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By Dr Tom Brownlee
15th June 2022 | 8 min read
In August 2017, one of sport’s true greats, Usain Bolt, stepped into London’s Olympic Stadium for his final ever race at the World Championships. Having been pipped at the post by pantomime villain Justin Gatlin in the blue riband 100m a few days earlier, the 4x100m relay was his chance to go out on a high – anchoring the Jamaican quartet in a fairytale finish to a historic, mesmerising career. Bolt received the baton in third place, about 3m off the lead. The stage was set for one final Bolt blitz in front of 90,000 adoring fans. Much like the 100m though, it wasn’t to be. This time, 30m into the final leg, Bolt pulled up clutching the back of his left leg. He had fallen victim to one of the most common injuries in sport – a pulled hamstring.
Thankfully for Bolt, many people no longer even remember this happening. And with a career like his, it’s easy for it to fade into the background behind the many world records and Olympic golds.
Relatively, Bolt had a career that was free from big injuries, especially during key events. But not all are as lucky. And for many athletes it is that same injury, the hamstring pull, that can be the cause of such torment.
Today we’re going to look at when and how hamstring injuries happen, how they can be prevented and how you might break the cycle of recurrences if they’re already ruining your training and competing. So, let’s talk about what for many is the most frustrating soft-tissue injury in sport.
If we want to understand how we can avoid or treat hamstring injuries, we need to work out why they’re happening in the first place. One of the tricky things with the hamstrings is they’re what’s known as biarticular, which means they are involved in moving two joints – they extend (or move backwards) the hip as well as flexing (or bending) the knee. It is often when the hamstring is stretching, not contracting, that it is most likely to become injured. For example, a very common mechanism of injury is when, during running, the hip moves forwards and the knee straightens at the same time as we move our foot from behind us to put it back down in front of us.
The reason behind this is we are stretching the hamstring both at the knee and hip simultaneously, with great force. This is a lot to ask if our hamstrings aren’t conditioned for this, or if there are other underlying issues. And when you consider how many sports involve explosive running, jumping, changes of direction or other high-powered movements, you can see why this type of injury is so common.
Now we understand how this muscle may sustain more injuries than others, let’s think about the underlying reasons.
One thing athletes need to be aware of is the difference between overtraining and overreaching. Overtraining is ultimately when we do too much. We ask more of our body than it is able to do for a sustained period, which can lead to injury or illness. Overreaching is what we want. It’s how we create change in a good way from exercise. This occurs by pushing our body slightly beyond where it is conditioned (like moving the pin on the weights machine down one plate after a few weeks, or upping the treadmill speed slightly). When this is done over a long period, supported by adequate rest and fueling, this brings about positive adaptation.
We can think about the conditioning level of the hamstrings in a similar way. If we go and do a session with a lot of sprinting in it, which asks a lot from our hamstrings, then we are more likely to sustain an injury if we are not conditioned for it. Conversely — and this is a constant balancing act for conditioning coaches — if we don’t do enough training then we are never able to build up our tolerance to cope with higher demands when they arise, which is typically during competition, when we need it most!
As well as risk factors based on our level of and approach to conditioning, which we might think of as external factors, there are also some internal risk factors to consider. Unsurprisingly, having weak hamstrings makes them more susceptible to injury but so does having one weaker than the other – what we know as an asymmetry.
Beyond strength levels, there is also an old adage that the biggest predictor of injury is previous injury. Sadly, we can’t magic an old injury away and similarly we can’t change our age, which is also a risk factor, with older individuals experiencing more hamstring injuries. Thankfully though, we now understand some of the techniques we can employ to help us to prevent such injuries even if we do tick some of the risk factor boxes listed above.
In soccer, where hamstring injuries account for 12-16 % of all injuries, making them the most common injury, they typically occur more frequently during the later stages of each half. This suggests that strengthening the hamstrings generally to resist an accumulation of fatigue is very important.
Specifically, improving eccentric strength is important – this is the strength that is used when the muscle is lengthening. If you imagine being on a leg curl machine, eccentric strength is used if you resist the weight as your leg straightens. If you think back to our mechanism of injury section, this type of strength helps us to combat those injuries occurring during such stretches under high force when we train or compete. It can be trained specifically by simply having a slower eccentric phase of typical exercises such as squats, leg presses or leg curls. The Nordic hamstring exercise is another great one to look up for improving eccentric hamstring strength.
Minimising the asymmetries we spoke of would also be advantageous. This can be done by incorporating some single leg, or unilateral, exercises such as lunges or step ups into your program. This removes the chance for our dominant leg to take more of the load when doing double leg exercises such as deadlifts or leg presses.
As I’ve mentioned, hamstring injuries have been shown to be more common in those who have had them previously. This suggests that perhaps people often rush back from such injuries and shows how important correct and appropriate rehab can be.
Beyond simply improving the strength of your hamstrings, another aspect that should be factored into rehab programs from hamstring injuries is improving your hip stability. Broadly the idea here is around reducing an undesirable amount of movement at the pelvis. As the pelvis is responsible for transferring forces between the spine and the lower limbs, it is thought that too much motion at this joining point can put the hamstrings under greater strain and therefore increase injury risk. This suggests a program of core and hip stability should be factored in when looking to reduce hamstring injury risk.
You may also think that hamstring flexibility might keep injuries at bay. The evidence here is a little ambiguous but it does seem that practices such as yoga can help with increasing range of motion and improve recovery time following injury,
Finally, moving forwards, it is recommended that a focus on movement quality should be sought where possible. In professional clubs this will be achieved by a structured, detailed assessment of a series of movement patterns such as how well an athlete squats, lunges, jumps etc. We should think of these movements as the foundation of a building – unless they are solid, you don’t want to build on them.
Similarly, if your fundamental movements aren’t of high quality, if you’re wobbling around all over the place for example, then no amount of increased single leg strength might save you from future injury. The reason for this importance is that sport is chaotic – we rarely move in nice straight, ordered lines like we do in the gym. This is why we need to ensure the basics are right first so when the chaos arrives we are better able to cope with it.
Although you may not be working in a professional environment, a physio or accredited strength and conditioning professional would be able to assess your movement competency and prescribe appropriate exercises to address any potential deficiencies.
Hamstring injuries certainly are best avoided. They can lead to lengthy spells on the sidelines as well as being difficult to shake without the correct rehab.
The best way to avoid them in the first place is through a mixture of overreaching of hamstring strength and sprinting in your training to bring about progressive overload while incorporating appropriate recovery periods. Specifically, eccentric hamstring strength and unilateral work is of key importance and will certainly serve you well.
If you’re unlucky enough to already be in the pattern of recurrent hamstring injuries then patience is key. Rushing back may be what you want to do but it won’t have a happy ending in the long run. Take your time, build your strength, and reap the rewards when you’re competing like Usain in his heyday!
Dr Tom Brownlee
Tom is currently a lecturer in applied sports sciences and has worked in elite sport for the last 10 years. Previous roles include working as a sports scientist at Liverpool FC, where he completed his PhD, and working across a number of other sports. He is passionate about physiology and has published papers on strength and conditioning, nutrition and youth development.
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