Headaches after training in heat, just dehydrated?

I’m fairly new to training, just starting in on my second time going through base and build. I have noticed that the day after I workout in the heat (80° f or higher) I usually wake up with a headache.

I assume this is dehydration, but I feel I am drinking enough water. I try to drink water all day, usually around 80oz. I drink water every 10-15 min when on the trainer, and drink like 40oz after the workout is over.

What am I missing? Is this a common issue? I am in sweet spot base low volume, workouts are only 60-90min so nothing crazy. On the podcast they talk about mixes and salt tablets but that seems to be geared towards much longer efforts like xcm or long triathlon so I kinda assumed my issue was something way more simplistic. Gatorade seems to help but don’t like all the extra sugar.

Any ideas?

Thanks, alex

Could be a lot of things. Salt depletion, water intox, etc. I’m not a doctor by any means, nor will I pretend to be a subject matter expert on this. Hydrate properly, and eat right. If that doesn’t fix your issue, go see a doc. My headaches were nasty this summer, and mine came from allergies

Oooh allergies might be part of it for sure. I guess I might also be asking how to know if I am ‘hydrating properly’ and if water alone is sufficient for riding


I’d say absolutely not. You have to replace the lost salt. This picture was after a 207-mile ride from Seattle to Portland in July 2018 where gallons of water, Gatorade, and Nuun were consumed. That white salt covered my jersey. My piss was dark yellow, and I felt like hell…replace that salt, bubba

Could it be as simple as adding some salt to my water bottle? Or does it need to be something fancier

@Alexjschneider I’m not a nutritionist, but I don’t see why that wouldn’t work; however,…:nauseated_face::nauseated_face::nauseated_face::nauseated_face: . I’m sure you can take salt tabs for those hot days. Nuun is another good option.

My brother and I drank coca-cola at the STP this year. We took salt tabs, lots of Nuun, water, and SOME Gatorade, the 20-ounce coke at mile 175 felt awesome. EDIT: we ate on the bike a lot: bananas, cliff chomps, fruit, etc

60-90 minutes of sweet spot is still a lot of work! A couple of questions (suggestions if you aren’t doing this):

  1. Are you properly fueled for the workout? I get the Gatorade/sugar issue. However, there are substantially better ways to pre-fuel (see nutrition advice threads; lots of good stuff)

  2. Are you properly recovering, including post-workout fuel (plenty of protein and carbs)?

I’d try some Nuun or a banana. I would sudpect electrolytes are the issue, inadequate potassium in particular seems to be a headache trigger in my experience.

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Dehydration and heat shock. I get them too with long workouts in summers of FL and TX. it’s a 2 day recovery so I am exclusively indoors in the summer. I have no time for all that recovery.

An easy way to check if it’s dehydration is to weight yourself before and after the ride. If those match, then it could be electrolytes that are depleted and so you’re not properly absorbing the fluids you did drink. I used to get these kinds of headaches after hot rides and between these 2 things it doesn’t happen anymore.

Just to throw in another point of view - it could be from being over hydrated. Drink too much water, especially that without electrolytes and your stomach osmolality is off meaning electrolytes are drawn from the blood into the stomach to balance it out. Without the correct balance you cannot absorb the water (I am lead to believe).

For me, I get bad migraines post workout if I get the hydration wrong. They come mostly when I am fully hydrated (pissing clear all day) and then throw in a couple of litres whilst on the trainer (2hr ride). I now keep my urine a pale straw colour during the day and stick to one biddon per hour max on the bike. I also add electrolytes to the water now.

I actually do not actively drink water during the day now. With two or three cups of tea/coffee (oh, and coffee will dehydrate you too), fruit, veggies etc I get more than enough water. If I am thirsty, sure I will drink water but don’t drink regardless anymore. It’s something that is often taught and it’s wrong IMHO. Drink to thirst, not the clock. There is no volume of water you should be drinking because it depends on other sources (food) and what you body needs.

So this is just me, my experience and YMMV but something to consider if it continues.

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I dealt with migraines after hard sessions for a very long time, then a family friend who works for Gatorade alluded that I was not consuming enough salt during. He recommended I increase it to 1000mg an hour and go from there. Since doing this and ensuring that almost every session I take in 1000mg an hour I no longer get migraines after. Hope this helps!


Are you doing these workouts outside on a stationary trainer or are you actually riding? If a trainer, do you have a fan pointing at you to cool you down?

Working out in the heat is tough but it gets easier as you get fit and properly acclimated. 60-90 is nothing crazy on a bike. My advice is try to workout during the coolest part of the day and avoid the sun. Also, someone mentioned allergies so it could be that as well. That’s usually a killer for me.
And your weight SHOULD NOT match your weight before the workout. It’s normal to lose a few pounds.

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No your spot on - table salt will do the job. Hydration tabs tend to be supplemented with micronutrients like calcium and potassium but if what you are after is replacing salts lost from sweat then table salt will do. Scott Mitchell (EF education and former Team Sky nutritionist) recommends a homemade sports drink in his book which is simply pineapple juice, water and LoSalt (a brand of Low Sodium salt in the UK)

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Dave-W can you share the name of the book please, thanks.

This summer I was getting headaches as well early summer before it got uber hot then I tried this system and my headaches went away. Note that I have not had a problem drinking water previously I normally monitor my urine color but my main consumption was water. So what I do now on workout days or race days is: 1. Upon waking up 500ml water and one salt capsule 2. Just before I head out the door for the ride(usually 1.5 - 2hrs later another 500ml with a isotonic sports drink and 1 more salt tab. 3.on bike two water bottles 750ml and 550ml the large bottle is SiS go or power bar tablets and small bottle only water. I start drinking 20mins into the ride and every 20min there after, when we pass a town with water fountains I refill the large and use the tablet of choice. I also use SIS electrolyte gels one per hour (I use more energy gels during each hour as well 90g carb intake). This has worked for me I have zero headaches post ride and zero cramping. I verified my system again this past Sunday during a race that had me on the MTB for 4.5hrs in 78F/26C to 93F/34C temps no problems.
Thats my story. I recommend you try some of the above ideas during your training and see what works for you.

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It’s called “Fuelling the Cycling Revolution”. Lots of good advice for general nutrition and general gut health as well as the cycling specific advice.

I moved from the UK to Thailand. Often have these symptoms despite pissing clear. Electrolyte before and after helps certainly, but your brain is still being cooked by the sun which gives the headaches. Get out early. Now when I ride indoor with aircon at the same tss, I don’t get the headaches.


I’ve always been of the opinion clear-urine is over-hydration. And peeing “too much” water out means you’re also losing electrolytes. In fact, the kidneys actually have to expend energy to actively re-absorb sodium (and other electrolyte). I’d go so far as to say a light-yellow urine is exactly the sign that your water intake and electrolytes are in balance. In the context of sporting activity, it’s better to go a bit over on electrolytes vs being low.

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