Often times, we classify people which are very tall as giants. Yes, they are giants but it may not be their intention to be giant due to the over secretion of hormone in the body caused that . According to science, those classified as giants are muscular weak in nature.
Giantism comes as a result of some deficiency in the human body and as such makes he human to grow morethan expected on stature and height. The bible talking about gianstism from the book of Genesis 6:4 :There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.
Based on human nature giants are not made to be strong due to the over secretions of human but according to the bible , they were very very tall and also strong even at old age that they never grew weak.