Hamstring strains are one of the main reasons for posterior thigh pain and are among the most common sporting injuries. In this blog post by QSMC Physiotherapist Abbey Le Busque, we will explore in-depth the causes, symptoms, treatment, and prevention of hamstring strains.
What are the hamstrings?
The hamstring muscles consist of four muscles at the back of your thigh:
- Biceps Femoris: long head and short head (BF-SH)
- Semimembranosus
- Semitendinosus
All muscles (except BF-SH) attach to your ischial tuberosity (sitting bone) and extend down to your knee. A result of the hamstrings crossing two joints is that they have multiple functions. The hamstrings act to extend your hip and flex the knee. All these actions are crucial for high-speed running, changing direction, and kicking sports.
What is a hamstring strain?
A hamstring strain is a posterior leg injury involving a tear to one or more of the hamstring muscles. They usually occur in two particular instances; slow velocity stretching type activities (e.g. gymnastics, dance) or high-velocity contraction type activities (e.g. sprinting). Rehabilitation time differs between the two types of tears, with the latter taking significantly less time to return to sport.
Causes of a Hamstring Strain:
A large majority of hamstring injuries occur whilst sprinting. In the late stages of swing phases (when inertial forces are high) the bicep femoris has a large eccentric (braking) moment required to control the leg. During this action, a reduction of eccentric hamstring strength, poor timing, and coordination can lead to injury to the muscle fibres, musculotendinous junction, and/or the proximal tendon. In higher velocity mechanisms the Bicep Femoris (LH) is more commonly injured.
Additional factors for hamstring strains are as follows:
- Several studies, mostly completed in the AFL and soccer athletic population, have suggested that previous hamstring injury (HSI) elevates your risk of a subsequent hamstring injury
- Lack of eccentric (braking) strength and limb-to-limb strength imbalances of >25% on force production testing are risk factors. This is due to the large eccentric force that is produced when sprinting to control the limb as it strikes the ground.
- Inappropriate training loads can be a factor in hamstring injuries. Hamstrings are composed mostly of fast-twitch muscle fibres which are more susceptible to fatigue. Therefore, training loads need to be monitored to ensure fatigue isn’t a factor in hamstring injuries.
- Poor running mechanics can play a role in hamstring injury. Poor control of your hips and pelvis can increase tension and demand on the hamstrings throughout the performance.
- Changes in the lumbar spine and/or poor pelvic control can lead to nerve dysfunction and resultant muscle weakness which can leave you predisposed to a hamstring injury.
Symptoms:
- Sudden and severe pain during exercise (sometimes described as a snapping sensation)
- Pain in the back of the thigh and the buttock with movement, specifically straightening the leg or bending over
- Tenderness through the back of the thigh
- Spasm/tightness through the hamstring
- Bruising, which can appear towards the bottom of the thigh due to gravity
- Weakness through your hamstring in comparison to your non-injured leg
Diagnosis:
Grade 1: A grade 1 hamstring strain will present as some tightness across the back of the thigh but allows you to walk normally. With some mild hamstring discomfort, it is unlikely you will be able to run without increasing pain. There may be mild swelling and tightness however bending your knee or extending your hip may not increase your pain greatly.
Grade 2: A more moderate injury severity may present with difficulty walking, and twinges through your posterior thigh during general activity. You may notice some swelling, spasms, bruising, and tenderness within the first 24-48 hours post-injury. Pain with hip extension and knee flexion is likely to be present.
Grade 3: This injury is quite severe in nature and the tear will involve half or all fibres of the muscle fibres. You may have trouble walking and require crutches due to pain and weakness in the posterior thigh. Swelling and bruising may be immediate in this case.
There are different areas of the hamstring that can be injured. There can be different timeframes applied to injuries that occur in certain areas.
Locations of Injury:
- A: Myofascial
- B: Musculo-tendinous
- C: Intratendinous
An MRI may be useful in the specific identification of the Grade and location of your injury. These identifications are important factors in determining the length of your rehabilitation and possible return to sport timeframe.
Lookout for referred hamstring pain:
Your sciatic nerve passes through the hamstring muscle group. If you have lower back pain or an injury, referred sciatic pain can mimic some of the symptoms.
Rehabilitation:
The primary objective of the rehabilitation is to return to the prior level of athletic performance with as minimal risk as possible. Your hamstring injury may start to feel better within a few days however it is important to engage in a proper rehabilitation process to avoid re-injury of your hamstring.
Once an accurate diagnosis is achieved, your physiotherapist will aim to achieve the following:
- Reduce pain and local inflammation
- Normalise range of motion
- Improve local hamstring strength and maintenance of surrounding muscles
- A focus will be held on the eccentric strength of your hamstrings
- Guide you back into running, speed, agility, and balance
- Improve technique in sports-specific tasks (e.g. – sprinting, hopping, landing, jumping, change of direction)
- Minimise risk of reinjury
At QSMC, our VALD equipment can produce accurate, objective data on your strength and force production to assist with your rehabilitation process.
Do I need surgery on my hamstring injury?
Surgery is not often provided for hamstring injuries. In the case of a rupture of the tendon or chronic degenerative hamstring injuries, surgery can be an option.
How do I make sure this never happens again?
As mentioned in this post, the biggest risk factor for hamstring injury is a history of previous injury. Therefore, it is paramount that your rehabilitation doesn’t stop once you have returned to your previous level of athletic performance. Exercises that have been researched to have the highest effectiveness in hamstring injury prevention are those that focus on regular eccentric strength training. Your physiotherapist may prescribe you exercises to continue to address eccentric strength and maintain your hamstring strength to minimise injury risk.
If you need further guidance on how to knock your hamstring rehabilitation out of the park – book in with one of our physiotherapists at QSMC.
