Heat stroke / the bonk / dehydration

davidof

Rode up to the Col du Colombier yesterday. It was about 35C. At the top had to stop and lie down for about 30 minutes. The feeling was of my whole body vibrating/resonating; it was impossible to ride in this condition - even downhill. Heart rate seemed ok. I'd been fueling on gels plus about 3 bottles of water for the climb (frequent fountains on the west side).

Does this sound like the bonk or heatstroke or maybe just dehydration? I was able to ride the 60km home.

drlodge

Don't know for sure but I would guess its the heat possibly combined with dehydration. In that temperature doing a long climb, your core temperature may be getting quite high and you simply needed to cool down - which won't happen quickly hence why you needed a 30 mins lie down.

cougie

Doesnt sound like the bonk to me. Most cyclists know what that is. I'd go with the heat.

hypster

I think you need to give a bit more information about how fast you were going, how long was the climb what sort of fitness level/weight are you etc. etc.

I've climbed Mont Ventoux in 40 degree heat in around 2 hours (so not that fast) and not experienced those sort of problems. Heat exhaustion is pretty rare unless you are riding competitively or pushing yourself very hard for a certain length of time. There are usually lots of warning signs telling you to slow down beforehand as well.

Over-hydration is just as likely as dehydration, especially as you say you have consumed 3 (750ml?) bottles. Over-hydration is regularly wrongly diagnosed as dehydration with dire consequences. Did you need to pee whilst recovering at the top for instance?

To tell if it was glycogen associated we would need to know how far you had ridden in total to get there and what energy products you consumed. I'm guessing it doesn't sound like that though.

davidof

No need to pee and I was still rehydrating at home but maybe I diluted electrolytes too much?

term1te

I've felt similar a few times and have put it down to blood sugars being too low rather than dehydration. I got myself pretty dehydrated last weekend, miss-judged the heat, length of ride, etc. 500 ml on a 110km hilly ride on a very hot day wasn't a good idea, but I just slowed down towards the end. I've had the "fluttering" feeling and being ever so slightly disorientated a couple of times, but it seems to happen quite soon into a ride maybe after the first big effort or hill. My heart rate drops and I just have to stop for a while and then limp home. The only common factor I can think of is that I'd eaten something sugary a couple of hours before the ride. On my commute home (37km) I normally have a banana just before I leave, but when I've hit the flutters, I've had a big slice of cake or similar in the mid afternoon. Maybe my blood sugar went too high, then over compensated and was too low by the time I got on the bike?

Don't know if that had any bearing on your situation, but I can sympathise with how you felt.

I hope the weather stays good down there, as I'm riding the Col du Colombier next week

herzog

Term1te wrote:

...I got myself pretty dehydrated last weekend, miss-judged the heat, length of ride, etc. 500 ml on a 110km hilly ride on a very hot day wasn't a good idea, but I just slowed down towards the end...

I had that on Weissenstein/Grenchenberg (K. Solothurn) last weekend too...power output towards the end of the ride was shocking (and not great at the start to be honest). My performance nosedives in the heat.

term1te

Herzog wrote:

Term1te wrote:

...I got myself pretty dehydrated last weekend, miss-judged the heat, length of ride, etc. 500 ml on a 110km hilly ride on a very hot day wasn't a good idea, but I just slowed down towards the end...

I had that on Weissenstein/Grenchenberg (K. Solothurn) last weekend too...power output towards the end of the ride was shocking (and not great at the start to be honest). My performance nosedives in the heat.

I was in the same part of the world, nearly died on the Saturday taking in the Scheltenpass from Delemont side then back to Basel via Balstal and Waldenburg. On the Monday I did the 140 km "Jura Derby" starting in Boningen and rode the Scheltenpass from the other side then through the Gorge du Pichoux. Beautiful day, drank loads, no cakes before hand, but several en route. Got my best time on the course and a couple of Strava KOMs on the way.

herzog

Term1te wrote:

Herzog wrote:

Term1te wrote:

...I got myself pretty dehydrated last weekend, miss-judged the heat, length of ride, etc. 500 ml on a 110km hilly ride on a very hot day wasn't a good idea, but I just slowed down towards the end...

I had that on Weissenstein/Grenchenberg (K. Solothurn) last weekend too...power output towards the end of the ride was shocking (and not great at the start to be honest). My performance nosedives in the heat.

I was in the same part of the world, nearly died on the Saturday taking in the Scheltenpass from Delemont side then back to Basel via Balstal and Waldenburg. On the Monday I did the 140 km "Jura Derby" starting in Boningen and rode the Scheltenpass from the other side then through the Gorge du Pichoux. Beautiful day, drank loads, no cakes before hand, but several en route. Got my best time on the course and a couple of Strava KOMs on the way.

Nice, I think > 30 degC and hills are not a healthy combo!

meanredspider

It might be worth looking up hypoglycaemia (too low blood glucose) to see if the symptoms match.

