Hydration Indoors
An indoor gym in August can be hotter than the field outside it, and a pool deck hides sweating completely. Send the same cold bottle you would send outdoors, and do not let the absence of sun convince anyone that heat is not a factor.
Indoor heat has no warning signs
Outdoors there are cues everyone reads without thinking: sun, a hot car, a weather forecast, other parents complaining. A sports hall gives none of them, and the temperature check most families make simply does not happen.
The result is that indoor sessions in summer are routinely under-prepared compared with outdoor ones in the same weather.
| Cue | Outdoors | Indoors |
|---|---|---|
| Heat index | Checkable, and used by clubs | No equivalent for the room |
| Visible sun | Obvious | Absent, though the hall may be hotter |
| Visible sweat | Clear | Clear in a gym, invisible in a pool |
| Shade | Available or not | Not the relevant variable |
| Air movement | Often some | Often none at all |
Gyms and courts
Basketball, volleyball, indoor football, gymnastics, and wrestling all take place in halls that can be considerably warmer than outside, particularly in the evening after a building has absorbed heat all day.
Treat a hot hall exactly as you would treat a hot field: cold bottle, drinks at every break, a spare dry shirt.
- Ask what the hall is like rather than what the weather is.
- Send the same cold bottle you would send outdoors.
- A spare shirt for afterwards, because indoor sessions soak a kit too.
- Wrestling and gymnastics warrant particular attention, given the clothing and the effort involved.
Pools, where sweating is invisible
Swimmers sweat and lose fluid like any other athlete, and neither they nor anyone watching can see it happening. Pool decks are also humid and warm, which slows the body's cooling.
The practical consequence is that swimmers frequently finish a session meaningfully behind on fluid without anyone, including the swimmer, noticing.
What kind of indoor session is it?
A cool, ventilated hall
A hot hall or an evening session in summer
A pool session
What to pack for indoor sessions
Almost identical to the outdoor list, minus the hat and the shade.
Still needed indoors
- A cold bottle, and a second one for long sessions.
- A dry shirt for afterwards.
- Something to eat straight after, particularly for evening sessions.
- Fluid in the car on the way home.
Not the issue indoors
- A hat and sunscreen.
- Shade.
- The heat index, which does not describe the room.
- The assumption that indoors means cool.
When to raise it with the coach
If a hall is consistently hot, if there are no scheduled drink breaks, or if bottles are not allowed on the deck, that is worth raising with the coach or the club. Johns Hopkins guidance for young athletes is that they should have unlimited access to water during activity.
It is a reasonable question, and asking it once at the start of a season is easier than asking it after a bad evening.
Questions about indoor hydration
Do swimmers need to drink during training?
Yes. Swimmers sweat and lose fluid like any other athlete, and neither they nor anyone watching can see it. A bottle on the deck and scheduled drinking are the answer.
Can an indoor gym really be hotter than outside?
An unventilated hall that has absorbed heat all day can be, particularly for an evening session. There is no published index for it, so ask what the hall is actually like.
What if bottles are not allowed on court?
Ask the coach how drink breaks are handled. Johns Hopkins guidance is that young athletes should have unlimited access to water during activity.
- Heat-Related Illness and Young Athletes, Johns Hopkins Medicine, hopkinsmedicine.org.
- How to Keep Young Athletes and Active Kids Safe in Hot Weather, American Academy of Pediatrics, HealthyChildren.org, healthychildren.org.
- Heat and Athletes, Centers for Disease Control and Prevention, cdc.gov.