Strenuous exercise -- particularly weight training -- creates microscopic tears in your muscles. The nutrients you eat determine how well your muscles repair these tears and, in turn, how much strength you gain. Apart from eating healthful food, you must get enough sleep and eat frequent meals for the greatest muscular strength.
The most important nutrient in muscle repair, which allows your muscles to become stronger, is protein. In order to make muscular gains, average adults need between 1.4 to 1.8 grams per 1 kilogram of weight daily -- that is between 7 and 9 grams of protein per 11 pounds of weight -- according to the Academy of Nutrition and Dietetics.