Gramercy

Last night was the first time I rode in semi-warm weather with a HR monitor on. The temp was in the low 80's but humid when I started out. Doing a sustained effort I'll usually get my heart rate into the upper 160's or low 170's if I'm pushing it (this isn't a race pace, but just working hard). Last night while riding with someone I could barely hold their wheel and my heart rate was in the mid 180's for about 3 minutes before my body felt like it was shutting down. After that I only did smaller efforts but my heart rate still jumped up to about 180bpm, so about 10bpm higher than usual.

I assume drinking very cold water helps, and I know that the pro's get ice in a sock and put it under their jersey close to their neck - does this help cool the body enough to lower one's heart rate? If I'm racing or riding in warm weather, I feel like I'll get dropped by others if my body isn't efficient. Is the only way to get used to the weather to ride more in it? Can I do something else to keep my heart rate down or is this just natural?

kleng

I think this explains the increased heart rate in hot and humid conditions

Heat and exercise: Keeping cool in hot weather - Mayo Clinic

noglider 

I'm not convinced you need to drink cold water, though I don't know. All I know is that you have to drink a sufficient quantity of water. Look at athletes who do day-long events without cold water available.

When I get inside, I do put ice in my water to help cool down, but I don't think it's necessary for my health, just for my comfort. And I'm done exercising by then.

Kopsis

Everyone you're riding/racing with is dealing with the same thing. Just like altitude, you have to train for the conditions you'll be riding in if you want your body to adapt. If you don't live in a place that routinely subjects you to higher temps, you may want to spend some time on a stationary trainer where you can limit the amount of cooling (just make sure the puddles of sweat on the floor won't be a problem ).

OldsCOOL

I call it, "heat acclimation". Ride in it or sit home in the shade. Pay attention to hydration and slow down. You get used to it sooner or later.

achoo

Drinking cold water or holding an ice pack against yourself might make you feel better for a bit, but it really won't make much difference while you're still riding. Your body simply has to dump too much heat. Your body is something like 20-30% efficient, which means that it needs to dump about three times as much energy as heat compared to the amount of energy used to generate motion. Put 200W of power into your pedals and your body has to dump about 600W worth of heat - that's the heat put out by SIX 100W incandescent light bulbs. Maybe if your metabolism is really efficient you only have to dump FOUR 100W bulbs worth of heat.

IIRC, HR is affected by temperature, so that's one factor. HR will also increase as you get dehydrated, which is more likely to happen when it's warmer. Fitness also matters. The fitter you are, the less your HR will drift up during a workout.

gsa103

The heat capacity of water is ~4.2 J/(g*K). 1 L of water is 1 kg. Drinking a liter of water at 5 C and raising it to body temperature (37 C) requires 134 kJ of energy. Equivalently, that much heat reduces your body (75 kg of basically water) temperature by ~0.4 C. If you drink a bottle of cold water you can lower your body temperature by about 1 deg F. That's a huge difference, since the body temperature typically keeps a very narrow range.

While you don't need to drink cold water, if you have it available it makes a big difference.

Also, even professional riders can over heat if its too hot. Here's an exerpt from an interview with Jens.
Jens Voigt Interview: California Dreaming | Trek Factory Racing

schiiism

You might already be aware, but these insulated bottles are awesome for keeping your water cold for longer:

CamelBak | PODIUM BIG CHILL 25 oz Insulated Water Bottle for Cycling

They do hold less water than their non-insulated counterparts so I wouldn't use it when it's not needed

Looigi

Yes. Blood flow is increased to help transfer heat from your core your skin where it can be dissipated so heart rate goes up accordingly.

noglider 

That's what I'm trying to say. Drink it if you can. If you don't have it, drink what you have.

Thank you for the detailed information, too. It is helpful and interesting.

StanSeven

Let me guess - you were a liberal arts major in college

noglider 

Darth Steele

I have two of these..and they don't work.. 30-45 minutes into your ride and the water temperature is the same as the ambient air, maybe slightly cooler.

but I have never noticed that the water is "cold"

Darth Steele

My concern is keeping salt/waste product produced from sweat off of my skin, allowing my skin to do it's job without being inhibited. Usually I have a lot of crystallized salt all over my face and riding kit.

It is essential to continuously replace lost sodium and potassium while riding

achoo

1. If your body is dumping 500+W of heat because you're putting out an average of 200W while riding, that 134kJ will be moot in a bit over 4 minutes. Just like I said earlier, it'll make you feel better for a while, but it won't make much difference.

2. Good luck keeping your water at 5C while riding in 35C temperatures.

3. Good luck drinking a full liter of water fast enough for the mass of water to have an appreciable effect on your core temperature.

achoo

Not really essential to do it continuously - or even continually - while you're riding.

Unless you're going for a long ride, then yeah.

But for an hour or two? Plain water will work for normal people, even if you're going hard.

bowzette

Agreed and if it is really humid it is much harder as there is little to no evaporation and it is difficult to cool from sweating. Just take it easy and give yourself time to adapt.

gsa103

The cast majority of your cooling is convection & evaporation, I agree. What cold water helps with is adjusting the balance. Given that you body temperature is basically fixed, the small 1-2 deg F rise in body temperature makes virtually no difference to your cooling rates. This is especially true once you've achieved saturation with sweat. Sweating more doesn't help.

Let's say, you're dumping 500W of heat, but only able to cool 450 W. That 134 kJ is enough to keep you balanced for 45 min of riding. You don't need to drink it all at once, the important thing is that it does have meaningful effect on keeping your core temperature down.

bikepro

Absolutely correct. When riding in the heat, your body also used more energy to regulate your core temperature, consequently, you need to eat more.

bikepro

Some people, myself included, loose a lot of sodium when they sweat. It also shows up as yellow sweat stains. I always use an electrolyte, such as NUUN, when riding in the heat.

TrojanHorse

I have about 6 of 'em and they're great. They're not smaller though - 25oz is 25oz, the bottle is slightly larger to accommodate the insulation.

Anyway, I fill my first one half way with ice and the second one all the way with ice and top off with water and they stay cold for 2.5 hours. My son's frame is too small for these, so he stuffs his regular bottles with ice and they're melted and warm long before mine. YMMV.

FLvector

For rides less than 40 miles I usually just drink water. Beyond that I'll supplement.

I don't usually notice a build up of salt on my skin during the summer months since the sweat is usually flowing too fast. During the other times of year in FL when the temps and humidity are lower, then I'll notice the salt on the skin and kit as the sweat is more likely to evaporate. I'd suspect this will be different for riders in other climates. I don't get concerned about the salt on my skin, but does make me want to hop in the shower sooner. I agree with the comments about getting acclimated to hot and humid conditions. Your body gets used to it. I do enjoy a cold drink during a hot ride, but I believe the cooling effects on the core are very temporary. Pour cold water over your head and body/jersey makes a bigger difference.

kleng

have you tried freezing one of your bottles instead of using just ice, it would have melted by the time you need it, giving a very cold drink in about an hour depending on the temp.

Campag4life

Freezing a plastic water bottle can cause it to crack but there is also a bigger issue. Drinking very cold water on a hot ride for those with normal versus buck teeth can cause a tooth ache. Studies have shown that riders with a tooth ache will ride slower than the same rider without a tooth ache riding in elevated temperatures. This is not widely known among the general cycling population but most tooth fairies learn this in their training.

OldsCOOL

I put icecubes in mine.