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Among older adults with obesity, a combination of aerobic and resistance exercise paired with a weight-management program was most effective at improving overall physical performance and reduction in frailty, researchers reported.

The combination exercise regimen showed the greatest improvement in Physical Performance Test scores (27.9 to 33.4 points [21% increase]) when compared with weight-management programs paired with aerobic training alone, or resistance training alone (29.3 to 33.2 points [14% increase] or 28.8 to 32.7 points [14% increase], respectively; P=0.01 and P=0.02 after ), according to Dennis T. Villareal, MD, of Baylor College of Medicine in Houston, and colleagues.

As reported in the , the clinical trial also found that all exercise groups had improvements in physical function (P<0.001 for between-group comparisons) as well as a 9% decrease in body weight compared with the control group.

The researchers explained that because the prevalence of obesity among the elderly population is rapidly increasing, due to the aging of baby boomers, the team conducted the trial in order to help identify the best treatment for obesity among the elderly population.

"However, weight loss to treat obesity in the elderly remains controversial, because obesity causes frailty in the elderly, and weight loss could further the loss of muscle mass and bone mass and might worsen frailty," Villareal told MedPage Today. "Weight loss is the cornerstone of management of obesity, yet whether weight loss is net beneficial or harmful in the obese elderly is not clear. Moreover it is usually recommended that weight loss be combined with exercise, although the specific type of exercise to combine with weight loss that provides the most benefits especially with respect to physical function in the elderly is not known."

"The specific adaptations to aerobic exercise -- i.e., the gain in peak oxygen consumption -- and resistance exercise -- gain in strength -- could interfere with each other when performed together," he added, citing prior research that has reported a smaller gain in strength with combined aerobic and resistance exercise regimens compared with resistance exercise alone. Therefore, the group hypothesized that a resistance-only exercise regimen would net the most significant improvement in strength and overall physical function.

The 26-week trial included 160 adults with obesity (body mass index ≥30),who were age 65 or older, with stable body weight and medication use, who had mild-to-moderate frailty (considered to be a score of 18-21 on the modified Physical Performance Test.) Additionally, the participants were all sedentary, which was defined as having less than 1 hour of regular exercise a week.

The participants were randomized into four study groups:

• Aerobic exercise training
• Resistance exercise
• Combination aerobic and resistance exercise
• Education-only control

All the intervention groups were enrolled in a weight-management program, which recommended a balanced diet with a net daily energy deficit of 500-750 kcal, while the control group exclusively attended monthly healthy-eating educational sessions.

In regards to secondary study outcomes, strength increased the most in the combination and resistance exercise groups (272 to 320 kg [18% increase] and 288 to 337 kg [19% increase], respectively) compared with the aerobic group, where the level of strength was maintained (265 to 270 kg [4% increase])(P<0.001 for both comparisons).

The combination group, as well as the aerobic exercise groups, showed the greatest increase in peak oxygen consumption, measured in milliliters per kilogram of body weight per minute (17.2 to 20.3 [17% increase] and 17.6 to 20.9 [18% increase], respectively) versus the resistance group (17.0 to 18.3 [8% increase]) (P<0.001 for both comparisons).

The aerobic group reported the greatest decrease in lean mass (55.0 to 52.3 kg [5% decrease]), compared with the combination and resistance exercise groups (56.5 to 54.8 kg [3% decrease] and 58.1 to 57.1 kg [2% decrease], respectively). Similarly, the aerobic group experienced the largest decrease in bone mineral density at the total hip (grams per square centimeter; 1.018 to 0.991 [3% decrease]) versus the combination and resistance groups (1.010 to 0.996 [1% decrease] and 1.047 to 1.041 [0.5% decrease], respectively) (P<0.05 for all comparisons).

Villareal added that although his group was somewhat surprised by the significant physical function improvements reported among the combination group, "the finding is important because it shows there is no interference in the adaptations to resistance or aerobic exercise when they are performed together."

The findings also demonstrate that there was an additive effect due to the improvement in peak oxygen consumption from aerobic exercise, in addition to the improvement in strength from resistance exercise training, he explained. The improvements reported in the combination group were consistent with the reported improvements in the SF-36 physical-component test and Functional Status Questionnaire. In addition, although combination exercise was unable to fully eradicate muscle and bone mass loss, due to modified diet and caloric restriction, the regimen was able to successfully minimize those losses, Villareal pointed out.

The researchers noted that despite the well-designed nature of the randomized, controlled clinical trial, the participant sample might not be fully generalizable to the greater population of older adults with obesity since all participants were physically able to complete a lifestyle modification program; additionally, the majority of the sample population were well-educated, Caucasian women.

"Future research would be to follow these research participants over a longer period of time to determine if the weight loss and gains in physical function are sustained and thus maintain their functional independence for as long as possible, and importantly, whether it will delay the need for institutionalization/nursing home admission and decrease the risk of death," Villareal said.

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