[COLONEL KURTZ]

Toolbox: Hydration Advice and Science
Tuesday, July 03, 2007 7:17:11 AM PT

by Dr. Stephen Cheung, Ph.D.

You’re probably used to carrying a water bottle around with you everywhere you go and drinking so much that you run to the bathroom more often than a toddler getting weaned off diapers. Meanwhile, sport drink companies sprout faster than tech companies, each touting itself as the magical elixir. So just how much do you need to drink and what should you be chugging? …

This article was originally published during the depths of the big European heat wave in 2003 that was indirectly linked to over 30,000 (not a typo) deaths. That was also the Tour where Lance got completely dehydrated and lost the first big TT to Ullrich. We’re reprinting it here with some give and take between practical advice from Josh Horowitz of Liquid Fitness and my scientific feedback.

The “Dry” Facts…
Camelbak’s got the most scientifically accurate slogan in all of corporate history when it came up with the “Hydrate or Die” motif. The proper mix of carbohydrates, proteins, fats, vitamins, and minerals in your diet is important, but water trumps them all as THE essential nutrient. IRA hunger strikers in the late 1970’s lasted 60-80 days without food. However, if they had tried that without drinking water, they probably wouldn’t have lasted a week! And that’s just lying about shouting anti-English slogans. Add exercise and the heat of summer and the threat of dehydration becomes even more severe. The world record sweat-meister? Try 3.7 kg/h by the runner Alberto Salazar (1) during training prior to the 1984 Olympics in LA. That’s over 5% of his body weight every hour!

Make no mistake about it, short of sickness or injury, NOTHING will affect your daily performance more than your hydration status. Study after study has demonstrated that even a very slight amount of fluid loss (1% body weight) results in significantly decreased performance in both endurance and power sports. In fact, my own Ph.D. research (2) found that proper hydration prior to exercise (i.e., making sure you’re not dehydrated to begin with) is more important than either fitness or heat acclimation in determining your tolerance to exercise in the heat.

What’s so bad about dehydration? The first place that fluid is lost from is your blood. With less blood to pump throughout your body, your heart has to pump more frequently to maintain the same rate of blood delivery to the muscles. This results in “cardiovascular drift,” where your heart rate increases even though your power output is constant, placing unnecessary stress on your heart. In addition, the body also tries to preserve blood flow to the muscles, meaning there is less blood going to the skin to dissipate heat. Keep this going much more and the elevated body temperature will ultimately cause fatigue by actually decreasing the ability of your brain to activate your muscles (3). When dehydration gets even worse, then the water loss from your muscles themselves will cause cramps, spasms, or worse. You’ve all seen the images of Paula Newby-Fraser staggering and collapsing within sight of the Hawaiian Ironman finish line, so take steps to make sure nothing like that ever happens to you.

Planning to Drink
It is absolutely critical to plan out and practise your hydration strategy. Here are some practical tips from Josh and my scientific comments on them:

Josh: If you have a big event the next day, drink a big bottle the night before. When my team is at a hot stage race such as the Tour of the Gila, we go by the rule, if you don't wake up 2 or 3 times during the night to pee, you probably haven't drunk enough. Make sure your pee is clear the night before and the morning of. Unless you are taking a ton of vitamin supplements, clear pee means you are well hydrated.

Stephen: Due to changes in fluid distribution throughout your body, both body mass itself and urine colour can be inaccurate measures of actual hydration status. For example, if you are in a state of lowered hydration status (hypohydration), drinking lots of water will still produce fairly clear urine. Therefore, body mass and urine colour can be useful indices for long-term monitoring, but may not be able to pick up problems with acute changes in hydration. The most accurate and reliable indices of fluid balance remains blood measures, which are not overly practical for athletes. This again highlights the need to maintain a long-term and consistent hydration plans and not “cram” the fluid intake or recovery.

Josh: If you have a problem remembering to drink on the bike, make a rule for yourself. No matter how you feel, every 5 minutes take a sip, set your watch alarm every 10-15 min to remind yourself to drink, or better yet, take a sip any time you see anyone else in the group do it.

