We Ran in EXTREME Temperatures

What Happens When You Run In Extreme Temperatures? Sarah and Mo went down to the University of Brighton Labs to find out…
↓↓ Do you notice changes when you run at different temperatures? Should we go and take on an extreme marathon? Let us know in the comments! ↓↓
What’s in this video?
00:00:00 - Running at Extreme Temperatures: Cold Experiment
00:03:17 - Running in the Cold with Body Temperature Measurements
00:06:38 - Running in the Heat and Training Results
00:09:33 - The Influence of Hydration and Climate on Physical Performance
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[@tr3eehugg3r]

Now that’s dedication! Thumbs up for having to put that thermometer in and run with it 🤣

[@runningchannel]

😂😂 serious dedication!

[@Namoraslife]

I definitely take running in cold weather over warm weather, but -10 degrees is really cold. Everything down to 0 degrees is fine, but everything above 25 degrees just feels like torture to me. Mad respect for your dedication to science!

[@sundayrunday7586]

My cold cutoff for outdoor running is -20. Mostly because my hands never warm up. -10 is fine, -15 is iffy. 😂

[@laughingstar3945]

Being a beginner runner living in a country where it's always 30+ degrees Celsius is hell

[@nathalieasselin2251]

Writing from Canada where -10 is actually not that bad, so it’s very funny to see your reactions. However, I would be quite incapable of running in too much heat. Good job to you both 😊

[@matildami5943]

I had the same thought as a Finn, -10 is still quite nice!

[@hellomark1]

I'm Canadian so we tend to get both extremes, in fact I find it funny that you think -10C is cold :) though this winter was pretty mild, the coldest I ran in this year was like -18C with a windchill of -35C. The worst part about windchill like that is you absolutely need to cover all of your skin, so I had a mask on, but it was getting wet from condensation, and having a wet cloth over your mouth while trying to breathe hard is not unlike what I imagine getting waterboarded feels like. If I had to do it again I'd want a more rigid mask that gets held away from my face. Conversely the summers here can sometimes get up to the high 30s, and running in that definitely slows you right down. It takes time to get acclimated to both.

[@vickyshaw1709]

Definitely with Sarah on this one. Give me cold any day. My best races are always the ones in February. Did a 10k in August last year when it was the heatwave and felt like I was dying !!

[@MsTrinichic]

I'm in the Caribbean and running in the heat is quite normal for us! We tend to run earlier in the morning or evening to avoid the heat but it doesn't account for the humidity either. Love the content guys

[@roryfree4707]

As an australian, I would be interested to see if more heat-adapted people would do better in the hot climate and worse in the cold climate. I've run on a few 35+ degree days before. Because of how unbelievably cold -10 sounds to me, when they said the cold extreme was -10, I was expecting the hot extreme to be something like +45!

[@alexandreparadis2776]

I find it way harder to run in the heat, but even harder in heat and humidity. I also become dehydrated too quickly. Cold temperature has never bother me (at least up to -25 degrees Celcius), but I cannot do long run as my water bottle freezes :) Very interesting video!

[@runningchannel]

If you're not used to running in humid weather it's really tough and a big shock to the system!

[@nk-dw2hm]

With the cold you can always put more layers on, there's only so much you can take off in the heat (especially when it's sunny)

[@fighterinmkiwiscience3517]

You are lil kid lol😂

[@jonl2938]

Come to North Bay, Ontario, Canada for a Parkrun next winter! The coldest I did was around -25… when you finish you are very, very frosty from breath freezing on you while you run. Much harder to breath as well, stings the lungs on big breaths. Then in the summer we get some insanely humid hot days, the warmest was around 30, plus humidity on top of that. The joys of continental climate!

[@juliae5639]

Loved this video! I live in Canada and ran during the winter up to -27C. I found as long as I dressed properly and it wasn’t windy then it was ok! However at +24 I start to struggle

[@matildami5943]

Funny reading through the comments as a Finn, as I definitely agree with all the Canadians saying the cold temperatures aren’t so bad! :D

[@scottbeesley894]

Super interesting, but as I’m sure all runners would agree, when you’re actually running outside you have the breeze “blowing” on you as you run through the air. This makes a huge difference in all temperatures vs the still air of a treadmill.

