To Örebro University

Introduction: Competitive freediving involves repeated voluntary breath-holding, during which hypoxic events such as loss of motor control (LMC) or blackout (BO) may occur. Although nutrition may influence metabolic responses tohypoxia, evidence in competitive freedivers remains limited. This study aimedto investigate the relationship between dietary habits and self-reported hypoxicevents in Spanish competitive freedivers.

Methods: A cross-sectional study was conducted in 71 competitive freedivers(19 women: 39.4 ± 9.3 years; 52 men: 41.9 ± 8.6 years). Participants completeda questionnaire on training characteristics and hypoxic events. Events were classified as LMC or BO, and participants were categorized according to the mostsevere event experienced. Dietary habits were assessed using a validated foodfrequency questionnaire (PREDIMED). Associations were examined using chisquare or Fisher’s exact tests, and significant variables were included in a binomiallogistic regression adjusted for age, sex, and years of practice.

Results: Overall, participants showed moderate consumption across dietarygroups, with higher intake of fruits, vegetables, and protein-rich foods; and lowintake of ultra-processed foods and alcohol. Male divers consumed moderateamounts of protein-rich foods, whereas female counterparts reported lowerintake [χ2(2) = 8.53, p = 0.014; Fisher’s exact test, p = 0.010]. Overall, 21 freedivers(29.6%) reported at least one hypoxic event. The occurrence of hypoxic eventswere associated with years of practice (p = 0.003) and consumption of stimulant beverages (p = 0.013). Beginners experienced fewer events than expected,whereas divers with >4 to 10 years of practice were overrepresented. In theadjusted model, years of practice remained significantly associated with hypoxicevents [OR = 3.06, 95% CI (1.43, 6.53), p = 0.004]. Moderate stimulant beverageconsumption emerged as a potential associated factor [OR = 12.54, 95% CI (1.27,123.9), p = 0.031].

Conclusion: Hypoxic events in competitive freedivers were primarily associatedwith years of practice, suggesting that cumulative exposure may be a relevant riskfactor. Overall dietary habits showed no clear relationship with hypoxic events,although stimulant beverage consumption may warrant further investigation