hey guys, it is said to gain strength and size, low rep high weight for skinny... while high rep moderate weight for non-skinny... how it can be explained why low rep high weight is suit for skinny... i try high rep moderate weight still i get sour feeling after workout... any theories or concepts behind the meaning?

for size, it's the diet that determines it. If you eat like chicken, no matter how many reps you do, you wont grow big.

High rep moderate weight is for endurance
Low rep high weight is for strength

Do correct me if i'm wrong.

size doesnt grow big even i use low reg high weight if i eat chicken? i tot chicken breast is rich in protein which is good for muscle growth?

First of all, weight training with whatever reps range will grow those muscles be it 3x12 or 2x20 or 5x5. A lower reps (3-5) routine is focused more towards strength, medium reps (5-8) for mass and high reps (8-12) for hypertrophy.

But all those training would be useless if one didn't ensure that he has a good diet. A proper diet would gives the body enough nutrition for muscle recovery hence bigger muscles.

perfect explanation