Bodily Fluids
Part II
Lonnie Lowery
Last time we covered some fluid compartment basics, the magnitude of fluid losses in the
heat and during exercise, and what muscle-specific consequences resulted. This time
we’re diving into the hormonal consequences of exercising without a bottle of fluid inhand, broadly-accepted hydration guidelines and even hydration supplements that
“work”. Go grab a tall glass of iced tea and let’s get right to it!
Dehydration: Who Needs Added Stress?
I train hard, freaking hard most of the year. For those of you who are like me, there’s
very little room to maneuver beneath your overtraining threshold. Guys (and girls) who
are doing five sets of five or 10 sets of three – before even moving on to other
movements – don’t have the luxuries of a weekend warrior. We’re waging an almost
daily war with heavy weights. It’s no longer okay to skip the pre-, mid- or post-workout
fluids. Our tolerances and resources are already spread thin.
I’m talking about the whole-body level now. I’m talking about unnecessary elevation of
stress hormones and a rise in catabolic/ inflammatory immune factors. They rise in the
bloodstream during (particularly hot) exercise when fluids such as sports drinks aren’t
consumed. Examples include catecholamines (e.g. adrenaline, nor-adrenaline) and
interlekin-6 which, like cortisol, can be reduced by imbibing dilute carb drinks.(14,15,16)
Although these regulatory substances have their time and place in the scheme of things,
we don’t want them running wild on us chronically. Among other things, they make
recovery tough. Why add physiologic stress beyond your already-brutal bouts with the
iron?
Perhaps it’s best to summarize all of the consequences of dehydrating in the heat, from
both Part One of this article and from what we’ve just discussed. More importantly I’ll
offer a biological fix for each. You’ll see quickly that the fix is basically the same: drink
something dilute before, during and after your workouts. The details on how to do so will
follow the summary of problems.
Summary Table.
The Problem
Plasma Volume Drain, Decreased
stroke volume, Reduced Aerobic
peak (endurance performance)
Reduced Muscle Blood Flow,
Struggle to Maintain Muscle and
Skin Perfusion
Hyperthermia, Muscle Protein
Denaturing, Heat Illness
Cell Dehydration, Cell
Catabolism, Muscle Soreness
The Biological Fix
Maintain plasma volume
Maintain plasma volume, flow to capillary beds
Sweat! It’s bodily cooling to the tune of 580 kcal per
liter; see above
Maintain cell volume, especially in hot
environments
Elevated Stress Hormones and
Catabolic Cytokines
Maintain plasma volume
General Recommendations:
 Pre-hydrate with a full 16-17 oz. bottle of dilute (4-8%) carb drink with just 6-20g
added protein about 30-45 minutes before exercise. The goal is to raise blood
volume, blood sugar (glucose), and blood amino acid concentrations.
 Some athletes choose glycerol drinks for even greater plasma volume increases.
 Drink just 6-8 ounces (about a half coffee cup worth) of a dilute carb beverage
like a sports drink every 15-20 minutes during exercise.
 Afterwards, the traditional, stronger protein-plus-carb post-workout drink
(perhaps 16-32 oz.) should supply enough fluid to more than replace any weight
losses incurred via sweat. That is, an acute two-pound weight loss during a
workout should be replaced with 2.5 pounds worth of fluid within two hours, the
excess accounting for lingering elevations in metabolism and sweating.
Hydration Supplements
So perhaps the “Dr. Frankenstein” in you has you wondering how one might push
hydration efforts into overdrive with supplements. I’m here to tell you that it can indeed
be done - but it’s probably not necessary for guys who train regularly. If you are among
the tiny fraction of the population who can actually claim your place among a dying
breed of modern-day warriors, you’re already doing yourself a favor.
What I’m saying here is that natural PV expansion of about 4-12% does occur and lasts
for about 3-4 days after a bout of hard-exercise.(17) I’ve seen it directly in the lab.(12)
It’s yet another one of those things that male us so different from sedentary persons. I’ve
removed data from the Y-axis below for reasons concerning scientific publication but the
graph still offers a good illustration of what happens during and after a treadmill workout.
