title: Moderate cardiorespiratory fitness is positively associated with resting metabolic rate in young adults.
abstract: 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.
  
  
  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).
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  clinicaltrials.gov Identifier: NCT01746186.
authors.affiliation: Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia. Electronic address: shookr@mailbox.sc.edu.
authors.forename: Robin P
authors.initials: RP
authors.lastname: Shook
authors.affiliation: Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Hand
authors.affiliation: Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia.
authors.forename: Amanda E
authors.initials: AE
authors.lastname: Paluch
authors.affiliation: Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia.
authors.forename: Xuewen
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia.
authors.forename: Robert
authors.initials: R
authors.lastname: Moran
authors.affiliation: Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia; South Carolina Cancer Prevention and Control Program, Arnold School of Public Health, University of South Carolina, Columbia; Department of Family and Preventive Medicine, University of South Carolina, Columbia.
authors.forename: James R
authors.initials: JR
authors.lastname: Hébert
authors.affiliation: John Ochsner Heart and Vascular Institute, Ochsner Clinical School, University of Queensland School of Medicine, New Orleans, LA; Department of Preventive Medicine, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA.
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Lavie
authors.affiliation: Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia; Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia.
authors.forename: Steven N
authors.initials: SN
authors.lastname: Blair
mesh_terms: D000328:Adult; D001481:Basal Metabolism / Q000502:physiology*; D001823:Body Composition / Q000502:physiology; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D002149:Energy Intake / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D055815:Young Adult