Push hard in workouts, then take things easy


August 31, 1993|By Colleen Pierre, R.D. | Colleen Pierre, R.D.,Contributing Writer

Pioneers didn't need step aerobics to stay healthy. They got their daily dose of fitness by just staying alive. Clearing, plowing and planting from dawn till dusk would put a health club workout to shame.

So the recent pronouncement of the Centers for Disease Control and Prevention and the American College of Sports Medicine makes a certain kind of sense. The organizations said that 30 minutes of yard work a day is enough to make you fit. Physical work can take the place of a contrived workout.

I like the concept, especially for couch potatoes. It's a step in the right direction that will improve circulation, tone muscles and burn a few calories. But 30 minutes in the yard is not a day on the farm.

Maybe this is exercise backlash. We're revolting against "marathon mentality" and "buns of steel." But overreacting sells us short.

Take the current myth that the only way to get rid of body fat is to exercise slowly.

Years ago, exercise physiologists found that anaerobic exercise, the kind that leaves you breathless, is fueled by glycogen (stored carbohydrate). Aerobic exercise, the kind you can talk your way through, is fueled by a combination of glycogen and triglycerides (fat).

Someone then made the false assumption that the only time you use fat for fuel is while you're exercising aerobically. Not true. You can use stored body fat any time you eat fewer calories than you burn. Researcher William McArdle, says you may burn a larger percentage of calories at a slower pace, but the actual number of fat grams burned is higher if you go faster.

For both fitness and safety, "hard-easy" training is your best bet.

Once or twice a week, push it for a few minutes. Get a little breathless. The rest of the time, stay at a "talking pace," but move along. Gradually, you'll get more fit in the same amount of time.

Colleen Pierre, a registered dietitian, is the nutrition consultant to the Union Memorial Sports Medicine Center in Baltimore.

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