[@Tildamathi]

What a fascinating video! Love the more scientific content. Thank you to you both 🙏

[@ismovanutube]

I'm so happy to see this video. I moved to South Vietnam 6 years ago and took up running a year ago. It always makes me smile when I see people complaining about the temperatures being hot above 20 degrees. I have never ran in less than 26, but these days, before the rainy season starts, it's 32 at 4 in the morning with 100% humidity. Heat isn't the issue, humidity is the killer. In over an hour easy jog you sweat a liter. Not easy to stay in Zone 2 either, your heart is working hard to keep the body cool. But the upside is, training in the heat is similar to altitude training, so worth the sweat. The most important is to get electrolytes after. And don't need to drink unless it's more than an hour, given you're well hydrated. I almost always run fasted as well, so it's also important to eat after the run.

[@Jojo-eb1gi]

Whatever they are being paid they both need a raise for this! Great viewing - Sarah saying “I’m trying to keep the probe in” was a beautiful moment 😂😂😂

[@saukkima]

Thanks! Great video once again 👏🏻I definitely enjoy the cold more as I live in Finland. I can actually run quite comfortably in like -26°C. Of course the pace is low and must have multiple layers of clothing.

[@starky88]

Great video! I live in Australia yet perform much better in the cold! The heat drains me, makes me light headed when I run in it. I can run further and much more comfortably in the cold.

[@bjsmithart]

I’m definitely a cold weather runner. My heart rate skyrockets in the heat. Living on the south eastern coast of the US means the coming months are going to suck

[@suzyaustin6066]

Wow! Well done to you both this looked hard! The things you put yourself through for us! 😂 We greatly appreciate it.

[@craigrwc]

Great video! Lots of great takeaways from this. But were there any fans to simulate actually moving through the cold air? I felt like Mo's sweat in the cold wouldn't be like that running outside in sub-zero temps. Would love to see you all come do a winter race in Canada next winter! I'm sure lots of us would want to join you in that, too

[@Marktburgess]

Really interesting video. Living here in Peru I experience the heat during the summer here in Lima and especially when I run in the jungle, and also the cold in the mountains, (obviously altitude is also an issue with this). Really interesting how your data coincides with my perception when I run in the heat and the cold. The most interesting thing is that I have adapted over the years to living here and run much better in the heat of the jungle now than I did when I first went in 2008. I still love running and see a difference in my times when I come back to the UK. Thanks guys,

[@debrascott8775]

I love running in the cold. Great description of the cold leg skin but eventhing else is warm.

[@knittinggurl]

Love this. Ottawa Race Weekend (in Ontario Canada) just happened this past week which coincided with the 1st heatwave Ottawa has gotten this year. Honestly May 18th, there was an overnight frost advisory, and yesterday we had a heat warning! As a Canadian I do much better running in the cold than in the heat. It is amazing how well your body warms up once you get going. It's really fascinating to see what the temperature does to each individual. Now try running in -20 with a windchill of -30! I've definitely accidentally gone for a run in that before.... oops!

[@Jamieaverageaussierunner]

Thanks guys this was some quality content. I live in Brisbane Australia and work as a critical care nurse so I have to run at weird times throughout the day/night, over our summer I was often running in 32-35degree heats but with very high humidity! It can be brutal. Did they set specific humidity for this or was it dry? Found these studies pretty interesting. Fair play keeping that probe in situ 😂

[@st4331]

I'm in Thailand and we've been having a heatwave. Last Sunday it was 36C in the shade but 48C in the sun. I planned to do 10km, but stopped after 6.5 as my HR wouldn't stop drifting up! Went out again yesterday and it was a cooler 35C (in the shade), but it still felt like hard work. And yes, I take plenty of water! I'm looking forward to running in the UK when I'm back in a few weeks for a cool summer!

