The hamstrings are a group of three muscles located in the back of the thigh (Figure1). The muscles extend from the bottom of the pelvis, down to the back of the knee. The hamstring muscles work to extend the hip and bend the knee, so are important in activities such as walking, running, squatting and jumping.
Figure 1: Hamstring muscle group made up of 3 muscles
A muscle strain is commonly referred to as a pulled muscle, or muscle tear. It occurs when the muscle fibres are stretched or torn. Depending on the severity and nature of the injury muscle strains are graded as mild, moderate or severe.
The two most common causes of a hamstring muscle strain are overstretching and overloading of the muscle fibres. Overstretching injuries are seen in sports involving excessive kicking or a high demand of flexibility, such as gymnastics. Overloading injuries usually occur when someone is sprinting. This is because the hamstring muscles work hard to control and slow down the leg as it swings through, ready to make contact with the ground on the next stride.
Symptoms of a Hamstring Strain:
Symptoms of a hamstring strain typically include an immediate sharp pain in the back of your thigh. The area of the pain is generally quite specific. This means you should almost be able to directly point to the area overlying where the actual injury is.
Depending on the severity of the strain, you might also feel an increase in pain with activities that either contract or stretch the hamstrings, such as kicking, walking/running or bending over. You can also experience bruising, muscle tightness, muscle weakness, and in some cases an indent within the muscle belly.
Several factors increase the risk of a hamstring strain occurring. Most of these are controllable. The most common factor is overload and muscle fatigue. This could be the result of overtraining, a history of previous hamstring strain, strength imbalances of the muscles around the hip and thigh, poor running technique (biomechanics), and reduced muscle flexibility (Shield & Bourne, 2017).
If you suspect you have strained your hamstring, it always best to seek an assessment from a physiotherapist to determine the type and severity of the injury. There are also other areas of the body that can refer pain into the back of the thigh, including the lower back, hip joint, buttock muscles and neural structures. A physiotherapist will be able to tell whether it is your hamstring or another body part causing your pain, and prescribe the best rehabilitation approach for you.
Hamstring Muscle Strains and Imaging:
Imaging for a hamstring strain is not usually required; however if your physiotherapist suspects you might have ruptured the muscle fibres or a tendon then imaging, such as an MRI, might be necessary to confirm this. The severity of most strains though can be determined by a detailed physical assessment, carried out by your physiotherapist.
Management of Hamstring Strains:
Early management phase
If you suspect you have suffered a hamstring strain, the goal of management in the first 48 hours is to reduce the pain and decrease swelling within the muscle. Use the RICE principal (Rest, Ice, Compression and Elevation), and manage movements and activities that aggravate and increase your pain. The aim is to optimise the healing process and give the irritated tissues a chance to settle. It is important you see your physiotherapist as soon as possible after this initial 48 hours, so they can start you on a return to sport/activity rehab program.
Strength, flexibility and running
Your rehab program will include things like improving muscle strength and flexibility, and if relevant looking at your running capacity (specifically sprinting and changes in direction).
Strengthening exercises start at a low level. The goal is to build strength within the scar tissue at the site of the strain. Over a number of weeks the exercises are progressed to develop strength with relevance to movements that occur at both the hip and the knee (as these are the joints the hamstring controls).
Examples of exercises used in this phase of rehab include squats, single leg deadlifts and the Nordic Hamstring exercise (Figure 2). Similarly, as the hamstrings gradually get stronger, running is progressed from low intensity, such as pain-free jogging in a straight line, to moderate and high intensity running (depending on the activity you want to return to).
Pain free stretching can also be applied in order to restore normal range of motion at both the hip and knee, and this can be graduated as the muscle scar tissue continues to heal and strengthen.
Figure 2: Nordic Hamstring Exercise
Return to sport/work
At the moment there is no consensus on a guideline or criteria for the safe return to sport/activity after a hamstring strain that aims to maximise performance and minimise the risk of recurrence. Re-injury and prolonged rehab are common with hamstring strains. Therefore it is important you undertake a tailored program that gradually works towards you returning to a specific sport or work environment.
Your physiotherapist will be guided by your progress to ensure your strength; movement and control are relatively equal to your un-injured leg. In sporting contexts, generally one to two weeks of maximal training is desired before returning to competition
Within the sporting population hamstring strain recurrence rates vary between 15-65% (Sconce et al., 2015) the first month of returning, and this risk can remain elevated for 12 months. Granted this high risk of re-injury, ongoing conditioning and hamstring management is paramount even after you have successfully returned to competition.
The strongest evidence lies with the Nordic hamstring exercise (Figure 2) as this helps reduce the rates of re-injury by 60-85% (van der Horst et al, 2013). It is also important to consider other aspects of hamstring rehabilitation such as flexibility and load management. Your physiotherapist will be able to guide you with these and help you incorporate them into an ongoing injury prevention program.
If you have any questions regarding hamstring strains and the rehab process, please feel free to contact any of our physiotherapists. You can find the contact details for each clinic on the About page on our website.
Oakley, A., Jennings, J., & Bishop, C. (2017). Holistic hamstring health: not just the Nordic hamstring exercise. British Journal Of Sports Medicine, bjsports-2016-097137. http://dx.doi.org/10.1136/bjsports-2016-097137
Mueller-Wohlfahrt, H., Haensel, L., Mithoefer, K., Ekstrand, J., English, B., & McNally, S. et al. (2012). Terminology and classification of muscle injuries in sport: The Munich consensus statement. British Journal Of Sports Medicine, 47(6), 342-350. http://dx.doi.org/10.1136/bjsports-2012-091448
Sconce, E., Jones, P., Turner, E., Comfort, P., & Graham-Smith, P. (2015). The Validity of the Nordic Hamstring Lower for a Field-Based Assessment of Eccentric Hamstring Strength. Journal Of Sport Rehabilitation, 24(1), 13-20. http://dx.doi.org/10.1123/jsr.2013-0097
Shield, A., & Bourne, M. (2017). Hamstring Injury Prevention Practices in Elite Sport: Evidence for Eccentric Strength vs. Lumbo-Pelvic Training. Sports Medicine, 48(3), 513-524. http://dx.doi.org/10.1007/s40279-017-0819-7
About the Author:
Liam graduated from the University of Queensland with honours in 2016. Liam’s areas of professional interest include all aspects of musculoskeletal physiotherapy. He recently traveled away with the Queensland under 18 men’s hockey squad as the team Physiotherapist for their national carnival.
His personal interests include spending time with friends and family, as well as playing football.