Hydration for the Tokyo Olympics: To Thirst or Not to Thirst?
What this entry can carry
A short BJSM editorial written ahead of the Tokyo Olympics on the "drink to thirst vs planned hydration" debate for competition in the heat. The article has no abstract; its full text was checked on 2026-09-28 (publisher's version, Radboud repository), and every specific figure below is labelled; the base's quantitative hydration evidence sits in the studies it points to, not here.
Key Findings (commentary; checked against the full text 2026-09-28)
Framing: drinking to thirst and planned hydration are both viable; which is better depends on context — exercise intensity and duration, ambient conditions, and the sport's rules on access to fluids
In the heat the authors favour a planned hydration strategy over thirst alone for high-intensity exercise with an elevated sweat rate and for activities lasting >60 min, because thirst may only be perceived once ~1.5 L of body water has been lost and is relieved before rehydration is complete; drinking to thirst may suffice for low-to-moderate intensity exercise <60 min in cool climates (full text, checked 2026-09-28: publisher's version, Radboud repository)
Starting euhydrated and rehydrating properly between sessions are stressed as being as important as drinking during competition, and hydration regimens should be athlete-specific (sweat rate and composition, e.g. sodium); the editorial does not discuss heat acclimation or cooling
The often-quoted ">2% body mass loss impairs endurance" threshold belongs to the wider literature, not to a measurement in this editorial; the base's blinded evidence for it is James 2017 REF-226 (~2.4% loss → less work in a 15-min test)
Practical Application
This is an expert editorial, not a study: it argues that for hot-weather competition a planned drinking schedule is safer than relying on thirst, while thirst-driven drinking remains acceptable for shorter or cooler events. Treat it as framing; take the numbers from REF-226 (hypohydration and performance), REF-221 (sweat-rate norms) and REF-223 (when sodium testing pays).
Not from this paper; the base's own practice: in heat, decide the drinking plan before the start (bottles per hour from your own sweat-rate test) rather than waiting for thirst; aim to keep body-mass loss modest, and pre-cool where logistics allow.
Limitations
From the record: an editorial (PubMed publication type "Editorial") with no abstract; it reports no data of its own, so no sample, design or effect size can be cited from it.
There is no abstract; the full text was read on 2026-09-28 (see the correction below), and the lines above carry that label.
How this entry was checked and changed
Why this level
regraded 2026-09-27 from B: editorial, expert opinion, no data of its own
Content correction 2026-09-27
Source has no abstract and was not verified; the entry stated ">2% body mass", "thirst lags by 0.5-1% body mass", ">25°C, >70% RH", "first 50% of effort" as findings -> not traceable; removed or relabelled as commentary/house practice.
Type "position statement", Level B -> editorial, expert opinion, Level C per rubric. Tier "mixed (review/meta)" -> N/A.
2026-09-28: added Limitations from the Europe PMC/PubMed record (editorial, no abstract) (Europe PMC/PubMed PMID 32883691).
2026-09-28: journal volume/pages corrected from the DOI's Crossref record (55, 14-15 -> 55(8), 410-411).
2026-09-28: lines labelled "full text; not checked" read against the open-access full text (publisher's version, repository.ubn.ru.nl hdl 2066/238785): 0 confirmed, 1 corrected ("hot/humid conditions -> planned schedule" -> planned strategy for high-intensity/high-sweat-rate exercise and >60 min in the heat; thirst felt only after ~1.5 L lost), 0 removed.
2026-09-28: text-status lines updated after the full-text check (publisher's version, repository.ubn.ru.nl hdl 2066/238785): Type, intro and Key Findings header now say the text was checked; remaining Key Findings bullets read against it: 1 confirmed (>2% threshold not measured here), 1 corrected (context factors = intensity, duration, ambient conditions, rules on fluid access), 1 corrected (heat acclimation and cooling are not in the editorial -> pre-exercise euhydration, between-session rehydration, individual regimens).
2026-09-30: the Limitations line still said the text was not checked, contradicting the 2026-09-28 full-text reading; updated.