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Objective: To determine whether moderate cardiorespiratory fitness (CRF) or moderate to vigorous physical activity (MVPA) is associated with elevations in resting metabolic rate (RMR) similar to findings previously observed in endurance athletes., Participants and Methods: Using a cross-sectional design, we measured CRF, RMR, body composition, energy expenditure, and time in MVPA via an arm-based activity monitor in 423 young adults (mean age, 27.6 years). Based on the results of a fitness test, participants were classified into CRF tertiles (low, moderate, or high) by sex., Results: There were significant differences among the low-, moderate-, and high-CRF groups for mean ± SD body mass index (calculated as the weight in kilograms divided by the height in meters squared) (28.1 ± 4.1, 25.1 ± 3.4, and 23.6 ± 2.5, respectively; P<.001) and fat mass (28.8 ± 9.7, 20.5 ± 8.2, and 14.8 ± 6.5 kg, respectively; P<.001) but not fat-free mass (53.1 ± 11.5, 53.5 ± 12.4, and 54.7 ± 12.1 kg, respectively; P=.49). There were no differences in mean ± SD unadjusted RMR among the groups (1533.2 ± 266.2, 1519.7 ± 267.6, and 1521.9 ± 253.9 kcal/d, respectively). However, after statistical adjustment for differences in body composition, the moderate- and high-CRF groups had a higher RMR compared with low-CRF individuals by 39.7 and 59.9 kcal/d, respectively (P<.05). After further adjustment for MVPA, RMR was higher in the high-CRF group compared with the low-CRF group by 51.2 kcal/d (P<.05)., Conclusion: In this large sample of young adults representing a range of CRF, there was a positive stepwise gradient in RMR across tertiles of CRF independent of body composition. Also, MVPA was independently associated with RMR, although this relationship was modest. These findings underscore the multidimensional role of CRF and MVPA on health., Trial Registration: clinicaltrials.gov Identifier: NCT01746186., (Copyright © 2014 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.)

Background: High levels of obesity among African American women have been hypothesized to be partially resultant from a lower resting metabolic rate compared with white women. The aim of the current study was to determine if differences in cardiorespiratory fitness and moderate-to-vigorous physical activity are associated with differences in resting metabolic rate among free-living young adult African American women and white women., Methods: Participants were 179 women (white women n = 141, African American women n = 38, mean age = 27.7 years). Resting metabolic rate was measured using indirect calorimetry, body composition using dual energy x-ray absorptiometry, cardiorespiratory fitness via maximal treadmill test, and moderate-to-vigorous physical activity using an activity monitor., Results: African American women had higher body mass index, fat mass, and fat-free mass compared with white women but lower levels of cardiorespiratory fitness. No differences were observed between African American and white women in resting metabolic rate when expressed as kcal/day (1390.8 ± 197.5 vs 1375.7 ± 173.6 kcal/day, P = .64), but African American women had a lower resting metabolic rate when expressed relative to body weight (2.56 ± 0.30 vs 2.95 ± 0.33 mL/kg/min, P < .001). After statistical adjustment for differences in body composition between groups using linear regression models, African American women had a lower resting metabolic rate compared with white women (1299.4 ± 19.2 vs 1400.4 ± 9.2 kcal/day, P < .001). The addition of cardiorespiratory fitness reduced the differences among groups by 25%. The addition of moderate-to-vigorous physical activity did not improve the model., Conclusions: The present study confirms that African American women have a lower resting metabolic rate compared with their white peers, and low cardiorespiratory fitness explained 25% of this difference. Variables associated with resting metabolic rate, such as cardiorespiratory fitness, represent possible points of tailored interventions designed to address high levels of obesity seen in certain demographic groups., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Purpose: The Energy Balance Study (EBS) was a comprehensive study designed to determine over a period of 12 months the associations of caloric intake and energy expenditure on changes in body weight and composition in a population of healthy men and women. Method: EBS recruited men and women aged 21 to 35 years with a body mass index between 20 and 35 kg/m[superscript 2]. Measurements of energy intake and multiple objective measures of energy expenditure, as well as other physiological, anthropomorphic and psychosocial measurements, were made quarterly. Resting metabolic rate and blood chemistry were measured at baseline, 6 and 12 months. Results: Four hundred and thirty (218 women and 212 men) completed all baseline measurements. There were statistically significant differences by sex uncovered for most anthropomorphic, physiological and behavioral variables. Only percent of kcals from fat and alcohol intake, as well as energy expenditure in light activity and very vigorous activity were not different. Self-reported weight change (mean ± SD) over the previous year were 0.92 ± 5.24 kg for women and -1.32 ± 6.1 kg for men. Resting metabolic rate averages by sex were 2.88 ± 0.35 ml/kg/min for women and 3.05 ± 0.33 ml/kg/min for men. Conclusion: Results from EBS will inform our understanding of the impact of energy balance components as they relate to changes in body weight and composition. Initial findings suggest a satisfactory distribution of weight change to allow for robust statistical analyses. Resting metabolic rates well below the standard estimate suggest that the evaluation of the components of total energy expenditure will be impactful for our understanding of the roles of energy intake and expenditure on changes in energy utilization and storage.

Successful aging encompasses more than just the prevention of disease and disability; the truly well-lived life is demonstrated by a sense of vitality and independence, freedom from bodily pain, and the continued involvement in meaningful activities. While physical inactivity and sedentary behaviors accelerate the aging process, deliberate exercise and other forms of activity delay and/or prevent the onset of age-related pathologies such as frailty, osteoporosis, sarcopenia, and cardiovascular disease. This review surveys the evidence that supports the position that physical activity is a necessary component for the development and maintenance of the physiological resources that are foundational to physical and cognitive functioning and 'living well' in one's later years. [ABSTRACT FROM AUTHOR]

Physical activity improves health. Different types of activity promote different types of physiologic changes and different health outcomes. A curvilinear reduction in risk occurs for a variety of diseases and conditions across volume of activity, with the steepest gradient at the lowest end of the activity scale. Some activity is better than none, and more is better than some. Even light-intensity activity appears to provide benefit and is preferable to sitting still. When increasing physical activity toward a desired level, small and well-spaced increments will reduce the incidence of adverse events and improve adherence. Prior research on the relationship between activity and health has focused on the value of moderate to vigorous activity on top of an indefinite and shifting baseline. Given emerging evidence that light activities have health benefits and with advances in tools for measuring activities of all intensities, it may be time to shift to zero activity as the conceptual starting point for study. [ABSTRACT FROM AUTHOR]