People who are “double jointed” can bend, extend, and rotate their joints well beyond what most people’s bodies allow. They can touch their thumbs to their forearms, bend their pinkies back past 90 degrees, place their palms flat on the floor without bending their knees, and hyperextend their elbows and knees past straight. Some can contort their fingers, wrists, or shoulders into positions that look impossible. The correct term for this is joint hypermobility, and it affects roughly 1 in 500 to 1 in 800 people.
What Hypermobile Joints Can Actually Do
The “tricks” most people associate with being double jointed are real demonstrations of an unusually large range of motion. Clinicians measure this using the Beighton score, a nine-point checklist that awards one point for each of these movements you can perform: bending forward to place your hands flat on the floor with straight knees, hyperextending each elbow past neutral, hyperextending each knee past neutral, bending each pinky finger back beyond 90 degrees, and bending each thumb back to touch the forearm. A score of four or more indicates hypermobility.
Beyond party tricks, that extra range of motion translates into real physical advantages in certain activities. In throwing and overhead sports, hypermobile shoulders allow a greater arc of motion that generates more torque. This can increase throwing velocity for baseball pitchers, javelin throwers, and football quarterbacks. In gymnastics, figure skating, and dance, the added flexibility makes it easier to achieve extreme positions, whether that’s a full split, an exaggerated arabesque, or a deep backbend. Swimmers with hypermobile ankles and shoulders can often achieve more efficient strokes. For musicians, especially pianists and string players, flexible fingers and wrists can make wide stretches across keys or fretboards more comfortable.
Why Some Bodies Are Built This Way
No one actually has extra joints. The name “double jointed” is a misnomer. What’s different is the connective tissue, specifically the collagen and other proteins that form ligaments, tendons, and joint capsules. In hypermobile people, these structures are looser or more elastic than typical, allowing bones to move through a wider range before the soft tissue stops them. The underlying causes involve variations in the genes that code for collagens, proteoglycans, glycoproteins, and related enzymes. About 5 percent of adults have some degree of hypermobility with no other symptoms at all.
Hypermobility tends to be more common in women, younger people, and certain ethnic groups, though it occurs across all demographics. Children are often more flexible than adults, and some people “grow out” of noticeable hypermobility as their connective tissue stiffens with age.
The Tradeoffs of Extra Flexibility
That impressive range of motion comes with a cost. Loose connective tissue means joints rely more heavily on the surrounding muscles for stability. When those muscles aren’t strong enough to compensate, joints can sublux (partially slip out of place) or fully dislocate, sometimes during ordinary activities like reaching for a shelf or rolling over in bed. Research on wrist hypermobility has found measurable deficits in grip strength, joint proprioception (your body’s ability to sense where a joint is in space without looking at it), and overall hand function compared to people with typical joint mobility.
That proprioception issue matters more than it might sound. If your brain gets less accurate signals about joint position, your balance and coordination can suffer, and your reaction time for correcting an awkward movement slows down. This helps explain why hypermobile people often describe themselves as clumsy or prone to ankle sprains and similar injuries, even though their flexibility might suggest otherwise.
For most hypermobile people, these are minor inconveniences. Occasional joint popping, some stiffness after sitting too long, or a knee that hyperextends when standing. But for a subset, hypermobility is part of a broader connective tissue condition.
When Hypermobility Is Part of Something Bigger
Hypermobile Ehlers-Danlos Syndrome (hEDS) is diagnosed when generalized joint hypermobility occurs alongside chronic pain, soft or stretchy skin, abnormal scarring, hernias, or heart valve differences like mitral valve prolapse. The prevalence of all EDS types combined is roughly 1 in 3,000 to 1 in 5,000. A related diagnosis, Hypermobility Spectrum Disorder (HSD), applies when someone has some of these symptoms but doesn’t meet the full criteria for hEDS. The combined prevalence of HSD and hEDS is around 1 in 600 to 1 in 900.
Because connective tissue exists throughout the body, not just in joints, these conditions can affect skin elasticity, blood vessel walls, the digestive tract, and the cardiovascular system. In rare and severe subtypes, complications like aortic dissections can be life-threatening. For most people with garden-variety hypermobility, though, these systemic risks don’t apply.
How to Protect Hypermobile Joints
The single most important thing hypermobile people can do is build muscle strength around their loosest joints. Stronger muscles act as a brace, compensating for ligaments that don’t provide as much passive stability. Light weights and resistance bands are better choices than heavy lifting, which can strain already-loose joints. The goal is slow, controlled movements that build stability without pushing joints to their extreme endpoints.
Low-impact aerobic exercise like walking, swimming, cycling, and dancing keeps joints healthy without the jarring forces of activities like running on pavement or contact sports. One counterintuitive guideline: people with very flexible joints should generally avoid aggressive stretching. Overstretching muscles that are already loose can further destabilize the joints they support, increasing injury risk rather than reducing it. If you’re hypermobile, your warm-up is better spent on activation exercises that wake up muscles than on deep static stretches.
Working with a physical therapist or trainer who understands hypermobility makes a significant difference. They can identify which specific joints need the most support, design exercises that strengthen without strain, and help you recognize movement patterns (like locking your knees into hyperextension while standing) that gradually wear joints down over time.