Myths and Truths of Exercise
by Kevin Kirk

When I considered writing about misconceptions about exercise, I wondered whether there was really any need to address many of these “old-fashioned” ideas.  An exercise professional gets lots of continually updated information on research in the field, and it is sometimes more difficult to get a handle on what misinformation has effectively been debunked, and what still persists.  However, I’ve recently been asked a lot about the following ideas by people I thought were more in the know, so I decided to address them.  What follows are some of the classic “myths” about exercise, and the correct facts (or at least as we know them today).

1.  Exercising your (fill in your most-hated body part here) will burn the fat in that area This is popularly known as “spot reducing.”  No exercise can target a particular store of subcutaneous fat that is stored on a person’s body.  Exercising a muscle will condition that muscle, but not have much effect on the surrounding tissues.  Thus, if you want to get rid of a beer belly, all the abdominal crunches in the world won’t take it away.  After thousands of sit-ups, you’ll have much stronger abdominal muscles, but that blanket of fat will still be covering them.  If you see an advertisement for an exercise routine, or diet, that shouts “Gets rid of that problem tummy fat!” – be forewarned.

2.  Muscle turns to fat when you stop exercising Muscle and fat are two different tissues.  One is stored energy, the other creates movement.  The reason that athletes and exercisers have less fat is that the muscles doing the moving require lots of energy, so not much gets stored as fat, or (even better) the fat stores are tapped to fuel the exercise.  When a person stops training, their eating habits often don’t adapt as quickly to the lower energy requirement.  Thus their muscles may get smaller from less use, and the food (fuel) that was utilized immediately when more activity burned more calories gets saved, so fat stores become larger.

3.  There is fat-burning zone an exerciser There is no optimal level for burning fat as you exercise.  True, the higher the intensity of the exercise, the more energy comes from stored carbohydrate (and less from fat).  Remember two things:  when trying to lose weight, it’s the total energy expenditure that’s important, not where the energy comes from during the exercise; and even at higher intensities, more total fat is probably being utilized than at the lower level.  Two factors that do increase the percentage of fat metabolized:  your fitness level (better conditioning leads to more fat burning – both during exercise and at rest); and the length of the exercise session (more fat is burned the longer the activity continues). 

4.  Strength training will make you “muscle bound.”  Much like muscle and fat are two different, independent tissues, strength and flexibility are two independent properties of muscles.  Larger muscles are not necessarily tighter.  I might argue that better strength leads to better range of motion, as a stronger muscle would be able to pull a joint farther against the increasing resistance of the opposing (and stretching) muscle.  This is particularly true with older adults.  In the classic study at Tufts that started the strength training revolution for seniors, measurable improvements were shown in range of motion at the end of the year, even though no stretching was done as part of the program.

5.  Women who lift weights will develop big, i.e. manly, muscles If I had a nickel for every time I’ve heard that worry… A large factor for muscular hypertrophy (growth) is testosterone.  Very few women have levels of this hormone high enough to produce muscle size and definition like men.  I have helped hundreds of women with strength training exercises.  Not one of them has ever complained of developing muscles that were “too big,” nor have I ever thought that of any of them.  However, even if you are one of those women, worrying about big muscles is no excuse to skip strength training.  Muscles aren’t balloons, which once blown up would stay that size.  If you begin strength training and see muscle definition that is more than you are comfortable with, simply ease up on the workouts and the muscles will get smaller again.

6.  Sweat it off.” Any weight lost from sweating comes from loss of water (dehydration).  Even the most intense workout in the gym burns less than a thousand calories.  That’s less than a third of a pound.  So if you are three pounds lighter when you head back to the locker room, you’ve lost a lot of water.  The weight will come back once you start rehydrating. To avoid problems, that water should be replaced as soon as possible.  It’s a good idea to weigh yourself before a workout and again at the finish – especially in hot and humid conditions.  Then drink as much water as necessary to get back to the starting weight (12-16 ounces for every pound lost).  Tip:  take off your sweaty clothes before weighing at the end. They hold a lot of the water you lost and will mask the actual water loss that has occurred internally.

7.  It’s okay to start out exercising at an easy level, but after a few weeks you have to raise the level Exercise intensity is a measure of how hard your body is working during an activity.  Intensity is relative.  In order to see improvements in your fitness level, you have to work with your heart rate at a certain percentage of its maximum, or lift a certain percentage of a muscle’s maximum force.  Notice I said to see improvements in fitness level.  Exercising below those levels will still burn calories, maintain fitness levels, and accrue all kinds of health benefits.  And of course, maintaining your exercise just above the threshold will continue to improve your fitness level.  What I mean is, if you’ve been exercising at 60% of your maximum heart rate, you will not need to start working at 80% after a while.  You will need to increase the exercise level to get to that 60% as your fitness improves, but it will feel just as easy.

8.  If you can’t do exercise regularly, you shouldn’t do it at all A good axiom to remember is: any exercise is better than no exercise!  Again, there are thresholds of frequency (i.e. three times a week) that may be necessary for improving fitness levels, but any exercise helps maintain your current physical abilities, provides health benefits, and of course burns calories.  The research over the years has shown that it takes less exercise than you would think to create improvement, so move whenever you can.

9.  If you’ve missed a few workouts, you have to make up for it on the next one I’ve had more than a few clients who have missed some time and dreaded their first session back.  They usually find just the opposite- we take it easy and work our way back into the routine.  One of the easiest ways to get injured while exercising is to fail to account for lost fitness after a layoff and start right back at the same level.  If you are not sure where your fitness level is, miss on the conservative side, see how you feel afterward, and gradually bring the level back up over several workouts, depending on how long you’ve been away.

10.  As you get older, there is nothing you can do to prevent or reverse physical decline This simply isn’t true.  I could spend an entire article debating this one, and so we’ll wait until next time.