We know that the average person training 3 times per week (drug free) with proper nutrition, intensity, and resistance levels can pack on approximately 4 pounds of muscle in one year. There have been some cases with gains as high as 18 pounds of pure muscle. We thought you might like to know just when does that muscle begin to develop? Here are a couple of factors to consider while developing your workout regiment.

1. Muscle fibers are always synthesizing (making proteins), as well as breaking down proteins. Usually there is a balance between synthesis and destruction. Any stimulus will alter this balance to either make or destroy more.
2. Resistance exercise will alter the fluid distribution in muscles so that more enters the muscle and you get a swelling immediately after exercise. This is just transitory.(pump)
3. We have found that after one week muscle fibers of humans are larger with two sets of resistance exercises.
4. After one week in space, rats and humans lose about 25% of their muscle mass (leg muscles)

You can see that a muscle responds very quickly to various stimuli. You can also see that muscle atrophies quite rapidly when not in use. Food for thought, see ya at the gym.