Today on RunningPhysio we're doing a 'blog swap' – I've handed the keys to Adam over at TheSportsPhysio and I'm trusting him not to redecorate or put up any of those horrid 80's posters with wolves on or dolphins jumping a reflection of the moon! Luckily Adam is pretty trustworthy and I'm sure the blog is in safe hands! He has worked in elite sports and has a wealth of experience to draw from, follow him on Twitter via @adammeakins.

So the hamstrings, the ‘hammy’s’ those muscles that run down the back of your leg, the ones that commonly get overlooked until it’s too late. You only had to be watching the recent London 2012 Olympic 100 metres final to see Asafa Powell pull up 60m down the track or watch Andy Carroll limp off and be ruled out for 6 weeks after his debut game with West Ham a few weeks ago to realise how common hamstring injuries in sport can be, but what about in running?

Well Tom has asked me to talk to you about hamstring tears in running, what are the chances of you having one? What happens when they tear and what you can do to reduce your risk and optimise your recovery quickly?

Now luckily, or unluckily depending which side of the treatment couch you’re on, I have dealt with plenty of hamstring tears especially in my years of working as a physio in football, as this is one of, if not the most common injury in football.

However they are also fairly common in other sports, but what about running, well I can tell you from first hand experience having suffered a hamstring injury a few years ago, they do occur in running, but to tear a hammy, you usually have to be sprinting hard or trying to slowing down rapidly, or changing direction sharply or kicking something, which runners do do, (apart from kicking something… except maybe that mad dog chasing you) just not as often as in a sport such as football, I did mine leaping through the Forest of Dean on a trail run.

There are other ways to tear a hamstring , the overstretch tears that dancers experience a lot but these tend to be done at slower speed and less traumatic than the high speed explosive tears from sprinting and running and its these that will be more relevant to runners.

So we know they are common but what are your chances of suffering a hamstring tear as a runner, well unfortunately I can’t tell you, as I was unable to find any specific study on just runners alone, all the studies are done in sports such as football, rugby or athletic track events, for example a great study done by Woods et al 2004 done over two years back in 1997-1999 in professional football found the incidence of hamstring tears to be the highest prevelant injury with rates as high as 28% with between 8-25 days out per injury depending on severity and where it tore.

But it’s fair to say that if you’re a runner who sprints, jumps and leaps a lot, such as a trail or fell runner, or someone who does regular hill sprints or any high intensity sprint session then your chances will be significantly higher to tear a hamstring rather than a runner who maintains a consistent steady pace, you’re more likely to develop a hamstring tendinopathy, but that’s another article completely.

So why do these hamstrings tear?

Well its due in part to their anatomy and the role they play when running. First their anatomy, the three hamstrings control movement at two big joints, the hip and the knee, and we know that muscles that have to work this way, simultaneously controlling movement at two joints are more at risk of injury, it’s also believed that most hamstrings usually tear during the late swing phase or the running cycle, just at maximal knee extension i.e. just before your foot is about to land on the floor, this phase of the running cycle is when the hamstrings are having to act like a brake, slowing your leg down as its been powerfully swung forward underneath you by the strong forceful contraction of the quads and hip flexors muscles, but as they are acting as a brake they are also being elongated to near their maximal length by both the straightening knee and the flexing hip. This is called eccentric muscle contraction (concentric contraction is the opposite when the muscle shortens such as when the heel comes up towards your buttocks in the early swing phase)

So the hamstring has to stretch to near is max length and simultaneously contract to slow your leg down, this produces a great deal of tensile strain within the muscle and if it reaches a critical point it will tear. It tears usually at its weakest point that being an area called the musculotendinous junction, this is where the muscle belly changes into the tendon, and its usually the biceps femoris muscle (the hamstring down the outside of your leg) that this occurs in, but they can tear in other areas and in any of the other hamstring muscles depending on a lot of different factors.

So how do you know if you have torn your hamstring rather than just strained it?

