Inflammatory proteins during childhood and adolescence have been shown to be predictors of cardiovascular disease in adulthood(Reference Juonala, Viikari and Rönnemaa1). Likewise, higher levels of body fat seem to play a pro-inflammatory role in adolescents(Reference Wärnberg, Nova and Moreno2). However, there is limited knowledge about the role of physical activity and fitness on inflammatory proteins in adolescents. Therefore, the aim of this study was to examine the relationships between self-reported physical activity (PA), fitness, body mass index (BMI), and inflammatory proteins. A sub-sample of 193 adolescents (92 girls), aged 13–17 years old and enrolled in the AFINOS study, was selected for the current study. PA was assessed by a global activity rating (compared to others of your age and sex, how much PA do you get?). Similarly, fitness was self-reported by the following question: how is your physical fitness? Both PA and fitness assessments were rated on a 5-point scale ranging from 1 (much less active/very bad) to 5 (much more active/excellent). Weight and height were also obtained by self-report and BMI was calculated (kg/m2). C-reactive protein (CRP, mg/dl), ceruloplasmin (mg/dl) and complement factors C3 and C4 (g/l) were determined, and logarithmic or square roots transformations were applied when necessary. Student's t test showed no differences between sexes regarding age and BMI. Adolescent boys were more active and fit than girls (both P=0.001). No sex differences were found for inflammatory proteins, except for ceruloplasmin, adolescent girls reaching higher levels than boys (P=0.002). PA was significantly related with fitness (r=0.546, P<0.001) but not with BMI (r=−0.132, P=0.077) after controlling for age and sex. Fitness was also related with BMI (r=−0.301, P<0.001) after controlling for age and sex.
Table 1. Partial correlations controlling for age and sex (n=193)
*P<0.05.
PA was not significantly related/associated with inflammatory proteins, but borderline significances were found with ceruloplasmin (P=0.066) and C3 (P=0.072). On the contrary, fitness and BMI were significantly related with all the inflammatory proteins tested. When BMI was included as confounder, fitness was only significantly related with celluloplasmin (r=−0.195, P=0.008) and C3 (r=−0.216, P=0.003). These results suggest that PA has a potential beneficial effect on low-grade inflammation in adolescents due to its role on fitness.
