Coconut Water - The Bizarro Sports Drink

Posted on July 14, 2014 by Allen Lim, PhD | 2 Comments

Coconut water is naturally sweet and high in the electrolyte potassium. So it’s not uncommon for people to ask about the use of coconut water as a real food sports drink. But, when assessing the use of coconut water as sports drink, what comes to mind is C.G. Jung’s idea of “shadows” – the aspects of our lives that are in actuality completely opposite of what we think or perceive. It’s an apt reference point, because if sports drinks have a dark shadow, it’s coconut water.  Coconut water is fine if you just want something real to drink when you’re not exercising or for short duration exercise (< 90 minutes or less) (1), but if you’re sweating a lot during prolonged exercise, it’s definitely the wrong choice.

In the realm of human physiology, coconut water is the exact opposite of what we need to replace the sweat we lose when we are exercising. The reason for this is that the primary electrolyte in coconut water is potassium, whereas the primary electrolyte in sweat is sodium. More specifically, 16 oz of coconut water contains 950 mg of potassium and only 50 mg of sodium. In contrast, 16 oz of sweat contains anywhere from 200 to 700 mg of sodium, and only about 50 to 110 mg of potassium (2,3) (Table 1).  


Coconut Water



Sodium (mg)



450 ± 250

Potassium (mg)



80 ± 30

Calcium (mg)



25 ± 17

Magnesium (mg)



6 ± 6

Table 1. Electrolyte Content in 16 oz of Coconut Water, Skratch Exercise Hydration Mix, and Sweat.

The high sodium and low potassium content of sweat reflects the relatively high sodium and low potassium concentration found in our blood or vascular space that feeds our sweat glands. This difference is due to the fact that pumps in our cell membranes that set up the chemical-electrical gradients across cells that allow proper cell function and communication, do so by pumping potassium into cells and sodium out of cells, making intracellular (inside cells) potassium levels very high compared to sodium, and extracellular (outside of cells) sodium levels very high compared to potassium.

Because water equilibrates between the major spaces across the body, which include our vascular space (blood vessels), extracellular space, and intracellular space, when we consume an excess of sodium we tend to shift water into our vascular space and when we consume an excess of potassium we tend to shift water into our cells. This is why, in some people, excess sodium consumption can raise blood pressure. Likewise, when we consume foods or liquids that are very high in potassium, we tend to increase our intracellular water stores. 

During exercise, however, increasing the water volume in our vascular space is what is critical to help provide the necessary blood volume to deliver oxygen, eliminate heat, and provide valuable fluid for sweat. So in the context of exercise, consuming water and ample sodium is much more important than consuming potassium, not just to replace what we lose in sweat, but to maintain an adequate blood volume to meet the increased demands on our circulatory system especially in the heat (4,5). In contrast, consuming coconut water or plenty of fruits and vegetables that are high in potassium along with water isn’t a bad strategy for rehydrating cells when recovering, though it’s important to remember that we don’t deplete nearly the same amount of potassium during exercise as we do sodium.  

In most cases, drinking a bottle or two of coconut water during exercise isn’t going to kill us, as our kidneys are pretty good at keeping our electrolyte concentrations in check, especially if consumption isn’t excessive. But it definitely isn’t going to help us during exercise compared to a good sports drink with adequate sodium. That said, drinking only coconut water for long periods of time while exercising in the heat is one of the rare situations that could lead to dangerous electrolyte imbalances within the body that may be extremely harmful. While, a lot has been written about the hyponatremia that can occur if we only drink water during prolonged and heavy exercise in the heat, drinking only coconut water can exacerbate the situation, since the excess potassium consumption only compounds the inadequate sodium replacement (6).  Thus, in situations where drinking water alone can be harmful, be assured that drinking only coconut water may be just as is or even more harmful (7).

Ultimately, coconut water is the exact opposite of what we need when we are sweating heavily during exercise. It’s like Bizarro – Superman’s opposite – a character that Alvin Schwartz, one of the original writers for the Superman strip, found inspiration for through C.G. Jung’s “shadow” archetype. Just like Bizarro and Superman, there are a lot of similarities between coconut water and the all-natural Exercise Hydration Mix on the surface – both contain the same amount of calories, both contain electrolytes, and both are made with real food ingredients. But don’t be fooled, when you take a closer look, the reality is that coconut water is the Bizarro sports drink. 


1. Kalman, D. S., Feldman, S., Krieger, D. R., & Bloomer, R. J. (2012). Comparison of coconut water and a carbohydrate-electrolyte sport drink on measures of hydration and physical performance in exercise-trained men. J Int Soc Sports Nutr, 9(1), 1. 


