Influence of cardiorespiratory fitness on obesity-associated inflammation in women and men: The FATCOR study

Background and Aims Cardiorespiratory fitness has been postulated to lower chronic inflammation in obesity. We assessed sex-specific associations of inflammation with cardiorespiratory fitness in overweight and obese persons. Methods and Results Peak oxygen uptake (VO2max) was measured by treadmill in 566 participants (age 48±9 years, 60% women) with body mass index >27.0 kg/m2 in the FAT associated CardiOvasculaR dysfunction (FATCOR) study. Fitness was identified from age- and sex specific reference levels of VO2max. The inflammatory markers C-reactive protein (CRP), serum amyloid A (SAA), kynurenine:tryptophan ratio (KTR) and pyriodoxic acid ratio (PAr) were measured by mass spectrometry. In the total study population 63% had obesity and 74% were cardiorespiratory unfit. Unfit women had the highest fat percentage and the highest serum levels of CRP and SAA (p<0.05). In multivariable linear regression analyses in women, higher CRP (β -0.15, p=0.001), SAA (β -0.10, p=0.03) and PAr (β -0.09, p=0.03) were associated with lower VO2max after adjusting for confounders. In multivariable analyses in men, higher PAr (β -0.14, p=0.02) was associated with lower VO2max. In multivariable analyses in obese women, higher CRP and PAr remained associated with lower VO2max (p<0.05), while in obese men there was no significant association. When normalizing VO2max for fat-free mass (VO2maxFFM) higher CRP, SAA and PAr index were associated with lower VO2maxFFM in women, while only higher PAr index was associated with lower VO2maxFFM in men. Conclusion The association of inflammation with lower cardiorespiratory fitness was more pronounced in women than men, in particular when obesity was present. Clinical trial registration URL: http://www.clinicaltrials.gov NCT02805478.