Cycling in hot and humid environment
 

How to deal better with this?
I was cycling many times at 36 C temperature with just a little discomfort, when air humidity was normal. But cycling at only 31-33 C with high air humidity is a real pain, 10-20% less efficient and unjustified high heart rate. Hydration is not an issue, with almost two liters of liquid with minerals for 2 hours.
I am just wondering how pros are dealing with this, since I never heard about failing a race due to warm air and high humidity.

Need more fluids because sweat is less effective. Watch the pros in these conditions, they will get ice packs from the team car sometimes.

Acclimate, hydrate, replace sodium, ride conservatively. Other than active cooling, there is literally nothing else to do.

The Real Science of Sport podcast covered this. Pros are getting the right hydration and will do heat acclimatization training, but that's not what separates them from amateurs. You'll still see pros dunking water over their heads and putting ice packs behind their necks, but their fitness gives them a lot more headroom on the thermometer before they suffer as much as amateurs do.

I think acclimation is the key. If you aren't prepared it's going to suck a lot more.
And of course drink and eat.

Excellent point. I can’t find a quick number for how much the heat response expands the vascular space that the heart has to pump blood through, but it’s big and you need big reserves to perform under those conditions, especially with the inevitable volume loss due to sweating.

I was out on a very hot ride a couple weeks ago, and another rider put a handful of ice cubes down the back of my jersey neck. With a snug jersey, the ice just kind of sat there between my shoulder blades and cooled me for a little while. It was a neat trick that I'd never known about before that day.

I think it was RacerEx who posted some data about using an ice vest on a trainer, and even outside. Of course I don't remember any of it but it was obvious how it made a difference in performance.

I have an absorbent wrap that cools the neck vessels by evaporation. Never tried it on the bike, but it certainly works on the boat. Just feels a bit clammy.

I add electrolytes to my bottles to help. Anyone racing in high temps and humidity will be doing this; adding SiS Go! or something similar to their water.

Where I live now it isn't too bad, humidity is not high albeit temperatures can get over 40C in peak Summer. Where I used to live, in Durban, South Africa, it is both hot and humid so we used ice - placed cubes in our bottles.


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Go out very early in the morning before it gets hot.

It's something you do have to get use too. High humidity and high temps do sap my energy more noticeably. But not to be left out for seriousness, being in a hot dry climate might also leave you not realizing how bad you are until you are really bad off and very dehydrated.

Humidity over 90% on days at 90 - 95°F (32 - 35°C) does immediately feels worse than even 100°F at just 60% humidity. But with the higher humidity it seems I always know that I need to drink more and search for ways to stay cool. With high temps in low humidity, I sometimes find I don't hydrate as well as I should and also don't realize when my body is way too hot until it's almost too late.

What I learned on summer vacation:
 

Ride Across Indiana (RAIN) in 2019 kicked my tail, heat index 100-105 from 10 am to 7 pm or later, and the ride is 165 miles long.
Ride Across Wisconsin (RAW) in 2019 found me bonking at 183 miles. Cramps and generally bad.

Before 2021: 1 century a year, maybe. 2-3 metrics, and when I rode in 90+ degrees, I took 2 water bottles and limited myself to 55 miles or so.
I knew what didn't work: alcohol consumption, water only, not pacing, and too long at rest stops.
As a former consistently 2:30-2:40 marathoner, I only drank water. I thought I was good. NOT.

2021: 16 centuries in 11 states, including Hotter'N Hell Hundred in Texas, a 228-miler (RAW) and training rides from 50 to 150 miles, in the heat of the summer.

When planning 2021, we asked advice from 3 cyclists, all over 60 or pushing 60, who were stronger than us.
They'd had heart issues, cancer, etc. Tough as nails. Myself: 1 minor heart attack and a minor stroke.

They were all about:
1-Consistent daily hydration: water, tea, non-sugary stuff. None drank sodas or sugary drinks.
2-Moderate alcohol at the most, moderate caffeine at the most.
3-Preparation and staying ahead of the hydration curve on rides.

We formed a group and planned for our 228-miler by riding in the heat all summer, establishing a routine and getting to know each other's style and being able to spot any issues. We also practiced 2-minute pulls in a pace line, ride etiquette, and communicating. In the heat, good habits help a lot.

Pre-ride hydration:
No alcohol within 2 days.
1 hour before: a concentrated hydration drink. Some used Hammer products only, some used other brands. I used Skratch Hyper (sea-water!).

Ride hydration:
First two bottles, sort of keep the prep hydration going. I used 50/50 Beta Red and Skratch (regular). Stay ahead of the curve. Others used their preferred brands.
Every bottle thereafter included a product, be it Nuun, Hammer, Fizz, DripDrop (which we all liked the best). I've since switched to Ultimate.
10-mile maximum gaps between "cheers!" reminders. 1 bottle per 20 miles became about the standard, and we timed stops to find stores, etc with ice/water. Carried our products.

Recovery hydration:
Low-fat chocolate milk or ice tea with honey.
We did drink alcohol after, but that buzz came cheap.
We simply avoided sugar pretty much all the time, very moderate on caffeine and alcohol.

