Hamstring injuries are a common problem that affects many athletes. These injuries can be slow to heal with a very high rate of recurrence or re-injury. Hamstring injuries are often associated with sports that require fast acceleration and deceleration such as running (intervals), football, soccer, and rugby. Among medical researchers, there is a considerable lack of consensus regarding what precipitates a hamstring injury. Some of the more common theories are lack of strength, flexibility, muscle imbalances, and not warming up before an athletic event. However, it is agreed upon that hamstring injuries are usually not the result of a direct trauma, referred to as a “Non Contact Event”.
The hamstrings are called bi-articular muscles because they cross both the hip and knee joints. This is an important consideration because a hamstring injury can affect your hips, low back, knees, and the motion patterns of the entire lower extremity. If we consider fascial connections (posterior line), we will see that a hamstring injury can affect a very large area.
After the initial tear of the hamstring muscle, there is usually some bleeding which may show up as a small to large bruise over the hamstrings.
The bleeding from a hamstring tear is followed by an inflammatory response with an increase in cells called fibroblasts. Fibroblasts are cells that are involved in the synthesis of collagen, which is the structural framework for all tissues. Fibroblasts are also involved in wound healing and the formation of scar tissue.
As the inflammatory process of a hamstring injury begins to resolve, scar tissue is often formed. Scar tissue is a weak, inflexible, easily re-injured tissue that can decrease range of motion and create abnormal motion patterns. It is scar tissue that most likely accounts for the high rate of recurrence of hamstring injuries.
From a symptomatic perspective, most hamstring injuries seem to resolve with time. In reality these injuries often do not completely heal, but are the catalyst for a series of injuries due to residual scar tissue and compensations that this tissue creates.
Grading a Hamstring Injury
It is important to evaluate the degree of hamstring injury so that appropriate treatments can be implemented. Hamstring strains are graded from 1 to 3, 3 being the most severe.
Grade 1 Strain
The injured person can still walk, though with some degree of difficulty. There may be minor swelling, stiffness, and pain. In a grade 1 strain there is only minor tearing of the hamstring muscle. A common analogy is comparing a muscle to a piece of tissue paper. In a grade one injury there are only minor tears in the tissue. There should be only minor pain on hamstring resistance with no significant loss of strength.
Grade 2 Strain
The injured person may have difficulty walking and could be in considerable pain. There may be swelling, and some degree of bruising. In a grade 2 strain there is moderate tearing of the muscle. To use the tissue analogy there would be a significant number of tears in the tissue, compared to a grade one sprain.
The patient may not be able to straighten their knee. There also may be considerable pain on hamstring resistance.
Grade 3 Strain
A grade three strain is a severe or complete tearing of the muscle. To use the tissue analogy, the tissue could now be torn in two pieces. This type of strain may require surgical intervention to reattach the muscle.
Any action that causes the hamstrings to contract will cause severe pain. Walking will be extremely difficult; the injured person will require crutches. There could be a complete loss of function.
Treatment of Hamstring Injuries
Initial Acute Injury
Right after the injury in the acute stage you should use RICE, the acronym for rest, ice, compression and elevation. If you have access to laser therapy this will also reduce the inflammation and speed the healing process.
NSAID’s are often immediately prescribed for hamstring injuries. For short periods of time, these medications may be beneficial. Taking NSAID’s for longer than seven days is generally not advised, as they can slow the healing response and decrease the overall quality of tissue leading to further injury. Steroid injections at one time were often used to treat hamstring injuries, but these injections are no longer advised by many practitioners.
Start Treatment ASAP
Mobilization of the injured hamstring as soon as possible is essential in achieving a speedy recovery. This would include passive stretching and strengthening exercises that should be performed in a pain free range of motion.
Initially isometric strengthening exercises are recommended, followed by a gentle progression into isotonic exercises. Isometric exercises use static contraction of a muscle without any noticeable movement in the angle of the joint. In an isotonic exercise, tension remains unchanged but the muscle’s length changes. An example would be weight lifting.
Upper body exercises should also be performed to maintain physical conditioning. Aerobic exercise should also be performed. Aerobic exercise will speed the healing process by increasing cellular energy (ATP production) and increasing circulatory function. Improving circulation will increase oxygen input to the muscles and increase the removal of waste byproducts. Swimming is an excellent exercise for a hamstring injury (Stay within a pain free range of motion).
Manual therapy can reduce the formation of scar tissue and speed the overall healing. The longer that the injured person waits for therapy to begin the longer the resolution time may be.
The removal of any physical restrictions that form in the hamstrings, or other related areas, is essential for a full resolution. Some of these restrictions can be removed through the process of self-myofascial release (foam rollers, self-massage, and gentle stretching). If the restrictions are severe enough then a manual therapy practitioner (MSR, ART, Graston, Massage) will be needed to break the restrictions.
It is important to note that any time a restriction is removed from one muscle, the antagonistic and synergist muscles must also be assessed for restrictions. This is a key point that many manual therapists overlook. For a full resolution of a hamstring injury, myofascial adhesions must be removed from the entire kinetic chain not just at the site of pain. Many of these restrictions will only be found with a more in depth biomechanical analysis and palpatory examination.