+1. I don't think they're drinking Dasani water...

i drink a couple shots fo espresso a day, and normally have one ro two double shots right before a race. Never seemed to hold me back...

I often drink some coffee before a hard workout, and I kinda think it's helpful. (I think there may even have been a study that reached that conclusion, but I'm too lazy to find it.) I don't think I've ever ended up more dehydrated than normal as a result.

1,000 ml = 1 liter, or just over a quart.

500 ml = 2.1 cups. And that's 8oz for a standard cup. Standard Starbucks "cups" are at least twice that.

Some MD or expert right there. The internet is the gospel I tell ya.

I don't think I went for a ride this year without having coffee in me. Could have been dehydrated, I guess. I have got nothing to compare it to!

I have a teammate who's doing his Masters in Ex.Phys. and recently did a study on caffeine. He hasn't published but it sounds like he's found the same thing. That coffee dehydrates you is a myth.

It's never been an issue with me, no matter the length of the ride. I prefer a cup of coffee for my caffeine fix, but Hammer gel Espresso and Tropical also contain caffeine. The Hammer Nutrition site recommends people refrain from caffeine for 5 days before races for the maximal effects of caffeine if you plan to use it during your race.

That would be a huge mythbuster...i'd be interested in seeing that.

Pretty much every morning ride consists of me doping up on Cheerios, a banana and coffee.

Works great for me.

His theory is that people focus on how much they have to pee. Why do they have to pee? Because they're full of water, hot caffeinated water, but water just the same. But when he gave athletes caffeinated water vs. regular water, put them on a treadmill, weighed them, and accounted for how much was lost to sweat and urine, it came out even.

Junk food the day before a big ride, or on a big ride, makes my stomach go crazy. Therefore, I don't recommend.

Did you just confuse mg with mL?

Genius, that's 5-600 mg of caffeine. Not coffee, caffeine. Thanks for playing though. Internet gospel indeed.

Several foods, including coffee, cause yellow urine color

A lot of goos and sports beans have caffeine. This doesn't mean that it's really good for you, but does suggest that a lot of us do like caffeine when exercising.

<yawn>

Well one thing I won't do anymore is drink 4 cups of coffee before a ride. Heart rate was all messed up and I really just had to find a tall bush...

In addition to being a diuretic, caffeine is a vasodilator so it can help improve breathing and oxygination. So it certainly can help some folks improve performance when exercising.

They're talking about milligrams of caffeine. You're thinking milliliters of fluid.

Hmmm sounds like there could be something there. I have always been under the impression (by impression I mean I was taught this by my various exercise science professors) that caffeine pulled water from the interstitium. Which thereby was turned into urea and then excreted from the body as urine. Now the problem here is that if he isn't seeing any change in urine amount then that is definitely worth looking into. I think that the effect of caffeine pulling water from the interstitium unnecessarily is what causes the dehydration.

But then again i'm not the one doing my grad work on it. My grad work involves the correlations between positive thinking and mental resilience, now that is some crazy stuff!

Yes, it is a myth. Same as drinking beer dehydrates you. Yes, drinking either will make you pee, duh. Taking a caffeine pill before a ride will not make you pee. QED.

The main effect of caffeine for a bike rider is that it spares glycogen. The caffeinated rider derives a larger portion of energy from fat stores at normal riding intensities. It's a good thing. IME taking caffeine at the start will not make me more tired at the end. IOW it's not necessary to wait until one is tired to derive benefit from caffeine. In fact, the opposite may well be the case.

In this same myth-busting vein, it has now been well established that the best hydration one can do after a ride is to drink one beer. On a recent 3-week bike tour in the Czech Republic, I drank 1/2 liter of beer every riding day with lunch and another after riding. I would say it had a positive effect, much like any sports drink would. Czech lagers are not strong, usually about 4.4%. Although I did not notice any performance-depressing effect of the noon beer, it did have a psychologically depressant effect, a well-known effect of alcohol. But it tasted so good I drank it anyway.

woops, repost

I don't, but it's working fine for you keep doing what you're doing.

I remember hearing a story on NPR a few years back that the scientific research showed that coffee does not dehydrate you. It just doesn't hydrate quite as well as water, juice, soda etc. As a heavy coffee drinker at times in my life I never felt like it was dehydrating me. Now alcoholic beverages not being a diuretic is news to me.

Coffee is not a diuretic.

I wish the same could be said for beer.