2. Shirreffs, S. M., & Maughan, R. J. (1997). Whole body sweat collection in humans: an improved method with preliminary data on electrolyte content. J Appl Physiol, 82(1), 336-341. 


3. Adams, R., Johnson, R. E., & Sargent, F. (1958). The osmotic pressure (freezing point) of human sweat in relation to its chemical composition. Q J Exp Physiol Cogn Med Sci, 43(3), 241-257. 


4. Sawka, M. N., & Montain, S. J. (2000). Fluid and electrolyte supplementation for exercise heat stress. Am J Clin Nutr, 72(2 Suppl), 564S-572S. 


5. Sharp, R. L. (2006). Role of sodium in fluid homeostasis with exercise. J Am Coll Nutr, 25(3 Suppl), 231S-239S. 


6. Schucany, W. G. (2007). Exercise-associated hyponatremia. Proc (Bayl Univ Med Cent), 20(4), 398-401. 


7. Noakes, T. D., Goodwin, N., Rayner, B. L., Branken, T., & Taylor, R. K. (1985). Water intoxication: a possible complication during endurance exercise. Med Sci Sports Exerc, 17(3), 370-375.




Posted in Science

A Quick Read on Hyper Hydration From Dr. Allen Lim

Posted on November 11, 2013 by Allen Lim, PhD | 7 Comments

The Back Story:

For the last two years, we’ve been making a secret drink mix that is extremely high in sodium to over-hydrate or “hyper-hydrate” athletes immediately before they put themselves in grueling situations where they end up sweating more than they can possibly drink.

Given its purpose, we called the product our Hyper Hydration Drink Mix and kept access to it limited to only our most hot and sweaty customers – NASCAR drivers, fire fighters, and a handful of professional runners and cyclists. We weren’t trying to be elite by limiting the product’s access. Rather, we had legitimate concerns about the product’s taste and worried about what might happen if the product was used inappropriately or without hands on instruction.

So for almost two years, we tinkered, studied, and worked carefully with a cast of characters – some very fast, others slow, but all extremely smart & sweaty - to evolve our formula until we reached a point that we felt, when used as directed, the product was safe, effective, and palatable for the general athletic population to use as a method to preemptively hydrate before events known, or with the potential, to elicit severe dehydration.

It took us a while, but we felt it important to take the time and care. As part of that diligence, we want to emphasize that our Hyper Hydration Drink Mix is not a sports drink or a “use every time you exercise” product. More to the point, this product is not intended for casual hydration. In fact, we encourage you not to use our Hyper Hydration Drink Mix until you finish reading this blog, talk to your coach, health care professionals, visit google, and give your individual situation and this product some real consideration. It may not be for you. But if you decide it is, then our experience has been that it’s probably exactly what you’ve been looking for. 

 First, a Review of Sweat – Water & Salt:

 When it’s hot or more appropriately when we get really hot, whether it’s through intense exercise or from baking under a garish sun, we sweat to cool our bodies. Without that sweat and the evaporative cooling that comes with it we can overheat and literally start cooking ourselves from the inside out, which isn’t exactly good for either performance or one’s health. Unfortunately, as we sweat we also dehydrate, losing precious water and salt, both of which are critical for normal bodily functions. It’s a bit of a catch 22. Either overheat or dehydrate or both – all of which are bad.

 While the body is almost 60% water by weight, a 70 kg person doesn’t have 42 liters (1 kg of water = 1 L of water) of water to spare to keep them cool. Depending upon the situation (airflow, temperature, work intensity), exercise performance can suffer with as little as a 2-3% drop in body weight due to dehydration. By the time someone loses 10% of body weight from dehydration (7 kg or 15.4 lbs for a 70 kg or 154 lb person), it’s likely that they are critically ill or very close to it. Unlike stored fuel in the form of carbohydrate or fat, we’d kill ourselves before we even came close to tapping into all of our water reserves.

 In addition to thinking about total body water, it’s also important to realize that the water stored in our body isn’t all in one big reservoir. About two-thirds (2/3) of it is inside our cells (intracellular space) while the other one-third (1/3) is outside of cells (extracellular space). Of the water outside of the cells only one-fifth (1/5) of it is in the circulatory system as plasma in the blood (intravascular space), while the other four-fifths (4/5) lies in the space between blood vessels and cells (interstitial space).

The net result is that for an average person our blood volume is only about 5-6 liters, with only about 2.5-3 liters of that being water or plasma. Because maintaining that small plasma volume is critical to keeping our cardiovascular system functioning and precious oxygen flowing to our cells, it’s very easy to see how quickly even a small amount of dehydration can affect performance and thermoregulation (i.e., the maintenance of a stable body temperature).  Although, our body can quickly shift water from one body space to another to maintain central blood volume and blood pressure, in the heat or during heavy exercise, sweat rates can easily reach rates as high as 2-4 liters per hour, which puts an incredible strain on our total body water reserves and on the availability of water in our cardiovascular system. One way to think of it is that in an hour or two of intense exercise in the heat, our bodies need to find a way to replace almost all of the water in our blood.

