Athlete Hydration: Beyond Performance Toward Long-Term Health

Research on fluid-electrolyte balance in athletes has largely emphasized acute hydration strategies to preserve performance, particularly under conditions of prolonged exercise and heat stress. While this focus has yielded valuable practical guidance, it has overshadowed the potential long-term health implications of habitual low water intake (LWI). Emerging evidence from non-athletic populations indicates that chronic LWI, often characterized by persistently elevated arginine vasopressin (AVP) and concentrated urine, may increase renal, endocrine, and metabolic strain, showing associations with insulin resistance, low-grade inflammation, and chronic disease risk. Notably, evidence suggests that up to 40% of the non-athletic population fail to meet the fluid intake recommendations. Furthermore, a considerable proportion of athletes are habitually classified as low drinkers (i.e., ~ 58% consuming < 35 mL·kg^-1·day^-1), despite being exposed to recurrent and substantial fluid and electrolyte losses during training and competition. Although total body water may remain within normal ranges in these individuals, markers of renal concentrating stress suggest sustained activation of fluid-regulatory systems. Whether this physiological state poses long-term health risks for athletes remains unknown. This short communication argues that habitual LWI represents an underappreciated and potentially modifiable health risk in athletic populations. We highlight critical gaps in longitudinal and mechanistic research, calling for a paradigm shift in sports nutrition that recognizes total daily water intake as both a performance variable and a determinant of long-term health.