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Associations of cardiorespiratory fitness and body mass index with incident restrictive spirometry pattern
  1. Joey M Saavedra1,
  2. Angelique G Brellenthin1,
  3. Bong Kil Song1,
  4. Duck-chul Lee1,
  5. Xuemei Sui2,
  6. Steven N Blair3
  1. 1Department of Kinesiology, Iowa State University, Ames, Iowa, USA
  2. 2Department of Exercise Science, University of South Carolina, Columbia, South Carolina, USA
  3. 3Departments of Exercise Science and Epidemiology & Biostatistics, University of South Carolina, Columbia, South Carolina, USA
  1. Correspondence to Dr Angelique G Brellenthin, Department of Kinesiology, Iowa State University, Ames, Iowa 50011, USA; abrellen{at}iastate.edu

Abstract

Objectives Restrictive spirometry pattern (RSP) suggests an impairment of lung function associated with a significantly increased risk of premature mortality. We evaluated the independent and joint associations of cardiorespiratory fitness (CRF) and body mass index with incident RSP.

Methods Data from the Aerobics Centre Longitudinal Study included 12 360 participants (18–82 years). CRF was assessed by maximal treadmill test and categorised into five groups. Body mass index was categorised into normal weight (<25.0 kg/m2), overweight (25.0–29.9 kg/m2) or obesity (≥30.0 kg/m2). RSP was defined as the simultaneous occurrence of forced expiratory volume in 1 s/force vital capacity ≥lower limit of normal and forced vital capacity <lower limit of normal.

Results There were 900 (7.3%) cases of RSP (mean follow-up: 6.9 years). Compared with category 1 (‘least fit’), HRs (95% CIs) of RSP were 0.78 (0.63 to 0.96), 0.68 (0.54 to 0.86), 0.70 (0.55 to 0.88) and 0.59 (0.45 to 0.77) in categories 2, 3, 4 and 5 (most fit), respectively, after adjusting for confounders including body mass index. Compared with normal weight, HRs (95% CIs) of RSP were 1.06 (0.91 to 1.23) and 1.30 (1.03 to 1.64) in overweight and obese, respectively. However, the association between obesity and RSP was attenuated when additionally adjusting for CRF (HR 1.08, 95% CI 0.84 to 1.39). Compared with the ‘unfit and overweight/obese’ group, HRs (95% CIs) for RSP were 1.35 (0.98 to 1.85), 0.77 (0.63 to 0.96) and 0.70 (0.56 to 0.87) in the ‘unfit and normal weight,’ ‘fit and overweight/obese’ and ‘fit and normal weight’ groups, respectively.

Conclusions Low CRF was associated with a greater incidence of RSP, irrespective of body mass index. Future studies are needed to explore potential underlying mechanisms of this association and to prospectively evaluate if improving CRF reduces the risk of developing RSP.

  • Physical fitness
  • Body Mass Index
  • Lung

Data availability statement

These third-party data are not freely available. These data cannot be shared publicly because of contractual restriction outlined in the University of South Carolina Data Use Agreement for the Aerobics Center Longitudinal Study. Data are available from the University of South Carolina (contact ACLS@mailbox.sc.edu) for researchers seeking to obtain or use data from the Aerobics Center Longitudinal Study (ACLS) who meet the criteria for access to confidential data. The data underlying the results presented in the study are available from ACLS@mailbox.sc.edu. Not applicable.

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Data availability statement

These third-party data are not freely available. These data cannot be shared publicly because of contractual restriction outlined in the University of South Carolina Data Use Agreement for the Aerobics Center Longitudinal Study. Data are available from the University of South Carolina (contact ACLS@mailbox.sc.edu) for researchers seeking to obtain or use data from the Aerobics Center Longitudinal Study (ACLS) who meet the criteria for access to confidential data. The data underlying the results presented in the study are available from ACLS@mailbox.sc.edu. Not applicable.

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Footnotes

  • Contributors AGB contributed to the conception, design and preliminary analysis of the work, with JMS and BKS performing additional analyses and interpretation of the data. JMS was responsible for drafting and redrafting of the manuscript. AGB, BKS, D-CL, XS and SNB contributed to the critical revision of the manuscript to ensure important intellectual content. All authors approved the final version. AGB is the study guarantor.

  • Funding This study was supported by the National Institutes of Health grants (AG06945, HL62508, DK088195, and HL133069). SNB has received unrestricted research grants from The Coca-Cola Company, but these grants were not used to support this manuscript.

  • Disclaimer The funding agency had no role in the study design, data collection, data analysis, data interpretation or writing of the manuscript. Interpretations or conclusions herein do not represent the views of the National Institutes of Health.

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.