5 Reasons you shouldn’t work out

Jul 4, 2010 at 6:21 p.m. ET

The growing awareness of the benefits of exercise has given rise to many confounding myths about physical activity. Should you break a sweat when carrying a baby? Are you ever too old to get fit? Does being sick or injured give you a free pass to quit exercising altogether? Here, we debunk those workout-skipping myths and give you the skinny on when skipping your sweat is OK.

Pregnant woman exercising

Myth: You shouldn't work out if you are pregnant

Pregnancy is certainly a time to modify your lifestyle to protect your health and that of your baby, but that doesn't mean kicking back in the recliner eating bon bons for nine months. Unless your doctor has recommended that you abstain from physical activity for medical reasons, doing light to moderate exercise while pregnant affords you numerous health benefits.

Exercise during pregnancy can:

  • Help a mom-to-be maintain a healthy pregnancy weight
  • Promote healthy postpartum weight loss and fitness
  • Reduce the risk of gestational diabetes
  • Decrease the risk of pre-term birth
  • Enhance mood and relieve stress
  • Give moms-to-be more energy
  • Help strengthen pelvic muscles
  • Prepare pregnant women for the rigors of childbirth

Talk with your doctor about the best workout plan for you. Your body may change during pregnancy, but the more fit you are before, during and after you give birth, the healthier you and your baby will be.

Myth: You shouldn't work out if you are sick

Studies show that light to moderate exercise can boost the immune system -- meaning that, when you're feeling a little under the weather, a brisk walk may do you more good than slouching on the couch all day. If you have a fever and feel drained of energy, working out may do more harm than good. Exercising when you are really sick can impair your immunity, increasing your chances of getting sicker. Further, if you work out at a gym, you put others at risk of illness by spreading your germs on the machines and fitness tools. Bottom line: When you're suffering from the sniffles or other mild cold symptoms, get some fresh air by going for a walk or leisurely bike ride; if you have the flu, a fever, congested chest or nausea, take a rest from exercise for a day or two until you start feeling better.

Myth: You shouldn't work out if you are at a healthy weight

You're stoked with your jean size and the number on the bathroom scale, so why should you have to endure the rigors of a workout, right? Wrong. Physical activity isn't something you do solely to lose weight. Yes, exercise keeps your body toned and increases your muscle strength -- but it also improves your brain, heart and bone health, boosts your mood, fosters quality sleep and helps you manage stress. Exercise is also a natural way to defy the effects of aging: Skipping that workout increases the odds of dull, sagging skin, no matter how well you fit into your size-4 jeans.

Myth: You shouldn't work out if you have an injury

Yes, it's acceptable to take some time off from the gym if you've been injured and prescribed bed rest to heal. If you've recently had a sports injury or minor surgery, or if one part of your body is immobilized in a cast, however, you can still find ways to work out within the constraints of your physical limitations. Before you begin, get exercise recommendations from your doctor or physical therapist and follow them.

Tips for working out when injured:

  • If you have a foot injury, the rowing machine, swimming or other non-weight-bearing exercises can help you maintain your cardiovascular fitness, as can resistance training with your uninjured leg and upper body.
  • If you have a leg or knee injury, try the upper body ergometer or one-legged cycling or rowing along with upper body strength training.
  • For shoulder or arm injuries, use the stationary cycle, elliptical or treadmill with an incline. Lower- body weight training is fine, too.
  • Low-back injuries are tricky because impact and many types of exercises can increase pain and risk of injury. Swimming, slow walking and recumbent cycling may prove beneficial, but discuss exercise guidelines with your doctor first.

Modifying your workouts while you're injured will not only prevent deconditioning and injury-related weight gain -- it also can help you maintain your sanity and good spirits while recovering.

Myth: You shouldn't work out if you are over 55

Being over 55 may mean you can soon retire, but it doesn't mean hanging up your gym clothes for good. Research shows that working out can reduce the risk of Alzheimer's and dementia, promote healthy weight maintenance and metabolism, boost bone and joint health, reduce the risk of heart disease and diabetes, provide arthritis-related pain relief, improve posture and ward off depression and anxiety. Physical activity also slows down the aging process, meaning regular exercise can help keep you youthful, beautiful and strong. As you get older, you may have to change the types of workouts you do, but fitness in any form will do your mind and body good regardless of your age.