What Happens to Your Body When You Stop Exercising? How Fast Do You Lose Muscle? Everything You Need About Training & Muscle Loss
How Long Does It Take to Get Out of Shape?
There's no hard and fast rule about how long it takes to lose your fitness edge. Generally speaking, if you're very fit to begin with, your body will remain in a fitter state longer than someone who's not fit, even as your workouts cease.
That being said, a study in the Journal of Applied Physiology suggested that skipping workouts for just two weeks can significantly reduce your cardiovascular fitness, lean muscle mass, and insulin sensitivity and two months to lose all of your fitness gains. But there are varying opinions on the matter. Many experts agree that about two weeks is a pretty standard number after which your body will start to fall out of shape with no exercise.
Cardiovascular Fitness Typically Fades Faster Than Muscle Strength
When you skip too many workouts, the strength of your heart and lungs will fade first. One study found that after just 12 days without exercise, VO2 max, a measure of cardiovascular endurance, dropped by 7 percent, while blood enzymes associated with endurance performance decreased by 50 percent. Likewise, four weeks of inactivity among endurance cyclists resulted in a 20 percent decrease in VO2 max. Keep in mind this is among trained athletes, among those new to exercise, gains in VO2 max completely disappeared after four weeks of inactivity.
As for muscle strength among athletes, it appears to hold steady even after a month of inactivity – but there are significant differences among certain types of muscle fibers. Your body has three types of muscle fibers: slow, fast, and super-fast twitch muscle fibers.
Slow-twitch muscles are the red muscles, which are activated by traditional strength training and cardio exercises. Fast and super-fast muscles are white muscle fibers, and these are only activated during high-intensity interval exercises, like sprints.
"Medicine and Science in Sports and Exercise published a review of several studies on the subject that looked at runners, rowers, and power athletes. For all of these groups, muscular strength fibers appear not to change, even after a month of inactivity.
Long-Time Exercisers Have an Easier Time Bouncing Back
If you've taken a long break from the gym, you might be nervous about returning to your workouts. You should ease back in gradually to avoid injury, but if you're a life-long exerciser, you'll have an easier time getting back into shape than someone who only recently started.
Your age also plays a role. The older you get, the faster your muscles atrophy if you're not regularly engaging in appropriate exercise. In addition, it will take you longer to gain it back. When comparing 20- to 30-year-olds with 65- to 75-year-olds, the older group lost strength nearly twice as fast during six months of inactivity.
That being said, if you're past your 30s, please don't let that discourage you. Older adults can gain a two- to three-fold increase in strength after just three or four months of weight training.
Are You Skipping Your Workouts Because They Take Too Long?
If time is the factor leading you to skip workouts, here's a simple hack you can use: cut down on the duration of your workout while increasing the intensity. Exercise experts are quickly abandoning the old exercise advice – the recommendations that suggest you need 45 or 60 minutes of moderate-intensity activity to best stay in shape.
Study after study is showing that this is not true nor the best way to exercise, both in terms of its health benefits and its duration. You can actually reap much greater benefits by exercising in short, high-intensity bursts known as interval training than you can by exercising for longer periods at a slower pace. High-intensity interval training research that (HIIT) burns more calories in less time. The HIIT training approach we recommend consists of 30 seconds of maximum effort followed by 90 seconds of recuperation, for a total of eight repetitions.
How Much Time Should You Rest Between Workouts?
An equation to keep in mind is that as intensity increases, the frequency can be diminished. As a general rule, you do not want to do high-intensity interval training exercises more than three times a week. For beginners, start with twice a week initially, and then move up to three when you feel ready.
With High-Intensity Exercise, They Say Less Is More
One of the major benefits of high-intensity exercises is that it allows your body to produce human growth hormone (HGH), commonly referred to as "the fitness hormone." However, if your body hasn't fully recovered from your Monday session and you come back and do a HITT training again on Wednesday, instead of growth hormones spurt, you're going to get in a cortisol spurt. You're going to completely undermine what it is that you're after."
When Should You Skip the Gym?
One of the benefits of being fit is that you can take time off and recover and use the reserves that you have built up to help you recover. It is kind of like having stored fat during times of famine. One time to rely on those "reserves" is when your body is under stress from being sick. You'll generally want to seek rest as your body mobilizes to fight off the illness, but you'll need to listen to your body to know for sure.
If you have enough energy to tolerate it, increasing your body temperature by sweating from exercise will actually help to kill many viruses. Over-exercising will place more stress on your body, however, which can suppress your immune system, so you should keep the intensity of your workouts on a low-moderate level if you're sick (such as taking a brisk walk). It's generally advised that you avoid exercise if you have symptoms that are "below your neck," such as:
Coughing or chest congestion
Widespread body and muscle aches
Vomiting, upset stomach, and/or stomach cramps
But no matter what your symptoms, you need to be very careful and listen to your body. If you don't feel up to it, and all you want to do is get some rest, then that's what your body needs. And we can't stress enough that if you don't feel well, you should not do your full, normal exercise routine, as that could clearly stress your immune system even more and prolong your illness if you are not careful and wind up overdoing it. By all means, high-intensity exercise should be avoided when you're sick because any kind of intensive exercise boosts production of cortisol, a stress hormone that inhibits the activity of natural killer cells—a type of white blood cell that attacks and rids your body of viral agents.