Combined aerobic and resistance training linked to metabolic adaptation in older women
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An exercise program with both aerobic and resistance training is associated with metabolic adaptation in older women with overweight and obesity, according to study findings published in Obesity.
“We were surprised that such a small volume of exercise and weight loss induced metabolic adaptation at the level of resting metabolic rate,” Catia Martins, PhD, associate professor in the department of nutrition sciences at the University of Alabama at Birmingham, told Healio. “Despite combined aerobic and resistance exercise being associated with metabolic adaptation, this exercise regimen should continue to be recommended in this population, aiming at minimizing the loss of lean tissue that occurs with aging.”
Martins and colleagues conducted a secondary analysis of a study in which 80 women aged 60 to 74 years participated in a 32-week combined aerobic and resistance exercise training program (80% white; mean age, 64.8 years). Participants were randomly assigned to perform resistance and aerobic training once per week (n = 25), twice per week (n = 32) or three times per week (n = 23). Body weight, fat mass and fat-free mass were measured by DXA scan. Losses of fat mass and fat-free mass were converted to energy lost using the energy coefficients of 9.3 kcal/g for fat mass and 1.1 kcal/g for fat-free mass. Resting metabolic rate was measured after an overnight fast at least 48 hours after the last exercise session. Measurements took place at baseline, 16 weeks and 32 weeks.
The study cohort had a 0.7 kg reduction in body weight (P = .018), a 1.2 kg reduction in fat mass (P < .001), and a 0.7 kg increase in fat-free mass (P < .001) from baseline to week 16. Measured resting metabolic rate decreased 44 kcal per day from baseline to week 16 and was lower than the predicted resting metabolic rate of 59 kcal per day (P = .002). The cohort had a cumulative mean energy loss of 641 kcal per week at 16 weeks.
Among 53 women with data available at all three time points, no change in body weight, fat mass and fat-free mass was observed from week 16 to week 32. Measured resting metabolic rate decreased by 45 kcal per day at week 16 (P = .007) and 74 kcal per day at week 32 (P < .001) compared with baseline. The measured resting metabolic rate was lower than the predicted rate by 64 kcal per day at 16 weeks (P = .001) and by 94 kcal per day at 32 weeks (P < .001). The increase in metabolic adaptation was significant from week 16 to week 32 (P = .013).
No difference in metabolic adaptation was observed between women who lost weight and those who did not lose weight. In regression analysis, age, baseline fat-free mass, resting metabolic rate, respiratory quotient and change in net oxygen consumption were predictors of metabolic adaptation at 16 weeks. All of the factors except for baseline respiratory quotient were also predictors of metabolic adaptation at 32 weeks.
“Given the small number of studies on the impact of exercise on metabolic adaptation, particularly in older adults, and the importance of energy balance in modulating this phenomenon, more research needs to be done to confirm the present findings under conditions of neutral energy balance,” Martins said. “Moreover, more studies are required to explore if the same phenomenon is seen in men, other age groups and BMI classes.”
For more information:
Catia Martins, PhD, can be reached at catia197@uab.edu.
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