Endocrine Abstracts

Introduction: The long-term mountain cycling effects on cognitive development for better performance, are still not fully elucidated. Notwithstanding, this type of exercise may induce a link with energy metabolism and sympathetic nervous system. We previously observed that a mountain cycling ultramarathon, induced a comodulatory influence of genetic- and exercise-associated factors on inflammatory and haemoglobin catabolic marker haptoglobin. We hypothesised that inflammatory process may induce hypothalamic-pituitary-adrenal (HPA) activation with consequent neuromuscular functional changes in long-term mountain cycling.

Methods: Fifty-five non-professional athletes (mean age 44.8±7.1 years) participating in a 9-day mountain cycling ultramarathon (TransPortugal) were evaluated. Before and immediately after race were determined the following parameters: insulin, glucose, uric acid, creatinine and platelets by standard methods; IL-6-plasma, BDNF-serum, cortisol-salivary and irisin-serum by ELISAs. Δ% represents values adjusted for plasma volume. Body composition was evaluated by BIA-Quantum-X. Participants were also categorized according to the number of courses completed (<9 or 9 courses).

Results: After race, IL-6 and platelets increased by 1129.7% (P<0.0001) and 13.3% (P<0.0001), respectively, while BDNF and cortisol levels didn’t change (P>0.05). At post-race, BDNF was directly correlated with % fat mass (r=0.286, P<0.05), glucose (r=0.294, P<0.05), platelets (r=0.462, P<0.01) and inversely correlated with skeletal muscle mass (kg) (r=−0.469, P<0.01). Post-race IL-6 was directly correlated with Δ% uric acid (r=0.341, P<0.01), Δ% insulin (P=0.287, P<0.05), Δ% HOMA-IR (r=0.289, P<0.05), Δ% HOMA- β (r=0.315, P<0.05) and post-race cortisol (r=0.368, P<0.01). The Δ% cortisol was directly correlated with Δ% creatinine (r=0.319, P<0.05), Δ% uric acid (r=0.439, P<0.01), Δ% glucose (r=0.332, P<0.05), Δ% insulin (r=0.293, P<0.05) and Δ% HOMA-IR (r=0.373, P<0.05). The completers of 9 courses, presented higher values of the Δ% IL-6 (P=0.043), Δ% cortisol (P=0.008), and post-race BDNF levels (P=0.053). Only for completers, the fastest (≤3715 min) presented lower values of BDNF in relation to the athletes of intermediate group (3715–4030 min) (P=0.013). Irisin levels were lower for athlets with better performance/fastest (P=0.033).

Conclusion: The HPA-axis hyperactivity may decrease BDNF production via IL-6 inflammatory response activation. The increased BDNF levels for 9 courses completers could reflect an management capacity, throughout multiple mediators of HPA axis, autonomic nervous system, and components of the immune system. Cerebral blood flow may decrease during very high intensity exercise, compromising the production of BDNF and, as such, consumption of foods rich in nitric oxide precursors may improve the flow, decreasing the inflammatory process.