Figure 1. PV Changes after 45 min. Moderate Treadmill Running
--Insert graph--
So our blood volume adapts to anticipate future stress. Very cool. But because it’s
nonetheless tough to keep pace with more rigorous sweating during competition, one
might be interested in glycerol. This hyperosmotic compound reliably expands plasma
volume by up to 700cc, or a 7.5% jump in plasma volume!(10, 19) The dosing is simple,
about one gram per kg of body weight along with about 1.5 liters of fluid an hour or two
before exercise.(20) Does glycerol supplementation always boost actual exercise
performance? No.(8) Will it hyper-hydrate you, offering some level of protection from
the unwanted stress of fluid loss? Yes.(8,10,19) So, if you’re like me and you often end
up drenched from head-to-toe and weighing 2-4 pounds less after a workout, the science
behind glycerol is worthy of consideration.
I’d like to also make a few points regarding supplements that probably do not really
matter one way or the other. First, unless you run marathons and lose eight pounds during
exercise, sodium replacement probably isn’t necessary. Data Deity, Mel Williams
suggests that if you are not acclimatized to the heat and/ or if you are untrained, you will
lose more sodium in your sweat. Hence, you might consider salting your food for a week
or two before initiating hard training in hot environments.(23) For most of us, however,
it’s not a big deal. Sodium’s presence in sports drinks is actually more likely to help
glucose transport in the intestines or to encourage increased palatability and intake for
most exercisers; it’s not to restore a state of depleted bodily sodium (called
“hyponatremia”). I encourage everyone to go check out the (free) ACSM guidelines
noted in the references as a good overall knowledge base on what you probably need and
what you don’t. Second, regardless of what anecdotal hyperbole you’ve heard, creatine
monohydrate has not been reliably linked to hydration problems. The Creatine
Roundtable I just did with David Barr may help fill-in more on this front. If you want
more, Watson and colleagues just (re-)confirmed the benign nature of creatine regarding
hydration status.(21) Finally, coffee/ caffeine do not induce physiologically relevant
dehydration.(9) Yes, caffeine can induce diuresis (I’ve seen this directly during canine
surgeries in grad school) but not enough to cause a problem. This outdated notion needs
debunked. I’m sick of hearing it. (Where’s Dave Barr? He loves to break out the mental
floss!)
Hydration: A “Top Five” Consideration
Although less sexy to some, fluid replacement is one of the biggest things we can do
nutritionally to keep our muscles growing and our personal records coming. In fact, it’s
right up there with nutrient timing (peri-workout carbs and protein), daily calorie balance,
macronutrient changes and dietary variety. But perhaps you don’t believe me, so let’s do
a little thought experiment.
Ask yourself how long a person can survive without vitamins and minerals? Without
protein, carbs and fats? Now ask yourself how long he’d last without water. When it
comes to fluids, we’re not talking months or weeks – we’re talking mere days. Don’t
become complacent. It’s widely known that thirst lags behind need; by the time your
hypothalamus kicks-in, you’re already screwing yourself. Drink in a prophylactic
manner. And while we’re talking prophylaxis, you may want to take 7-14 days to
acclimatize to hot weather before returning to butt-busting workouts, as we alluded to
earlier.(23) Track acute weight losses during workouts, record occurrences of dry mouth
in your training log and even keep an eye on how dark your urine is pre/ post exercise.
This triumvirate is useful.(2,13) These preemptive strikes, considering the intake
recommendations above, will help you more than most guys even realize.
Dr. Lonnie Lowery is an exercise physiologist and licensed nutrition professional,
working – and working out - with collegiate athletes in hot environments. He can be
reached at Lonman7@hotmail.com or via the Staley Coaching Club
(http://www.staleytraining.com/coaching/).
References and Further Reading
1. American College of Sports Medicine. Exercise and fluid replacement. Med. Sci.
Sports Exerc. 1996; 28(1): i-vii. http://www.acsm-msse.org/pt/pt-core/templatejournal/msse/media/0196.htm accessed. June 28, 2006.
