By Rebecca J. McVey MS, ATC, ATC/L
The hamstring is composed of three muscles: the biceps femoris (outer thigh), semitendonosus and semimembranosus (inner thigh). These muscles cross at two joints, the hip and knee, making them biauriculate. Hamstring strains are very common in many types of activity. The crossing at two joints along with deceleration and change of direction cause the hamstring muscles to be eccentrically contracted while being passively stretched. These two actions place high stress load on the hamstring muscles, making them the primary mechanisms of injury/strain.
The most common site for hamstring strains or any type of muscle strain is at the musculotendinous junction, the weakest aspect of any muscle. This is where the muscle and tendon (bands of connective tissue that connects the muscles to the bones) are joined together. In some instances the hamstring tendon may avulse, the pulling of the tendon away from the bone. The most common site in the hamstring for an avulsion injury is where it connects to the ischial tuberosity, the bones you sit on.
Hamstring strains are caused by weakness, fatigue, improper warm-up, imbalance in muscle strength when compared to the quadriceps, and over stretching the muscle in activities like sprinting or in fast twisting motions. Hamstring strains can be categorized as acute or chronic. An acute strain is an injury that has happened right away and usually heals up quickly. A chronic strain is a strain that persists past three months or a strain that has a tendency to come back repeatedly (which means that it has never truly healed).
Hamstring strains can be further categorized by the extent of damage done to the muscle. The first category, the less severe out of the three and the most common, is called a Grade I strain. With a Grade I strain there is minimal (micro) muscle fiber tears. With this type of injury one may feel mild pain in his/her hamstring with movement and palpation, along with very minimal loss of function/motion, minimal to no swelling, and no bruising or muscle deformity. One may be able to return to light activity with a Grade I strain. The second category is classified as a Grade II strain. With a Grade II strain, there may be moderate to partial tearing of the muscle fibers. A person suffering from a Grade II strain may or may not feel or hear a “popping” sensation at the initial time of injury. He/she will have moderate pain, be point tender with palpation over the injured muscle fibers, have minimal to moderate loss of function/motion, swelling and bruising, and in rare cases, have muscle deformity. The last and most severe type of strain is Grade III. In a Grade III strain, there is a complete tear in the muscle fibers. The injured person will most likely feel or hear a “popping” sensation, muscle deformity, and immediate pain. He/she will have moderate to severe loss of function/motion, swelling, and bruising.
Just like with all injuries initial treatment consists of R.I.C.E. This pneumonic is short for Rest, Ice, Compression, and Elevation. Rest is very crucial after an injury. Many people will not take the time to properly rest and these people are the majority of chronic hamstring strain sufferers. A good way to understand this is by looking at glue. In order for glue to strengthen it must have time to rest or set itself. The chemicals must have time to form their bond and harden to make the bond strong. Just like in any injury, the body must have time to let the chemicals involved in healing bond and repair the weakened tissue in order for the new muscle tissue to strengthen and prevent further injury. If you try to take the objects being glued together apart before it has rested/set, the glue will not be strong enough to hold the pieces together, and the area between will weaken, leading to the bond between the two objects eventually breaking. One should consult a healthcare professional to determine how long his/her rest time should be. Ice is also very important because it actually decreases blood flow to the injured site, which in turn decreases swelling and the chemicals that cause pain. It also helps to decrease pain because it numbs the surrounding nerves. One should only ice for approximately 15-20 minutes a few times a day with at least 2 hours in between. Compression is important because it also helps to reduce swelling and bleeding into the muscle. Elastic bandages are the most common type of compression used. The wrap should be snug, but not tight, starting at one’s knee and moving toward his/her hip. Some people suffering from a hamstring strain have reported that wrapping their hamstring after injury has helped to lessen their pain. This may be due to compressing the muscle fibers together and helping keep the area warm. Elevation is also important because it helps to reduce swelling. When elevating, one wants to make sure that the injured area is above the heart. A physician may also recommend nonsteroidal anti-inflammatroy drugs (NSAIDs), such as ibuprofen, to help relieve swelling and pain. There is still much debate between physicians on when NSAIDs should be taken, so one should be sure to consult with his/her physician before taking any medication.
To help prevent re-injury, rehabilitation needs to occur, which includes muscle strengthening and stretching. With any type of strengthening program one should consult his/her doctor or professional health care clinician before starting. With acute hamstring strains, one should be careful not to overstretch the muscle. Stretching should be done gently and should be pain free. Remember that a strain is a tear in the muscle fibers and if you stretch too much or too hard, you will continue to stretch the torn muscle fibers and they will never have a chance to heal properly. The majority of strengthening should focus on the hamstrings and consist of eccentric and functional exercises. However, other muscle imbalances may be present which may be predisposing the hamstring to injury. These areas must also be strengthened in order to decrease the chance of re-injuring the hamstring. Chronic hamstring sufferers may benefit from neural glide exercises. It has been found with chronic hamstring strains there may be a build up of scar tissue around the nerves found within the hamstring, restricting motion of the nerve and causing hamstring pain. Neural glides will break up the scar tissue and allow the nerve to move freely in it’s covering, causing the reduction of irritation and pain. Soreness may be felt after this exercise due to the break up in scar tissue. One type of neural glide exercise is to lie on one’s back and bring the involved hip up towards their chest until the thigh is perpendicular to the floor. Once this position is reached, the knee should be straightened until pain is felt and the then bent. This step should be repeated about 20 times once to twice a day.
Hamstring pain may also indicate low back injuries, so one should consult his/her physician or health care professional to rule this out.
For more information on hamstring injuries and other injuries visit www.kort.com.
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*Disclaimer: The information included in this article should NOT be used in place of a visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
Rebecca J. McVey, MS, ATC, ATC/L, is an athletic trainer for Kentucky Orthopedic Rehab Team, splitting her time working at their J-town clinic location and Christian Academy of Louisville. She has served as the interim Program Director for Georgia Southern University’s (GSU) Undergraduate Athletic Training Education Program for a year and served as their Clinical Coordinator before that. In the past she has served as the Head Athletic Trainer for GSU’s Campus Recreation and Intramurals Department and also served as the Assistant Athletic Trainer for GSU’s collegiate athletics for two years where her main sport was Men’s Basketball. She has a Bachelors degree from Minnesota State University, Mankato and a Masters degree from Georgia Southern University.