We know that skeletal muscular strength stays about the same during a month of not exercising. However, as mentioned above, athletes can start losing muscles after three weeks of inactivity. You lose cardio, or aerobic, fitness more quickly than muscle strength, and this can start to happen in just a few days.
Will 2 weeks off gym muscle loss?
If you take a week or two away from the gym, you probably won't lose strength or muscle mass. If you take more than three weeks off, you'll lose at least a little bit of strength and muscle, but you'll regain it quickly when you start lifting again.
Does muscle go away if you don't workout?
When you aren't working out regularly, your body composition starts to change. With little physical activity, muscle cells will shrink. With less calorie burn, fat cells will start to expand, making the body look softer.