Lots of girls and boys between the ages of 10 and 16 may be experiencing pain related to their rapid growth. Unfortunately as we grow, all the action takes place at the growth plates in our bones, and it does take some time for the muscles, ligaments and nerves to adjust to their new positions. This means that hamstrings that were allowing you to get into the splits easily three months ago might be a little short for the new leg they are attached to! As tempting as it is to stretch them out constantly, it is also a time when we have to be REALLY careful about how much, and how hard we stretch.
Unfortunately, a lot of your muscles attach to the bones right on the growth plate. For instance, the tendon that attaches your knee cap to your lower leg does so right on the growth plate of your tibia (shin bone). Your hamstrings also attach to a softer bit of bone at the base of your pelvis. If you stretch too vigorously, or are pushed into a stretch by someone else (try and avoid this wherever possible) you can actually pull the muscles where it attaches onto the bone, or even pull a little piece of the bone away. This is called an avulsion injury. Where your hamstrings attach...