[@steven7169]

I was in Malaysia during that heat wave, absolutely savage! I think the humidity in South East Asia is what makes it so hard.

[@runningchannel]

Do you notice changes when you run at different temperatures? Should we go and take on an extreme marathon? Let us know in the comments!

[@tr3eehugg3r]

It’s extremely humid and hot where I live in the summer. (Over 85% humidity and 38 degrees C plus) I also feel like my form suffers in the heat. I do more treadmill runs in the summer but run outdoors during all the other seasons!

[@teresahungkey2289]

Oh yeah can't wait for the extreme marathon video!!! You are great ( all of you) by the way!!!

[@nk-dw2hm]

You forgot to pin this at the top, but heart rate goes through the roof for me when Temps go up. Would love to see someone do a long run/marathon in a subfreezing temp, then immediately fly to a hot location and do another.

[@AlwaysForwardRunning]

Love all of Sarahs remarks and her overall personality :) And Mo is just a Champ :)

[@wendydavan4979]

Sorry I can't get past the running with a thermometer up you know where. Good on you guys and thank you for the information it was very unexpected and interesting

[@ederlikessoccer]

Interesting how where we come from affect our present and how humans can adapt to a new environment. All it takes is time and training.

[@GlaucusBlue]

Great video, absolutely cold, I struggle with heat, dehydration and even heat stroke in summer. Cold, just can push harder and faster, and need less fluids, although fingers need about 3 layers of gloves.

[@separator94]

This was actually really interesting. Thanks for putting yourselves through torture for the running sciences! Personally, I can't stand running in the cold. I live in upstate NY, where half the year is cold, so I just use my treadmill during that time. There are a lot of days where it's between 20°F (-7°C) & 0°F (-18°C), and with the wind it feels considerably colder than that. Cold enough that your face feels like it's literally burning. Not to mention all the ice that's on the ground which is a constant hazard. In the summer it gets up to around 90°F (32°C) here and I don't mind it at all. As long as I'm well hydrated and wearing sunscreen, that is. Running at high temperatures indoors doesn't sound too fun but I'd definitely consider checking it out in the winter time. I'll have to look into if there are any places like that near me. Thanks again guys, for your dedication and constantly excellent content. It's both informative and motivating.

[@Running111]

Great idea for a video, very important topic to cover.🤔 In previous videos, I was addressing electrolytes (especially sodium) intake since I am running in the very hot climate during summer. Here in Montenegro average is 31° Celsius. I prefer hot weather since warming up is not such an issue.😅 Breathing is also easier. Dressing up is also much easier. You can stop running anywhere all wet and not risking to catch a cold. The only difficulty is managing water inatake, tricky part since water wash out electrolytes.

[@TheUnabridgedMe]

I am trying to start my running journey which I know will be difficult anyway but it will be made more challenging because I am currently in the Middle East where temperatures are already rising. They are already reaching 38oC with another ten to go during the summer season. Even running indoors on a treadmill will be difficult. I’m determined though, so it’s over to loads of water and building gradually whilst being ready to adapt when I need to. My wish is to go from zero to half marathon by January if the heat doesn’t derail me first. Thanks for the fab videos!!

[@nialltoh7338]

Love the video. There are different type of heat whether it is desert dry heat or rain forest humid heat. You don't sweat when running in Dubai heat and you feel less tired vs running in high humidity rain forest climate where you sweat bucket loads. There is the risk of heat stroke when running in heat too.

[@juliaincanada]

I feel like either temperature extreme is normal for running where I live. Running in minus 10 in the winter is pretty usual, but summer running in 25 in high humidity is also normal.

[@ericaainslee901]

Runner here from Winterpeg (Winnipeg) in Canada, where it regularly dips down to the -20's C . I think the coldest I've run outside is -35 with windchill. When dressed with the right gear, winter running is so refreshing!

[@PhiruzGo]

You are defiantly welcome to the island where I live, for a 'real life test' when it comes to HEAT, we just entered the hottest season of the year here in Koh Samui, Thailand. And the polluted northerly winds just went away so the sky is as lovely as it should be [all year around].

