With the Ironman World Championship in Kona this Saturday, this Research Roundup is a heat and humidity special for triathletes and other endurance athletes, built around four big topics instead of four single studies. How much heat and humidity each slow you down when you separate the two, what the largest reviews say about heat acclimation and whether sauna and hot baths work as well as active methods, how fast heat adaptations arrive and how fast they fade, and which in-race cooling strategies work, while also being practically feasible.
HIGHLIGHTS AND KEY TOPICS:
Separating heat from humidity: a study that held the vapour pressure of the air constant from 18°C to 27°C and 36°C, then doubled it at 36°C, and why dew point is the number you want to check before a hot race.
A meta-analysis of 135 studies and 1,531 participants: how short, medium and long heat acclimation protocols compare, and which of four approaches (constant work, isothermal, self-regulated and passive) comes out ahead.
Sauna and hot baths after training: what a stricter meta-analysis of 10 controlled studies found, why the control groups matter so much, and the case for active heat training when time is short.
How many heat sessions, how long and how hot: a review of 211 papers, the free online predictor that comes with it, and whether the sessions need to be on consecutive days.
Five weeks of home-trainer heat sessions in 20 elite cyclists: when haemoglobin mass starts to move, how quickly the gains decay, and how to plan around these dynamics before racing.
Four days of 90-minute heat sessions: what changed after such a short protocol, why time-to-exhaustion results look so much bigger than time trials, and whether feeling adapted without being adapted could backfire in an all-day race like an Ironman.
Ice caps, a cooling neck collar, the Omius headband and water dousing in running studies: which ones improved performance, what they did to core temperature, and why Mikael ends up defending a gadget.
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