We did several centuries above 90 degrees, one above 100. We were fine. We did a 100/100 3 weeks before the double, and 150 2 weeks before, both weekend in the upper 90's. The hydration scheme worked well. Each was left to their own on clothing, caps, sleeves, etc, but the sun is not your friend for those kind of miles. I switched from Chamois Butter to Diznutz for it's ability to withstand sweat, and I switched from padded saddles to straight carbon for the ability to move around. Others did what was comfortable for them.

Results: No cramping, no bonking across the group. Plenty of PR's in the group on 100's and even metrics, Climbing PR's, etc etc.
Exception: don't give blood on Tuesday and do a 8,000' century on Saturday, or follow that with a 9,000' century in 90-degrees the next Saturday.

The mileage paid off. One member didn't want to do more than a couple 100-milers before the 228. He didn't do the back-back weekend or the 150, preferring a different regimen. He weakened considerably at about 165, but due to his hydration routine, actually recovered well by 185 and we were good to the end. His hydration helped him overcome his mileage deficiency.

Hotter'n Hell Hundred: Easy-peasey, and really, it only got to 100 during the last half, just the 90's in the first half.

All I can say is that it was a great time from May to September, and consistently planning and carrying out the routine made it doable.

Your results may vary, but when I go out now, over 50 miles, I pre-hydrate and keep at it.

Wearing jersey you can unzip all the way down will help a lot.

Pacing will matter more for long rides in hot and humid. This could mean slowing down a bit. Don't expect to push as hard as you can on much lower temperatures or you'll overheat and possibly get heatstroke.

In Atlanta - part of the Sweat Belt - we either deal with high temps and high humidity or wait 'til October to ride. I agree with beng1 - the simplest and most effective solution is to just ride early in the morning. The past two weeks saw temps near or over 100 with high humidity. But at 6am, the temps were in the mid- to upper 60s. My club rides at 6am during the week. On weekends, we start at 7 or 7:30 depending on the expected noon temp. Even down here, it's rarely above the upper 80s by noon.

I did the Battle of Atlanta (Peachtree 10K) that year it was 100+
Not the finest hour for anyone, or even half-hour.

Electrolyte requirement — especially sodium — goes way up on long and hot rides.

The last time I did Climb to Kaiser was on the hottest day of the year, in an already hot part of California. My computer recorded 120F near the end of the ride.

My ride time was a little under 9 hours, and even though I was drinking Gatorade from the aid stations, it wasn't enough. I ended up in the Clovis emergency department with hyponatremia. Unpleasant and dangerous.

I remember that story. I think you said you got a little relief from eating the salt on your skin? One of my club mates did RAAM solo for the first time when he was about 60 and suffered hyponatremia and had to be hospitalized. He gained about 15 pounds of water weight and couldn't put his shoes on. DNF.

The next year he came back and became the first over 60 finisher in the race. He learned a lot by failing.

I wish I could ride in warmer weather but I’m extremely prone to heat related issues. Below freezing doesn’t bother me near as much at triple digits.

What I found works best when temps are over 100F and humidity is high? Slow way down.

When I did the TransAm Bike Race, it was 100-120F but dry in the West and low 100F with super high humidity towards Mississippi and Ohio River areas. There is no way to shed all the heat from riding hard in humid conditions. Conduction and convection are useless with those conditions. Radiational cooling work in the dark. Evaporative cooling is basically all you have unless you use ice and in hot humid conditions, evaporation is more limited than say out West with low humidity air. It is also very hard to replace all of your fluids riding in very hot and dry conditions for 12-16 hours per day but it can be done. If you're skinny and acclimated, you can ride harder than unacclimated and chubby in humid temps but eventually your core is going to get hot. I found riding slower worked fine.

While virtually all heat casualties are hyponatremic to some extent, this kind of "normal" sodium deficiency has to be distinguished from water intoxication, which is what it sounds like your friend had. Drinking too much during hot weather exercise may seem unlikely, but it's a significant danger and can be deadly. Unfortunately, data I've seen suggest no reduction of risk from consumption of sports drinks instead of plain water. I still suspect sodium supplemented drinks help, but the observational data available don't pick up the signal for some reason.

There have been a number of deaths at the L.A. Marathon attributed to hyponatremia. These have typically been people who are relatively untrained and had spent upwards of 5 hours on course, likely guzzling water and nothing else.

I've felt that as long as I continue to eat as well as drink lots of water I should be protected and I am more likely to dehydrate than over-water. I've suffered terrible nausea on a few hot climbing rides and hope to not repeat that.

You remember correctly. I was throwing up every few minutes, so I couldn't take in any salt. I was alone in a wheelchair in the hallway of the Clovis Emergency Department for hours (waiting room was full), so I started licking my arms.

After about 1/2 hour of arm licking, the vomiting stopped and I was able to lift my head, so I left. Never saw a doctor. I was fine by the next day.

Lesson learned.

Dehydration is inevitable and tolerable to a degree. Water intoxication is not. You’re an old dog and know what you’re doing.

Woof woof!