A 28-year-old woman trying desperately to lose weight through a sound diet and exercise program was excited after a recent aerobic-exercise class.
"I just got a great workout," she told Kris Alesna, a Santa Monica private trainer. "I sweat buckets."
Alesna had to undo a myth he says many exercise enthusiasts believe--that perspiration is a prime indicator of a workout's effectiveness. "I told her some people are able to perspire more easily than others," said Alesna, who explained to his client that a workout's cardiovascular-conditioning worth cannot be measured by sweat droplets.
The sweat ethic isn't the only fitness myth making the rounds of exercise enthusiasts. Experts cite a number of other common misconceptions about fitness.
.1 Regular exercise increases the appetite and may lead to weight gain.
Yes and no.
"The immediate effects of a bout of vigorous exercise probably depresses the appetite," said Kurt Hobbs, supervising exercise physiologist at Centinela National Athletic Health Institute, Culver City.
"And the more severe the exercise, the more it depresses the appetite, usually for up to an hour after exercise," said Michael Yessis, a professor of physical education at Cal State Fullerton.
Over the long term, exercise boosts the metabolic engine, experts say, resulting in regular exercisers often eating more calories (but also burning more) than sedentary people.
"Permanent boosting of the basal metabolic rate will occur only after six months to a year of exercise," pointed out Peg Angsten, vice president of communications for the Aerobics and Fitness Assn. of America in Sherman Oaks.
But be careful, some experts say, not to think you need more food than you do. "A lot of people who exercise feel psychologically they have to eat more," Hobbs said.
"Overall," he added, "evidence indicates that exercise is useful in weight control. That doesn't mean that everyone who exercises is lean. But when we look at a large population, we find that people who are physically active weigh less."
.2 If you stop exercising, your muscles turn to fat.
"Muscle atrophies, but it doesn't turn to fat," Yessis said.
"Muscle tissue and adipose tissue are two separate (kinds of) tissues," Hobbs agreed. "It's like trying to turn an apple into an orange. If you are completely sedentary, you will increase your fat stores. Muscles atrophy and fat stores increase."
.3 Eating before workouts isn't wise.
It depends, experts say, on the amount and the type of food.
"I usually advise eating an apple or some other fruit about 30 minutes before exercising," Hobbs said.
"As long as it's light and has some sort of fruit base, that's fine," Alesna agreed.
Full meals, Hobbs added, should be eaten at least two hours before exercise sessions.
.4 Exercising through colds or the flu can minimize them.
Many exercise enthusiasts swear by physical activity as a foolproof way to work through colds or flu.
But many experts caution against exercising in the midst of such illnesses.
"In general, stay away from exercise throughout a cold or other illness," Yessis advised. "Your body needs the energy to fight off whatever illness you have."
He added, however: "If you're in the down phase of an illness, mild exercise could help. It might help increase circulation and get the body functioning more efficiently."
"If you feel you're getting a cold, especially if you have a fever, you should not exercise," added Allen Smith, a clinical exercise physiologist at Fit Dimension, an outpatient exercise facility operated by the Santa Monica Hospital Medical Center.
"You're robbing your body of the ability to fight disease," Angsten pointed out.
Working out through an injury, however, is a different story, at least in
Linda Huey's book. "There's always something you can do during injury rehabilitation," says Huey, a Santa Monica private trainer and kinesiologist. A runner with a stress fracture, for example, might be able to cycle or swim.
.5 Exercise can help you feel better, but it's no fountain of youth.
In a sense, exercise can be a fountain of youth, believes Herbert A. de Vries, a professor emeritus at USC and author of "Fitness After 50" (Scribner's, 1987).
As proof, he points to pioneering studies he did while he was in the exercise sciences department at USC. He introduced more than 200 retirement community residents, ages 56 to 87, to a fitness program that included a walk-jog routine, calisthenics and stretching. In six weeks, the participants' blood pressures decreased, their body fat declined and their maximum oxygen transport increased. (Maximum oxygen transport refers to how efficiently the body can use oxygen to create energy in muscles.) In addition, neuromuscular signs of nervous tension diminished.