Since you're doing several repetitions, try to go a little farther each time. Go only as far as you can, to improve your own range of flexibility. Swimming and healthy stretching promote muscle harmony. It's important not to overstretch. Be sure to move into and out of each stretch slowly, maintaining normal breathing.
Kids go through quick growth spurts sometimes growing three to six inches taller in one year.
The rapid growth can create tightness. Healthy stretching educates muscles to adapt to the lengths the body needs in order to rotate properly. A locked hip means the muscle groups that connect to the hip have shortened to the point that they severely restrict hip rotation. It's painful and makes other muscle groups pick up the load, sometimes injuring them as well. Locked hips, for example, can cause inner-thigh strains.