by David Gutierrez, staff writer
(NaturalNews) While both aerobic exercise and resistance training will improve your overall health, only aerobic exercise is actually helpful in producing weight loss, according to a study conducted by researchers from Duke University and East Carolina University, and published in the Journal of Applied Physiology.
“Given our observations, it may be time to seriously reconsider the conventional wisdom that resistance training alone can lead to weight and fat loss,” lead author Leslie H. Willis said.
The study was funded by the National Heart, Lung, and Blood Institute, a division of the National Institutes of Health.
Researchers assigned 234 sedentary adults between the ages of 18 and 70, all of them overweight or obese, to take part in one of three supervised exercise programs for eight months. The participants were assigned either to aerobic training, resistance training or a combination of the two.
Participants in the aerobic group exercised vigorously for approximately 45 minutes three times a week, raising their heart rates to between 70 and 85 percent of maximum. Participants in the resistance group performed three sets of eight to 12 repetitions on eight separate resistance machines three times per week, exercising all major muscle groups. The amount of resistance experienced increased over the course of the study, to compensate for the participants’ increasing strength.
Participants in the combination group performed all the same exercises as participants in both the aerobic and resistance groups.
At both the beginning and end of the study, researchers measured each participant’s weight, waist circumference, body composition, and cardiopulmonary fitness and strength. A total of 119 participants finished the study with complete data. The researchers believe that this makes the study the largest randomized trial of its kind.
Weight loss vs. muscle-building
The researchers found that while participants in both the aerobic and combination groups lost weight, participants in the resistance group actually gained weight, due to increase in lean body mass (which is more dense than fat). Likewise, both body fat percentage and waist circumference significantly decreased in both the aerobic and combination groups, while there was no change in the resistance training group.
Resistance training and combination training were both effective at increasing lean body mass, while aerobic exercise had no effect. Due to the combination of decreasing body fat mass and increasing lean body mass, a combination of aerobic and resistance training was by far the most effective method of decreasing body fat percentage.
According to Willis, the study has important implications for busy people who are seeking to improve their health with only a limited amount of time spent exercising each week.
“If increasing muscle mass and strength is a goal, then resistance training is required,” Willis said. “However, the majority of Americans could experience health benefits due to weight and fat loss.
“The best option in that case, given limited time for exercise, is to focus on aerobic training. When you lose fat, it is likely you are losing visceral fat, which is known to be associated with cardiovascular and other health benefits.”
For those short on time, aerobic, not resistance, exercise is best bet for weight, fat loss
BETHESDA, Md. (Jan. 2, 2012)—A new study led by North Carolina researchers has found that when it comes to weight- and fat loss, aerobic training is better than resistance training. The study is believed to the largest randomized trial to directly compare changes in body composition induced by comparable amounts of time spent doing aerobic and resistant training, or both in combination, among previously inactive overweight or obese non-diabetic adults.
The study is entitled “Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults.” It is published in the December 2012 edition of the Journal of Applied Physiology published by the American Physiological Society.
Methodology
A total of 234 previously sedentary overweight or obese males and females, age 18-70 years of age, were enrolled in one of three eight-month supervised protocols: aerobic training (AT), resistance training (RT), or a combination (AT/RT). Of the total, 119 participants completed the trials and had complete data for the variables of interest in the article.
Those assigned to aerobic training exercised vigorously, at about 70-85% of maximum heart rate. They exercise approximately 45 minutes three days per week throughout the study period.
Individuals assigned to resistance training also exercised three days a week, completing three sets of 8-12 reps on eight resistance machines that targeted all major muscle groups. Resistance was increased throughout the study to maintain a steady level of challenge as the participants gained strength.
Individuals who were assigned to AT/RT performed all the exercises assigned to both AT and RT groups. At the end of study each enrollee was assessed for weight, body composition, waist circumference, cardiopulmonary fitness and strength compared to their baseline.
Key Findings and Conclusions
The researchers found:
The groups assigned to aerobic training and aerobic plus resistance training lost more weight than those that did resistance training only. In fact, those who did resistance training only actually gained weight due to an increase in lean body mass.
Fat mass and waist circumference significantly decreased in the AT and AT/RT groups, but were not altered in RT. However, measures of lean body mass significantly increased in RT and AT/RT, but not in AT. The finding suggest that aerobic exercise is more effective in reducing these measures.
Lean body mass increased with both RT and AT/RT, but not AT. Having the benefit to of both modes of exercise allowed AT/RT to decrease body fat percent significantly more than either AT or RT due to decreased fat mass combined with increased lean body mass.
Importance of the Findings
According to Leslie H. Willis, an exercise physiologist at Duke University Medical Center and the study’s lead author, “Given our observations, it may be time to seriously reconsider the conventional wisdom that resistance training alone can lead to weight and fat loss.”
Willis added, “If increasing muscle mass and strength is a goal, then resistance training is required. However, the majority of Americans could experience health benefits due to weight and fat loss. The best option in that case, given limited time for exercise, is to focus on aerobic training. When you lose fat, it is likely you are losing visceral fat, which is known to be associated with cardiovascular and other health benefits.”
Research Team
In addition to Leslie Willis, the study was conducted by Cris A. Slentz, Lori A. Bateman, Lucy W. Piner, Connie W. Bales and William E. Kraus of the Duke University Medical Center; and Joseph A Hourmard and A. Tamlyn Shields of East Carolina University.
Funding
This study was conducted with funds provided by the NHLBI, National Institutes of Health (2R01-HL057354).
NOTE TO EDITORS: The article is available online at http://bit.ly/Rs7Rp4 For additional information, or to schedule an interview with a member of the research team, please contact Donna Krupa at dkrupa@the-aps.org, @Phyziochick, or 301.634.7209.
Physiology is the study of how molecules, cells, tissues and organs function to create health or disease. The American Physiological Society (APS; www.the-APS.org/press) has been an integral part of the discovery process for 125 years. To keep up with the science, follow @Phyziochick on Twitter.