[@thomasc6127]

Oh yeah. We love those summer runs

[@rupertebery3252]

Did a fair bit of running summer just passed (in Australia) and relate strongly to your heat struggles.

[@aylaamon3267]

Cold weather for distance, definitely! I grew up in the American Midwest, and would routinely run when it was -25F. But, since getting older, I've noticed that I do short intensity (like 400s) better in the heat. I remember hearing something at a track meet once that sprinters like heat? What's the science behind that?

[@wheezy64]

Interesting challenge , well done team.

[@joelg4849]

Being in Australia i prefer the heat to run in. However the hottest race i competed in was 38°c by 10am. That was absolutely brutal.

[@daenathedreamy9053]

Wow, what a cool challenge! For extremes, I think I would go with cold, I prefer winter running (around zero degrees). Interestingly, I found out for myself that during winter long runs I need more fuel. Funny, that for the extreme heat you went with only 35 degrees. That’s been a normal summer here lately. I don’t love it, but I go for it rather than the detested treadmill. Next time, try 45 degreed!

[@anthonyhickling8867]

As long as I remember my winter kit, cold is fine. I had a cold snap up by Inverness this year which meant a couple of -10 C runs but fortunately no thermometers required

[@user-pf1bo3wv7t]

I live in Dubai so I definitely would do better in the heat! Amazing Mo doing that whilst fasting!

[@ayseaktalayhippchen8684]

I ran my 10k PB at -10°C. And took almost double the time at 37°C. Heat is definitely worse, but a huge part of the challenge was running under the hot bright sun. This laboratory experiment completely eliminates that part, which is very significant under real-life conditions.

[@Ultimaus]

I am actually really really acclimated to cold running despite being born in Malaysia I currently live in Canada and when the temperature is near even 15c my heart rate will be +20bpm from my base 8c heart rate. It would take me 3-4 runs of about 1 hour to average out. Weather conditions are a huge obstacle to overcome you can't train for all of it at once but you can work towards your specific goal race. I think all of the group agers trying to be competitive are usually trying to find every advantage they can get for their goals but this video was great for highlighting genetic differences in heat acclimations. Really neat data. Would love to see a fancy pants meta analysis on all the pros that run in a particular climate to see how the data differs.

[@wking8]

Cold weather is the best to run. I feel incredible. The heat, I shut down

[@stephenqueen6946]

Yep, summer running can be fun (pain) especially without lots of water like you didn't have! I think my first marathon was in ~30-35 here and I went through 6-8L of water in that time. No, it was not a PB.

[@nk-dw2hm]

It'd be interesting to hear more of a breakdown of the science and data, when talking about adaptation is that just how the core temp reacts in each climate or what else went into it?

[@nk-dw2hm]

I'm in the midwest US, where I'm the winter it gets to -60 at times. I usually don't run when it's below 0f/-20c, and now that spring is arriving we're hitting 75f/25c. Going to have to switch to biking only by the time it gets to 100+f/37+c

[@Melissa-hq9mp]

I don’t know how much better I do technically speaking, but I definitely feel better running in the heat. I feel much happier and stronger being crazy hot and sweating like crazy with a beet red face in the sun than I do when my feet, hands and nose is cold lol. Living in NB Canada we get weather ranging from -30C(or colder) to +30C (or warmer) through the year. As it is right now it’s currently 6C (feels like 2C) and I haven’t been able to convince myself to go for a run all week 😂 It would be very interesting if I could do one of these test haha.

[@DevonPixie1991]

Last 2 summers I struggled. So far this summer seems better. I think changes in medication have helped. Today the thing that slowed me down was being careful after I almost collapsed at parkrun on Saturday. I will go steady until I’ve had chance to confirm with a doctor if it’s safe to go full speed again. I had to huge heart rate spikes 30bpm faster for no reason and both times I felt unwell with the later one being enough to cause the collapsing incident. It was also one of the harder parkruns in the UK (in the top 5 as of 2023)

[@dougcsmith]

Without control of the dew point temperature, the air temperature means very little. I can comfortably run at 46°C in the Southern Nevada desert with a little breeze and a dew point below freezing. I do not feel hot or stressed and at 76 years old I can easily run for an hour or two as long as I drink 1/2 liter of flavored salt water per 15 minutes. I do not feel hot under these conditions!

