The hamstring muscles are actually a group of 3 muscles located in the back part of your upper leg. The hamstrings muscles originate from the pelvis (buttocks) and the femur (leg bone) on the backside of the leg and cross the knee joint to insert on the medial (inside) and lateral (outside) part of the leg just below the knee. The main jobs of the hamstrings are to extend (straighten) the hip and to flex (bend) the knee.   In addition, some of the hamstring muscles play a role in rotating the lower leg.

The most common thigh injury is a hamstring strain.   These injuries can often occur when the hip is flexed and the leg is extended, as in a single leg front kick. This is because 2 of the 3 muscles that make up the hamstring group cross over two joints (the hip and the knee).   These muscles are maximally stretched when the hip is bent and the knee is straight, and if movements are quick, the muscle can get strained or even tear.

Certain physical findings can increase your chances of getting a hamstring injury, such as:

• Tight hamstring muscles – (inability to completely straighten your knee on standing)
• An imbalance between the muscle strength in the upper leg (hamstrings and quadriceps)
• Tightness of the quadriceps or hip flexor muscles (inability to completely stand up straight while the legs are straight — you will notice that you bend forward at the hips slightly if your legs are otherwise straight)
• Insufficient warm up before exercising
• Poor muscle coordination
• Muscle fatigue
• Muscle strength or flexibility imbalances

Usually a hamstring injury will present with pain on the backside of the upper leg, possibly with swelling, bruising, and an associated popping sensation at the time of injury.   If the hamstring muscle is fully torn, there may be an obvious mass which is actually the muscle contracting into a “ball”.

Treatment of hamstring injuries can be broken down into the acute phase that occurs immediately after injury and for the first 2-3 days. The sub-acute phase that occurs for several days to a few weeks after injury and the chronic phase that begins several weeks after injury.

Acute treatment of a hamstring injury generally follows the acronym PRICE.

Protection – In a severe hamstring strain or tear, an individual may require a crutch or a cane to protect the injured leg while walking.

Rest – for the first few days, remain off the injured leg as is possible, as this will enable the hamstring to begin healing.   The caveat is that stretching muscle begin shortly after injury because the muscle will scar down as it heals leading to further muscle tightness and predisposing you for another injury.

Ice– using a plastic bag filled with ice and water for 20 minutes 3 times a day is helpful to further reduce swelling. Heat is initially not recommended because heat increases the blood flow and is thought to worsen swelling. However, a few days after an acute injury heat can be helpful as heat increases blood flow to the injured area and helps with healing.

Compression – An ace wrap or compression dressing should be applied to the upper part of the thigh to prevent further swelling.

Elevation – Elevating the injured leg helps to further prevent swelling.

As mentioned above, hamstring injuries require both stretching and strengthening in order to recover. The main issue is that after a tear or strain, the muscles heal by scarring down. This scarring results in decreased flexibility of the muscle.

One big mistake athletes and weekend warriors make after sustaining a hamstring injury is to return too quickly to their prior level of activity. It is very important to only return to exercise after the pain has subsided. This is because if you return to exercise too early, you will change your biomechanics (i.e. alter your posture or positioning) to compensate for the pain. This altered position or step length while exercising can allow the muscle to shorten. When the muscle heals and contracts (shortens and scars down) you are then at increased risk for a repeat strain or tear.   Typically it takes at least 4-6 weeks for the muscle to properly heal.

It is helpful to begin stretching and strengthening exercises under the supervision of a qualified physical therapist so that you do not re-injure yourself and you can recover optimally. It is possible to regain or even surpass your pre-injury strength and flexibility with a proper treatment regimen.

PRP or Platelet Rich Plasma injections are sometimes recommended for assistance with tissue repair and quicker recovery time. However, an article published in 2015 from the Department of Sports Medicine at St Lucas Andreas Hospital in Amsterdam, reviewed the data for the treatment of hamstring injuries and found that lengthening exercises (stretching the hamstrings) provided the quickest return to play time, but did not affect re-injury rate. PRP injections did not improve outcome or re-injury rate when compared to controls. Therefore, at this time, it appears that a physical therapy regimen focusing on first stretching the hamstring muscles, then strengthening them (while maintaining improved flexibility) provides the best chance for recovery and return to exercise.   It was also suggested in this study that progressive agility training and trunk (core) strengthening and stability might reduce re- injury rates.

As always, if you suspect you might have a hamstring injury or other leg injury it is important to be evaluated by a trained health care professional. It is quite possible that you will be referred to a physical therapist for optimal treatment that includes a both a stretching and strengthening regimen. While initially your treatment will focus on the injured muscles, it will be important to analyze and treat your body mechanics to prevent repeated injury.