Double-jointedness, also called joint hypermobility, means that you have greater range of motion in some or all joints than most people. Here’s a simple way to find out, based on what’s called the Beighton Test, a standard way to measure hypermobility:
• Standing with your knees straight, can you bend forward from the waist and put your hands flat on the floor? If yes, score 1 point. (Be careful trying this if you have back or knee problems.)
• Can you bend one or both elbows slightly backwards? Score one point for each elbow.
• Can you bend one or both thumbs down to touch your inner arm? Score one point for each thumb.
• Can you bend one or both little fingers back beyond 90 degrees? Score one point for each little finger.
• Can you bend one or both knees slightly backwards? Score one point for each knee.
Most people can’t do any of these things. If you can, consider yourself hypermobile in that joint. A score of at least 4 means you probably have generalized joint hypermobility—that is, many of your joints are flexible beyond the normal limit. If so, you’ve likely been aware of this since childhood, when perhaps you were able to bend your body into curious shapes or do splits.
How far a joint can move, referred to as its range of motion, is determined by many things, including genetic factors affecting bones andcollagen (a type of connective tissue) in the joint.
Hypermobility can be a plus. Being double-jointed is common among professional dancers and is advantageous, since it allows them to demonstrate feats of flexibility on stage.Famous pianists such as Sergei Rachmaninoff have been noted for the unusual flexibility of their hands. Competitive athletes, notably swimmers, may profit from extra flexibility. Some training, such as yoga and gymnastics, aims to increase range of motion and may attract people who are hypermobile.
But there can be drawbacks, too. Hypermobility can occasionally cause chronic joint pain or overstretching of tendons, or a tendency to dislocate joints, especially the shoulder. Hypermobile dancers, for example, may overdo stretching, which can make joints unstable and prone to injury. Double-jointed athletes may also be more prone to injury. According to an analysis of 18 studies, published in the American Journal of Sports Medicine, being double-jointed increases the risk of knee injuriesduring contact sports.
For most people, hypermobility causes no symptoms or problems, but if you do have symptoms, such as chronic joint pain, consult a doctor, specifically a rheumatologist, to evaluate you. In rare cases, people who are overly flexible have a condition called hypermobility syndrome, which causes connective tissue defects elsewhere in the body and may contribute to asthma, irritable bowel, or other health problems.
If you are hypermobile, a physical therapist can help reduce the risk of injury by recommending strengthening exercises that help stabilize joints, as well as activities to improve balance, coordination, and proprioception (the ability of a joint to “know” its position in space).
Also see Knock Knees: Causes and Treatments.