Practising in Real Heat: Timing, Hydration and What Changes

Between June and September, heat is a real variable rather than a background condition. It changes how a body responds to effort, how it feels in a stretch, and how long it takes to recover. Two effects matter and they pull in opposite directions.

Heat makes tissue more compliant

Warm muscle and tendon lengthen more readily. This is why a practice in a hot room feels dramatically more open than the same practice in a cold one, and why people conclude that heat is making them more flexible.

The important caveat: increased compliance while warm is not the same as increased range that you keep. The reading you get at 40 degrees is a temporary one. If you use it to push into a range you have no control over, the tissue is still the tissue it was this morning, and the usual feedback about how far is too far is less informative than normal.

So heat is useful for comfort and unhelpful as a guide to how far to go.

Heat makes effort harder

At the same time, the cardiovascular cost of any given work goes up. Blood is being sent to the skin for cooling as well as to working muscle. Heart rate at a given effort is higher, perceived exertion is higher, and the point at which you feel unwell arrives sooner.

Humidity makes this substantially worse, because sweat that does not evaporate does not cool you. A humid 38 degrees is harder work than a dry 42.

Practical timing

Early morning is the best window in high summer, coolest air, lowest humidity in most coastal conditions, and daylight for the body clock.

Late evening is the second option, though on the coast the humidity often stays high well after dark, so it is frequently less comfortable than the temperature suggests.

Indoors in air conditioning is completely reasonable and needs no defence. The tradeoff is the cold-tissue effect, which means a longer warm-up before asking for any range.

Outdoors in the middle of a summer afternoon is not a sensible plan for sustained effort.

Hydration, without the mythology

Drink to thirst across the day rather than trying to front-load before a session. Thirst is a reasonably good guide for most people in most conditions.

If you are sweating heavily for extended periods, water alone is not the whole picture. Sodium is lost in sweat and replacing fluid without it is not ideal. For an hour of moderate indoor practice this is irrelevant; for long outdoor activity in summer it is not.

Dark urine, a headache and unusual fatigue after activity are the ordinary signs of having got behind. Feeling dizzy, stopping sweating, or confusion are different and mean stop and get help.

What to change in summer

Shorten sessions rather than reducing frequency. Do the demanding work earlier in the session while you are fresher.

Favour floor work and slower sequences in the hottest weeks and keep the strong standing work for cooler months or air-conditioned rooms.

Do not use how open you feel in the heat as permission to go further than usual. This is the specific way people hurt themselves in hot practice.

Where a teacher helps

Mainly in judging that last point, which is genuinely hard to self-assess. A teacher watching can tell when you have gone past controlled range into a place the heat has simply allowed, and can adjust a session to the conditions rather than running the same plan in July that worked in January.

Sessions are live on video, thirty or sixty minutes, from wherever you have air conditioning.

Questions people ask

Does heat make you more flexible?

It makes tissue temporarily more compliant, so you can move further while warm. That is not the same as an increase in usable range, and it fades as you cool. Treating the hot-weather reading as your real range is how people overreach.

Is it dangerous to practise in very hot weather?

Sustained effort in high heat and humidity raises cardiovascular strain and brings on heat illness sooner. Practising indoors, early, or at lower intensity is sensible in peak summer. Dizziness, confusion or stopping sweating mean stop and seek help.

When is the best time to practise in summer?

Early morning is usually best: coolest air, lower humidity, and useful daylight. Evening is second, though coastal humidity often stays high after dark. Air conditioning is a perfectly good answer, with a longer warm-up.

How much water should I drink around a session?

Drinking to thirst across the day works for most people in most conditions. For long, heavy sweating in summer heat, replacing sodium as well as fluid matters; for an hour of indoor practice, plain water is fine.