People usually have a growth spurt when they are going throw puberty. Some people grow more than others, The definition of a growth spurt is an occurrence of growing quickly and suddenly in a short period of time.
I really don't know hemoglobin is a protein that's all I can say :P
1. Some challenges that I faced in the pursuit of improved fitness included lack of motivation. When I wanted to work out or be active, it was hard to get started because of the fact that I was tired and unenthusiastic. To help overcome these, I use a reward system to motivate myself.
They permit a production of the large amounts of proteins and enzymes needed for muscle contraction.
