Inflammation and cardiorespiratory fitness in overweight women and men: the FATCOR study

Abstract

Abstract Background Women have more body fat compared to men, and adipose tissue is associated with chronic inflammation. Cardiorespiratory fitness has on the other hand been postulated to lower chronic inflammation. However, sex-specific associations of inflammation with cardiorespiratory fitness is less studied. Purpose To assess inflammatory markers in overweight and obese women and men according to cardiorespiratory fitness in the FAT associated CardiOvasculaR dysfunction (FATCOR) study. Methods Cardiorespiratory fitness was assessed by maximal oxygen uptake (VO2max) by cardiopulmonary exercise testing in 566 subjects (mean age was 48±9 years, 60% women) with body mass index (BMI) >27.0 kg/m2. Participants were grouped according to sex, and fitness status identified from sex and age specific VO2max thresholds. C-reactive protein (CRP) and serum amyloid A (SAA) were analysed using Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight mass spectrometry. Serum levels of the kynurenine:tryptophan ratio (KTR) and pyriodoxic acid ratio (PAr) were measured by liquid chromatography tandem mass spectrometry. All inflammatory markers were log transformed before inclusion in linear regression analyses. Results 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 compared to the other groups (p<0.05), while serum levels of KTR and PAr were higher only compared to fit men (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 age, fat percentage, hypertension and metabolic syndrome. In men, only higher PAr (β −0.14, p=0.02) was associated with lower VO2max in multivariable analyses adjusted for age, fat percentage and metabolic syndrome. In multivariable analyses in obese women only (n=213), higher CRP (β −0.15, p=0.01) and PAr (β −0.13, p=0.03) remained associated with lower VO2max, while in obese men (n=144) there was no significant associations between inflammatory markers and VO2max. Conclusion Among overweight subjects participating in the FATCOR study, cardiorespiratory unfit women had the highest serum levels of inflammatory markers. The association of inflammation with reduced cardiorespiratory fitness was more pronounced in women than men, in particular when obesity was present. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Western Regional Health Authority of Norway