It’s getting to be super hot on my long rides lately - usually 80ish at the start of a 4-5hr ride and we’re mid 90s by the end. 80%+ humidity
ive been noticing that late in these rides I just stop sweating.
I’m usually a heavy sweater (~2L / hour) and I drink a lot compared to my friends (incl 500g+ sodium)… but late in most hot rides (3ish hours? 4ish?) I feel like my sweat just stops, it gets harder for me to eat / drink and then my performance craters
Seems like the only thing that works is to just stop, drink a bunch of cold fluids and then limp home.
We’re into +105f “feels like†temps now here in SE Texas. I’ve been in similar situations as you. Just on Friday I tried to do an hour ride followed by an hour run, both z2. I hit the same thing after 30 mins into the run.
For me, it’s totally fluids and sodium - not enough of either. I’ve been using the Saturday app (I have no financial benefit by mentioning it) from Dr. Alex Harrison and the over heating events have dropped tremendously. It happens every couple of weeks now (like Friday), but it’s a lot better than two or three times a week. It’s especially helpful to me on threshold and VO2Max days.
Part of that is probably your body shutting down your effort so you down heatstroke out. You can improve some of that with training in heat but exercise caution as weee not invincible.
Obviously you’ll sweat less when your power drops a lot. It’s likely more of this than poor sweating first leading to the power drop.
Have you ever had your salt loss tested/measured. You may find you are losing far more than 500mg per hour, and could be 3-5x times that amount (I tested at 2965mg/hr in a lab running). Without salt, you cannot absorb water, etc so I would look there.
The problem with 4 hour bike rides is that you can never take enough fluids with you. If you are in a race there’s fluids available, on longer races, every twenty minutes, so there’s the clue. For me it’s 3 bottles an hour and even then salts and other things start to deplete. You literally need to pull a buggy behind you for what’s needed. I have tried doing loops and having additional fluids in my car, but let’s face it, that’s boring. But that’s reality.
Like they said in a movie many years ago “We’re gonna need bigger bottles”.
you dont mention how much you are drinking but here in penticton, bc, in the heat of the summer…i suggested rider to not ride longer then 2h before stoping for full refuelling. Most rider should be in the range of 2 full bottle a hour in those condition if not more and it mean frequent stop are needed.
but as long as we make frequent stops for refulling bottles… it s managable.
you dont mention how much you are drinking but here in penticton, bc, in the heat of the summer…i suggested rider to not ride longer then 2h before stoping for full refuelling. Most rider should be in the range of 2 full bottle a hour in those condition if not more and it mean frequent stop are needed.
but as long as we make frequent stops for refulling bottles… it s managable.
I also recommend freezing them in the heat of the summer… it allow for a little more cold drink and that can be a welcome element in the crazy heat!!!
when we do group ride…we often stash some bag of frozen bottle and ice somewhere along our route so everyone as easiest access to fluid in more remote places. You really need to make good planning in those conditions.
in my years as a professional, me and drtommy would stash case of 24 cans of coke in the river under rocks so we would have a full summer of cold drink waiting for us in one of the remote location of the ironman canada course… it was awesome to get there…put your head in cold water and grab a cold drink!
But my personal symptoms from the few time I’ve had what I’m pretty sure was the onset of heat exhaustion, are a sudden big drop power output, disinterest in food/drink. I kinda just want to lay down in the shade for a while - which is what I do. And I think the body starts to have disordered response to heat, e.g. disruptions in sweating, etc. For me this was mostly in the Anza Borrego desert at 110F+, but could cerainly happen at lower temperatures as well.
Camelbak bladders freeze well too (just leave a little slack for ice expansion while it freezes). Salt capsules are an easy way to take in extra sodium if your current methods aren’t giving you enough.
Right now, temperatures go from about 75 to upper 80s throughout a ride and humidity will drop from ~80% down to ~50% from start to finish on Oahu. Back when in Shreveport, it would be very typical of your conditions in the summer if not worse. There where mornings I would be up at 0300 at it was already 90 degrees.
I can empathize with your issue. Except you are going too hard for your current nutrition/fluids plan if you are having to limp home. You need to amend either your ride plan or your nutrition plan for the days like you are describing. If the ride wouldn’t be shortened I would stick with low zone 2, and much, much more fluid would be carried and consumed on these types of days. I drank 13 bottles at the Tour de Louisiane road race in 2019. That was only 5 laps, 80 miles, and 3 hours. Back in Shreveport I would usually have at least 4, 750 mL bottles on me at the start of long rides. I would also have another bottle that I would down immediately before hopping on the bike. This would typically get me to the store stop on our rides. Anywhere between 40-50 miles, 2-2.5 hours into the ride. When I knew that it was going to be particularly hot out, I would freeze half of my bottle. I would fill it halfway with drink mix and then lay it down horizontal in the freezer all night. In the morning I would add ice cold drink mix for the remaining half. The two in my jersey pockets would melt fairly rapidly by the time I would drink all the unfrozen liquid from the frame bottles. I would just rotate and then rotate again. Some days would see five bottles carried. I would use a bento or bar bag to carry other nutrition, tools that weren’t already on the bike, and phone. I also carry a spigot key with me in my saddle bag for emergencies.
Another aspect is to start earlier that you would think. I start my long rides on the weekends at 0515, with a current 0550 sunrise. It’s enough light to see without a solid headlight. I am back home before 1100 and before the heat of the day begins to really ramp up.
Plan to stop more as well. Continue to drink as normal but plan on two stops at the 30-35 and 65-70 mile points of the ride rather than once at 45-55 miles. I will drink at least two more bottles, if not 4 more this way. Stops shouldn’t take very long. Refill bottles and chug another drink/bottle and back rolling in all of about 5-8 minutes tops. I would eat my snacks while moving if time were an issue.
As someone else mentioned, you’re experiencing heat exhaustion. Cessation of sweating is a really bad deal. You need to double your sodium, at least, and increase your fluid intake substantially. I can’t say how much more fluid without knowing how much you’re consuming.
If you’re sweating ~2 L/hr, you’ll need to be consuming >1.4L/hr and probably closer to 1500-2000mg sodium per hour.
Our app is going to be worth a look. It solves this exact situation for virtually everyone. Please select the “heavy” sweater option during onboarding. If you need help, shoot me an email. It’s my first name at our website minus the www.
In the meantime, go buy some larger bottles or a bigger bladder for your pack. You’re going to need it. Here’s a discussion of lots of big bottles.
I started using app after recommendation here … on Monday I did 5hrs again (back to back days) in higher heat, higher power and finished strong.
Only big difference was following your hydration / sodium recommendations - which were about 4x increase in sodium and 50% increase in fluids. Carbs were about the same.
You might be onto something …. Will try again this week
I experience the same long ride performance increase after starting to use Dr Alex’s app (Saturday Morning) too. I have always been a kill it for 2 hours rider because after that I would feel terrible. Like you I needed a TON of salt with my drink to improve overall absorption of water and calories. I’m so glad you found a solution, it makes the long rides so much more enjoyable!