2. Armstrong, L., et al. Urinary indices during dehydration, exercise, and
rehydration. Int J Sport Nutr. 1998 Dec;8(4):345-55.
3. Cleary, M., et al. Dehydration and symptoms of delayed-onset muscle soreness in
normothermic men. J Athl Train. 2006 Jan-Mar;41(1):36-45.
4. Cleary, M., et al. Dehydration and symptoms of delayed-onset muscle soreness in
hyperthermic males. J Athl Train. 2005 Oct–Dec; 40(4): 288–297.
5. Cochrane, D. and Sleivert, G. Do changing patterns of heat and humidity
influence thermoregulation and endurance performance? J Sci Med Sport. 1999
Dec;2(4):322-32.
6. Deuster, P., et al. Hormonal responses to ingesting water or a carbohydrate
beverage during a 2 h run. Med Sci Sports Exerc. Jan;24(1):72-9,1992.
7. Ganio, M., et al. Fluid ingestion attenuates the decline in VO2peak associated
with cardiovascular drift. Med Sci Sports Exerc. 2006 May;38(5):901-9.
8. Goulet, E. et al. Effect of glycerol-induced hyperhydration on thermoregulatory
and cardiovascular functions and endurance performance during prolonged
cycling in a 25 degrees C environment. Appl Physiol Nutr Metab. 2006
Apr;31(2):101-9.
9. Graham, T. Caffeine and exercise: metabolism, endurance and performance.
Sports Med 2001;31(11):785-807.
10. Jimenez, C., et al. Plasma volume changes during and after acute variations of
body hydration level in humans. Eur J Appl Physiol Occup Physiol. 1999
Jun;80(1):1-8.
11. Jimenez, C., et al. Plasma compartment filling after exercise or heat exposure.
Med Sci Sports Exerc. 2002 Oct;34(10):1624-31.
12. Lowery, L. Assessing Post-Workout Recovery: An Issue of Timing. Sports
Cardiovasc Well Nutr 19th Annual Symposium. Chicago, IL: 2003.
13. Lowery, L. Physical Recovery & Improvement: It Happens Outside of Practice!
Ohio Dept. Education Broadcast Seminar. Akron, OH: 2006.
14. Melin, B., et al. Effects of hydration state on hormonal and renal responses during
moderate exercise in the heat. Eur J Appl Physiol Occup Physiol. 1997; 76(4):
320-7.
15. Nieman D. Influence of mode and carbohydrate on the cytokine response to heavy
exertion. Med Sci Sports Exerc May;30(5):671-678, 1998
16. Nieman, D. and Bishop, N. Nutritional strategies to counter stress to the immune
system in athletes, with special reference to football. J Sports Sci. 2006
Jul;24(7):763-72.
17. Neumayr, G., et al. Short-term effects of prolonged strenuous endurance exercise
on the level of haematocrit in amateur cyclists. Int J Sports Med. 2002
Apr;23(3):158-61.
18. Ploutz-Snyder, L., et al. Resistance exercise-induced fluid shifts: change in active
muscle size and plasma volume. Am J Physiol. 1995 Sep;269(3 Pt 2):R536-43.
19. Robergs, R. and Griffin, S. Glycerol. Biochemistry, pharmacokinetics and clinical
and practical applications. Sports Med. 1998 Sep;26(3):145-67.
20. Wagner, D. Hyperhydrating with glycerol: implications for athletic performance.
J Am Diet Assoc. 1999 Feb;99(2):207-12.
21. Watson, G., et al. Creatine use and exercise heat tolerance in dehydrated men. J
Athl Train. 2006 Jan-Mar;41(1):18-29.
22. White, J., et al. Fluid replacement needs of well-trained male and female athletes
during indoor and outdoor steady state running. J Sci Med Sport. 1998
Sep;1(3):131-42.
23. Williams, M. Nutrition for Health, Fitness and Sport. Boston, MA: McGraw-Hill
Higher Education.