Cardiovascular Fitness Gains Can Come Without Pain
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Side-stepping the “no pain, no gain” mantra, researchers here reported that the amount of exercise, not necessarily its intensity, can help improve cardiovascular fitness.
Duke investigators found that patients who walked at a brisk pace for about 12 miles a week matched the cardiovascular benefits for those who jogged that amount in a much shorter time.
Increasing the exercise intensity from walking 12 miles at 40% to 55% peak maximum oxygen consumption (VO2) a measurement of aerobic fitness, to jogging 12 miles at 65% to 80% VO2 did not produce any significant differences (p=0.14 and p=0.16), researchers reported in the October issue of Chest.
“Exercise amount appears to be more important than exercise intensity for eliciting gains in cardiovascular fitness,” said Brian Duscha, M.S., an exercise physiologist at Duke.
That’s not to say that more intense exercise wasn’t beneficial. In the seven- to nine-month study, patients who jogged either 20 or 12 miles a week lost weight, whereas the walkers did not.
The study might give clinicians some guidance on how much exercise to recommend to patients, the authors said. Although the cardiovascular benefits of exercise are well established, there has been conflicting evidence on what exactly to recommend. These latest findings, Duscha and colleagues wrote, specifically illustrate that 12 miles of brisk walking every week can go a long way toward improving heart health.
The findings are based on 133 men and women, with a body mass index (BMI) between 25 and 35, who were part of the Studies of Targeted Risk Reduction Interventions Through Defined Exercise trial. The patients’ ages ranged from 40 to 65 and all had mild to moderate dyslipidemia. The study excluded anyone with diabetes or hypertension.
Patients were randomized to one of four groups: low-amount, moderate-intensity exercise (the 12-mile walkers), low-amount, high-intensity (jogging about 12 miles a week), high-amount, high-intensity (jogging about 20 miles a week), and a control group with no exercise. The patients were not required to change their diet.
All participants underwent cardiopulmonary exercise tests at baseline and then again at the end of the study to measure any changes in peak VO2 and time-to-exhaustion.
Over the course of the study, the no-exercise controls did not change their peak VO2 or weight, and actually decreased their time-to-exhaustion (p<0.05).
However, all three exercise groups increased peak VO2 and time-to-exhaustion compared with their baseline measurements (p<0.001). Improvements in peak VO2 were the greatest in the two jogger groups compared with the controls (p<0.02).
Interestingly, the walkers did not significantly increase their peak VO2 when compared with the controls. However, they did rack up significant improvements in the time-to-exhaustion measure. In fact, stamina improved in all three exercise groups compared with baseline (p<0.001).
The authors noted that other studies have also found that increases in time-to-exhaustion, with or without improvement in peak VO2, resulted in decreased cardiovascular disease risk and improved plasma lipoproteins and body composition.
The authors concluded that recommending 12 miles of moderate brisk walking a week is safe for most patients who seek to improve fitness and reduce cardiovascular risk. Yet it is appropriate, they added, “to encourage higher intensities and amounts for additional benefit.”
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