Stephen: The average athlete can easily lose over 1 kg of sweat every hour, and cyclists can easily exceed this to the tune of 1.5-2 kg in hot weather. That is because one of the primary adaptations to both aerobic training and heat acclimatization is an increased sweating response. It is critical that you train yourself to replace as much of the fluid loss as possible DURING the workout.

This point also raises the recently popular concept of hyponatremia or water intoxication. This is a condition where you can drink so much water that you end up diluting your body fluids and electrolyte concentration in the blood. This can be just as dangerous, if not more so, than dehydration. I will cover this in much more detail in my next Toolbox. But for now, for prolonged exercise, avoid drinking solely water and mix in some sports drink. In addition, drink sensibly but don’t go overboard. Remember that your body can only empty and absorb about 1L/h from your gut, so don’t get into chugging contests while exercising.

Josh: Drink your favorite hydration drink and don’t add anything to it. The reason I say favourite is because if you like the taste, you’ll drink more. The reason I say don’t add anything to it (or consume electrolyte pills) is that the hydration drink already has the proper balance of electrolytes. If you supplement with more, your cells are just going to need more water to keep an optimum balance.

Stephen: Just as the best bike in the world is worthless if it doesn’t fit you correctly, the scientifically ideal sports drink is junk if you don’t like the taste of it and therefore won’t drink enough of it. For example, some important research has been done to test the effects of different flavours on voluntary drinking rates in children. Within reason, all of the major sports drinks out there fall within the generally accepted consensus on ideal carbohydrate and electrolyte composition, so experiment to find out what you find most drinkable. There is a major debate ongoing concerning whether scientists should be advocating

Josh: During stage races or multi day events, weigh yourself before and after each ride to see how much water weight you have lost. If you have lost more than 3% water weight then you have seriously harmed your muscle’s ability to perform and you know to drink more next time.

Stephen:Over the course of a stage race or a hard training block, proper hydration becomes even more important. Pack your own water and drink powder with you to races so that you don’t have to rely on others. Research by my former boss Ron Maughan (4) shows that you need to drink at least 150% and preferably 200% of your fluid loss post-exercise to ensure that you return to your normal hydration levels. In addition, the drink should have at least moderate amounts of sodium to help keep the fluid in your body. Carbohydrates are not essential for hydration purposes as long as you’re eating adequately, but it won’t hurt to have some to improve taste.

Josh: Warm up is a place where I think people forget to drink. When it is extremely hot, cut your warm up time by 40%. Your muscles will already be warm and if you do more than about 35 minutes, you're going to be cooked. If you don't have to get off your trainer during warm up at least once to pee, you aren’t drinking enough.

Stephen:This advice is especially important in crits and time trials, where the races are relatively short. Drinking DURING these events are mainly psychological, because there is not enough time for the fluid to be emptied from your stomach and absorbed through the intestines to do much good. My doctoral research demonstrated that maintaining normal hydration status prior to exercise was more beneficial than drinking during exercise of 90 min or less in very hot environments. However, some research has demonstrated that drinking a carbohydrate drink during a 1 h time trial improved performance (distance covered) compared to water alone, theorizing that the carbohydrate may trip a feedback loop directly to the central nervous system and enabling higher power outputs.

[jkuhlmann]

for some reason, by your thread title, i thought this was going to be an 'anti hydration' article...

i don't think you need to convince too many of us around here of the importance of water...

thanks for the article though.

[MikeMartial]

Originally Posted by jkuhlmann

for some reason, by your thread title, i thought this was going to be an 'anti hydration' article...

i don't think you need to convince too many of us around here of the importance of water...

thanks for the article though.

Me too. Hydration is obviously important, but this article was long-winded in explaining commonly-known key points. One thing worth emphasis, though:

This point also raises the recently popular concept of hyponatremia or water intoxication. This is a condition where you can drink so much water that you end up diluting your body fluids and electrolyte concentration in the blood. This can be just as dangerous, if not more so, than dehydration. I will cover this in much more detail in my next Toolbox. But for now, for prolonged exercise, avoid drinking solely water and mix in some sports drink. In addition, drink sensibly but don’t go overboard. Remember that your body can only empty and absorb about 1L/h from your gut, so don’t get into chugging contests while exercising.

