Random Thought Thread, aka The RTT (**possible spoilers**)
04-19-14, 06:55 PM
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Actually they do. You're much more susceptible to heat illness if you're dehydrated or under hydrated. People take this to mean proper or over hydration makes you immune to heat illness, which it doesn't.
The body cools itself in a variety of ways, one of those is sweating. Stop sweating and you lose that cooling, which is what happens when you're dehydrated. Core temp goes up, hello heat illness. Also worth noting that performance decreases as hydration goes down, there's actual studies that are hard to argue with on this point.
Fluid in the body is the primary coolant in any case. The body thermo regulates primarily by moving blood around. It's why blood flow to the extremities shuts off as our core temp goes down, and why certain places have a lot of heat exchanging capillaries close to the surface of the skin. That said hydration only goes so far and you can over hydrate and kill yourself.
The other factor that gets lost is the temp of the fluid you're drinking. Go out riding in 100 plus degree weather with regular water bottles and you're going to be drinking 100 degree water which is just adding to your heat load. Drinking cold water reduces it. A little bit of ice cold water does a lot more than a lot of warm water.
I developed a bunch of heat management strategies when I was racing in Texas summer heat, particularly for TT's. Proper hydration with a cool, electrolyte balanced solution was just one of several.
It wasn't a coincidence that my winning margins over the same folks tended to be greater in hotter weather, they would carry more heat load at the start, and a much greater heat load by the finish. Some were probably under hydrated, some were properly hydrated, and some were overly hydrated. Just one factor.
The body cools itself in a variety of ways, one of those is sweating. Stop sweating and you lose that cooling, which is what happens when you're dehydrated. Core temp goes up, hello heat illness. Also worth noting that performance decreases as hydration goes down, there's actual studies that are hard to argue with on this point.
Fluid in the body is the primary coolant in any case. The body thermo regulates primarily by moving blood around. It's why blood flow to the extremities shuts off as our core temp goes down, and why certain places have a lot of heat exchanging capillaries close to the surface of the skin. That said hydration only goes so far and you can over hydrate and kill yourself.
The other factor that gets lost is the temp of the fluid you're drinking. Go out riding in 100 plus degree weather with regular water bottles and you're going to be drinking 100 degree water which is just adding to your heat load. Drinking cold water reduces it. A little bit of ice cold water does a lot more than a lot of warm water.
I developed a bunch of heat management strategies when I was racing in Texas summer heat, particularly for TT's. Proper hydration with a cool, electrolyte balanced solution was just one of several.
It wasn't a coincidence that my winning margins over the same folks tended to be greater in hotter weather, they would carry more heat load at the start, and a much greater heat load by the finish. Some were probably under hydrated, some were properly hydrated, and some were overly hydrated. Just one factor.
However, I agree that heat illness does not require dehydration. Exercise induced heatstroke usually comes from "middle distance" exercise. Short events at extreme power do not last long enough to accumulate a lot of heat. Long events are done at low enough power output that the rate of heat production is less than the rate of heat dissipation.
On the topic of performance reduction due to dehydration I will mention the influence of slope. If time trialling up a steep enough hill it is faster to become dehydrated, and lose power, than it is to carry up sufficient water to maintain full power.
04-19-14, 07:09 PM
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04-19-14, 07:16 PM
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Exercise induced heatstroke usually comes from "middle distance" exercise. Short events at extreme power do not last long enough to accumulate a lot of heat. Long events are done at low enough power output that the rate of heat production is less than the rate of heat dissipation.
TX had their state TT in June or July. In four years I never raced below 90 degrees and around 50% humidity or greater. People, most of them slower folks, would argue against moving the date because "everybody has to deal with the same heat", which simply wasn't true. The guys who were riding at 300w were dealing with a significantly greater heat load than the guys who might be riding at 270 or someone at 240.
Had one of the better Master guys blink out during one of the events. A lot of people crawling in. Much more a heat tolerance trial than a bike race.
04-19-14, 07:46 PM
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I forgot about that radio contest. I think they called it "Hold Your Wee for a Wii" or something. That was awful.
04-19-14, 07:53 PM
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04-19-14, 08:40 PM
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Actually they do. You're much more susceptible to heat illness if you're dehydrated or under hydrated. People take this to mean proper or over hydration makes you immune to heat illness, which it doesn't.
The body cools itself in a variety of ways, one of those is sweating. Stop sweating and you lose that cooling, which is what happens when you're dehydrated. Core temp goes up, hello heat illness. Also worth noting that performance decreases as hydration goes down, there's actual studies that are hard to argue with on this point.
Fluid in the body is the primary coolant in any case. The body thermo regulates primarily by moving blood around. It's why blood flow to the extremities shuts off as our core temp goes down, and why certain places have a lot of heat exchanging capillaries close to the surface of the skin. That said hydration only goes so far and you can over hydrate and kill yourself.
