Association between physical activity, cardiorespiratory fitness and inflammatory biomarkers in healthy young adults

Low-intensity chronic systemic inflammation is related to an increased risk of cardiovascular disease. Studies suggest that C-reactive protein, one of the main inflammatory biomarkers, may be inversely related to physical activity levels and physical fitness. The aim of this cross-sectional study was to evaluate the associations between physical activity, fitness and inflammatory biomarkers in apparently healthy men (N=85) aged 18 to 30 years. C-reactive protein was measured using the ELISA method. Physical activity practice was assessed by questionnaire and accelerometry. Maximum oxygen uptake (VO2max) was estimated based on a cycle ergometer incremental test. In the unadjusted analysis, the mean concentrations of C-reactive protein in the sample was 1.59±1.16 mg/L, and was inversely correlated with VO2max (r=-0.32, p=0.03). The body mass index (BMI) and waist circumference also significantly correlated with C-reactive protein (r=0.37, p<0.001 and r=0.41, p<0.001, respectively). After adjustment for anthropometric characteristics (BMI and waist circumference), the association with fitness was no longer significant. No association was observed between physical activity levels (questionnaire and accelerometry) and C-reactive protein. We conclude the in this group of young adults there was an inverse association between fitness and C-reactive protein, and this association is explained by the influence of fitness on anthropometry.A inflamação sistêmica crônica de baixa intensidade está relacionada com maior risco de doenças cardiovasculares. Estudos sugerem que a proteína C-reativa, um dos principais biomarcadores inflamatórios, pode estar inversamente relacionada com a prática de atividade física e com a aptidão física. O objetivo deste estudo transversal foi determinar as associações entre os níveis de atividade física e a aptidão cardiorrespiratória, com biomarcadores inflamatórios em homens adultos jovens (18-30 anos) aparentemente saudáveis (N=85). A concentração sérica da proteína C-reativa foi avaliada pelo método ELISA. A prática de atividade física foi mensurada por questionário e acelerometria. O consumo máximo de oxigênio (VO2max) foi estimado por teste incremental em cicloergômetro. Na análise bruta, a média das concentrações de proteína C-reativa da amostra foi de 1,59±1,16 mg/L, e esteve significativamente correlacionada com o VO2max (r=-0,32; p=0,03). O índice de massa corporal (IMC) e a circunferência abdominal também apresentaram correlação significativa com a proteína C-reativa (r=0,37; p<0,001 e r=0,41; p