I normally bash the media bandwagon that initially brought this up; if anything, it stops people from drinking enough water, because they think they're going to die because of it. But with weather in the high 30's Celcius, people tend to lose and replace fluids at a greater rate, and hyponatremia is a consideration.

Yesterday I must have put back over 8 liters of water, 4 of which were an Accelerade mixture. Between a morning 20km singletrack ride, roofing my shed all afternoon, and 1.5 hrs of training at the dojo later that night, I would have easily been an electrolyte-depleted mess had I not mixed my H2O.

[COLONEL KURTZ]

The part I wanted everybody to get was the concept of "Cardiovascular drift". I probably should have edited and took out the more obvious stuff, but who knows what everybody knows.

I was watching the UFC preview on spike when they showed how Forest Griffen came in to Vegas eating nothing but chex mix (or something like that), and drinking nothing but water and had been for sometime. I think he still had to lose something like 7 to 10Lbs a day before the fight. I figured he was going to lose, and he did. You can't compete at a world class level if you show up a day before the fight in that kind of condition. That has never made sense to me. From what I've read it takes about 2 weaks for your body to recover from a starvation diet like that.

[COLONEL KURTZ]

Originally Posted by MikeMartial

Yesterday I must have put back over 8 liters of water, 4 of which were an Accelerade mixture. Between a morning 20km singletrack ride, roofing my shed all afternoon, and 1.5 hrs of training at the dojo later that night, I would have easily been an electrolyte-depleted mess had I not mixed my H2O.

Interesting. You must be experienced. I find that the people that have experience drink 1:1 (bottle of water:sports drink ), while inexperienced seem to just drink sports drink).

This Sunday I was going to go on a 100 mile road ride. I got about 50 miles out where I refill my bottles and found out I forgot my money, so I refilled with plain water, then called my wife to meet me on the road. I ended the day with 70 miles. I didn't want to go another 50 miles without electrolytes.

I could have made the trip back, but at what cost? I had to think about my training the next day. If my body is depleted, then my training the next day won't be nearly as effective. So I had to put pride aside for the bigger picture.

[MikeMartial]

Originally Posted by COLONEL KURTZ

The part I wanted everybody to get was the concept of "Cardiovascular drift". I probably should have edited and took out the more obvious stuff, but who knows what everybody knows.

Excellent point; here's a quick abstract I dug up on cardiovascular drift. Considering the recent high temps, it's worth it to note how hyperthermia can exacerbate the effects.

[spirez]

Here's another decent article by John Berardi on the use of sports drinks:

http://www.johnberardi.com/articles/..._nutrition.htm

[Cojofl]

Milk:

http://www.rte.ie/news/2007/0731/milk.html
http://nqr.farmonline.com.au/news_daily.asp?ag_id=43849
http://www.belfasttelegraph.co.uk/he...cle2820503.ece
http://journals.cambridge.org/action...ne&aid=1057236

[Cooz]

Dehydration kills even in this day and age.

http://www.odmp.org/officer.php?oid=18962

Now I'm sure most people aren't chasing drug dealers and/or illegal immigrants in the desert, but with this whacky weather (and with whacky I mean hot) any outdoor activity brings its risks.

[Hbs6]

Originally Posted by MikeMartial

I normally bash the media bandwagon that initially brought this up; if anything, it stops people from drinking enough water, because they think they're going to die because of it. But with weather in the high 30's Celcius, people tend to lose and replace fluids at a greater rate, and hyponatremia is a consideration.
.

Thats such a true statement, hyponatremia is pretty hard to achieve and most people would never have...well i guess the determination lol to drink enough water to fuck up there electrolyte balance, maybe for atheletes like us where we miught over do something but most people would never get enough water in.