The other factor that gets lost is the temp of the fluid you're drinking. Go out riding in 100 plus degree weather with regular water bottles and you're going to be drinking 100 degree water which is just adding to your heat load. Drinking cold water reduces it. A little bit of ice cold water does a lot more than a lot of warm water.
I developed a bunch of heat management strategies when I was racing in Texas summer heat, particularly for TT's. Proper hydration with a cool, electrolyte balanced solution was just one of several.
It wasn't a coincidence that my winning margins over the same folks tended to be greater in hotter weather, they would carry more heat load at the start, and a much greater heat load by the finish. Some were probably under hydrated, some were properly hydrated, and some were overly hydrated. Just one factor.
The body cools itself in a variety of ways, one of those is sweating. Stop sweating and you lose that cooling, which is what happens when you're dehydrated. Core temp goes up, hello heat illness. Also worth noting that performance decreases as hydration goes down, there's actual studies that are hard to argue with on this point.
Fluid in the body is the primary coolant in any case. The body thermo regulates primarily by moving blood around. It's why blood flow to the extremities shuts off as our core temp goes down, and why certain places have a lot of heat exchanging capillaries close to the surface of the skin. That said hydration only goes so far and you can over hydrate and kill yourself.
The other factor that gets lost is the temp of the fluid you're drinking. Go out riding in 100 plus degree weather with regular water bottles and you're going to be drinking 100 degree water which is just adding to your heat load. Drinking cold water reduces it. A little bit of ice cold water does a lot more than a lot of warm water.
I developed a bunch of heat management strategies when I was racing in Texas summer heat, particularly for TT's. Proper hydration with a cool, electrolyte balanced solution was just one of several.
It wasn't a coincidence that my winning margins over the same folks tended to be greater in hotter weather, they would carry more heat load at the start, and a much greater heat load by the finish. Some were probably under hydrated, some were properly hydrated, and some were overly hydrated. Just one factor.
Ex is right that as you get more dehydrated, your power output/speed drops, but you have to be noticeably dehydrated before it really shows up. In steady-state endurance events like a marathon, you just tend to slow down as you get hotter. People are much more prone to heat exhaustion during shorter duration events. For a short-term, high output effort, you can overheat yourself before your body has time to properly 'hit the brakes'. Sounds a lot like bike racing (big climb in the middle of a summer road race).
04-19-14, 09:15 PM
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All of what you've written is correct, but there are some interesting correlations in that book I linked to. The first is that they measured the level of dehydration of many people at a marathon (possibly the 'Comrades Marathon' in South Africa, I'm not sure), anyway, the faster runners finished the race in a greater state of dehydration than the slower finishers. I'm sure there's a happy medium in terms of water consumption, but it appears that one is better to err on the side of less
There would be a lot of variables in that conclusion though. All things being equal I would expect the fastest runners to be more dehydrated based on a simple heat equation. Not sure what the running kj/w number is, but certainly cycling is horribly inefficient; most of the heat doesn't transfer to forward motion. Faster runners would burn more kj, generate more heat, and sweat more.
If you had 5 identical cars the one driven fastest over 20 miles would burn the most fuel, or if you had an open loop cooling system that was regulated to a specific temperature, it would use the most coolant.
That might be more an effect based on cause, rather than an indicator of less hydration making you faster. Certainly that hypothesis bangs Into the findings of controlled studies of cyclists. But as Enthalpic pointed out, gradient and duration for cyclist can move that equation; marathoning is more weight sensitive than flat cycling so there might be a correlation there due to weight.
What is certain is that folks will over simplify this to fit their dogma
04-19-14, 09:39 PM
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Pay attention. I know you scout people's pee breaks on Strava when trying for KOM's on long segments. How and when you hydrate could be the difference between being a Strava Hero or a Strava Zero. Bicycling Magazine just ran a whole spread on the top 50 water bottles and 5 types of bottled water that could make you faster.
This is important stuff.
This is important stuff.
04-19-14, 09:52 PM
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Pay attention. I know you scout people's pee breaks on Strava when trying for KOM's on long segments. How and when you hydrate could be the difference between being a Strava Hero or a Strava Zero. Bicycling Magazine just ran a whole spread on the top 50 water bottles and 5 types of bottled water that could make you faster.
This is important stuff.
This is important stuff.
04-19-14, 10:01 PM
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Pro marathon runners are done in 2ish hours. People who die during marathons from hyponatremia are usually out there 5-6 hours.
When my friend/clubmate got hyponatremia during his first RAAM he gained 15 pounds of water, and he's a small guy. There was a threat of tornadoes so they had him get off the road, and he ended up in the hospital when everyone realized he had a problem.
