A lot of people feel that if they neglect even one workout session their muscles will start to weaken and eventually turn to fat. However, missing a week or two or even three will not cause the muscles’ atrophy. For this you should stop working out for several months.
An important fact is that it’s easier to re-gain lost muscle than it is to build new muscle Your muscles remember where you left off last time you worked them. You may have seen that if you have not lifted for three weeks, the first few days are difficult on your endurance and strength. However, you should also notice that after four or five days you’re back to where you were before, when you were training regularly. That is the essence of muscle memory. Let’s say you get in a car accident and can’t lift for a period. In this case your muscle will start to atrophy but you definitely can regain them. Muscle memory comes into play again. They remember where you last left off, and with a bit of work, your body will rebuild lost muscle back.