Well this can be extremely obvious, but also very tricky, for example, a severe or complete tear of a hamstring called a Grade 3 injury is easy to diagnose and spot, for starters you will have felt something ‘go’ or ‘pop’ or ‘crack’, you will also be lying on the floor feeling as if you have been shot or hit with an axe behind your leg, you will not be able to walk and will be in a lot of pain, you will notice bruising quickly appear in the next hour or so as the torn muscle leaks blood ‘a lot’ and it will be hot and swollen to touch, this class of tear is normally managed by surgical repair and then physiotherapy and will mean 6 months to a year out.

For a less severe partial tear called a Grade 2, you will have still probably felt something ‘go’ again but no popping sensations, you will have pulled up but still be standing and limping around, you will be able to walk but it will hurt, you may or may not get any bruising, and maybe able to feel some heat and swelling but might be harder to see, this is usually managed conservatively meaning no operation but lots of physio treatment and anywhere from 6 weeks to 6 months out.

However for the much more common smaller tears called a Grade 1, it can be harder to recognise, these are tricky little buggers it can almost feel like a small strain or niggle that can come on during a run, you can continue to run although it will cause a diffuse soreness behind your leg that can settle very quickly once you have stopped, so leading you to think you have not torn anything especially as you won’t see any bruising or feel any heat or swelling and feel nothing in normal day to day activities except maybe a twinge on getting up out of chairs or up/down stairs, most of these class of tears need to be properly managed and normally its anywhere of 3 -12 weeks of physio treatment

The reason it can be from 3 weeks to 3 months for the same injury is due to a couple of reasons first and most obviously with a Grade 1 tear runners can continue to run which they like to do, and tend to do, even in pain, this disrupts the healing processes and prevents the tear from healing, secondly it can depend on where the tear is located, if more in the tendon it heals slower than if in the muscle belly, all due to the differing bloody supply. Finally they are commonly misdiagnosed as just a strain and so again back to the same issue of allowing the runner to continue to run or even doing inappropriate rehab such as stretching the hamstrings in the early stages and so not allowing the tear to heal.

So what do you do if you think you have a Grade1 hamstring tear?

Well its simple if you’re a professional football player you go and have an MRI, that’s the gold standard, no room for misdiagnosis there (well 98% of the time), but you’re not going to get MRI when you go and see your GP or physio and complain of your hamstring pain as 1) they cost a fortune and 2) the waiting time to get one means it will be useless by the time you do.

So my advice if you think you have just a hamstring strain, err on the side of caution and treat it like a Grade 1 tear and go and see a physio for some advice and treatment. In my experience dealing with them like this, yes may take a little longer and may be frustrating at the start, but it will mean in the long run you won’t be back to see the physio a few weeks later with same problem.

So how do you treat a Grade 1 hamstring tear?

So first and foremost STOP RUNNING, this will be for at least THREE weeks, and yes I can hear you all groaning from here… believe me I don’t ask people to stop their sport lightly but if I think you have a hamstring tear I will insist.

Follow the RICE programme, Rest we covered above, Ice for a week or so regularly, Compress with either cycle shorts or tubigrip, and Elevate

DO NOT STRETCH your hamstrings for these three weeks or so, you will need to let the scar tissue lay down over the tear without disrupting it, if you keep stretching it will be unable to lay down effectively, you will be stretching plenty later on, save your energy for then.

Once the physio feels you have gone through the healing phase then the fun rehab can begin and eventually get you back out running, how long this last again varies and is based on individual factors and you will have to reach certain checkpoints before the physio lets you back 100% but on average it’s a few weeks.

Great so you're recovered and back out running, well a word of warning, you are now in the high risk category for suffering with another hamstring tear, with around 33% suffering another tear especially in the first few weeks after return to running, again I can hear you groaning from here… but you can reduce your risk of re injury.

So how do you reduce your chances of suffering a hamstring tear as a runner?

Well I’m sorry to say this again but I couldn’t find any specific studies done just on runners on how to prevent hamstring tears (us runners seem to be the poor relation of sports when it comes to good quality research), most prevention studies again have all been focused where the money is… football. But we can still use their findings and incorporate it for us runners.

First we need to identify your risk factors for getting a hamstring injury and as we said previous hamstring injury is a factor, in fact it’s the only conclusive risk factor that the research has found.

