Commuter8

Hi there,

I know this has been posted before, but I did not see any good answers.

I am a fairly experienced city cyclist. I ride almost daily as a commuter (5 years), and would like to do some longer distance riding. From time to time I experience headaches/nausea and fatigue after going for a longer rides (+40km). It is really important to me to build up to longer distance riding and maybe do brevets next year.

I am hoping someone can provide some input.

Some stats about me:
40 years old (lost 35lbs in the last 5 years)
35 lbs overweight
smoker (quitting)
blood pressure fine,
sometimes hypoglycemic (yes, I actually measure it from time to time)
not diabetic

This past Monday I went out for a long ride about 50km, and suffered the exact same headache/nausea that I experienced several years ago in the MS 150. Last time I thought it might be heat related, but I was riding in +6C (40s F) on Monday. Of course I was soaked in sweat, and a little cold by the time I got home, but not overheated.

Ride Length: 50km (30 miles)
Time: 3h
Drank: 2L of juice/water, 1 tea
Ate: Energy Bar, Two Apples, Bagel and Cream Cheese

Had a small nap after I rode, still didn't feel any better. Overnight sleep of 9h seemed to do the trick, as it did last time. Symptoms did not onset until about 1/2h of stopping activity.

So, places I have thought of looking:

Salt/electrolyte imbalance:
Although last blood test showed nothing irregular.

Hypoglycemic:
From time to time I can be hypoglycemic, but I felt I ate enough good food not to be (oatmeal, energy bar etc)

Dehydration:
I drank quite a bit, and my urine after the ride was not dark at all. I also drank lots of water once I finished the ride.

Oxygen depletion (yes, I am quitting)
Because I am a smoker, I may not have the lung capacity to deliver enough oxygen, although you would think the headache onset would happen during the ride, not an hour after.

Carbonfiberboy 

I'm going to guess it's hyponatremia. Riding in the 40s F, I'll drink about one liter in 30 miles, if that, and have a glass of recovery drink upon finishing. Some of my buddies wouldn't drink anything during a ride like that. So I'm saying you drank too much. Easy to test. Next time you go out for a ride of this length, try drinking just the one bottle, or drink to thirst: if you get thirsty, drink a few swallows. Never drink unless you are thirsty. That's the new rule. "Drink before you're thirsty" got a lot of people into trouble. I'm thinking that "drinking lots of water" after you got back is what actually brought on the headache.

There are other possibilities. It may be low blood sugar. Next time, drink a pint of chocolate milk as soon as you get back, then nap. It may also be exercise-induced anaphylaxis, but that seems unlikely considering what you ate.

Commuter8

Great insight! I started having a dicussion with myself about half-way into the ride, saying, I need to drink more, even though I really wasn't that thirsty. So on the ride I finished off one cage bottle, and then had about three or four large glasses of water when I got home.

Thanks for getting back to me. I think this is a very good guess. I know that during the MS 150 event I did have too much water, and had suspected hyponatremia.

I know I did another ride this summer around the same size and felt fine after wards, and I certainly didn't drink allot of water.

If anyone else has some inputs, that would be great. I think I might also mix in some salts with my drinks. After reading about hyponatremia I know I sweat out allot of salt.

ericm979

Everyone's different but I don't get symptoms of hyponatremia unless it's a 5 hour+ ride in warm weather. Three hours sounds pretty short to cause it.

2 liters is only 2.5 large bottles (they are about 28 oz). It's maybe a bit more than I would drink this time of year, but not that much more. And I am smaller than most riders. So it sounds reasonable.

It's easy to test- ride till you feel bad then eat some salt (1/4 to 1/2 teaspoon should be plenty). If you feel better in 10-15 minutes, then you were low. It should be pretty obvious. If not, its something else, like not eating enough or at the right time.

RonH

I'm not a doctor but this is what wikipedia says about it.
"Hyponatremia can also affect athletes who consume too much fluid during endurance events, people who fast on juice or water for extended periods and people whose dietary sodium intake is chronically insufficient.
The diagnosis of hyponatremia relies mainly on the medical history, clinical examination and blood and urine tests. Treatment can be directed at the cause (for example, corticosteroids in Addison's disease) or involve restriction of water intake, intravenous saline or drugs like diuretics, demeclocycline, urea or vaptans (antidiuretic hormone receptor antagonists). Correcting the salt and fluid balance needs to occur in a controlled fashion, as too rapid correction can lead to severe complications such as heart failure or a sometimes irreversible brain lesion known as central pontine myelinolysis."

Sounds like you may be drinking too much water for such a short ride.

Commuter8

Oh, and I forgot. I did smell ammonia when I finished the ride. I couldn't figure it out, but I thought it might be related.

Carbonfiberboy 

I believe the ammonia smell is from burning protein. Most people get that after a really hard ride. I don't think that has anything to do with your headache, but it does argue for a recovery drink with protein in it, such as chocolate milk.