I rode Alpe D'Huez 6 times in a day last week. At 5am it was freezing (literally) at the top but by early afternoon it was 33C hardly a breath of breeze and 94% humidity. I have to say that by the 6th climb I was seriously running on empty. I burned 7500kcals in the day - there's just no way you can compensate for that by eating. Quite a few people were on saline drips when we took one of our team to be treated - his core temp had dropped to 35C.. Be careful what you expose yourself to - it's only riding a bike up a hill after all...

davidof

meanredspider wrote:

It might be worth looking up hypoglycaemia (too low blood glucose) to see if the symptoms match.

I rode Alpe D'Huez 6 times in a day last week.

I wondered how you got on, it wasn't quite so hot last week as it is this week with a return to slightly cooler weather next week!

drlodge

meanredspider wrote:

I rode Alpe D'Huez 6 times in a day last week

Are you completely derranged? Bloody hell.

meanredspider wrote:

I stupidly rode Alpe D'Huez 6 times in a day last week

FTFY

davidof

Term1te wrote:

I've felt similar a few times and have put it down to blood sugars being too low rather than dehydration.

Yes perhaps that. I've read some more and all 3 of the suggestions I put in the subject could be the cause but it seems heat and low blood sugars might be the biggest factor. Its pretty rare that I have any issues.

They've done some gravelling on the Colombier so take care on the Culoz/Angelfort side, it is not too serious - not like the 4 inches of gravel they dumped at Chamrousse one spring, but still.

meanredspider

drlodge wrote:

meanredspider wrote:

I rode Alpe D'Huez 6 times in a day last week

Are you completely derranged? Bloody hell.

meanredspider wrote:

I stupidly rode Alpe D'Huez 6 times in a day last week

FTFY

It was for cancer charity - what can I say? 8) Still only 2/3rds the height of Everest though it was a century ride too

meanredspider

davidof wrote:

meanredspider wrote:

It might be worth looking up hypoglycaemia (too low blood glucose) to see if the symptoms match.

I rode Alpe D'Huez 6 times in a day last week.

I wondered how you got on, it wasn't quite so hot last week as it is this week with a return to slightly cooler weather next week!

Yup - thank god it wasn't so hot. Still, I've never ridden on a day with a 33 degree temperature range so that was new. I've done a write up over on Commuting Chat which goes into much more detail.

meanredspider

I used to work for a blood glucose meter company and, whilst the body is generally great at controlling blood glucose levels, it can do some stuff you're not expecting. For instance, a colleague took 2 or 3 gels before starting a marathon. The thing is your liver releases glycogen on the commencement of effort - he said he effectively went hyperglycaemic and felt very odd.

robbo2011

Term1te wrote:

I was in the same part of the world, nearly died on the Saturday taking in the Scheltenpass from Delemont side then back to Basel via Balstal and Waldenburg. On the Monday I did the 140 km "Jura Derby" starting in Boningen and rode the Scheltenpass from the other side then through the Gorge du Pichoux. Beautiful day, drank loads, no cakes before hand, but several en route. Got my best time on the course and a couple of Strava KOMs on the way.

Wish I'd known about the Jura Derby, sounds fun. On Monday I was really struggling in the heat, did a 120km loop from Lucelle through France down to Goumois and then back up on the Swiss side. On the climb out of Goumois to Saignelegier I had to stop, not because it was a difficult climb, just that I just completely ran out of energy. I had been eating and drinking lots but I guess it must just have been the heat. some coke, ice cream and energy gels got me going again, but i was reduced to a crawl for the rest of the ride.

robbo2011

Herzog wrote:

Term1te wrote:

...I got myself pretty dehydrated last weekend, miss-judged the heat, length of ride, etc. 500 ml on a 110km hilly ride on a very hot day wasn't a good idea, but I just slowed down towards the end...

I had that on Weissenstein/Grenchenberg (K. Solothurn) last weekend too...power output towards the end of the ride was shocking (and not great at the start to be honest). My performance nosedives in the heat.

To be fair, those are two tough climbs, especially in the heat!

I'll be on the Grenchenberg next weekend, will be leading a tour from Basel to Grenchen (as a BMC rider, where else!) via Lucelle, St. Ursanne, Soubey, Gorge du Pichoux, Moutier and Court. should be fun and hopefully a bit cooler.

term1te

You'd be hard pushed to find a more scenic route than the Jura Derby 140. Very well organised event with loads of food and warm tee en route.

Should apologize for hijacking the tread a bit.

RBS100

I sometimes wonder about those gels. Big spike of insulin from the gel plus a long hot glucose depleting climb. There surely would be times when it goes off kilter and you have yourself a hypo. Hot climate can also increase the likelihood of a hypo. IIRC metabolic rate increases.

I think you had a bit of combo. A hypo (trembling/resonating) and a touch of heat exhaustion.

davidof

RBS100 wrote:

I sometimes wonder about those gels.

I don't normally overdo it on the gels; I reckon they are a bit like rocket boosters; they buy you 20 minutes extra climbing but you can pay for it afterwards.

meanredspider

davidof wrote:

RBS100 wrote:

I sometimes wonder about those gels.

I don't normally overdo it on the gels; I reckon they are a bit like rocket boosters; they buy you 20 minutes extra climbing but you can pay for it afterwards.

Yes - though they aren't too calorific so it probably only generates a smallish spike but they are great for getting you out of trouble (as Wiggo found!) - certainly helped me.