Losing flexibility is actually a really common situation in young dancers. Often as tiny things they have had easy mobility, and with very little stretching were able to drop into the splits effortlessly. Unfortunately, as their bones begin to grow, their mobility can change, sometimes rather rapidly, and they will suddenly need to work quite hard to get back to where they were, in terms of flexibility. As the bones grow in adolescence, it is commonly explained that the muscles, nerves and other soft tissues must adapt to their new positions, especially when growth occurs rapidly. This does play a part, however often the reduction in mobility I have seen during such periods is far more than you would expect from simply the change in bone length.
I feel that a huge part of muscular tension is related to how comfortable we are feeling in our own body. Think about the tension that you get in your own shoulders when you feel stressed. We all hold emotional and psychological tension in our bodies and adolescents are no exception. Often as they are going through a growth phase they feel disjointed from their body, uncoordinated and a little scared at the changes that are going on. Their technical ability may also drop as their limbs change proportion relative to their body, and they may get angry at themselves for not being able to do things as well as they once could. Girls should understand that this is a very common occurrence and be reassured that it is not permanent! They may feel that they need to do more classes to catch up with their peers, yet the opposite is actually true. Reducing the number of dance classes, and including more hours of gentle limber, Pilates or Yoga classes with a well trained instructor who is used to dealing with young dancers will be very beneficial. This is also an ideal time for dancers to really begin to explore their body. Stretches should be performed to cover all of the body, as often stiffness in the spine can cause restriction in the nerves that run down the back of the legs, mimicking tight hamstrings. Stretches should not be pushed, as the potential for pulling muscles where they attach onto the bones is greatest during a growth spurt. Instead they should be encouraged to gently relax into supported stretches, and focus on discovering how to use the breath to assist stretches.
Frequent massage, whether from a trained professional, or a gentle rub from a family member can be very beneficial in relaxing tight muscles and assisting mobility into stretches. There should be no pain following treatment if done correctly, and definitely no bruising. Some “professionals” go too hard on adolescents (and adults too) in the belief of the old “No pain, No gain.” While some trigger point release techniques may be painful during treatment, this should be “good pain” and very short lived after treatment has ceased.