Most heat adaptation happens in the first one to two weeks of regular training in the heat, and a lot of it in the first five days (Périard, Racinais and Sawka, 2015). If you live and train in Malaysia, you already have that. What catches local runners out in a trail ultra isn’t the heat itself. It’s twelve hours of it, followed by a 3pm storm on a steep, muddy climb.
These tips are grouped by when you need them.
In the weeks before
- Do some long runs at race time of day. If your race starts at 6am and you’ll be out until the afternoon, your body needs practice running through midday, not only at dawn.
- If you’re flying in from a cooler country, arrive at least a week early or do 60 to 90 minute sessions in heat for 10 to 14 days before you travel.
- Measure your sweat rate on a long run, weighing yourself before and after. Heat-adapted runners tend to sweat more, not less, so your number is probably higher than you think.
- Practise running in wet shoes and socks. Find out where you blister before race day does it for you.
- Train on the terrain you’ll race on. Steep jungle climbs and rooty descents use different muscles from park loops.
- Rehearse your full race-day nutrition on at least two long runs, including anything you plan to take from aid stations.
Keeping cool on the day
- Pour water over your head, neck and forearms at every aid station. In humid air sweat drips off without cooling you, so outside water does the job your sweat can’t.
- Wear a wet buff around your neck and refill it with ice when there’s any.
- Wear a peaked cap for the exposed sections and a light, loose top that doesn’t hold water.
- Walk the climbs early, even the ones you could run. Heat punishes a fast first half more than any other mistake.
- Race by effort and heart rate, not pace. Your normal pace at 1pm in Negeri Sembilan is not your normal pace.
Fluid and sodium
- Drink to thirst, and never force down water you don’t want. Gaining weight during a race is a warning sign.
- Plan sodium per hour, not per aid station, once you know your sweat rate. Our sodium guide shows how to work out your own number.
- Use salty real food too. Salted peanuts, crackers and soup at aid stations all count.
- Carry a soft flask you can refill fast. Long gaps between aid stations on hot, exposed ridges are where people run dry.
Fuel
- Eat little and often from the first hour. Heat slows digestion, and runners who wait until they’re hungry usually can’t catch up.
- Pack savoury options for the afternoon. Sweet gels get hard to face after six or seven hours. A QC Stamina pouch in your drop bag gives you carbohydrate and protein in one drink when the aid station food doesn’t appeal. Mix it with water at the checkpoint.
When the storm comes
- Put a light rain shell and headlamp in your vest even if it’s sunny at the start. Storms under the canopy make it dark early.
- Carry spare socks in a zip bag for a drop bag or a long wet stretch.
- Use anti-chafe cream generously before the start and again at a drop bag. Wet clothes chafe fast.
Heat and rain in the same race is standard in Malaysia. The Angsi Forest Challenge 2026 race report shows what it does to the second half of a race, and who handled it best.
References
- Périard JD, Racinais S, Sawka MN (2015). Adaptations and mechanisms of human heat acclimation: applications for competitive athletes and sports. Scandinavian Journal of Medicine & Science in Sports, 25(Suppl 1), 20-38.