Equally important, however, is the fact that the water in our plasma or blood isn’t just water – it’s more of a salty soup, containing about 9 grams of sodium chloride per liter (3.5 grams from sodium and 5.5 grams from chloride) – an amount that is similar to the sodium concentration in chicken noodle soup which comes in at 3 to 4 grams of sodium per liter.  Since the water in our bodies or more specifically in our plasma is so salty, the fluid that enters any one of the two million sweat glands across our skin is also salty. In fact, while a number of electrolytes like potassium, calcium, and magnesium are also lost in sweat, sodium chloride makes up the overwhelming majority of the electrolyte loss in sweat. For this reason, electrolyte loss in sweat is really synonymous with salt loss. More importantly, it’s the loss or dilution of sodium, not chloride, that negatively affects our physiology – a phenomenon called hyponatremia that can result in a host of problems that range the gamut from fatigue, confusion, headache, nausea, muscle cramps, seizures, and in rare cases death. Because of these potential issues, getting a handle on the concentration of sodium in sweat (i.e., “sweat sodium”) and replacing that sodium in addition to water, instead of water alone, when dehydrated from heavy sweating is paramount to performance and survival.  

 Unfortunately, getting a handle on the amount of sodium we lose in sweat isn’t that easy. Unlike the relative ease of estimating water loss through changes in body weight using a simple bathroom scale, measuring sweat sodium requires expensive and less accessible equipment. When sweat sodium is measured, however, incredibly large differences between individuals are found, with sodium concentrations ranging from 300 to 2000 mg per liter of sweat with a median somewhere between 700 to 800 mg per liter. The bottom line is that the sodium concentration of sweat is not a “one size fits all” phenomena.

The reason behind this massive sweat sodium range is primarily genetic. When sweat first enters the sweat gland it has the same sodium concentration as blood at 3500 mg per liter (3.5 g/L). But as that sweat moves through the duct or lumen of the sweat gland towards the surface of the skin, small channels inside the duct reabsorb, on average, two-thirds of the sodium. But like many physiological attributes, the number and performance of these sodium specific channels is highly individual with a genetic basis that explains most of the extreme range in sweat sodium concentration. Non-genetic factors, however, can also affect sweat sodium. These factors include heat acclimatization (spares sodium), training (spares sodium), the sweat rate in and of itself (increases in sweat rate increase sweat sodium loss), body weight and shape (a low body surface area to mass requires more sweat), and dietary sodium intake (increases in dietary sodium increase sweat sodium loss). 

 Together, these genetic and non-genetic factors explain why some of us are consistently covered in white salt at the end of a long day of exercise while others are not. They may also explain why some more easily exhibit signs associated with severe dehydration and hyponatremia like cramping, nausea, fatigue, heat stress, and headaches after a prolonged period of heavy sweating despite the use of a sports drink.  Ultimately, whether someone knows their sweat rate or sweat sodium, these collective signs are a real world and real time barometer that are extremely important to pay attention to and understand.

The Problem:

 If you’ve paid enough attention to yourself during prolonged endurance exercise or during any activity that causes you to sweat at unreasonably high rates then you probably already have a pretty good sense of whether or not your current hydration strategies are adequate. But as a point of self-review, ask yourself the following questions:

  1. Do you find yourself in situations where you sweat way more than you can drink?
  2. Are you having problems figuring out how you’re going to get enough fluid during an event?
  3. Do you compete in very intense events where you simply can’t get anything to drink?
  4. As a result of sweating way more than you can drink or not having enough to drink, do you find yourself losing an excess amount of body weight (e.g., more than 5-7% in a single bout)?
  5. Do you end up feeling like total crud, especially relative to others, during or at the end of sweaty exercise in the heat? Feeling like crud might include headaches, nausea, irritability, muscle twitches, uncontrollable cramps, and poor performance and excessive fatigue.
  6. Are you covered in a lot of white crusty salt or more white crusty salt than others at the end of a long workout? For example, do dogs love to lick you and only you after a workout?
  7. Do you think or do people tell you that you sweat a lot more than everyone else around you? For example, has any ever asked you, “Why are you sweating so much?” Usually, little kids ask this a lot.
  8. Do you get really light headed all the time when you’re training hard and suffer from excessively low blood pressure?
  9. Do you feel better when you’re constantly popping salt pills during an endurance event and are you getting tired of popping all those salt pills? Would you rather eat a bag of chips, drink miso soup, or gnaw on pickles? Seriously, are you always craving salt?
  10. Is it common for you to get so dehydrated that you end up in a medical tent or a hospital getting IV hydration?

