Workout Weight Loss: Cardio Intensity Affects Outcomes

March 2, 2015 8:38 PM EST

Everyone knows that cardio exercise—by way of a bike ride or a sprint—is key to weight loss. But a high-intensity cardio workout may do a better job of decreasing blood sugar levels than lower intensity exercise, according to a new study in Annals of Internal Medicine.

The study assigned 300 obese people to a group: one that exercised with low intensity for long periods of time or another that engaged in high-intensity workouts for short durations. By the end of six months, people in both groups experienced similar levels of weight loss. But those who had exercised with higher intensities saw reduced two-hour glucose levels, a key measure for predicting conditions like heart disease and stroke. People in the high-intensity group saw a 9% improvement in glucose tolerance, compared to a negligible change in people who took part in low-intensity exercise.

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Increasing the intensity of a workout isn’t beyond the reach of most exercisers, according to lead study author Robert Ross, a researcher at Queen’s University in Kingston, Ontario. “Higher intensity can be achieved simply by increasing the incline while walking on a treadmill or walking at a brisker pace,” Ross says.

Still, while high-intensity exercise may have some unique health benefits, the study showed that any exercise is better than none. People who exercised lost 5-6% of their body weight, a 4- to 5-centimeter reduction in waist size.

The study challenges the way public health officials tend to think about the health benefits of exercise. Health organizations often issue guidelines based on time spent exercising. Instead, the study suggests, health officials should consider intensity as well.

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