What is a hamstring strain?
The hamstrings are a group of three muscles that run along the back of the thigh and work to stabilize and flex (bend) the knee. The muscles that make up the hamstring include biceps femoris, semimembranosus, and semitendinosus. When one or more of these muscles are injured it is known formally as a hamstring strain or more generally as a “pulled hamstring.” To qualify as a hamstring strain, the muscle injury would have to be considered acute.
In other words, it should have happened suddenly and you can easily identify the moment when the hamstring was injured. Typically, a hamstring strain is classified in grades, ranging from one to three. Grade I injuries involve a small microtrauma to the muscle and are somewhat painful; however, the muscle is still able to function relatively well. A grade II strain involves a partial thickness tear of the muscle, is quite painful, and the hamstring muscle function is impaired. You will notice difficulty with bending and straightening the knee and hip. Lastly, a grade III sprain is a complete tear of the entire muscle (typically only one of the 3 muscles making up the hamstring).
Because the entire muscle is torn, the nerves have also been torn so, interestingly, there is very little pain associated with this level of injury. The main thing you will notice with a Grade III strain is significant impairments in function, meaning knee and even hip movements will be very difficult. With any grade of a hamstring strain, there will be varying levels of swelling, heat, redness, and bruising around the injured area.
How does a hamstring strain occur?
For a hamstring strain to occur, the hamstring typically undergoes a sudden onset of high force and/or stretch. This results in the muscle fibres being torn to varying degrees of severity. A common mechanism of hamstring injury is when the muscle is contracting at the same time as it is lengthening, like when running or kicking a ball. As your leg is swinging forward, the hamstring is trying to decelerate your leg (so it’s contracting and working hard) but at the same time, in order for your leg to come forward, it has to lengthen. As such, hamstring strains are common in sports like soccer, football, and track and field.
Another important consideration is that there are factors that predispose people to hamstring injuries. Some factors are what we call non-modifiable, meaning we can’t do anything to change them. Others; however, are modifiable, meaning these are risk factors we work on in physiotherapy to prevent future hamstring injuries. Examples of key modifiable risk factors are muscle imbalances, poor lower extremity muscle control, improper warm-up, or a sudden increase in exercise intensity without gradually increasing exercise tolerance.
Physiotherapy for a hamstring strain. What to expect?
The physiotherapist will first complete a thorough assessment, ask questions about how the hamstring injury occurred, examine strength and range of motion, and likely palpate (using the hands to examine) around the area. The recovery timeline largely depends on the severity of the strain. With all muscle strains, the first phase of rehabilitation is PRICE: protection, rest, ice, compression, and elevation. Unfortunately, this requires stopping sports activities to give the hamstring time to heal. This is often a frustrating time so your physiotherapist will closely monitor the healing process so they can progress you to the next stage as safely and quickly as possible. The next stage involves gentle knee and hip range of motion, where you are trying to move the hamstring through its full lengthened and shortened positions.
You can also begin core exercises and gentle stretching. Gradually, your physiotherapist will begin adding hamstring strengthening exercises, eventually progressing to return to sport and high-intensity activities. While treatment is about helping the injured muscle recover, it is also about identifying modifiable risk factors that predispose you to injury. Any muscle imbalances, lack of core stability, or poor lower body muscle control will be identified by the physiotherapist in the assessment and will be included in your training program. While a hamstring strain can be frustrating, your physiotherapist will guide you through the injury, from diagnosis to return to sport, and ensure you receive the best possible care throughout the process. If you suspect a hamstring strain, visit a Panther Physiotherapy clinic near you!