[@debbie17]

I’m in Winnipeg Manitoba. Minus 30 in winter, plus 30 in summer. I love the heat, but my friends prefer the cold. 😊

[@rebeccametcalf4448]

🇨🇦 Canadian who loves the heat! I'll run in +30 C any day over the cold

[@agidomingo818]

just did my 34km trail in Thailand 2 weeks ago and it's 41 degrees outside! I am targetting a sub5 but you can't because the heat is unbearable. But I am happy I finished it. WIth all the 300 + participants in 34km 40+ are DNF

[@robertfarris7375]

Ok you guys win the "What is the wierdest thing you've ever done for your job" game. 😳

[@LauraTrauth]

Generally I like cold better but I have Reynauds which does make things challenging. I'm always in gloves up through the 50's F (10-15 C). But with the right ones, no problem running down to 0 F (-17 or 18 C). Wind it my nemesis though. Wearing glasses makes a balaklava or other face covering annoying. I can either have warm cheeks and nose OR I can see! If anyone knows a brand of winter face covering that doesn't cause glasses to fog, I'd love to know about it.

[@Kelly_Ben]

Same for both, Reynauds and glasses!

[@LevyPy]

35ºC and 70% relative humidity is normal in Rio de Janeuri in the summer, haha. Training here is difficult and a lot of people feel bad in races over 10 km. I prefer to run in the heat because I train that straight and in the cold it takes me longer to warm up and start performing well. But if the race starts after 06:30 AM it will probably get hot and very unpleasant weather. Today there was a marathon, it started at 05:30, but the weather cleared and at the end it was very hot.

[@geoffclarke3796]

I love hot sunny days with temperatures of 30C or more sitting in my garden with a cold beer or a G & T but I struggle running in hot weather and have performed poorly relative to other runners of similar ability to me on races on hot days. Have never run in temperatures much below freezing but I imagine it would be unpleasant expecially if combined with a significant wind chill. Optimum temperature for me is from 10 - 18C.

[@sundayrunday7586]

And now you know what it’s like to be a runner living in Alberta. Drops to -30 in the winter and up to +30 in the summer. Haha. I rarely run outside during either of those extremes.

[@ruthbrierley1798]

I used to live in Switzerland and ran through the Swiss winter with no probs. Now I live in the UAE and barely run outside in the summer, even before the sun comes up. I'm defo better in the cold.

[@mikestevenson1334]

Interesting results! I would much prefer the colder weather running, for sure =]

[@sundayrunday7586]

Me too. Especially -10. That’s comfortable, almost balmy, winter running where I live.

[@carlospagos89]

i hate the heat generally, not just in running terms. but i love running in the cold. i run in just shorts and tshirt and gloves until -3 then anything after that up until -8 is shorts and gloves and long shirt, havent ran in anything colder

[@sk8qbsk8]

Another Canuck here, def'ly prefer cold to hot weather running. My "ideal" temp is between 5-9C. Only thing i dislike w/ cooler temps is my nose wants to run like a faucet in the slightest bit of breeze. A handkerchief is part of my running kit at all times!

[@LauraTrauth]

Faucet nose temps for sure. I get gloves with snot patches and then just throw them in the wash after!

Interesting to see the graphs. As a Canadian, you will likely not be surprised to hear that I prefer colder temperatures. I think my favourite temperatures to run would be between 10 and 15C.

