The Science of Flexibility
While flexibility might appear to be about long and stretchy muscles, in fact, much of your flexibility is pre-determined at birth - dependent on the shape of your joints. The architecture of the joint - its shape and the thickness of the cartilage - account for 85% of your flexibility. This is something which is written in your genes and cannot be changed, no matter how hard you train. 10% is achieved through safe and sensible stretching of the muscles and the final 5% is based on other factors which we are less able to control, such as age, gender, levels of body fat, the temperature of the environment and stress.
As a rule, women are more flexible than men, particularly around the pelvic area which is wider in women to allow for birth. If you are born with healthy and stable joints that allow an above average amount of flexibility you will have a much better chance of becoming a successful classical dancer. For that reason dance schools operate strict selection processes for young hopefuls to ensure that nature has given them the right level of flexibility in order to train.
Training as a dancer from an early age with low levels of flexibility could lead to injuries later in life and intensive stretching at a very early age can have serious repercussions. Similarly if a would-be dancer has too much flexibility (known as hypermobility) then he or she may also be at a disadvantage. For instance if the foot is too flexible, dancing on pointe would be dangerous and people with hypermobility are more likely to suffer from dislocated joints.