Long-term physical activity modulates adipsin and ANGPTL4 serum levels, a potential link to exercise-induced metabolic changes.

Background: Within the presented prospective study, we aimed to illuminate the effect of long-term physical exercise on serum levels of adipsin (complement factor D) and angiopoietin-like 4 (ANGPTL4). Although past studies already outlined the effects of acute exercise, our trial design aimed to depict the development under long-term physical activity conditions.

Methods: Ninety-eight participants were included in the study and were asked to perform eight months of moderate physical activity for at least 150 minutes/week and/or vigorous-intensity exercise for at least 75 minutes/week. According to initial performance and performance gain throughout the study period, four groups were formed and subsequently compared. Blood sampling for the determination of routine laboratory parameters was done at baseline, after 2, 6, and 8 months. Additionally, adipsin and ANGPTL4 serum levels were concurrently quantified using commercially available ELISA kits.

Results: The study cohort consisted of 61.2% male participants with an average age of 49.3±6.7 years. Adipsin and ANGPTL4 were found to be strongly increased by long-term physical exercise. Participants displaying a performance gain of >2.9% throughout the study showed significantly increased serum levels of both biomarkers.

Conclusions: Serum levels of adipsin and ANGPTL4 were closely tied to the individual performance gain of the participating probands. An association of adipsin levels, initial performance, and serum triglycerides was found at baseline. Interestingly, this interrelationship was not detectable after eight months of physical training. This finding might indicate adipsin's involvement in linking triglyceride-balance to individual performance and energy demands in a homeostatic state.