Your Body

March 23, 2008

Dancers’ legs often seem to hold intuitive wisdom and muscle memory. But the kinesiology of the muscles that directs the legs into so many amazing moves is complicated, particularly when examining how those muscles work in tandem.


Take the quadriceps (front thigh muscles) and the hamstrings (located on the back of the thigh). The quadriceps femoris are aptly named because they comprise four muscles: rectus femoris, vastus medialis, vastus intermedius, and vastus lateralis. The latter three originate at the top of the femur (thigh bone) and attach to the kneecap; the rectus femoris originates on the hip, making it the only quad muscle that crosses both the hip and knee joints. The primary action of the quads is to extend the knee—like when you unfold a développé.


The hamstrings consist of three less bulky muscles: the biceps femoris and, deeper underneath, semimembranosus and semitendinosus. They originate at the ischial tuberosity (also referred to as the sitz bone) at the back of the pelvis and insert into the lower leg bones. They all activate the flexing of the knee—as in passé—and also extend from the hip, as you can feel in an arabesque. Therefore, all the hamstring muscles have a two-joint action at the hip and knee, making them more vulnerable to injury in movement.


According to Boyd Bender, a physical therapist for Pacific Northwest Ballet, the correct strength ratio of quads to hamstrings in dancers is generally about 60/40. Since the actions of the quadriceps and the hamstrings are opposite in nature, and dance requires fluid motion, they actually work in concert. Or at least they should. The powerful quads can sometimes overpower the hamstrings.


Bender says he usually sees more hamstring injuries than quad injuries. “The hamstrings are generally not strength stabilizing muscles,” says Bender. “They are fast twitch muscles that accelerate and decelerate the hip and knee while going through rapid changes of position.” (Fast twitch versus slow twitch refers to how the muscles are chemically wired to contract, either for speed or stabilization). Because the hamstrings cross the back of the hip joint, they can be influenced by dysfunction in the low back, like an overly tipped pelvis.


To strengthen the hamstrings, Bender advises working the muscles for both flexion and extension. That involves concentric strengthening (where the muscle is contracted during flexion) and eccentric strengthening (where the muscle is lengthened, but still taut, as in a battement to the front). “It’s also advantageous not to do just the traditional strengthening exercises, but also those that involve a little speed as well,” he adds. In other words, use the hamstring flexor machines at the gym, but add Pilates or Gyrotonics for dynamics of stretch, strength, and movement for a well-rounded regimen. Orthopedists classify hamstring injuries as grade 1 (mild, often accompanied by a limp), grade 2 (more pain and a pronounced limp), or grade 3 (severe, with the patient usually unable to walk). Injuries to the hamstrings can happen in two primary ways. “When the strain is closer to the butt, it is usually more spine-related than from the actual action of the muscle,” says Bender. When the hamstring injury takes place closer to the thick belly of the muscle, it may indicate that the hamstring was overtaxed by a movement unrelated to the spine.


The most common quad-related injuries surface at the patellar tendon, which joins the quad to the lower leg via the kneecap. But because the quads are a slow-twitch, stabilizing muscle group, they tend to be more injury-resistant.


For rehabilitating hamstrings, Bender advocates rest, electrostimulation therapy, ice, ultrasound therapy, and sometimes compression and wrapping. Grade 1 injuries can heal in 7–10 days but could take up to 3 weeks, while grade 2 requires 4–6 weeks. Grade 3 injuries can take up to 4 months. Hamstring strains closer to the pelvis generally need more healing time.


One of the biggest mistakes dancers make is overemphasizing stretching, rather than strengthening, hamstrings. Loose hamstrings are great, but they need to be backed up by strength.


Joseph Carman is a contributing editor to
Dance Magazine.


Photo by Nathan Sayers.