Cardiorespiratory fitness and the metabolic syndrome: Roles of inflammation and abdominal obesity

PLoS One. 2018 Mar 28;13(3):e0194991. doi: 10.1371/journal.pone.0194991. eCollection 2018.

Abstract

Objective: Individuals with metabolic syndrome have increased risk of type 2 diabetes and cardiovascular disease. We aimed to test the hypothesis that a high level of cardiorespiratory fitness (CR-fitness), counteracts accumulation of visceral fat, decreases inflammation and lowers risk factors of the metabolic syndrome.

Method: The study sample included 1,293 Danes (age 49-52 years) who from 2009 to 2011 participated in the Copenhagen Aging and Midlife Biobank, including a questionnaire, physical tests, and blood samples. Multiple linear regression models were performed with CR-fitness as exposure and plasma levels of cytokines and high sensitive C-reactive protein as outcomes and measures of abdominal obesity were added to test if they explained the potential association. Similarly, multiple linear regression models were performed with CR-fitness as exposure and factors of the metabolic syndrome as outcomes and the potential explanation by inflammatory biomarkers were tested. All models were adjusted for the effect of age, sex, smoking, alcohol consumption, socio-economic status, and acute inflammatory events within the preceding two weeks.

Results: CR-fitness was inversely associated with high sensitive C-reactive protein, Interleukin (IL)-6, and IL-18, and directly associated with the anti-inflammatory cytokine IL-10, but not associated with tumor necrosis factor alpha, interferon gamma or IL-1β. Abdominal obesity could partly explain the significant associations. Moreover, CR-fitness was inversely associated with an overall metabolic syndrome score, as well as triglycerides, glycated haemoglobin A1c, systolic blood pressure, diastolic blood pressure and directly associated with high-density lipoprotein. Single inflammatory biomarkers and a combined inflammatory score partly explained these associations.

Conclusion: Data suggest that CR-fitness has anti-inflammatory effects that are partly explained by a reduction in abdominal obesity and a decrease in the metabolic syndrome risk profile. The overall inflammatory load was mainly driven by high sensitive C-reactive protein and IL-6.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomarkers / metabolism*
  • Body Composition
  • Cardiorespiratory Fitness*
  • Exercise Therapy*
  • Female
  • Humans
  • Inflammation / complications
  • Inflammation / metabolism
  • Inflammation / rehabilitation*
  • Inflammation Mediators / metabolism*
  • Male
  • Metabolic Syndrome / etiology
  • Metabolic Syndrome / metabolism
  • Metabolic Syndrome / prevention & control*
  • Middle Aged
  • Obesity, Abdominal / complications
  • Obesity, Abdominal / metabolism
  • Obesity, Abdominal / rehabilitation*
  • Risk Factors

Substances

  • Biomarkers
  • Inflammation Mediators

Grants and funding

The Copenhagen Aging and Midlife Biobank has been supported by a generous grant from the VELUX FOUNDATION (VELUX 26145 and 31539). The Centre for Physical Activity Research (CFAS) is supported by a grant from TrygFonden. CFAS is a member of DD2 - the Danish Center for Strategic Research in Type 2 Diabetes (the Danish Council for Strategic Research, grant no. 09-067009 and 09-075724). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.