It’s the time of year when we promise ourselves that we’re going to eat better (and less), exercise more and drop some weight. Turns out you might want to skip the weight bench and hit the treadmill if you want to keep that last resolution but don’t have a lot of time to work out.
Researchers at Duke University have examined the impact of aerobic and resistance training on body and fat mass in overweight and obese adults and concluded that when it comes to losing weight, aerobic exercise has an edge.
“If you’re overweight, it’s good to lose fat and body weight,” Dr. Leslie Willis, an exercise physiologist at Duke and lead author of the study, said of aerobic exercise. “Spend time doing cardio training if that’s your main goal.”
She noted, however that she isn’t saying that resistance training is by any means a bad thing, and in fact remains vital because it promotes lean body mass — which becomes more important as we age.
The study, published last month in the Journal of Applied Physiology, surveyed 234 adults aged 18 to 70 who were overweight or obese. They participated in one of three eight-month programs consisting of aerobic training, resistance training and a combination of the two. The aerobic training group exercised at 70 to 85 percent maximum heart rate for 45 minutes three times a week. The resistance training group did eight to 12 repetitions on resistance machines, increasing weight as time progressed so they’d remain challenged. The remaining group combined the regimens of both groups. When they were done, each participant was weighed, measured and tested for cardio fitness, body composition and strength.
The study found the aerobic training group and combination groups lost the most weight, around 4 pounds. Those who did resistance training alone actually gained a similar amount of weight in lean body mass. While the cardio group lost weight, they also lost lean body mass. The cardio and combination groups also saw a reduction in waistline, the cardio group losing 1 and combination group losing 1.66 square centimeters. These groups also lost 1 and 2 percent body fat, respectively, whereas the resistance group saw little to no change. However, in the aerobic group, there was no alteration of lean body mass like there was in the groups that had some sort of resistance regimen.
Read this way, the study suggests that if you only have a few hours a week to work out and your goal is losing weight, concentrate your energy on aerobic workouts. It also shows that if you have the time, resistance training plus cardio is best to build lean body mass.
A problem, however, is that sometimes studies like this are taken too literally, said Dr. Abbie Smith-Ryan, an exercise and sports scientist at UNC. Although the science behind the study is “flawless” and adds great data to the body of knowledge on the subject, she said, it’s also important to consider additional practical factors before changing your workout routine.
“When I look at the changes in body fat alone,” she said, “it was just 4 pounds. While statistically significant, we would hope to see a larger change in body fat and weight with such a comprehensive training program.”
Much of Smith-Ryan’s research is in high-intensity interval training, where she noted that over less time performed a week, they are seeing some large changes. She agrees, though, that you shouldn’t tell people to stop resistance training, which can directly and indirectly influence metabolism by breaking down our muscles. The repair process is where the caloric demand arises, and the more intense the workout, the more calories we burn rebuilding those muscles.
“This to me doesn’t say, ‘Don’t do resistance training training, or just do aerobic training,’” she said. “They are both important. This study also highlights the importance of nutrition. Exercise is not only the important part of weight loss; nutrition is a big factor. The subjects were on a 2,000-calorie diet, which is practical, but there was such a small change in body fat and weight over a six-month period.
The main takeaway, then, is to find something that fits your goals (losing pounds, changing your shape, improving your cardio fitness) that you will stick with. Chances are if you only lose a few pounds and a percent or two in body fat in eight weeks, you won’t stick with it. Those looking to change their overall look need to up the ante with intensity and frequency. Oh, and eat less.
When Time Is Short, Go Aerobic to Slim Down
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When Time Is Short, Go Aerobic to Slim Down
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When Time Is Short, Go Aerobic to Slim Down
