People seem to know the hamstring muscles exist and that they are located in the back of the thigh but have little idea of what they look like and what they do. We know they cramp up a lot or are strained when stretched too far.
Let us take a look at
- Where the hamstrings are
- What they look and feel like
- What they do
- Pain patterns for hamstrings
- What you can do to loosen them up
Where the hamstrings are
The hamstrings are a group of 3 muscles located in the center of the back of the thigh as indicated in the illustration to the right. The four muscle bellies that comprise the group are smaller in mass than the four muscle bellies of the quadriceps group and the muscles of the adductor group.
What they look and feel like
There are three hamstring muscle bellies (semimenbranosus; semitendinosus; biceps femoris long head) that attach to the sit bones (ischial tuberosities) on the back of the pelvis. Due to their attachment to the sit bones the hamstring muscles affect the movement of the hip joint. A fourth muscle belly of the hamstring group (biceps femoris – short head) attaches to the lower half of the back of the femur (linea aspera of the femur). This muscle belly has no action on the hip joint. All four of the muscle bellies attach to bones of the lower leg – two attach near the top of the the larger tibia bone and two attach near the top of the slender fibula bone (head of the fibula). Due to their attachment to the lower leg bones the hamstring group muscles act to move the knee joint.
The three muscle bellies arising from the sit bones are long, strap like muscles. The semitendinosus has a
rather pronounced section of ropey tendon at the lower end. The semimembranosus has a pronounced tendinous section near the upper end. The area where these muscles turn from tendon to muscle are often prone to strain and build up of metabolic waste products from muscle exertion. These are sites where “knots” seem to form.
When you massage the hamstring muscle bellies that arise from the sit bones you can feel the ropey, tendinous nature of the tissue. This is more evident when you strum your fingers across the muscles from side to side as opposed to running up and down along the length of the muscle bellies.
The tendons of the hamstrings are rather pronounced at the lower end near the knee joint. You can feel the thin tendons on either side of the back of the thigh just above the knee.
What they do
Due to their muscular attachments the hamstring muscles act on both the hip joint and the knee joint. When the leg is free to move, three of the muscle bellies act to straighten (extend) the thigh at the hip. All four of the hamstring muscle bellies act to bend (flex) the leg at the knee. When the knee is bent, these muscle bellies can also cause slight inward or outward rotation of the lower leg.
When your legs are firmly on the ground and you are bending from the waist the hamstring muscles contract to control the forward bending at the waist. In a way they serve to pull on the sit bones and keep the pelvis from rotating forward. You do this movement when weeding in the garden, for example. When you lean forward or raise your arms overhead the hamstring muscles contract as well.
Jumping actions also engage the hamstrings as well as carrying heavy objects (such as suitcases, etc.) in one hand.
The hamstring muscles work perform the opposite actions of the much larger and stronger quadricep muscles on the front of the thigh. If the quadriceps muscles are exercised and developed they can cause over power the hamstrings muscles and cause them to be chronically tight.
So, you use these muscles a lot without realizing it.
By the way, often the hamstring muscles will cramp up when you shorten them by straightening the thigh and bending the knee at the same time. Another reason cramping occurs is due lack of proper blood supply and nutrition when the tissues are tight and squeezing the blood vessels that supply the muscle tissue.
Pain patterns for hamstrings
Overly tight or overly used hamstring muscles can develop trigger points in the muscle or the connective tissue surrounding the muscle fibers. Trigger points in muscle bellies on the inner part of the back of the thigh (semi-membranosus and semi-tendinosus) can cause pain symptoms and stiffness in the upper hamstring attachments at the sit bones and the crease where the thigh meets the gluteals. Trigger points in the hamstring muscles toward the outer back of the thigh (biceps femoris) can cause pain symptoms and stiffness in the back of the knee and upper calf.
Another consideration if you have chronically tight hamstrings is their effect on the sciatic nerve and resulting symptoms into the lower leg and foot. The sciatic nerve passes deep (under) the hamstring group as it runs down the back of the thigh on its way to the leg and foot. Tight hamstring muscles can impair the flow of vital nutrients to the nerve and inhibit or intensify the conduction of impulses along the nerve. Pain in the leg, ankle or feet can result. All too often the role of tight hamstring muscles in leg and foot pain is overlooked. So, a simple way to see if that is causing your symptoms is to gently massage the hamstring muscles to loosen them up and notice if there is a reduction of symptoms in your leg, ankle or foot.
Tightness in the hamstring muscles can also contribute to low back pain and discomfort since they are involved in stabilizing the pelvis when you bend forward at the waist. Chronic tightness resulting from habitual forward bending at the waist can contribute to chronic tightness in the muscles that run parallel to the spine along the back. Massaging the hamstrings along with the back muscles is important to restore balance.
What you can do to loosen them up
Fortunately these muscles are located in an area easily reached with your hands so self massage of the hamstrings is relatively easy to do. The best way to access the muscle bellies is to put them in a slackened position. Sitting on the floor or in a chair with the knee bent is a good way to start. Rest your palms on either side of your upper thigh and extend your fingers around the back of the thigh toward the center. Press your fingers into the muscle bellies and pull side to side to spread the muscle fibers apart. Alternate with upward and downward motions to elongate the fibers. Feel for tight, restricted areas and press into them with sustained pressure waiting for the tissue to melt. Move up and down the back of the thigh to address the entire length of the muscle. The short head of the biceps femoris is often neglected since it is tucked away beneath the long head of the muscle. Starting about two to three inches above the knee, towards the outside of the thigh, curl the fingers around the back of the thigh just inside the tendons you will find back there. Press slowly in toward the thigh bone. Move upward until you are about half way up the thigh.
You can also use foam rollers as you lay on top of the foam and roll upward and downward. This is good for superficial lengthening. I like to use a tennis ball to work on my hamstrings. I sit on the floor and place a tennis ball under my sit bone. Then I roll my thigh side to side across the tennis ball to spread the muscle bellies. Let the weight of your thigh press down into the tennis ball to a depth that engages the muscle. You can then roll the tennis ball up and down along the length of the muscle. I lift my body off the floor using my arms. This is good exercise for the upper body, too.
Make sure to stretch the hamstring muscles out after you massage them. One easy stretch is to sit on the floor and reach for your toes.
If you are lucky enough to have a partner you can have them massage the hamstring muscles for you.