by G. John Mullen, DPT 2011 | email@example.com
Sports drinks have grown into a billion dollar business beginning with the development of current industry leader, Gatorade, at the University of Florida. The market has rapidly expanded since and grocery store shelves are now lined with a myriad of drinks that promise to restore electrolyte levels following exercise or maintain body alkalinity. These sports drinks have convinced consumers to expand their use and are now consumed during meals or anytime someone feels like a quick snack (yes I said snack, as most of them should be considered snacks given their content, 122 calories in a 20 ounce bottle. To clarify, this amount of calories is great for an intense workout, but if you’re not working out it is a snack). Hydration status is deemed quintessential in any sporting event and proper hydration is needed for optimal performance, but the association between dehydration and electrolytes is not supported by the literature. Moreover, these drinks are constantly trying to alter the body’s pH status. Luckily the bodies naturally homeostatic state prevents you from oscillating between acidic to basic states. This article will dig into the volume of liquid needed to stay optimally hydrated, proper electrolyte consumption, muscle cramps, hydration and body pH.
Stat Fact: The amount of water in the human body varies with size, but a 154 pound person is estimated to contain 40 L of water. How can 12 fl ounces of alkaline water affect this volume?
Dehydration is a big deal and can wreak havoc on your athletic performance. The American College of Sports Medicine suggests “athletes should develop customized fluid retention plans to prevent excessive dehydration (more than a 2% loss in body weight).” This suggests athletes need to weigh themselves before and after exercise to determine the amount of fluid they lose. For most normal/sane people, weighing yourself pre- and post-workout is out of the question (we don’t blame you). Luckily, we can estimate water loss with exercise at approximately 1 liter per hour during moderate/intense exercise. This guesstimation does not address or account electrolytes, so why are they in the drinks?
Electrolyte consumption is a large selling point for companies. Most people believe electrolyte abnormalities are correlated with dehydration and muscle cramping…and everyone remembers the yellow and green liquid drenched athletes in Gatorade’s most recent campaign trying to convince you that their sugar water is the cure for fatigue and cramping. We’re pretty sure this discoloration was supposed to depict salt wasting via sweat (and not radiation poisoning), but after watching the commercial we were convinced they were selling the cure to cancer. On a side note, salt loss via sweat is another topic blown out of proportion by popular media. Yes, there is salt in sweat, but the total salt loss remains relatively minimal. Truth be told, your boy’s electrolyte concentration is higher following exercise than before exercise, since the volume of water is much higher relative to electrolytes, thus the concentration of electrolytes is higher, making us question the case for electrolyte-induced cramps. Recent literature suggests that poor muscle activation and fatigue cause exercise-induced cramps, not hydration status or electrolyte concentration6. Let’s look at a marathon as an example: two athletes can drink the same volume as one another, but only one will cramp…how did hydration status cause cramping given the same level of hydration? Anyone? Concurrent with this theory, we see highly deconditioned patients cramping after a few repetitions of exercise. Hydration or poor conditioning? It is hard to admit when society has been duped but it happens (the cigarette companies are still smiling the whole way to the bank). The sports drink industry got us. We will admit, while the comparison to tobacco is an overstatement, the sports industry is acknowledging their deception with their alteration in products (look at all the different G drinks Gatorade has recently developed containing a different mix of macronutrients). Now Gatorade is selling G2 which only has 70 calories. These new products contain more optimal post-exercise nutrition in line with Gatorade’s original promise (note: the quantity of sugar they contain remains questionable). Most notably, G1 provides slow acting carbohydrates and B vitamins to provide energy before the workout, G2 contains half the calories of regular Gatorade for a short high intensity workout and G3 provides a blend of protein and carbohydrates to recover muscle breakdown.
The sports drinks are not the only ones trying to convince exercisers to buy a questionable product. Look no further than water the new alkaline water craze. Alkaline water is supposed to balance the “acidity in the body.” Let’s look at the science behind this: in a normal day, you consume a spectrum of items that slightly (and only transiently) alter the bodies’ baseline pH if at all. Why would consuming one more item make a difference? The body has as amazing system for counter-balancing these minimal acidic shifts (exhalation, for example). During exhalation, the body gets rid of carbon dioxide (carbon dioxide acts like an acid in our bodies through a series of reactions) and thus slightly increases our body’s pH. Bicarbonate (an ion present in our bloodstream) also acts as an acid-base buffer. These buffers help prevent any changes in pH despite the wide variety of substances you consume and conditions your body experiences. Before we get carried away by the alkaline water craze, let’s discuss some chemistry…don’t be scared, we’ll take baby steps.
