Lots of people associate hamstring injuries with football players or sprinters, but the truth is any runner is susceptible to this kind of injury.
These problems are common in runners for several reasons, some of which are explained below. However, to start to address specific causes, it helps to have some understanding of the hamstrings and how they work.
The hamstring complex is made up of three muscles – semitendinosis, semimembranosis and biceps femoris. The hamstrings run down the back of the thigh, originating from the ischial tuberosity in the pelvis, and attaching to the tibia and fibula at the top of the lower leg.
Because the hamstrings cross both the hip and the knee joints, the muscles have functions at each. They bend (flex) the knee, and they work in conjunction with the gluteals to assist straightening (extending) the hip.
During running their main job occurs in the swing and early contact phases of foot strike. They work to increase ground clearance, counter quads action and reduce energy consumption by shortening the length of the leg (lever), improving the weight distribution as it swings through.
What causes hamstring injury?
Hamstring tightness is one cause that’s worthwhile investigating.
Running’s repetitive motion can cause the hamstrings to tighten over the course of a training session, especially if the route taken has little variation (for example on a treadmill or flat path).
Hamstring tightness can become chronic in people who spend a lot of time sitting, say in desk jobs or commuting long distances. Regular stretching helps reduce the risk of this.
Another factor predisposing hamstrings to injury is a phenomenon known as ‘quad dominance’. Repetitive miles load the quads, making them stronger and overly dominant when running. One consequence of this is hamstrings not being able to keep up with the force generated by the quads, resulting in potential tearing.
Tendinitis/tendinopathy are commonly caused by overuse, particularly in distance runners where hamstrings spend a lot of time contracting repetitively.
Often this occurs when the gluteal muscles are weak or not activated correctly, and the hamstrings become the dominant hip extender. Over time this can also lead to chronic hamstring tightness. In these cases, gluteal activation exercises and glut/hamstring strengthening, including eccentrics, can help clear it up.
For an acute tear, a period of rest (apply RICE management) and a gradual re-introduction of running, with an appropriate strengthening and stretching program, are recommended.
Hamstring strains, rather than acute tears, are more typical in distance runners. Microtears in the muscle occur which leads to chronic loss of flexibility and discomfort. This type of injury is best managed by reducing training intensity and mileage and applying ice after training, until symptoms clear.
To address some of the muscle imbalance or biomechanical factors mentioned above, it may help to enlist a sports trainer or physiotherapist, as assessment/treatment can be complex and it’s difficult to self-diagnose/prescribe.
Preventing hamstrings injury
For injury prevention, incorporate some ‘maintenance’ into your program.
Include stretching to keep hamstrings supple, strengthening to keep them strong enough to cope with the loads of running, as well as some technique work to make sure they are not being recruited in preference to the glut muscles during hip extension.
Avoid stretching cold muscles.
Cross-training, rather than just running, also reduces load and injury risk to hamstrings.