[@Dhoska]

@@thekatvita get a heat/moisture exchanger mask, they're amazing when running in lower temperatures, I use one that's called airtrim 😀

[@Dhoska]

@@thekatvita it's a little harder to breath than normal, depending which filter you use and you have to make a forceful exhale every once in a while to clear the filter from all the moisture so it doesn't freeze shut but it's 100 times better than cold lungs. I've been on 2 hour runs in -25C and it's great. Might look a little wierd running around in it but nobody is going to recognize you under that thing anyway lol

[@liamroche1473]

That's dedication. 😁

[@theunknown21329]

35°C is what I normally run in lol. Anything under 20°C feels what you feel at -10°C. Our bodies are crazy at adapting.

[@laurenaronson8289]

I live in south-central Ontario Canada and have extreme cold and hot running weather. I very much prefer colder running than the extreme heat. -10 is actually not too bad of you dress for it. 😊

[@skirtonbear1]

Wasn’t surprised. I do best in cold weather as I can’t control my core temperature with endometriosis making my heart hate the heat. But I don’t like the cold; just for running am I happy with cold weather. But Sacramento, California doesn’t get very cold. 🤷🏻‍♀️ Would love to run around London or somewhere in the UK.

[@andersstaffe1863]

I am for sure prefering to run in the cold. Still rember when I lived in Delhi. Even i ran all spring, and startet running at 0500 in the morning, it was very difficult to run when temperatures was abouve 35 degrees. It was 28 in the gym, and that felt ok. When monsoun hit, I had to walk home even the temperatur had dropped to around 30 degrees, when I was out for the first time.

[@CaptainBrash]

I really enjoy running in the hot and the cold. The rain im less keen on which is sucks as i live in Wales. xD Last year on that hottest day ever on record in the UK i took a day holiday and went for a long trail run

[@MattSwain1]

Tricky choice. I’ve cycled in the Alps when it was around 40 degrees C and was barely turning the pedals over in my easiest gear. Equally in the cold I struggle with my hands and feet but at least generally it’s just a matter of getting the right layers on so I guess I’d pick cold

[@JohnBirtchetSharpe]

I remember when being the younger bunch at the place of work just ment just getting the sandwiches and brew's 🤣.

[@karelnortier8283]

I had to train I the UAE during the summer and the heat and humidity was terrible 45 degrees and 67% humidity could not run more than 8km before I was dehydrated and started to cramp…cooler weather is definitely better.

[@84derbycounty]

Marathon des Sables or Death Valley Marathon then for Mo and UTMB for Sarah. Would also love to see Anna and Andy take on the cold at hot challenge at Brighton University.

[@hermeticallysealed]

that brings up something -- how do you pre-hydrate in the days leading up to a race/hard effort?

[@ismaelsaenz3914]

🎉❤ Sarah i kinda figured you would be more adapted to the cold running in the UK and all but i never would have gussed you were part polar bear😂. As for MO well he looked more heat acclimated and he also said he felt good in the chamber in the cold was a different story.😂 As for me? Well i have a summer marathon coming up in 6 weeks and 6 days right on the summer Solstice 88 degrees so these past few weeks i have been training my heart rate average was 141 on my last long run 5/1/23 been doing shorter runs 5ks at top speed most recent was May 3rd 19:52 in 80 degree weather stopped twice though😂 Anyway this is getting quite long so i will just inform you gonna do a long run today and will let you guys know how it turns out.

[@brannmacfinnchad9056]

Living in Alaska, much as I dislike it, running in the cold is definitely easier than the heat. My feet don't get cold while running, hands stay warmer, both compared to cycling in it. I think the coldest I've run in is around -20C, including estimated wind chill-- with hurricane force winds. I had a sheet of ice form up the windward side of my face. It's only 7c right now, and I'm wearing shorts and debating whether a shirt is necessary for runs. But cycling at 35c doesn't bother me at all.

[@medsuit1686]

Yesterday was the first hot day of sunshine here, had a treshold session. I wanted to give up on life after 15 minutes xD Ill take -10 over heat any day of the year please.

[@matthewcreelman1347]

Here in Canada, there are always at least a few days a year where running in extreme cold happens. I normally tap out at -20° C, but I ended up doing one run this winter at -25° C plus windchill. That was nasty. Even dressed for the cold, and used to the cold, and running at a five minute kilometre pace, I ended up having to cut the run short at five kilometres - my fingers felt like ice cubes.

