Relación entre la ingesta hídrica, la duración del entrenamiento y el gasto calórico en adultos físicamente activos

Introduction: Physical activity is a key determinant for cardiometabolic health, with caloric expenditure serving as an essential operational indicator of training dose in real-world conditions. Understanding its predictors allows for a better interpretation of the relationship between exercise habits and energy balance. Objective: To evaluate the predictive weight and direct relationship of fluid intake and session duration on caloric expenditure in physically active adults. Methodology: A quantitative approach with a cross-sectional observational design and analytical-correlational scope was conducted in 973 adults. Variables were obtained through multi-brand smartwatches and digital anamnesis, and data were analyzed using Pearson correlation and multiple linear regression. Results: A very strong positive linear association was identified between duration and caloric expenditure (r = .908; p < .001), and a moderate relationship with fluid intake (r = .357; p < .001). The regression model explained 83.5% of the total variance, highlighting duration as the predictor of greatest magnitude (β = .877) compared to hydration (β = .108). Discussion: The findings were consistent with studies pointing to temporal volume as the central determinant of energy expenditure over nutritional factors. The role of hydration aligned with research positioning it as a physiological facilitator of performance rather than a direct thermal driver. Conclusions: Session duration was the primary predictor of caloric expenditure, while hydration acted as a support for the continuity of effort. Public health strategies should prioritize temporal adherence to exercise for the control of energy balance.