The effect of drinking mineral waters on the physical performance of female rats and its metabolic support

Background and aim. Mineral waters are widely used in spa therapy and sports medicine, yet their effects on physical performance and underlying metabolic mechanisms remain incompletely understood. This study aimed to investigate the impact of three different mineral waters on swimming performance in female rats and identify key metabolic predictors of physical capacity. Material and methods. Sixty female Wistar rats (mean weight 262±22 g) were randomly divided into four groups: intact controls (n=10) receiving tap water, and three experimental groups (n=50) loaded with mineral waters (MW N1, N2, N3) at 3 mL/200 g body mass for 12 days. Swimming test until exhaustion was performed, along with comprehensive metabolic, hormonal, and electrolyte analyses in serum and urine. Discriminant analysis and multiple regression were used to identify predictors of physical performance. Results. Swimming duration ranged from 90 to 330 minutes and correlated most strongly with mineralocorticoid activity estimated as (K⁺ᵤᵣᵢₙₑ/Na⁺ᵤᵣᵢₙₑ)⁰·⁵ (r=-0.564; p<10⁻⁶). Multiple regression revealed that mineralocorticoid activity, calcitonin activity, glycemia, body mass, and uricemia together explained 65% of swimming test variance (R²=0.650; F₍₅,₅₄₎=20.1; p<10⁻⁶). MW N2 (highest Na⁺ content: 122.3 mM/L) significantly increased mineralocorticoid activity (2.71±0.38 vs 1.40±0.13 in controls; p<10⁻⁶) and reduced swimming duration by 16% (156±8 vs 187±2 min; p<0.001). MW N3 enhanced performance by 13% (210±8 min; p<0.05). Discriminant analysis correctly classified 96% of animals based on 12 metabolic variables. Conclusions. Mineralocorticoid activity is the primary determinant of physical performance in rats consuming mineral waters. High-sodium mineral water impairs performance through aldosterone-mediated potassium loss and electrolyte imbalance, while balanced mineral composition maintains or enhances physical capacity. These findings have important implications for mineral water selection in sports medicine and spa therapy.