In these studies, there was actually NO significant drop off in muscle mass after two weeks of detraining. Even if you are not training at all, you most likely will be doing some sort of normal everyday activity.
According to Jesse Shaw, D.O., associate professor of sports medicine at the University of Western States, this is typical for the general population, too: It usually takes between three and four weeks to start noticing a decrease in strength performance with a complete cessation of activity.
People are actually advised by trainers to take a break of 1-2 weeks. But it is only if a person has been doing intense workouts for over 8-12 weeks. A week off the gym will help the body recover and replenish. However, during the rest period the body will undergo some changes.
While you may experience a temporary decrease in muscle size and strength after two weeks of inactivity, it's not a significant loss. Muscle memory helps regain lost gains when you resume your workouts. Consistency is key for long-term progress, but a short break usually won't erase all your gains.
When you have been training for a long time and you go on vacation for 2, 3 or even 4 weeks, there is no real loss of muscle mass... it's all in your head! On the other hand, what is inevitable is that you will feel less energetic than usual, since your muscles will no longer be congested like after your training.
Your blood plasma volume starts to decrease, which leads to a decrease in cardiac output – in short, less oxygenated blood to your muscles. After about 10 days we start to see a knock-on reduction in VO2 max, between 4-5% after two weeks.
Physiological muscle memory
While they may lose muscle mass due to their inactivity, it will typically return more quickly than when they first put it on. This form of muscle memory occurs because when you first build muscle, your body adds new cells to those muscles.
Generally, it takes anywhere from two to 12 weeks to regain cardiovascular endurance and muscle strength and feel like you're back at your previous level of fitness.
How much muscle depends on the length of time you were immobile, but it's quite normal to lose as much as 30% in just two weeks. The good news is even moderate physical activity, like walking, can help reduce muscle loss.
As muscle cells get smaller, fat cells tend to get bigger. After all, the muscles aren't working hard enough to burn away calories. This can lead to weight gain as soon as 14 days (or earlier) once you stop exercising, according to Men's Journal.
Research shows you shouldn't be too worried about losing significant fitness if your break from running is less than two weeks. You'll lose some conditioning in your aerobic system and muscles, but pre-inactivity fitness will return quickly.
According to a 2013 study on muscle development, retention, and decay rates among specific athletes, declines in muscle strength would become noticeable in about three weeks. Thus, athletes can take between two and four weeks off from training without seeing any noticeable losses.
The Answer? Rest One or Two Days Per Week. For the best performance and to reach your goals in the safest and most effective way possible, plan for one to two rest days per week. Olenick recommended spacing these out — take one rest day mid-week and the other on the weekend, or in between bigger workouts.
Depending on your workout, muscle cells can grow back bigger and stronger anywhere from one to seven days later. While they grow back, you should work on different muscle groups to stay on a consistent schedule.
When this term is thrown around casually as a marketing tool for an exercise program, it might cause you to wonder, “Is muscle memory a thing? Can my muscles remember my workout?” Short answer: Yes, muscle memory is real, but it might not work as you think.
Although a small amount of natural muscle loss will inevitably occur with age, it can be slowed and sometimes even reversed.
Aerobic Capacity
Research shows significant reductions in VO2 max within two to four weeks of detraining, which is attributed to decreased blood volume and cardiac output. Another study found that most of the aerobic capacity gained through exercise over two to three months is lost within two to four weeks.
In the last decade, most researchers agreed if you took two weeks off from the gym, you were not only bound to lose all your gains, but you'd suffer some pretty serious psychological issues in the process.
Whatever the reason, before you know it, you're out of shape. Neglecting the gym every once in a while is nothing to worry about — after all, sometimes your body needs to rest and recover. But, when you hit pause on your workouts for more than a week, you might actually be throwing your fitness level into rewind.
Remember to start slowly and gradually increase the intensity of your workouts as you get back into the routine. It's also important to listen to your body and stop if you experience any pain or discomfort.
However, if overreaching is extreme and combined with an additional stressor, overtraining syndrome (OTS) may result. OTS may be caused by systemic inflammation and subsequent effects on the central nervous system, including depressed mood, central fatigue, and resultant neurohormonal changes.
Remember, if you're not injured or bedridden, try to get back to resistance training when you can. You've got about 2-3 weeks before you lose a significant amount of muscle mass and strength. If you are injured, incorporating light resistance exercises can help to maintain muscle function and metabolic health.