rumrunn6

gym membership

KraneXL

It does, but the body also has its limits. You can ride in the full summer sun (I used to ride to work from the gym and it was a miserable experience), if you want to harden up for some reason. But you certainly won't go as fast nor as long.

jefnvk

It was 92F here yesterday. I didn't want to go out, but I really need to do some adjustments on my bike for a tour next week and it has been this hot for days now. I made it 10 miles, with a break at an air conditioned brewery halfway, and returned with a jersey that I could literally wring out and most of my 20oz water bottle missing.

Just be careful what you do.

rumrunn6

I did that one time but made the mistake of having the chili with the beer

SylvainG

Temperature yesterday was 35C (it's been like that since last Friday) with a heat index of 44C on my commute back from work (20km), What I did is before taking a sip of water, instead of cleansing the water bottle sprout by squirting some water on the ground, I would squirt it over my helmet. That icy cold water (well, for about 30 minutes anyway), did feel good If I were to ride earlier in the afternoon when the sun is at its azimuth, I would wear my white sun sleeves and wet them from time to time to help cooling off.

vja4Him

I have lived in California, Central Valley, for over 30 years, and still have not gotten used to the terrible heat !!! I get heat and sun stroke very easily, so I must be very careful and cover up completely. I have lost most of my pigments, so sunscreen does not do any good. Even walking only short distances makes me dizzy. I also have high blood pressure and other health issues.

livedarklions

I just did a 110 mile ride on July 4, 50 miles in the relative cool of the morning, the last 60 in the mid-90s. Didn't do too bad, frequent breaks in air conditioning, lots and lots of water, and several gears down from my normal ones. I also ate a big meal at my favorite bbq place about 80 miles into the ride, but I'm weird that way. I do think the salt in that meal helped, and as always I suffered no ill effects from eating big during the ride.

That's a definite "don't try this at home" kind of story--I know my riding/meal habits are freakish.

Skipjacks

You can't safely go out and just deal with the heat if you're not used to it. You just can't.

You can't wake up one morning and hydrate by drinking a lot of water then go sweat like crazy. That will lead to heat stroke.

But you can safely deal with heat if you plan for it in advance and get used to it.

First off you need to acclimate to the heat. Your body, as a human, can acclimate to anything from the rain forest to the arctic circle. It just takes time to adjust. So if the temperate is normally 80 and it spikes to 100 for a day, you can't acclimate to that. If it's 100 all summer, just spend more and more time outside per day and you'll get used to it.

Second, hydration. You cannot hydrate quickly. You need to properly hydrate the day before going out in hot conditions. Water in your digestive track isn't doing anything fro you. You need it throughout your body and it takes time to get into all your internals. Once you are properly hydrated and sweat out the water, new water you drink will flush into the system much faster to help you stay hydrated. But you cannot be under hydrated and just start drinking a lot once you're already hot.

Third, heat is heat. Everyone say a dry heat is easier to deal with. Wrong. A dry heat is much more comfortable because you're not wet and sticky and gross. But a dry heat will suck the water right out of your body and it's much more important to replenish it with more water. You sweat just as much, you just don't realize it. Meanwhile a wet soppy humid heat with high air pressure will make you sweat buckets too. It's more gross because you're a sweaty smelly sticky mess. You won't dehydrate as fast, but it'll still happen. And the humidity causes other issues with breathing that restricts airflow to your cells because you're not a fish and can't breath water. So while dehydration is still a serious risk, heart attacks and heat stroke are big too.

Fourth, pace yourself. You're not on American Ninja Warrior. There are no prizes on the line. If you feel like you're overheating, stop and rest. Take a 10 minute breather. Or an hour. Don't forget to let your body reset a little. If you feel like you're dangerously hot, don't second guess yourself. Assume you are and rest. Biking is awesome, but it's not worth dying for.

Fifth, if it's miserable and you hate being this hot, don't be. You'll just make yourself hate biking, or walking, or whatever else you do. These things are supposed to be fun. Don't make yourself hate them.

KD5NRH

What, 87F daytime highs? It's still that hot here at 9:30PM. Grow a pair, stop screwing around with that pansy metric crap and go ride.

vja4Him

Where I'm from (Oregon) … 80 degrees is killer heat to many people … !!! After 30 years living in this terrible California heat, I'm still not used to the hot weather. I try to stay out of the sun, but can't get away from the heat. When cycling I wear a heavy-wet towel over my head, under my cap and cycling helmet.

u235

That is not totally correct. The evaporation of the sweat is what cools you. You sweat because your body is trying to use that evaporation to cool itself. If your sweat is not evaporating as rapidly like in higher humidity or you are standing still, you will have reduced cooling and if your body is still hot, it will sweat more to compensate. The heat index number attempts to give a standard "temperature" it feels like or the human-perceived equivalent temperature that takes into consideration the relative humidity (but not factors like wind/cloud cover). That heat index number is still not perfect for cyclists because you are usually moving adding a wind chill factor. 100F is still hot but it would be much worse if its 100F and 65% humidity compared to 35% humidity. In the end.. Dry or not.. If +-10 degrees heat index or actual temperature is the difference between you feeling ill or getting heat stress or heat stroke.. you should have slowed down anyway.

wphamilton

90° or even close to 90 is a killer heat wave in the UK. We'll see news reports of people dying because they don't have air conditioning, so I'd take it seriously. You can't just fill up on water, put a towel on your head and got out for a hard workout, not unless you're acclimated to it. Or maybe were, at one point, and can adapt quickly. Once you're used to it, it's no big deal and doesn't require any special preparation or practices.