The chemistry of water is an interesting subject as this aqueous solution makes up the majority of this fine planet and it is the first substance astronauts look for when identifying potential of life on planets. Water is composed of both H+ and OH– ions. These two quantities are the ying and the yang of water. If OH– concentration is greater than the H+ concentration, the substance is alkaline. In a perfect world, water contains equal amounts of H+ and OH– making the substance neutral with a pH of 7. During the alkaline example, the pH would be higher than 7. The pH scale is a bit tricky, but it works on a scale of multiples of 100 (4). This simply means if a pH is 8 there are 100 times as many OH– ions than H+ ions. In the case of alkaline water, there are more than 100 times as many OH– ions than H+ ions. To counterbalance the excess negative charge there must be other positive present (otherwise the water would be electronically unstable…not good). In most cases, positively charged metal ions take the place of H+ (some of which could be troublesome). Likewise, if water is acidic it will contain negative ions to balance out the positive charge of the H+ ions. During intense exercise the body creates a mythical fitness monster called lactic acid. Lactic acid is believed to play a role in fatigue (this remains debatable as the top sprint athletes maintain the highest lactic acid levels during competition and lactate can be converted to glucose during the Cori Cycle…a topic we’ll save for another day). As we were saying, consuming significant amounts of basic product like alkaline water could theoretically raise the pH of your blood. The question is “Why would you want to?” Research looking at the consumption of sodium bicarbonate, commonly known as baking soda, has shown mixed results in terms of improving performance during multiple bouts of exercise secondary by offsetting the transient acidic state created by lactic acid during vigorous exercise (1). We must caution you, however, that this approach has not been globally accepted by the sports community and is believed to only help in multiple bout exercise, not in a single bout race (How often do you run three 5k races in a day?). In addition, the quantity of baking soda suggested in the study has been show to irritate athletes’ gastrointestinal tract…probably not worth all the discomfort. If you still want to hop on the alkaline water bandwagon, we’re not going to stop you, but realize that the overpriced pH-modified liquid isn’t going to do much for you (your body already has a built-in & finely-tuned pH regulatory system). Oh, and whatever you do, don’t spend $5,000 installing a fancy water alkalinizing system in your home. Try tossing an Alka Seltzer in a cup of water, same result, 1/10,000th the price.
Stat Fact: It is estimated 70.8% of the Earth’s surface is composed of water!
Your Take Home Message
Make sure you know what you are ingesting and know do not believe everything as advertised. Remember sports drinks contain calories, almost as much as soft drinks, and should not be considered as a replacement to water.
What should you do differently?
Refuel the body properly during exercise and everyday life, know what you put into your body!
Questions? E-mail the Author: firstname.lastname@example.org
- Artioli G, Gualano B, Coelho D, Benatti F, Gailey A, Lancha AJ. Does sodium-bicarbonate ingestion improve simulated judo performance? Int J Sport Nutr Exerc Metab. Apr 2007;17(2):206-217.
- Lower S. Snake Oil on Tap. “Ionized” or Alkaline Water. July 20, 2010. Available athttp://www.chem1.com/CQ/ionbunk.html. Accessed July 24, 2010
- McClung M, Collins D. “Because I know it will!”: placebo effects of an ergogenic aid on athletic performance. J Sport Exerc Psychol. Jun 2007;29(3):382-394.
- Pidwirny, Michael (2006). “Fundamentals of Physical Geography (2nd Edition)”. PhysicalGeography.net. http://www.physicalgeography.net/fundamentals/7h.html. Retrieved 2007-03-19.
- Siegler J, Keatley S, Midgley A, Nevill A, McNaughton L. Pre-exercise alkalosis and acid-base recovery. Int J Sports Med. Jul 2008;29(7):545-551.
- Schwellnus, MP. Cause of Exercise induced cramps (EAMC)–altered neuromuscular control, dehydration or electrolyte depletion? British Journal of Sports Medicine. Nov 2009; 43: 401-408.