It takes plenty of time to build perfect body but when you miss several workout sessions, you will start losing the strength of muscles. You can miss workout session due to many reasons like illness, injury and due to lack of time. However, age, exercise program plays significant roles in how long muscles takes to lose strength.
Competitive athletes lose muscles fast as compared to recreational athletes because of their higher fitness levels. The competitive athletes could experience muscle atrophy after two weeks of inactivity. It is believed the recreational athletes lose muscle strength after 12 weeks of inactivity.
Type of Training
Your training program also impacts the rate of losing muscle. Endurance athletes may experience muscle loss slower as their muscles are leaner as compared to power athletes, who predominantly have fast-twitch muscle fibres.
Age and Gender
Muscle loss with an increase of fat in the muscle, also known as sarcopenia, is a common ageing process. The elder people may experience quicker muscle loss or more muscle loss during inactivity compared to younger individuals.
The competitive athletes lose muscle quicker than recreational athletes but their strength levels after stopping exercise are still higher than recreational athletes. Competitive athletes also tend to regain muscular strength levels quickly after resuming training. Furthermore, detraining not only influence your muscle size and strength but it also decreases your muscular endurance and cardiovascular fitness.
Stopping exercise has a negative effect on sedentary activity but it has one benefit of consistent exercise is building muscle memory. If once you establish the muscles then it is easier to retain after you resume exercise.
Some people are good to achieve a higher level of fitness by taking a break of two to four weeks from the gym, then resume the gym again and achieve an even higher level of fitness. If you use this approach or are returning to resistance training after injury or illness, starting slow is important.