidence that stretching of the hamstrings can prevent hamstring strains. However, let’s not throw out stretching completely. It has been shown that for runners over 25 years of age, a decrease in hip flexor flexibility is an independent predictor of hamstring injuries. Regrettably sports medicine is not yet at the stage where is can reverse aging… however we are perfectly suited to increasing hip flexibility, which needs to be addressed no matter the method utilized to achieve it.

While all of these interventions are great because they are relatively easy to administer and complete, we still have to discuss the most important muscle injury prevention strategy. PROGRESSIVE CONDITIONING. Completing systematic progressive running conditioning allows the muscles to develop the strength and physiological abilities required to perform your chosen discipline. This advice is not just hamstring specific – it works for all muscles required in your running whether it be sprinting or running a half-marathon.

So in summary, to prevent hamstring strains: do the Nordic hamstring exercise, balance any strength asymmetries, increase hip flexor flexibility (especially if you are over 25 years old) and most importantly, progressively condition your body over a period of time. Now that you will be able to avoid a hamstring injury the next blog entry will explore other commonly injured muscles.

Now let’s move further down the leg. The calf is a very common area to injure in professional athletes and weekend warriors alike. What does science say we can do to prevent the dreaded ping in the “old man’s muscle”?

Nothing.

I have scoured the internet, dug through medical archives, trawled ancient libraries, sought world expert opinion* and come up short. Prevention of calf musculature injuries is just not something that has been closely investigated to date. However there is some relevant research which I will combine with clinical experience to come up with a calf injury prevention plan.

Firstly we should talk a little about the anatomy of the calf complex. Most people are well aware of the gastrocnemius, the bulky muscle at the top of the calf made up of two parts. But just as important to know about is the soleus; located underneath the gastrocnemius.

The major difference between the gastrocnemius and the soleus muscles is their attachment above and below the knee joint respectively. The implication of the different attachments is that the muscles contribute differently depending on how bent the knee becomes. The more the knee bends, the greater the percentage of work the soleus does instead of the gastrocnemius and vice versa. We can exploit this relationship to allow for more targeted strength of one muscle versus the other. This becomes extremely relevant when we see the comparison of injury rates between the muscles.

Recent MRI findings analysed by Dr Andrew Rotstein (Victoria House Imaging) of calf injuries in the AFL showed that of 63 in season injuries, 30 of these caused missed matches. Of those injuries that caused missed matches, 22 of them involved the soleus (19 were due to the soleus alone). Not only was the soleus more likely to tear, but it was also more likely to make an AFL player miss a game. Clearly we can’t ignore the soleus if we want to prevent calf injuries.

Good examples of soleus strengthening exercises are the seated calf raise or a bent knee calf raise. If you are not in a gym with a seated calf raise machine, you can do the same thing at home with some weights resting on the knee (small children are perfect for this if you can keep them still).

When most people think of the calf muscle they are thinking of the muscle named gastrocnemius. How can we guard the gastrocnemius from injury?

As for most parts of the body, strength is the real key to avoiding injury. Rod Whiteley and his colleagues at Aspetar looked at the average amount of straight leg calf raises a person could do on the edge of a step. The average number of raises was 23 from a group of 156 subjects (312 calves) who ranged in age from 18 – 70 years old. Try this test at home and if you find you are off the pace then you at least have a target number you can build towards.

Further to working on the endurance of that gastrocnemius by doing a high number of repetitions per set, I also recommend spending time working on building strength. This is achieved by lifting heavier weights fewer times. Runners will be given the advice to do 5 sets of 5 repetitions and set the weight at a level that makes the 5th repetition quite difficult to achieve. It has been shown that concurrently training for strength and endurance increases performance in elite level runners, and if it can improve them, it should be able to improve the rest of us!

So there you have it, the currently available scientifically based preventive strategies for keeping those muscles in great shape.

* Some of these actions may not have technically happened.

Lear more about Darren McMillan by visiting http://opsmc.com.au/person/darren-mcmillan/

References

McHugh, M., & Cosgrave, C. (2009). To stretch or not to stretch: the role of stretching in injury prevention and performance. Scandinavian Journal Of Medicine & Science In Sports. http://dx.doi.org/10.1111/j.1600-0838.2009.01058.x

NELSON, A., KOKKONEN, J., & ARNALL, D. (2005). ACUTE MUSCLE STRETCHING INHIBITS MUSCLE STRENGTH ENDURANCE PERFORMANCE. Journal Of Strength And Conditioning Research, 19(2), 338-343. http://dx.doi.org/10.1519/00124278-200505000-00017

Sedano, S., Marín, P., Cuadrado, G., & Redondo, J. (2013). Concurrent Training in Elite Male Runners.Journal Of Strength And Conditioning Research, 27(9), 2433-2443. http://dx.doi.org/10.1519/jsc.0b013e318280cc26

Cresswell, A., Lïescher, W., & Thorstensson, A. (1995). Influence of gastrocnemius muscle length on triceps surae torque development and electromyographic activity in man. Exp Brain Res, 105(2). doi:10.1007/bf00240964

Miaki, H., Someya, F., & Tachino, K. (1999). A comparison of electrical activity in the triceps surae at maximum isometric contraction with the knee and ankle at various angles. Eur J Appl Physiol, 80(3), 185-191. doi:10.1007/s004210050580

Croisier, J. L., Ganteaume, S., Binet, J., Genty, M., & Ferret, J. M. (2008). Strength imbalances and prevention of hamstring injury in professional soccer players: a prospective study. Am J Sports Med, 36(8), 1469-1475. doi: 10.1177/0363546508316764

Freckleton, G., Cook, J., & Pizzari, T. (2014). The predictive validity of a single leg bridge test for hamstring injuries in Australian Rules Football Players. Br J Sports Med, 48(8), 713-717. doi: 10.1136/bjsports-2013-092356

Gabbe, B. J., Bennell, K. L., & Finch, C. F. (2006). Why are older Australian football players at greater risk of hamstring injury? J Sci Med Sport, 9(4), 327-333. doi: 10.1016/j.jsams.2006.01.004

van der Horst, N., Smits, D.-W., Petersen, J., Goedhart, E. A., & Backx, F. J. G. (2015). The Preventive Effect of the Nordic Hamstring Exercise on Hamstring Injuries in Amateur Soccer Players: A Randomized Controlled Trial. The American Journal of Sports Medicine. doi: 10.1177/0363546515574057

Petersen, J., et al. (2011). “Preventive effect of eccentric training on acute hamstring injuries in men’s soccer: a cluster-randomized controlled trial.” Am J Sports Med 39(11): 2296-2303.

Thorborg, K. (2012). “Why hamstring eccentrics are hamstring essentials.” Br J Sports Med 46(7): 463-465

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