I had a great ride today, 20+ friends came out for my birthday ride to Mount Baldy. One guy went up there last night with a cake that had my picture on it. The restaurant kept the cake until today, I was surprised big time.
When my friend/clubmate got hyponatremia during his first RAAM he gained 15 pounds of water, and he's a small guy. There was a threat of tornadoes so they had him get off the road, and he ended up in the hospital when everyone realized he had a problem.
I had a great ride today, 20+ friends came out for my birthday ride to Mount Baldy. One guy went up there last night with a cake that had my picture on it. The restaurant kept the cake until today, I was surprised big time.
04-19-14, 10:11 PM
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Pro marathon runners are done in 2ish hours. People who die during marathons from hyponatremia are usually out there 5-6 hours.
When my friend/clubmate got hyponatremia during his first RAAM he gained 15 pounds of water, and he's a small guy. There was a threat of tornadoes so they had him get off the road, and he ended up in the hospital when everyone realized he had a problem.
I had a great ride today, 20+ friends came out for my birthday ride to Mount Baldy. One guy went up there last night with a cake that had my picture on it. The restaurant kept the cake until today, I was surprised big time.
When my friend/clubmate got hyponatremia during his first RAAM he gained 15 pounds of water, and he's a small guy. There was a threat of tornadoes so they had him get off the road, and he ended up in the hospital when everyone realized he had a problem.
I had a great ride today, 20+ friends came out for my birthday ride to Mount Baldy. One guy went up there last night with a cake that had my picture on it. The restaurant kept the cake until today, I was surprised big time.
04-19-14, 10:17 PM
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As I was lining up for my big (103 mile) RR last month, I saw the crew from the organizer filling up the neutral water bottles...from the spigot the race hotel used to water the lawn. Hey, it was wet, and by the time I needed it I didn't care.
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04-19-14, 10:18 PM
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Happy birthday, John!
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04-19-14, 10:19 PM
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Here's some interesting reading. I'm not sure exactly how much this relates to bike racing. I do know that the pros at The Tour who have access to a lot of water (from the crowd) on hot days are as prone to pour it over themselves than to drink it. I think it's probably an issue of cooling more than it is actual hydration. The just cut out the middle man of drinking the water and waiting to sweat.
https://www.usatf.org/groups/Coaches...yStatement.pdf
Next Level Nutrition: The ESSA/SDA Conference ? Tim Noakes and the Hydration Debate - Part 1
Next Level Nutrition: The ESSA/SDA Conference ? Tim Noakes and the Hydration Debate - Part 2
https://www.usatf.org/groups/Coaches...yStatement.pdf
Next Level Nutrition: The ESSA/SDA Conference ? Tim Noakes and the Hydration Debate - Part 1
Next Level Nutrition: The ESSA/SDA Conference ? Tim Noakes and the Hydration Debate - Part 2
04-19-14, 10:48 PM
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Pro marathon runners are done in 2ish hours. People who die during marathons from hyponatremia are usually out there 5-6 hours.
When my friend/clubmate got hyponatremia during his first RAAM he gained 15 pounds of water, and he's a small guy. There was a threat of tornadoes so they had him get off the road, and he ended up in the hospital when everyone realized he had a problem.
I had a great ride today, 20+ friends came out for my birthday ride to Mount Baldy. One guy went up there last night with a cake that had my picture on it. The restaurant kept the cake until today, I was surprised big time.
When my friend/clubmate got hyponatremia during his first RAAM he gained 15 pounds of water, and he's a small guy. There was a threat of tornadoes so they had him get off the road, and he ended up in the hospital when everyone realized he had a problem.
I had a great ride today, 20+ friends came out for my birthday ride to Mount Baldy. One guy went up there last night with a cake that had my picture on it. The restaurant kept the cake until today, I was surprised big time.
04-20-14, 04:31 AM
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Happy birthday John! No better way to celebrate it then with a ride with a group of friends
04-20-14, 05:48 AM
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04-20-14, 06:08 AM
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Happy birthday big john.
04-20-14, 06:57 AM
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You're totally on point. I wanted to make the brief point that it's a mistake to believe that "just add water" is sufficient to prevent overheating. Of course dehydration increases those risks, but once someone is developing symptoms, the response that many well-meaning people have, which is to start them drinking lots of water, is both incorrect and dangerous. Water is necessary for vasodilation and sweating and all that stuff to be fully effective of course, lowered blood volume makes cooling less effective. But people need to remember that the immediate problem is core body temperature, and that it's going to lag behind rehydrating by quite a lot.
04-20-14, 07:16 AM
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On chocolate bunny #4 . Send help, might not be able to move in about 30 minutes.
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Chuck
Demain, on roule!
Regards,
Chuck
Demain, on roule!