livedarklions

I'll agree with fourth and fifth, but there's way too much nonsense in second and third to let go. Your body absorbs water quite rapidly, and is designed to regulate fluid balance within a fairly narrow range. Your kidneys are working constantly to eliminate any excess fluid. If you drink more than you need, you just end up urinating more. Thus, what you drink the day before really won't matter as long as you hydrate the morning of your hot work out. Unless you get up a lot in the night, it is normal to wake up a little dehydrated, and that's going to be true whether or not you overhydrate the day before. Research suggests that you should be ok if you make up this dehydration 45 minutes or more before you work out. https://breakingmuscle.com/healthy-eating/how-long-does-it-take-to-get-hydrated . It's important in hot conditions to keep drinking because of the excess sweating, but you can overdo it, especially if you're not also replacing the electrolytes you're sweating out as well.
Another poster pointed out that the stuff you have in there about dry heat doesn't account for how much more effective sweating is as a heat regulator in dry conditions, but I also think nonsense about humidity causing breathing problems shouldn't go unanswered. No matter how humid it is outside, unless you're actually under water, the air you're breathing in is going to be far less humid than what you are breathing out. That's because your lungs are where blood meets oxygen. Some of the water in blood evaporates in this transaction, and thus you can fog a mirror with your breath even on the most humid or dry of days. Depending on weather, humid air may have more pollen and/or pollution than dry air, and those can cause breathing problems, but the idea that the water in humid air is somehow cutting off oxygen to cells is utter nonsense.

KraneXL

Well he stated a contradiction then corrected it...kinda. In any event, the heat index is suppose to make up for the various discontinuities associated with various types of heat but in the end, makes little sense since there's no standard as to what a temperature at a specified humidity feels like.<br /><br />

For example, who makes that determination? Scientist? Athletes? A random sample of the population? Old white men? I've always found it perplexing when a weather caster says its 90 degrees, but it "feels like" 110? As compared to what?

wphamilton

Compared to a heat index of 90

Seriously, it's because evaporative cooling is less effective the higher the humidity, nothing more mysterious than that. The National Weather Service has a brief explanation of the science https://www.weather.gov/ama/heatindex

Rollfast

When it's really hot those who know I ride are pretty helpful with keeping my bottle filled with water, and it's about 750 mL. I also keep track of where to get it filled on the way. If nothing else works there is the hospital fountain and a kitchen sink next to the coffee at the ER and the drinking fountain at the grocery store.

If I have enough money I'll stop and get diet Dew in there now and then

KraneXL

Except that you may not feel what I feel. How much more? Some like it hot.Back to Square One: That's not science.

Rollfast

80 degrees is a warm, rundown apartment. In December. Feels GOOD.

wphamilton

If you say so I won't try to dissuade you, but I believe that the National Weather Service formula, based on work by scientists of the NOAA, is indeed science.

It's not about what you "feel" per se, btw - it's about thermodynamics. "How it feels" is just the easy way to explain the effect to non-scientists (ie, most of us).

livedarklions

I saw in the bike helmet thread that you're a neurologist--any idea how this adaptation process occurs? Are there physiological changes? Is it true that once you have a heat stroke, your ability to deal with hot weather is permanently impaired?

Thanks!

wphamilton

Not even close to a neurologist, sorry. I am a software engineer and data scientist, so I couldn't even begin to describe how the adaptation occurs.

livedarklions

It's just a measure of whether heat is going to be transferred from your skin to the ambient air or vice verse, and how efficiently. That can be determined objectively by formula. How you react to that transfer is not determined by that formula. Different people will react to the same transfer differently, but it's still the same transfer.

As a thin person, I respond much better to 100 degrees than I did when I was a fat prson. It's still 100 degrees objectively. The same would be true of heat index numbers.

Question for somebody who actually knows stuff--doesn't the heat index have to assume a "normal" level of humidity as the basis for comparison to the scale?

livedarklions

Whoops! I got my data scientist mixed up with my neurologist in the MIPS discussion.

MoAlpha

Given the characteristic nerdiness of both professions and the partial effectiveness of many treatments in neurology, you might never notice the error. I have been mainly a lab geek for the last decade and what I know of heat-related illness and I learned from reading outdoor medicine related to my other manly pursuits.

That said, heat stroke is a syndrome occurring when body temp gets above about a nominal 40º C (104º F) from environmental heating. The number seems a bit arbitrary, since healthy marathoners have shown core temps as high as 108 after finishing and you certainly wouldn't hesitate to treat . Anyway, in heat stroke, there are physical changes to cellular proteins and membranes which impair function and trigger a diffuse inflammatory response, which leads to collapse of the circulation and organ damage and, paradoxically, fever. This often happens in the face of dehydration and electrolye depletion making the cascade faster and more devastating. Heat exhaustion essentially is a milder version of the above, but may not be readily distinguishable in the field. Anyway, assuming you survive, which the majority of exercise-induced cases will, yeah, you should be careful out there. For instance, you might lose a lot of the excess kidney capacity that gives most of us a cushion against various insults.

Heat acclimation, as I understand it, is a functional shift in the cardiovascular system and kidney to maintain a higher blood volume and for the skin glands to sweat, more, earlier, and more dilutely. All of these things decrease susceptibility to heat-related illness. There have to be other changes, but those are the main ones.

livedarklions

There you are!

It's amazing how fast that acclimation happens. I took a really long ride during an early hot spell in April where the temps reached the upper 80s, and swore I'd never do that again, but on the 4th last week, I rode a century in 95 degree heat (with AC breaks, of course), and really didn't feel bad at all. I kind of thought my skin seemed less salty and nasty after the 4th, now I'm pretty sure of it.

Thanks for the explanation. Sorry for getting you two mixed up.