Question: My girlfriend started training a few months back and now wants to change gears and not gain any more muscle but retain muscle mass. What is the right approach? Is not progressing on her lifts anymore going to do the trick?
Answer: While very few men don’t want to gain more muscle (if a man says they don’t want more muscle they’re either an athlete trying to avoid going up a weight class, or they’re lying) and even fewer women will gain enough muscle for this to be a problem (unless they’re using anabolic steroids or other growth drugs). However, there are some women who are naturally very responsive to strength training and do gain muscle quickly and may want to simply maintain their physique without continuing to gain beyond some point.
You’ve already guessed the answer; the way to stop gaining and maintain what you have is to simply reduce and remove the key factors from your workouts that are required for stimulating muscular strength and size increases; intensity and progression.
If you stop progressing the resistance on exercises for muscle groups she doesn’t want to keep growing and have her perform those exercises only for a fixed number of repetitions whether or not she has achieved momentary muscular failure and maximum intensity of effort, those muscles will stop getting bigger and stronger. Assuming you make no other changes in her workout, if you keep her resistance and repetitions the same on those exercises they will eventually cease to be challenging enough for her to stimulate further improvements in strength and size.
The lack of these factors is a big part of the problem with many people’s training and the reason they are not making gains in strength and size. The vast majority of people do not train anywhere near as intensely as they are capable of, and many do not keep a workout chart or journal to track and evaluate their performance and systematically progress the resistance they use. Without these their progress will be hit and miss, and far from optimal, if they make any noticeable progress at all. So, to look at this another way, if you want to stop making muscular strength and size gains another solution would be to do what almost everybody else in the gym is doing, and if you want to get the best results possible do the opposite of them, train with a high intensity of effort and with progressive resistance.