How long does it take to get out of shape?
The short answer: It depends. Generally speaking, though, it doesn't happen quickly.
For a recreational exerciser -- someone who works out two to three times a week and is "fit enough to keep up with a 3-year-old" -- it takes two to four weeks of inactivity for there to be a notable change in your conditioning, says Jo Zimmerman, an instructor in the department of kinesiology at the University of Maryland.
The more serious athlete, someone training for a marathon, would feel this decline more acutely, but deconditioning happens in proportion to how much effort is being put into getting in shape in the first place.
Regardless of your fitness level and goals, "detraining" (a fancy way of saying you've logged more hours on the couch than at the gym) affects different parts of the body -- cardiovascular system, muscles, waistline -- in different ways.
CARDIOVASCULAR SYSTEM
The first thing to slide is aerobic fitness. After 10 to 14 days with little or no physical activity, the body's ability to effectively consume and use oxygen, measured in sports laboratories as VO2 max, begins to decline, says Jessica Matthews, a senior adviser for health and fitness education for the American Council on Exercise.
Studies show "notable reductions in VO2 max within two to four weeks of nontraining, mostly due to decreased cardiac output and decreased blood volume," she says.
When you work out, explains Zimmerman, "your heart gets big in a healthy way -- every beat can handle more blood" and you produce more capillaries in your muscles. When you detrain, the heart gradually loses its ability to handle extra blood flow, and those new capillaries wither. It sounds dire, but, Zimmerman says, "it's safe and normal."
It can also be reversed once a person resumes regular exercise.
MUSCLES
Detraining has a less immediately dramatic impact on muscular strength and endurance. During the first few weeks off, the effects are slight, Matthews says. After about four weeks off, however, muscle fibers begin to shrink, and some time between then and eight weeks, that decline becomes measurable, Zimmerman says. Muscles feel less firm; arms start to sag a bit.
But this, too, is reversible.
WEIGHT
The effect on weight is more straightforward. "It's a simple input-output problem," Zimmerman says. If you stop a daily workout that would have burned 300 to 400 calories and you want to maintain your weight, "you are going to need to reduce your intake by 300 to 400 to match."
What's less simple is how those extra calories might look on your body. Despite what many people think, "when you get fit, you are not turning fat to muscle," Zimmerman says. Fat and muscle are two different types of tissue. When a body stops working out, muscles will eventually shrink back to where they started; if you eat more calories than you burn, the extra calories are stored as fat.
But the fat and the muscle are not replacing each other.
"And it doesn't go in reverse, either," Zimmerman says. "You don't turn muscle into fat."
EVERY LITTLE BIT HELPS
How do you stop the slide? The answer is harsh and obvious: Try not to stop exercising in the first place. Of course, if you are seriously injured or ill, it's smarter to rest than to go on trying to exercise, thus exhausting your body of energy needed to heal and recover. (And remember, too, that rest and recovery are a vital part of any exercise regimen.)
If the problem is an injured body part, there often are alternate exercises. If the problem is your too-busy schedule, there also are alternatives that require less time. If you can't run, you might be able to walk, bike or swim, use a rowing machine or an elliptical glider. Add stairs to your daily routine.
Or if you are able, do bodyweight exercises (pushups, squats, lunges) or light weightlifting, even using common items, such as the box of cat litter or the cat. If that's too strenuous, try a chair workout.
These exercises could seem insufficient to someone used to training for an intense athletic endeavor like a marathon. Getting back to that level requires even more patience, perseverance and humility.
Author and Runner's World columnist Hal Higdon says he tells runners that for every one day of inactivity, it takes two days to return to their earlier fitness level.
ActiveStyle on 07/06/2015