Obesity is common among older adults and has been found to exacerbate age-related functional decline and contribute to frailty. Researchers found that the most effective strategy to elicit weight loss while maintaining physical function and preserving lean muscle mass and bone mineral density is a combination of aerobic exercise and resistance training in addition to a weight loss diet.
Obesity is common among older adults and has been found to exacerbate age-related functional decline and contribute to frailty. Further, losing weight among this population is of concern as weight loss has been found to accelerate the age-related decline in muscle and bone mass and result in osteopenia and sarcopenia. Accompanying weight loss with exercise has been shown to improve physical function but does not necessarily prevent muscle and bone loss or reverse frailty. The type of exercise coupled with a weight loss program may be important as the physiological adaptations to aerobic and anaerobic exercise are different. An increase in peak oxygen consumption results from cardiovascular adaptations of aerobic exercise, whereas improved neuromuscular adaptations results from resistance training aimed at improving strength. Combining these two exercise modalities may improve everyday physical function required for independent living than either exercise alone.
A study published in the New England Journal of Medicine evaluated the effectiveness of aerobic and resistance exercise on physical function and maintaining muscle and bone mass in conjunction with weight loss. A total of 141 older adults (65 years of age and older) completed this study. Obese (having a body mass index of 30 or greater), sedentary (engaged in less than 1 hour per week of physical activity), and mild to moderately frail individuals were recruited.
The study spanned 26 weeks and participants were randomly assigned to one of four testing groups: weight management plus aerobic training, resistance training, or combined (both aerobic and resistance training), and a control group (neither weight loss nor exercise). The weight management program consisted of a balanced diet with 1 g of high-quality protein per kg body weight per day along with a daily energy deficit of 500 to 750 kcal. The aerobic exercise training sessions occurred 3 times per week and were 60 minutes in duration. Participants engaged in 10 minutes of flexibility exercises, 30 to 40 min of aerobic exercises, and 10 minutes of balance work. Intensity of the aerobic training started at 65% of the participant’s peak heart rate and increased to 70 and to 85% by 6 months. The resistance training group similarly attended 3 training sessions per week of 60 minutes with 10 minutes of flexibility training, 30 to 40 minutes of resistance training, and 10 minutes of balance exercises.
Participants performed 1 to 2 sets of 8 to 12 repetitions of nine upper and lower body resistance exercises at 65% of their one-repetition maximum and proceeded to 2 to 3 sets at 85% of their one-repetition maximum by study completion. The combined group engaged in 3 weekly training sessions of 75 to 90 minutes in duration. Similar to the other two groups, participants performed 10 minutes of flexibility exercises, 10 minutes balance exercises, 30 to 40 minutes of aerobic exercises, and 30 to 40 minutes of resistance exercises. The control group was the only group that did not modify their diet or exercise throughout the study period. All groups were given daily supplements containing 1500 mg of calcium and 1000 IU of vitamin D.
Physical function was the main outcome measure and was assessed with the Physical Performance Test which included seven standardized everyday tasks. Frailty was measured using the Functional Status Questionnaire and by peak oxygen consumption on a graded treadmill walking test. Strength, balance, and gait speed were also measured. Body composition and bone mineral density were assessed using dual-energy x-ray absorptiometry and magnetic resonance imaging. All measures were taken at baseline and at 6 months, with the exception of the Physical Performance Test which was taken at 3 months in addition to baseline and 6 month time points.
Researchers found that on average, all exercise and weight management groups decreased their body weight by 9%. The combination group exhibited higher physical function over the intervention period from baseline than the aerobic and resistance groups. All groups had greater increases in physical function compared to their baseline measures and the control group. Peak oxygen consumption also increased in the combined and aerobic groups to a greater extent from baseline measures than in other groups. Lean mass and bone mineral density at the total hip was maintained to a greater extent in the resistance and combination groups as compared to the aerobic group. Despite the negative energy balance, participants demonstrated that aerobic training improved cardiovascular fitness and resistance training improved strength and maintained lean muscle mass.
In conclusion, the most effective strategy to elicit weight loss while maintaining physical function and preserving lean muscle mass and bone mineral density was the combination of aerobic exercise and resistance training. This research is important for guiding professional recommendations on weight management programs in obese older adults. Strengths of the study include the randomized controlled design and the high adherence of the participants to the comprehensive lifestyle programs. However, only older adults without physical limitations were recruited. Other study limitations include the small sample size, that the population consisted primarily of white, well-educated women, and differences due to sex were not analyzed.
Written By: Samantha L. Logan