Some people are able to add muscle to their legs quickly, while others have to follow a training program for months before noticing a difference. Age, hormones, training history, genetics, diet and supplementation can all affect the speed at which you're able to build bigger legs. However, there are still time ranges within which most individuals can expect to see improvements.
Speed of Gains
According to exercise physiologist, Alan Argon, the rate of muscle gain is most directly related to training experience. Someone new to resistance training may increase muscle mass by 1 to 1.5 percent of his total body weight per month, while an experienced person who has trained for over two years might only see a 0.25 to 0.5 percent monthly increase. For example, an inexperienced, 130-pound person may gain nearly two pounds of muscle in a month. With a solid leg training plan, a substantial portion of these gains could be in the legs.
Gaining Muscle Faster
Train legs for growth by following a plan that stimulates hypertrophy. The best range is around three to five sets of eight to 12 reps per exercise. Do intense compound exercises that integrate multiple lower body muscles, such as squats, deadlifts and leg presses. Perform isolation exercises to target specific muscles, including leg extensions, leg curls and seated calf raises.