Author(s): QUARESMA, M., NAKAMOTO, F.P.1, MARQUES, C.G.2, SANTOS, L.M.1, DEGANI-COSTA, L.H.1, NAVARRO, L.S.1, NAVARRO, G.S.1, AGUIAR, V.1, FERREIRA, R.F.S.1, ALVARES, L.A.M.A.1, Institution: CENTRO UNIVERSITÁRIO SÃO CAMILO, Country: BRAZIL, Abstract-ID: 2468

INTRODUCTION:
The impact of low energy availability (LEA) on bone mineral density (BMD) in transgender women athletes (TWA) remains uncertain, and discussions about LEA have garnered attention in recent years. Thus, we aimed to assess and compare nutritional parameters among volleyball players divided into TWA, cisgender women athletes (CWA), and cisgender men athletes (CMA). Additionally, we aimed to examine the association between nutritional parameters and BMD.
METHODS:
This is a cross-sectional study. Inclusion criteria involved healthy volleyball players aged 18-39 years; TWA under gender-affirming hormone therapy (GAH) for at least six months. Participants visited the laboratory once. We utilized Dual-energy X-ray absorptiometry to assess body composition (i. e., femur BMD, fat mass and appendicular lean mass (ApLM)). We evaluated blood biomarkers (e.g., vitamin D, calcium, and parathormone [PTH]) in accordance with biochemical kit recommendations. Also, participants completed health and sociodemographic questionnaires along with a 24-hour food recall. Statistical comparisons were conducted using the ANOVA test, and associations were explored through linear regression, considering biological plausibility. Model quality was confirmed using AIC and R2 in regression analysis. Data analysis utilized Jamovi® 2.3.21 version.
RESULTS:
Data from a preliminary sample of 22 subjects are presented as mean (SD). The mean duration of GAH was 6.8 years, and the average age of GAH onset was 22 years. The ANOVA test indicated no differences in age (30.4 (2.62), 26.0 (4.24), and 28.9 (4.38) years), body mass index (23.2 (3.52), 23.9 (2.57), and 26.8 (5.01) kg/m2), and fat mass (20.9 (9.53), 19.8 (8.81), and 21.4 (10.1) kg) among TWA, CWA, and CMA, respectively. Energy intake is different among groups (F(17,2)= 8.28; p= 0.003; η2ρ= 0.493). For instance, CMA consumed more energy than CWA (Mean Difference [MD]: 1410 kcal; p= 0.003) and TWA (MD: 1142 kcal; p= 0.021), with no significant differences between CWA and TWA (MD: 268 kcal; p= 0.764). However, carbohydrate (F(17,2)= 1.55; p= 0.240; η2ρ= 0.155), protein (F(17,2)= 1.79; p= 0.197; η2ρ= 0.174), and lipid (F(17,2)= 2.01; p= 0.65; η2ρ= 0.191) intake did not differ between groups. Furthermore, serum levels of vitamin D (F(18,2)= 0.415; p= 0.666; η2ρ= 0.044), PTH (F(19,2)= 0.720; p= 0.501; η2ρ= 0.078), and calcium (F(19,2)= 2.49; p= 0.109; η2ρ= 0.208) also did not differ between the groups. Linear regression results (R2: 0.813; F= 4.34; p= 0.036; sample power: 75%) indicated that, regardless of ApLMI, energy intake, vitamin D levels, calcium, and PTH, TWA was negatively associated with femur BMD (B= -0.77; 95% CI: -1.32 to – 0.21; p= 0.018). In contrast, CWA showed no associated with femur BMD compared to CMA (B= -0.31; 95% CI: -0.86 to 0.23; p= 0.227).
CONCLUSION:
In conclusion, the energy intake of TWA was lower than CMA, with no differences in macronutrient intake or blood biomarkers. Moreover, TWA was negatively associated with femur BMD.