The amount of exercise a person engages in per week may be more important than the intensity of the exercise.
A study in the October issue of CHEST, the peer-reviewed journal of the American College of Chest Physicians (ACCP), shows that adults who participate in mild exercise, such as walking briskly for 12 miles or exercising for 125 to 200 minutes a week at moderate intensity can significantly improve their aerobic fitness and reduce their risk of cardiovascular disease. Unlike most exercise interventions, this finding suggests that amount may be equally or more important as exercise intensity.
“The classic exercise regimen has a component of intensity up to 80 percent of someone’s maximum for health benefits. Our study demonstrates that you can exercise at an intensity much less than that and still achieve fitness benefits,” said lead author Brian D. Duscha, Duke University Medical Center, Durham, North Carolina. “People find exercise ‘hard’ and few people want to exercise at an intensity higher than they have to. Walking briskly for 12 miles a week per week is realistic and does not require anyone to incorporate a hardcore training regimen. Increasing your mileage or intensity will give you even greater health benefits.”
Researchers from Duke University Medical Center examined the effects of different exercise training regimens on 133 sedentary, overweight, nonsmoking patients, ages 40 to 65 years, who had abnormal levels of fat in their blood. Patients were divided into four exercise groups: high-amount/high-intensity (HAHI), the equivalent of jogging 20 miles per week at 65 to 80 percent peak VO2; low-amount/high-intensity (LAHI), the equivalent of jogging/walking up an inclined treadmill approximately 12 miles per week at 65 to 80 percent peak VO2; low-amount/moderate intensity (LAMI), the equivalent of walking approximately 12 miles per week at 40 to 55 percent peak VO2; and a control group of nonexercising patients. All patients underwent cardiopulmonary exercise testing twice at baseline and after 7 to 9 months of exercise training.
All exercise groups significantly improved their absolute and relative peak oxygen consumption and time to exhaustion (TTE) compared to baselines scores. Although the HAHI group showed the greatest improvements in peak VO2 overall, increasing exercise intensity from 40 to 55 percent to 65 to 80 percent (at a controlled amount of 12 miles/week) did not significantly improve peak oxygen consumption, yet increasing the amount of exercise did produce improvements. An increase in exercise amount also demonstrated a graded increase in TTE between groups, although data were not statistically significant.
“Although our results did point toward amount being more important, it is very likely fitness levels can be improved by increasing either amount or intensity,” said Duscha. “This is illustrated by the tiered effect the exercise dose had on fitness improvements across our groups. We believe with more people in the study, increasing intensity would also have been significant.”