Sports science hydrates for the next game. A new paper asks about the next decade.

Sports science has spent decades refining how athletes should hydrate around training and competition — how much to drink, when, and with what electrolyte mix, mostly in service of protecting performance during a given session. A short communication published in Sports Medicine argues that focus has left a much bigger question largely unstudied: what habitual, day-to-day low water intake does to an athlete's body over years, independent of any single workout [s1].

The scale of the problem, as the paper frames it

The paper cites evidence that up to 40% of the non-athletic population fails to meet standard fluid intake recommendations [s1]. Among athletes specifically — people who, unlike the general population, lose substantial fluid and electrolytes through recurrent training and competition — the paper reports that roughly 58% are habitually classified as low drinkers, defined as consuming less than 35 milliliters of fluid per kilogram of body weight per day [s1]. That means a majority of athletes in the studies the paper draws on are under-consuming fluid by a standard benchmark, despite facing fluid losses the average sedentary person doesn't.

Why total body water numbers can look fine anyway

The paper makes a distinction that explains why this problem has been easy to overlook: total body water can remain within a normal range in habitually low-intake individuals, even as other markers point to sustained physiological strain [s1]. Specifically, chronic low water intake tends to show up as persistently elevated arginine vasopressin — the hormone that signals the kidneys to conserve water — alongside concentrated urine, both markers of the kidneys working harder than they would with adequate intake [s1]. A hydration check that only looks at total body water could miss this entirely.

The long-term health question

Drawing on emerging evidence from non-athletic populations, the paper describes associations between chronic low water intake and elevated renal, endocrine, and metabolic strain — including links to insulin resistance and low-grade inflammation [s1]. Critically, the paper is explicit that whether this same physiological pattern poses long-term health risks specifically for athletes — who are exposed to it under different conditions, layered on top of intense physical training — remains unknown [s1]. This is not a paper reporting a new finding of harm in athletes; it's a paper arguing that the question hasn't been adequately asked.

What the paper is calling for

The authors describe this as an underappreciated and potentially modifiable health risk in athletic populations, and call specifically for a shift in how sports nutrition treats water intake — as both a short-term performance variable, which is how it's mostly studied now, and a determinant of long-term health, which the field has largely left unexamined [s1]. They highlight gaps in longitudinal and mechanistic research as the specific barrier to answering the question definitively [s1].

What this means, and doesn't mean, for an athlete reading this

This is a call for research, not a clinical finding that habitual low water intake is definitively harming athletes' long-term health — the paper says plainly that whether the pattern poses long-term risk in this population is unknown. What it does establish is a documented gap between how athletes are commonly assessed for hydration (largely around single training sessions) and a body of markers — sustained hormonal and renal signals — that a majority of athletes may be showing on a chronic, daily basis without it being flagged by conventional total-body-water checks. Nothing here amounts to a specific fluid-intake target or recommendation for any individual reader; the paper's own conclusion is that the research needed to set one, for athletes specifically, doesn't yet exist.

Sources

• Athlete Hydration: Beyond Performance Toward Long-Term Health — Sports Medicine, 2026-04-22