Carbohydrates are an important energy source for strength training. Stored as glycogen in the muscles, it is the fuel used to supply energy for short, intense bursts of power. The harder and longer you work out, the more glycogen your muscles require. Once these stores of glycogen are gone you energy level will drop and you will have to stop exercise. So Carbohydrate should be a major concern of athletes doing strength training exercise in the hopes of building lean muscle.
Experts recommend at least 400 to 600 grams of carbohydrates per day to keep your muscle glycogen stores high.
You may use this formula to work out your personal requirement; a:
3.6gr carb x body wt(lbs)= grams carb/day
For a 140 pound person this is about 504 grams per day or about 2,000 carbohydrate calories and 720 grams or 2,900 carbohydrate calories for a 200-pound person.