It’s Thigh Time: Understanding The Body’s Power

A great deal of the body’s athletic power is produced in the upper leg, generated mostly from the quadricep muscles, which act to extend the knee. The quads are responsible for motion and also for stability. When standing still or walking they provide the counterforce that keeps the legs from collapsing.

The thigh bone, or femur, is also very strong. Thick and cylindrical, it’s the longest bone in the body, running from hip to knee, enduring immense stress while bending often in the process. Although strong and hardy the femur can be a site of stress fractures among athletes. When in a semi-squat position, knees bent slightly and hips flexed with the torso erect, one can feel the muscles of the thigh strain. When jumping and landing from that position it generates 8 to 10 times bodyweight, subjecting the femur to significant forces.

The rectus femoris, which lies at the front of the thigh and acts as both the knee and the hip; and vastus medialis oblique are both key muscles of the quadriceps. The quads culminate in a single tendon that runs over the patella and attaches to the lower leg. The vastus medialis oblique and vastus lateralis keep the patella in proper alignment, one pulling the kneecap laterally toward the outer part of the knee and the other pulling it in toward the body’s midline.

The longest muscle in the human body, the sartorius starts by the hip joint and travels diagonally across the front of the thigh, attaching on the inside just below the knee joint. A hip muscle, tensor fascia lata functions as a sling that pulls on the femur, helping to steady the trunk on the femur. The iliotibial band is a thick band of connective tissue that begins at the pelvis, crosses the hip, and inserts below the knee joint, crossing over its outer edge. You can feel it most prominently when the knee is slightly bent.

The hamstrings are a group of three muscles that run parallel to each other up and down the back of the thigh. They include the biceps femoris, which has a short and long head, on the lateral side, and semitendinosus and semimemebranosus on the medial side. The upper portion of each attaches on the pelvis, just below the buttocks on the sitting bone, which is known as the ischial tuberosity and is located at the lower end of the pelvic bone. The lower portions of the medial hamstrings attach to the inner portion of the tibia. The biceps femoris attaches on the outside to the fibula, just below the knee joint. These two cable-like tendons behind the knee are part of the hamstrings. The hamstrings are biarticular flexing the knee and extending the hip. When bending forward, the hamstrings work, along with the muscles of the lower back, like strings of a marionette to control the trunk of the body and raise it back up to a vertical position. The hamstrings also tighten eccentrically when walking or running to decelerate the swing of the lower leg so that the knee joint doesn’t snap each time it extends. The hamstrings have tendons that extend into the belly of the muscle tissue. Since strains frequently occur at the junction between the muscle tissue and the tendon the hamstrings may be at higher risk for this type of injury.

Biarticular muscles like the hamstrings tend to be more prone to injury if they perform different functions at each joint. When sprinting, for example, the body may require the hamstrings to forcefully contract to extend the hip, propelling the body forward at the same time that these muscles are stretched over the knee joint. Even though the muscles of the upper leg and the bone beneath them are among the strongest structures of the body they are also subject to significant stress.

Due to their huge bulk in an exposed area of the body, the quadriceps, in particular the rectus femoris, are susceptible to contusions and or direct blows. These are most likely to occur when another individual or an object collides with the thigh while contracted. Contusions tear muscle fibers, which leak fluids into the surrounding area, causing blood to pool. This is known as a hematoma, or more commonly, a bruise. If the bruise is particularly deep, scar tissue that forms within the injured muscles can calcify. The resulting condition, known as myositis ossificans, can be both painful and disabling.

Immediate RICE therapy is recommended. Keep compression constant and apply cold therapy, for 20 minutes, at least 2 to 4 times a day for the first 48 hours. That will minimize swelling and the likelihood that myositis ossificans will occur. For the first 48 hours avoid doing anything that stimulates blood flow to the area, including massage or heat. On day 3 motion is encouraged, the muscle itself will heal on its own in approximately 3 weeks, longer if the damage was extensive. The most important thing to ensure is that scar tissue that develops as a natural part of the healing process doesn’t form in a way that will inhibit movement. If myositis ossificans has formed, extended rehabilitation may be required.

Iliotibial band friction syndrome is inflammation of the iliotibial band, the bursa located between the ITB and the lower end of the femur. The ITB’s function as a knee stabilizer involves it sliding over the lateral surface of the knee joint, about 3,000 times for each mile, as it bends and straightens. Overuse, poor biomechanics or lack of specific stretching can cause the band to become tight and less resilient, squeezing the bursa and causing irritation. The condition is most common among distance cyclists and runners and is especially aggravated by running downhill. Pain is localized over the outer portion of the knee, but in rare cases pain can be felt over the hip joint as the ITB slides over the bone in that area as well. Another common sensation is a creaking feeling on the lateral aspect of the knee joint. Among potential causes of ITB friction syndrome are tightness of the ITB, over pronation, slanted roads, leg length discrepancy and overuse. Over pronation increases the rotation of the lower leg, tightening the ITB and creating more friction between it and the bone. Most paved roads are slanted for drainage at the edge of the road, creating a false discrepancy in the length of one leg compared to the other if running in the same direction for extended periods of time. ITB syndrome tends to afflict the shorter leg; as little as 1/4 inch difference can create biomechanical problems. Running longer distances than normal, or running downhill when not accustomed to it can lead to ITB friction syndrome.

To treat ITB friction syndrome, apply a cold gel pack to the knee 2 to 4 times a day for 20 minutes. If the pain is chronic, rest from the offensive activity for 2 weeks. During this time, cross-train with activities that don’t cause pain, and begin by performing mild stretching exercises for the ITB. When the acute phase subsides, begin incorporating ITB crossover stretches as part of an exercise routine, particularly after warm-up and after the workout itself. Other measures that my reduce strain on the ITB: use a heel pad on the lateral side of the heel, when over pronating. Cyclists should experiment with shifting the seat height and toe position. In general toeing outward will take pressure off the ITB, as will raising the seat or moving it further back.