Drinking plenty of liquid is the right thing to do during a heatwave: it’s essential to stay hydrated to protect the kidneys. But there is debate over whether that drink should be ice-cold or hot.

The Japanese competition of snowball fighting, Yukigassen, is a brutal game of dodgeball ramped up to be more than a little dangerous. You’ll need two teams of seven and a whole array of pre-made snowballs, as well as protective gear to keep your face and head from feeling the sting of the balls. Believe us when we say that you’ll be grateful for the padding when it’s all over. Certainly one of the more aggressive cold weather sports, it is also quite the intriguing experience. Urban Iditarod View in gallery via deseretnews.com Here’s another sledding offshoot and one of the more famous extreme cold weather sports that was actually taken out of the Olympics due to its danger to competitors. You go diving headfirst down a hill using nothing but a tiny sled that resembles a skeleton (hence the name) to do it. You can use any sled you want, but for the love of all that is holy, please put on a helmet and a mouthguard. If only to reduce cleanup later on. Ski Biking View in gallery via lenzsport.wordpress.com What we do know is that fans aren’t always a foolproof solution. In a 1999 heatwave in Cincinnati, 17 people died – and 10 had fans which were switched on when the people were found dead. Of course, what we don’t know is if they would have died sooner without the fans, or if the reason these people had bought fans was that they lived in the hottest buildings. But there is one possible problem with these findings and that’s the the method used to measure the temperature. The brave volunteers were given rectal thermometers. As Ollie Jay, associate professor in thermoregulatory physiology at the University of Ottawa, has pointed out, the liquid from a cold drink goes straight to the stomach, not far away from the rectal thermometer. It’s little wonder, therefore, that the temperature appears to go down. It is true that hospital admissions do rise during heatwaves and that many of these patients will be older.

Verdict: False – if the air outside is hotter than indoor. But at night opening the windows may give you some relief. So, you’ve gotten yourself a pair of skis but hate the idea of hitting the hill along with every other snow bunny, waiting in long lift lines, and contending with inebriated souls who class drinking in the snow as one of the primary cold weather sports. Then it’s time to attach yourself to a horse, a motorcycle, a set of dogs, or anything else that moves to find the unbridled fun (read: stark terror) of being drug along like a water skier over the unforgiving ground. Make sure you add in some jumps for good measure. Yukigassen View in gallery via travelalberta.com These were all small studies, though, and they weren’t looking specifically at body temperature, so we can’t prove that beer cools you down. But they do show that one or maybe two small beers can still hydrate rather than dehydrate you. So perhaps that single beer in Ice Cold in Alex was worth the wait. But that doesn’t mean that only the elderly are at risk in a heatwave. Young babies and people with chronic health conditions are more likely to have issues aswell. So is anyone with mobility issues, simply because it’s harder to walk to the window to open it or to fetch drinks to replace the liquids lost through sweating. If it’s hot during the day and the night, it can be hard for the body to cool down at all. The European heatwave of 2003 is estimated to have killed at least 30,000 people; some figures put the total as high as 70,000. Of the 15,000 who died in France, 1,321 were under the age of 64. Fans are less effective when it’s humid. Although the air is still moved around, it’s already laden with moisture, making it harder for the sweat to evaporate.

A more recent study had similar findings. Although isotonic sports drinks and plain water were more effective at hydrating, beer was still more hydrating than expected. And a Spanish study involving 40 minutes on a treadmill found that water and beer both rehydrated them to the same extent. No one knows exactly why when we know that drinking beer tends to make people go to the loo. One hypothesis is that because the body is dehydrated and needs the fluid it retains more of the beer than it would other fluids. The theory behind choosing a hot drink is that it temporarily heats you from within. This causes you to sweat more, which cools you down. The human body can produce up to two litres of sweat per hour, which is an effective way of reducing your core body temperature. During heatwaves, everyone has plenty of tips on how to keep cool. But which tips and facts stand up to scientific scrutiny on the hottest days of the year? We look at the evidence for whether you should: Fans are used widely. One case report even gives an example of three patients with heatstroke who were cooled down using the downdraft from a light helicopter.But if that liquid is not replaced you soon become dehydrated – so some recommend avoiding hot drinks altogether. Some also argue that you shouldn’t have too much tea or coffee, as these contain dehydration-causing caffeine. However, there is little evidence that moderate amounts of caffeine act as a diuretic. If you like a bit of speed in your cold weather sports, then ice sailing could be the winter endeavor for you. True, you’ll need to get a specialized boat for this. One that is mounted on skids that can move across the ice. Once you do, there’s no end to the enjoyment that can be had on a blustery day. It’s paddleboarding and windsurfing meets ice skating and a hell of a good time. Snow Polo View in gallery via israelandbeyond.me

But until randomised controlled trials are conducted, we can’t know for sure what effect a fan might have – and such trials are not easy to plan. Researchers would need to have everything ready to go as soon as a heatwave began. Even then, they might wait several years until the temperatures are just right. You should only open the windows if the air outside is cooler than the air inside, which is most likely to happen at night. In really hot weather, you should close the windows during the day. Because there’s more shade indoors the air might even be cooler. Even if you can get a breeze to flow through your home or office, if it’s a hot breeze it won’t cool you down and when the pollen count is high it could make hayfever worse.

Skijoring

If it is just one beer, it might not hurt you. In various studies, researchers have made people exercise until they’re hot and then compared their recovery when they drank beer with or without alcohol. In one 1985 study of people exercising in a warm, humid environment, as you might expect, the “peak urine output” occurred after the beer which is not good. It shows the body is losing rather than retaining liquid. But compared with alcohol-free or low-alcohol beer the difference was surprising small.