Growth rate then slows until the adolescent spurt when the growth rate increases again. Growth rate then decreases until full height is reached. Bone development Bones develop from a cartilage growth plate, called epiphysial plates, at each end of the bone shaft. The bone lengthens as cartilage is calcified into bone on the diaphysial border, thus lengthening the shaft. At the same time, cartilage continues to grow on the epiphysial border, so the epiphysial plates retain a constant width of cartilage throughout.
Growth ends when the plate eventually calcifies.
Muscles Muscle mass increases steadily until puberty, at which point boys show faster muscle growth. The hormonal changes at puberty also affect body composition in terms of fat. Coaches need to make female athletes aware that until they are 19, they will steadily gain in muscle and so will naturally be gaining weight and that by eating the right kinds of foods is the way to avoid unwanted weight gain. The changes in female body shape during the growth spurt has its particular injury risks. The hips widen, placing the femur at a greater inward angle.