But there are other modifiable risk factors found in the research but they aren’t conclusive, they are a lack of flexibility of both the hamstrings but also the hip flexors and quads, poor strength ratios between the quads and hamstring , poor coordination of the pelvic and trunk muscles, fatigue and poor warm up strategies prior to exercise. So although not conclusive if we use our common sense and address these then your chances of suffering a hamstring tear have got to be reduced.

First let’s look at flexibility.

The hamstrings are notorious as being a tight group of muscles but this isn’t the only group to look at the relationship between the hamstrings and the hip flexors and quads is complex and addressing tightness in all of these is essential.

If we keep it simple for sake of time and just say if the hamstrings and hip flexors and quads are tight then the movement at the hip and knee joints is restricted and place extra strain on the soft tissue around them so loosening them allows better joint movement, so less strain.

Some of the best stretches I feel for these muscle are as below

There has been much debate of the role of stretching before running etc, and I don’t want to get into this now, but it’s safe to say if you loosen these tight muscles regularly not just before you go running you won’t be going far wrong. (More on stretching from Adam here)

Next let’s look at hamstring strength.

Keeping the hamstrings strong, but especially the eccentric phase, which if you remember a while back we said is when the muscle is lengthening as it’s contracting is also key. All running activities tend to be quad dominate and these quad muscle get stronger and stronger when running so the ‘pulling’ on the hamstrings gets more and more as the leg swings forward underneath us, if the hamstring can’t keep up with the stronger quads it will be prone to tearing.

A ratio of 1:0.6 or 66% has been used for a long time for the hamstrings but this is only for its concentric strength, for example if your quads can push 100kg your hamstrings should be able to pull 66kg.

But a much more useful and important ratio is the eccentric ratio and opinion here is divided as what’s the best, but for most a ratio of 1:1 is used, (1:1.2 if you’re an elite athlete) for example for every 100kg your hamstring can pull as the knee bends, it must be able to resist 100kg as your knee gets straightened (120kg if you’re an elite athlete)

A good way of testing this and finding out if you are achieving these ratios is with an Isokinetic Dynometer as shown below, this is me testing one of our young Watford FC lads last season, but again not many will have access to this, instead just take it as read that you won’t have these ratios, I haven’t met many that do, so doing some hamstring strengthening exercises is a must especially the eccentric phase is essential

Some good hamstring eccentric strengthen exercises

The last exercise the single leg RDL (Romanian Dead Lift) is also really good for helping that other factor mentioned the coordination and control of movement around the hip and pelvis as it challenges your balance as well as gets you strong.

Finally a word on warming up.

Ensuring you are prepared for any athletic activity is a must but even more so for explosive or sprinting activities.

In my opinion no runner spends long enough warming up, when I first started working in football I was amazed by the length of the warm up compared to the length of the training sessions, sometimes the warm up can be as long if not longer than the planned training session.

I have brought this philosophy back to not only my training, but also my patients and with great success. I now insist that all my patients especially those with past hamstring issues to do a dynamic warm up for at least 50% for the time you have planned for any high intensity session sprints etc and at least for 25% for a ‘normal’ paced run, this is minimum, so, for example if you have planned a 30 min interval sprint session then warm up for at least 15 min, or, going for a 30 min jog, then at least a 7 min warm up, how many of you do this…. None I bet,

Again there is much debate as to what’s the best warm up etc etc, I don’t want to get into this instead here are a few of my favourite warm up drills for runners.

Lunge walking, Donkey kicks, High kick pull backs, Sideways running, Backwards running, Toes walking, Dead leg running

The list could go on and on…

My final thoughts are, running at a steady constant pace is low risk of producing a hamstring tear but this risk increases if you start to do any sprinting, leaping, jumping or sudden changes of direction, and increases even further if you have had a previous injury.

You can reduce this this rick by ensuring you have good flexibility in not just your hamstrings but also hip flexors and quads and ensuring your eccentric hamstring strength is better. Finally make sure you warm up for a lot longer than you normally do.

Thanks and happy running…

Adam