Precious Bodily Fluids


Precious Bodily Fluids
by Lonnie Lowery, PhD

Now that I've got your attention with the title, let's try to raise our thinking from the lower centers of bodily function and get more cerebral, shall we? (Admittedly there are those, like a certain editor around here, who can weave both into an entertaining editorial, but I'm not going to attempt that bit of literary stunt pilotry.)


Now that I've got your attention with the title, let's try to raise our thinking from the lower centers of bodily function and get more cerebral, shall we? (Admittedly there are those, like a certain editor around here, who can weave both into an entertaining editorial, but I'm not going to attempt that bit of literary stunt pilotry.)

Let's go beyond the obvious – let's talk "advanced hydration". Maybe you think the topic is remedial, but I assure you, I've got some new and definitely interesting things to share!

Now, we must understand why the seemingly obvious recommendations are made – then we must go a step further so we can tweak such things as circumstances dictate.

I've always hated blind obedience and I bet you do, too. As warrior nerds and T-men we have no time for neon-colored sweat or corporate gimmicks. We want to actually understand because there's a clear link between knowledge and success. There's plenty of summer left and there are some things that you should know beyond what sports drink commercials try to spoon-feed you.

So let's fill our tanks – both physical and mental.

Training Without Draining

I was stunned when I first learned where water losses came from. As we lose weight during a workout and our clothes grow heavy with sweat, that water doesn't just appear. A significant portion used to be blood (plasma) volume!

Plasma, or similarly serum comprises a bit over half of whole blood. Here's a graph of how it goes away under different conditions...

Plasma Volume Loss

Data in graph from references below.

Whether it's exercise (which seriously affects plasma volume), heat (which affects it even more), or even a squat workout that induces a shift of fluids into the interstitial space (a "pump"), we sacrifice a little bit of our overall blood volume as we exercise.

If you're anything like me, you've actually suffered the effects of all three of these stressors at once! Ugh! This is a big deal considering that we can only lose an estimated 1% of body weight from dehydration before side effects occur like performance decrements, weakness, fatigue, and eventually heat illness (especially as we go beyond 5% dehydration).(23)

Once heat illness does hit (heat exhaustion and god forbid, heat stroke) it can be three months before heat tolerance resumes.(23) Some individuals can irreversibly lose heat tolerance as thermoregulatory centers of the brain become permanently damaged. So dehydration in the heat is no joke.

Perhaps even more disturbing, acute body mass loss from ramped-up sweating and panting can be doubly dangerous for us men. According to some late 90s data from a researcher named White and his colleagues, men's losses can double that of women's!(22) This research was done both indoors and outdoors during steady state running, so it's fairly representative of what many of us endure.

We need to appreciate that the heart muscle is pulling double duty as we exercise in the heat, perfusing both working muscles and the skin (for cooling). As exercise continues, heart rate rises beyond the needs of the muscular workload, a phenomenon called cardiac drift.

Without sufficient plasma volume to push around, the stroke volume of the heart falls-off (stroke volume x heart rate = cardiac output). This effect actually reduces peak oxygen usage, called VO2-peak or even aerobic capacity.(7) Even if you're not an endurance athlete, general conditioning still requires some level of aerobic capacity.

And on the skin perfusion side of things, it's important to realize that sweating is our number one way to cool off. A liter of sweat, about the amount evaporating over 60-90 minutes of exercise, carries away an amazing 580 kcal of heat! Of course, this doesn't mean that sweating in a sauna can replace dieting, as heat can be injected from the environment; it doesn't all come from muscular work and burning of stored fat. At any rate, sweating is good and the more fit you are, the better you are at it!

Muscle Jerky

How does flat, shrunken, dry and cooked sound to you? These adjectives are a desirable description of turkey or beef jerky – not of your biceps or quads! And such descriptions are less of an exaggeration than you might realize. First, cells do dehydrate and shrink. As a generality, this causes catabolism (breakdown) within the cell, as has been described by the likes of Dieter Haussinger (whose work has admittedly been exaggerated by unscrupulous supplement companies).

You might think of cell shrinkage and catabolism as a kind of anti-insulin effect. Instead of swelling muscle glycogen concentrations and protein synthesis making you bigger, the opposite type of effect is making you smaller. Sure, about two-thirds of our body's water is within our cells (the "intracellular compartment"), but it's not impervious to loss.

And from a larger tissue-level viewpoint, blood flow (perfusion) to the muscle suffers when you dehydrate. Forgetting about the water issue for a moment, low perfusion is not conducive to nutrient delivery either (and again looks like the opposite of how insulin helps us grow).

Second, there is at least some connection between lifting, hot environments, muscle temperature and heat shock proteins.(4) Heat shock proteins, or HSPs are a protective cellular response to stress, and were first described in relation to – you guessed it – heat.

It's not news that our muscle proteins can and do denature in response to various stressors, not unlike the way an egg protein turns white in a frying pan. Yikes! Dehydration hurts our ability to cool off and muscle contractions add to the stress by raising local temperatures. Again, flat, shrunken, dry and cooked sounds like a meat product Randy "Macho Man" Savage would hock in a commercial; no bodybuilder wants to shrink up and bring new meaning to the term "Slim Jim". Keep your muscles full with pre-, mid-, and post-workout drinks.

Also, there are fairly new data suggesting that eccentric exercise (lengthening contractions or "negatives") leave even more muscle trauma when done in the presence of dehydration and hyperthermia... that is, at least from a muscle soreness perspective.(4)

Now, negatives are great for hypertrophy but they are also brutal, so don't dehydrate when lifting in the heat! All bodybuilding exercise involves negatives on some level, so your recovery time frames could become even longer. If you're interested in muscle structural damage beyond simple soreness, go check out Muscle Masochism here on the site. The take home message here yet again is: Don't be a "jerk". Take along a cold sports drink during hot summer training!

Okay, so hydration is so fundamental to performance and growth, but what about the hormonal consequences of exercising without a bottle of fluid in-hand?

Dehydration: Who Needs Added Stress?

I train hard – freakinghard 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 interleukin-6 which, like cortisol, can be reduced by imbibing diluted 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. 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.

The Problem The Biological Fix
Plasma Volume Drain, Decreased stroke volume, Reduced Aerobic peak (endurance performance) Maintain plasma volume
Reduced Muscle Blood Flow, Struggle to Maintain Muscle and Skin Perfusion Maintain plasma volume, flow to capillary beds
Hyperthermia, Muscle Protein Denaturing, Heat Illness Sweat! It's bodily cooling to the tune of 580 kcal per liter; see above
Cell Dehydration, Cell Catabolism, Muscle Soreness 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're 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.

PV Changes

Figure 1. PV Changes after 45 min. Moderate Treadmill Running

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're not acclimatized to the heat and/ or if you're untrained, you'll 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 Update 2006 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 to be 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.

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 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 Med2001;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.