Saturday, October 26, 2013

Your Muscles are Thirsty

By Robert Wildman, PhD, RD, FISSN 

When you're watching elite physique competitions like events constituting Olympia Weekend, it can be easy to come to the conclusion that water is something to be "shed" in the quest for a more defined physique. While it's definitely true that dehydration practices are common in contest prep, in any other setting water is quite simply the most important anabolic nutrient you can ingest. Unfortunately, it is also one of the most overlooked.
A few years back, the Gatorade Sports Science Institute collaborated with Bally Total Fitness on a hydration-focused study, and researchers determined that more than 40 percent of participants going into a group exercise class were partially dehydrated.1 How strongly this percentage carries to strength training individuals is unclear, but there's no doubt about the negative impact that dehydration has on performance in weightlifting, as well as on muscular growth and recovery.

You've probably heard that the human body consists of approximately two-thirds water. However, this number barely begins to portray the importance of H20 from a muscular or training perspective. Let's plumb the depths of what water means to you in the gym.


You may recall hearing somewhere—like in one of my previous articles, for instance—that muscle is more than 80 percent protein on a dry weight basis. However, it's equally important to remember that your muscles aren't dry. In a living, moving body, skeletal muscle is more than 70 percent water. All contractions and all of the heavy muscle proteinsynthesis operations take place underwater, so to speak.
During resistance training, water is driven from blood into muscle cells and surrounding areas—known as interstitial space—based on the muscle squeezing during contraction. This creates the "pump" sensation, but on a more fundamental level, it's also just what muscles do when they try to move a heavy load. However, when body water is compromised because of poor fluid consumption, often in combination with excessive sweating, water is drawn out of muscle and back into the blood. This ensures the preservation of circulation and keeps your blood pressure at safe levels.
When you don't have enough water to fill the muscle cells, you're at risk of losing more than your pump. Research studies have shown that when cells lose water, and thus volume, protein production can slow down and protein breakdown can speed up.2-4 While researchers are still working out the details, it seems likely that post-exercise muscleprotein synthesis (MPS) would also be hampered in an dehydrated state.
Greater muscle breakdown, less new muscle growth—if the implications of that don't make sense to you, then you're definitely operating a quart low. Go get a glass—or maybe a jug—of agua before reading any further.


Several studies have indicated that during aerobic performance, such as running or cycling, performance begins to decrease when dehydration progressively exceeds 2-3 percent body weight loss.5 That may sound like a lot, but research has also shown that the thirst sensation doesn't really kick in until you're already dehydrated. So if it helps, think of it this way: If you're thirsty, your performance is being affected.
For intense training, such as multiple sprint sessions and weight training, the window is slightly larger, but the impact can still be dramatic. Power generation is thought to become compromised at 3-4 percent reduction in body weight, but one research study was able to show that upper and lower body power output was reduced after 3 percent dehydration. The researchers concluded this simple amount was enough to increase athletes' risk of injury.6-7

When researchers have looked more closely at how dehydration negatively impacts strength training, they have seen effects on both objective and subjective markers. In one study, participants were dehydrated by three percent before performing three sets to failure of the bench press, lat pull-down, overhead press, barbell curl, triceps press, and leg press, with a two-minute rest period between both sets and exercises. Another group performed the same routine, but properly hydrated. The researchers determined that total repetitions (all sets combined) were significantly lower when the participants were dehydrated, but subjects also perceived the exercises as more difficult, and they needed longer for their heart rates to recover.8
In a different study, researchers determined that measures of back squat performance were significantly decreased in later sets at levels of dehydration as low as 2.5 percent, and even more so at 5 percent.9 When the total work performed during a training session is decreased in such a way, so is the level of stimulus to build muscle and improve strength.10 Put another way, leaving your water bottle at home could mean leaving gains on the table.



When we do the math, it becomes clear that our dietary need for water far exceeds any other essential nutrient. The symptoms of water deficiency begin to show much more rapidly than for any other nutrient, and as such, water should be a top priority throughout the day—especially if you train.
General recommendations for people who train and sweat are 3.5-7 liters per day, or the equivalent of about 7-15 pounds of fluid. Taking in this much water requires dedication, but it's worth the trouble. While many weight trainers and other strength athletes will hydrate before and train with water bottles close by or frequent the water fountain, others ignore hydration opportunities before and during training.
Don't leave your results up to chance. Staying hydrated is the cheapest, easiest way there is to maximize your performance in the gym and afterward, so keep a bottle close at hand and always know where you can get more!
  1. Stover EA, Petrie HJ, Passe D, Horswill CA, Murray B, & Wildman R (2006). Urine specific gravity in exercisers prior to physical training. Appl Physiol Nutr Metab, 31(3), 320-7.
  2. Ritz P, Salle A, Simard G, Dumas JF, Foussard F, & Malthiery Y (2003). Effects of changes in water compartments on physiology and metabolism. Eur J Clin Nutr, 57 (Suppl 2) , S2-5.
  3. Schliess F, & Häussinger D. Cell volume and insulin signaling (2003). Int Rev Cytol, 225, 187-228.
  4. Häussinger D, Roth E, Lang F, & Gerok W. Cellular hydration state: an important determinant of protein catabolism in health and disease (1993). Lancet, 341(8856) , 1330-32.
  5. Bardis CN, Kavouras SA, Arnaoutis G, Panagiotakos DB, & Sidossis LS (2013). Mild Dehydration and Cycling Performance During 5-Kilometer Hill Climbing. J Athl Train, epub ahead of print.
  6. Kraft JA, Green JM, Bishop PA, Richardson MT, Neggers YH, & Leeper JD (2012). The influence of hydration on anaerobic performance: a review. Res Q Exerc Sport, 83(2) , 282-92.
  7. Jones LC, Cleary MA, Lopez RM, Zuri RE, & Lopez R (2008). Active dehydration impairs upper and lower body anaerobic muscular power. J Strength Cond Res, 22(2), 455-63.
  8. Kraft JA, Green JM, Bishop PA, Richardson MT, Neggers YH, & Leeper JD (2010). Impact of dehydration on a full body resistance exercise protocol. Eur J Appl Physiol, 109(2) , 259-67.
  9. Judelson DA, Maresh CM, Farrell MJ, Yamamoto LM, Armstrong LE, Kraemer WJ, Volek JS, Spiering BA, Casa DJ, & Anderson JM (2007). Effect of hydration state on strength, power, and resistance exercise performance. Med Sci Sports Exerc, 39(10), 1817-24.
  10. Wildman REC, Miller BS, & Wilborn C (2014). Sport & Fitness Nutrition. Kendall Hunt Publishing

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