Endocrine Abstracts

Introduction: The interaction between bone and energy metabolism may be enhanced in high demanding physical activities. We hypothesize that genetic background may modulate the exercise-associated bone and energy responses of athletes participating of a mountain cycling ultramarathon.

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 the race were determined the following parameters: insulin, glucose, uric acid and creatinine by standard methods; IL-6-plasma and carboxyglutamic acid residues of osteocalcin (Gla-OC)-plasma by ELISAs. The genetic polymorphisms of leptin-LEP-rs1137101, βeta−2 adrenergic receptor-ADRβ2-rs1042713, Osteocalcin-BGLAP-2274911 were determined by PCR-RFLP. 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: The genotype’s frequencies of polymorphisms analyzed were: LEP (homozygous G 0.29, heterozygous 0.51, homozygous A 0.20), ADRB2 (homozygous Gli 0.51, heterozygous 0.25, homozygous Arg 0.07) and BGLAP (homozygous T 0.60, heterozygous 0.31, homozygote C 0.09). The athletes with LEP polymorphism AA+AG genotypes (versus GG) had a favorable predisposition to: complete 9 courses, adjusting for age, gender, average speed, % fat mass and waist circumference (OR=5.0 [1.1–22.5], P=0.036) and to finish the race faster, adjusting for age, fat mass percentage in the pre-test, pre-run waist circumference and all stages (OR=8.0 [1.1–61.1], P=0.044). For this model, the LEP-A carriers presented higher Δ% uric acid (P=0.041) and Δ% Gla-OC (P=0.037). In 9-courses completers, LEP-A carriers presented a gain increase in Δ% IL-6 (P=0.012). For the ADRB2 polymorphism, athletes with AG+GG genotypes (versus AA) presented lower levels of post-race: insulin, HOMA-IR and HOMA-B (P<0.05). For BGLAP polymorphism, athletes with CC+CT genotypes (versus TT) had higher post-race levels and Δ% of HOMA-IR and HOMA-B (P<0.05). Covariance analysis showed a significant effect of LEP-A carriers on Δ% glucose (F=4.712, P=0.036), controlling for Δ% Gla-OC, Δ% IL-6, age, average speed and completers. Other covariance analysis showed significant effect of basal skeletal muscle mass on the Δ% Gla-OC (F=4.650, P=0.037), controlling for Δ% uric acid, creatinine, glucose, age, average speed and completers.

Conclusion: The LEP, ADRβ2 and BGLAP polymorphisms, related to bone and energy metabolism, may modulate the performance of athletes. This work supports a hypothesis of the influence of a co-modulatory action between genetic factors and mediators released during long-term exercises.