Physiology Growth Spurt		The growth spurt is a big deal. It is responsible for 20% of our adult height and occurs over 2 to 3 years. It occurs earlier in females, with a peak height velocity (PHV) of roughly 9 cm/yr occurring during Tanner stages 2-3. It occurs later in males, usually at 12-14 years (Tanner stages 3-4), with a PHV of 10 cm/yr and lasts 2 years longer. So, those girls who are really tall in the 5th grade are usually the shortest by 7th and 8th grade, while their male counterparts are just taking off right around that time. When you talk about weight, however, it's a little bit different and even more substantial. We gain roughly 50% of our adult weight during the time of the growth spurt and puberty. Females have a decrease in their lean body mass (LBM) to 75-85% with relatively more adipose tissue forming. Males tend to go the other way, with an increase in LBM to 90% due to androgen effects. Return to top of page