[@alanshrimpton6787]

Prefer hot but have no problem with either but mainly because Auckland NZ doesn't really do hot or cold it does mild extremely well no matter what time of year.

[@runningchannel]

We would love to run in NZ Alan! 😁

[@Thegreat772]

Definitely prefer the cold! I was feeling it on that hot run

[@michaelmulligan0]

Can you give any advice on running in the current U.K./Ireland temperatures (that we aren’t really used to) and running when on (even warmer) holidays? Currently in week 9 of a 22 week marathon programme (and up to 14 miles)

[@T1MB05L1C3]

Well it's winter for about 6 months of the year where I live so I'll take anything above -5C I've done everything (realfeel/wind chill/heat index) from -40C to 45C

[@Ali94749]

Living in Tokyo I have run in 35 degrees a few times in summer. Its brutal.

[@gustavomendieta]

A video on running in high altitude would be interesting.

[@SchvennMeister]

Pshaw. -10C is perfectly comfortable for us Canadians. We don't like it and I'm the first person to complain that it's not +20 all year long, but still -10C is not cold. That's just "brisk". -25C is "cold". 35C however, is brutal for running and I do better in cold. I just don't like it. Interesting rebranding. I preferred the old one, because it was more obvious, but the colour scheme of the shirts is cool.

[@amandalucas79]

To echo some others, as a person born and raised in Canada, and Western European by ancestry - it is no shocker that I prefer the cold. -10C in the winter is quite a pleasant temperature I think, I’ve done as cold as -20C and that starts to be a bit more tricky. Anything above 15C and I turn into a complete wimp 🥵

[@bobmob1837]

I try not to run when its under -16 C but it’s more about the fact that my knees hurt after rather than being uncomfortable in the cold. Cold weather is fun i think but the layers of clothing…annoying!

[@SebastianSonntag]

I definitely prefer running in colder temperatures, and I've never, ever felt too cold during a run. I've done winter trail runs at -25°C in the Austrian alps in shorts and a t-shirt. I'd estimate that for a given effort I get about 1% faster with every degree Celsius temperature drop.

[@andrewmcalister3462]

Thanks Mo and Sarah for really putting yourselves in the suffer box for this video. 🥵🥶

[@jimcrants7517]

I'm writing from Minnesota, and I've run at both of those extremes (and down to -25 C once, but probably never again). I feel like the humidity is critical. At 45% humidity, 35 C is comfortable. On the other hand, much below -10 C, and my lungs get too irritated by the aridity, and it's not worth running. There is no such thing as a humid -15.

[@arranlinton-smith1145]

I'm comfortable up to 20oC and then any long run over that temperature is a massive challenge!

[@RosieOutdoors]

I definitely prefer colder weather over warmer weather - I get warm so quickly.

[@davidha8389]

-10C is not very cold, but I live in the upper Midwest in the USA. Prefer -10C to 35C any day of the week. Would also prefer -10C to 27C as well.

[@runningchannel]

What temperature do you tend to run in David?

[@Veroweithofer]

I live in Chicago and both extremes are normal for us. I am careful though at both ends.

[@godanswers]

Writing from Singapore where I do most of my runs in the mornings/evenings when it's around 28degC. I'm running the Revel Big Bear Marathon in USA where the race day temperature last year was 6-20degC. How should I adjust my training or racing for this? Thanks!

[@prattoychanda3322]

When I saw 35 degrees C I started laughing. Then I realised they were serious. Here in Bangladesh average temperatures in summer is 37 and super humid.

[@AlexG-kb6ny]

I would much rather run in cold weather than hot. I have ran in negativities temperatures up to -11 for months. It’s fine provided you have warm gear and it’s not windy. Wind does change it a lot.

[@benjaminkuch2558]

8 years ago I ran a 400m race at like 39°C. I actually ran a PB at that time 😅