We all know that kid from elementary who was able to bend their fingers back more than we thought was humanly possible. When you reacted, they would respond “Oh, I’m doublejointed”. The term double jointed implies that a person with unusual flexibility has twice the average number of joints which is not the case at all.
People with “double-jointedness” actually have hypermobility syndrome, a condition that allows them to move a bone within a joint to its fullest capacity, but without experiencing the pain or discomfort that the average person would feel when extending a joint beyond its normal range.
Extreme flexibility in people with hypermobility can be caused by a combination of several factors. Double jointed people can have a very shallow socket, enabling more movement in both directions. Shallow sockets, combined with bone ends that are smoother than normal, also help joints slip and move more easily in any direction. Ligaments and cartilage that stretch beyond the usual extent impact joint flexibility in the same way. For some people, being double-jointed can be very painful and impose moderate to severe limitations in daily life.
We have all been double jointed or hypermobile at some point in our lives. In childhood, we could bend from the waist and touch our fingertips to the floor while keeping our legs straight. Typically as we age, our ligaments, cartilage, and bones harden and lose their suppleness. This is another great reason to include some flexibility exercises in your workout routine – to help the muscles, ligaments, and cartilage stay flexible and slow down the hardening which then inhibits your movement.