Hamstring Strain

Hamstring strain is a common sporting injury due to the muscle being prone to tears and strains. They are common in sports that need a large amount of speed, power and agility such as rugby (54% of injuries), AFL, athletics (14%), basketball and football (10%). It hasn’t been un-noticed that 2019 appears to be the year of hamstring injuries with some big-name players in the NRL suffering tears to their hamstrings early in the season such as Tom trbojevic and Matt Moylan. To understand why this is happening to these professional athletes so early in the season we need to know what hamstring injuries are, the anatomy of the muscle, signs and symptoms of an injury, possible factors that make an athlete more at risk and ways to prevent hamstring strains from occurring. When an injury does occur, we must know what to do and how to manage it to return to play as soon as possible.

WHAT ARE HAMSTRING STRAINS/TEARS?
Acute hamstring injuries occur when there is a forceful contraction of the posterior thigh muscle/s or a sudden movement, this occurs when hamstrings decelerate hip flexion and knee extension. The person immediately feels discomfort and is aware of what has happened, there can be an audible pop. A Hamstring strain can occur in one or more of the three muscles in the group.
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ANATOMY OF THE HAMSTRING

• The hamstrings are composed of 3 muscles on the posterior thigh, bicep femoris (long and short head), Semimembranosus, Semitendinosus.
• The top of these muscles attaches to the pelvis and run down along the posterior aspect of the femur and attach just below the knee joint on the tibia and fibula (shin bones).
• The hamstrings are innervated by the sciatic nerve.
• The hamstring performs two movements flexion of the knee joint and extension of the hip joint.

SIGNS AND SYMPTOMS
Hamstring strains are classified from grade 1-3 depending on severity.

Grade 1 (Mild)

• Overstretching muscle fibres or tendon without tearing the muscle.
• Minimal to no loss of muscular strength or flexibility.
• Increased tightness of the muscle during stretching or through full range of motion.
• Mild discomfort felt along the muscle on palpation.
• There may be discomfort when sitting or walking uphill/stairs.
• Depending on the severity there may be mild swelling and difficulty doing daily activities including walking.

Grade 2 (Moderate)

• Partial tear in muscle fibres.
• Strength and flexibility of the muscle decreased.
• Pain is more immediate and greater than grade 1.
• Pain on range of motion and contraction of the muscle.
• Pain when pressing on the muscle.
• Change in normal walking and sometimes sudden twinge of pain.
• There may be bruising and swelling.

Grade 3 (Severe)

• Major tear or complete rupture of the muscle. The muscle can be bunched together making a depression where the tear has occurred.
• Total lack of muscle function.
• Immediate intense pain in the back of the thigh usually sharp.
• Difficulty walking or weight bearing.
• Large bruise and swelling within a few days after injury.
• Usually occurs at the origin of the muscle.
• May need surgical repair to re-attach the muscle.

​RISK
Hamstring injuries usually occur due to an imbalance between itself and the quadriceps muscle. The quadriceps are large and powerful group of muscle that extend (straighten) the leg at the knee joint. When there is a powerful contraction of the quadriceps muscle it may over stretch the hamstring and place a large load on the muscle.

• Previous hamstring injury.
• Increasing age of player.
• Sudden change in movement (acceleration or deceleration).
• Poor flexibility.
• Weakness in the muscle.
• Muscle fatigue.
• Muscle imbalances, hamstring to quad ratio.
• Poor or no warm up.
• Body mechanics.
• Psychological factor.
• Poor technique during activity.

PREVENTION

• Proper warm up before exercise including sport specific function movements as well as sport specific skill drills.
• Include speed work within training program to allow the hamstring to sustain high acceleration forces.
• Have a high level of endurance to prevent muscular fatigue.
• Include stretching, functional and strength training within the program.
• Having adequate pre-season preparation prior to competition to ensure readiness to play.
• Gradual increase in training duration and intensity.
• Wearing the right and comfortable protective gear and footwear.
• Adequate recovery times between session to allow the body recover and prevent burning out/over-training.
• Avoid activities that cause pain.

ACUTE MANAGEMENT

• RICER protocol for the first 48-72 hours; rest, ice, compression, elevation and referral. The leg should be elevated when applying ice. The ice should be used for 20 minutes every 2 hours. This protocol will reduce the swelling and bruising of the muscle.
• Another protocol for acute hamstring injuries is the No HARM protocol. This is no heat, no alcohol, no running or activity and no massage. This will also help to decrease bleeding and swelling in the tissue.

REHABILITATION

• Rehab will vary based on the severity of the injury.
• restore flexibility of the muscle.
• Re-activation of muscle fibres.
• Progressive eccentric loading on the muscle.
• Restore endurance.
• Strengthen the hamstring back to usual strength.
• Strengthen other muscles of lower limb and trunk.

RETURN TO PLAY (depending on how well managed the injury is)

• Grade 1 = 1-3 weeks.
• Grade 2 = 4-8 weeks.
• Grade 3 (may require surgery) = approximately 3 months.

Early return to play and/or poor rehabilitation of the injured muscles will increase the chance of re-injury. Full range of motion and strength is required along with the muscles ability to endure full speed training. The player must be able to perform sports related activities such as jumping, sudden change of direction and twisting.

Joshua Hallinan
Chiropractor
Working Tuesday and Thursday at Health Associates

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References
Prior, M., Guerin, M., & Grimmer, K. (2009). An Evidence-Based Approach to Hamstring Strain Injury: A Systematic Review of the Literature. Sports Health, 1(2), 154–164. 

Hamstring Strain Injuries: Recommendations for Diagnosis, Rehabilitation, and Injury Prevention Bryan C. Heiderscheit, Marc A. Sherry, Amy Silder, Elizabeth S. Chumanov, and Darryl G. Thelen Journal of Orthopaedic & Sports Physical Therapy 2010 40:2, 67-81 

Hamstring strain injuries Opar, D.A., Williams, M.D. & Shield, A.J. Sports Med (2012) 42: 209.

Verrall GM, Slavotinek JP, Barnes PG, et al Clinical risk factors for hamstring muscle strain injury: a prospective study with correlation of injury by magnetic resonance imaging British Journal of Sports Medicine 2001;35:435-439.

Sherry, Marc A., Tyler S. Johnston, and Bryan C. Heiderscheit. "Rehabilitation of acute hamstring strain injuries." Clinics in sports medicine 34.2 (2015): 263-284.

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