There’s a possibility that you think these questions are crazy and that you answered “no” to most of them. If that’s the case and none of the issues listed above are a problem for you, then you can stop reading. Our Hyper Hydration Drink Mix isn’t for you and you don’t need to waste your time and money to try it.

On the other hand, if these questions resonate with you and you feel like you’ve just locked eyes with someone standing off in the distance - someone who really understands you, then we may be on to something. Despite our irrevocable propensity for jocularity (i.e., we like to laugh at ourselves & keep things funny), this really isn’t a laughing or joking matter. Severe dehydration resulting in both water and sodium loss can be very dangerous. But so can loading up on a lot of water and sodium that you don’t need, which is essentially the solution that we’ve come up with to help all of the folks out there who do answer the questions above with a definitive “yes.”

 The Solution (Common sense, inspiration, and the formula):

 One thing to realize is that, despite the product we’ve developed, there is no one simple solution to all of the problems listed above. Ultimately, common sense and safety during any activity needs to rule supreme. So as a reminder, realize that you still need to take care of yourself with proper nutrition, sleep, and training. No single product will ever make up for self-awareness and consistent preparation. With that in mind, also realize that science is not a set of facts, it’s the testing of theories. And in the realm of your personal performance, you are the experiment, which requires a level of precision, care, and honesty that may lead you to conclude that our Hyper Hydration Mix does or doesn’t work for you. Ultimately, knowing how something works for you as an individual is far more important than knowing how it works for others, despite the fact that every bit of data informs our personal decisions.

That all said, the basic question we’ve been working on is how to safely and effectively maximize the water and sodium reserve within the body, in particular the volume of the intravascular space (i.e., the water & salt in the cardiovascular system, aka, vascular space or plasma volume), to preemptively combat dehydration. Obviously, one strategy is to simply drink more water and increase dietary salt intake in the week or days before an event. Many bowls of miso soup come to mind.  In addition, another practical idea is to dramatically increase the intake of carbohydrate in the week or days before an event, since stored carbohydrate in the form of muscle glycogen contains a significant amount of water. If these two strategies are implemented properly, many athletes will gain anywhere from 3-5 pounds of water weight – an indication that they are properly tapered and nourished before an event.

 While there are a host of other techniques that have been used, with varying efficacy, to hyper hydrate the body immediately before exercise, we’ve drawn inspiration for our Hyper Hydration Drink Mix from the most effective and commonly used technique for treating severe dehydration and for increasing intravascular volume - IV hydration using normal saline. Normal saline, also known as an isotonic saline solution, has the same osmolarity and the same sodium chloride concentration as the plasma in the vascular space, making it a perfectly balanced solution to quickly rehydrate the body.

As a point of education or review, osmolarity refers to the number of molecules per liter of solution and can be thought of as analogous to the number of total passengers on a plane. This is different than concentration, which accounts for the mass or weight of those molecules in a given liter of solution and is analogous to the weight of the passengers on a plane. It’s the osmolarity of one solution relative to another that determines the movement of water across a membrane. In order to keep water within the vascular space, the osmolarity needs to be kept constant. Otherwise water would shift from an area of low osmolarity or osmotic pressure to an area of high osmotic pressure.  Likewise, the concentration of sodium also needs to be kept constant since most physiological functions depend on a stable sodium concentration. For example, if the concentration of sodium where to decrease in the blood, also resulting in a drop in the osmolarity of blood, water would begin shifting out of the vascular space, into the interstitial or intracellular space, essentially dehydrating the cardiovascular compartment. At the same time, water would also be excreted by the kidneys to help return the concentration of sodium back to normal - a situation that would further dehydrate the body as a whole. Ultimately, osmolarity and concentration rule supreme. An ideal sports drink, for example, needs to have the same sodium concentration as sweat and a very low osmolarity compared to blood so that water in the gut can rapidly move into the blood stream. Similarly, the ideal solution to increase total body water, especially in the vascular space before sweating ensues, needs to have the same sodium concentration as blood or plasma as well as the same osmolarity making it “isotonic.”

Under the right circumstances, IV hydration with normal saline is safe and effective. But the use of IV hydration immediately before an athletic event in an otherwise healthy individual is not the right circumstance for a number of reasons. First, it’s just not practical or efficient. In fact, a number of studies have demonstrated that in patients that are conscious and free of gastro-intestinal problems, oral rehydration is easier and faster than IV rehydration. Second, the use of IV hydration is cost prohibitive for most athletes, though there are a number of reports that in some sports like American football, that the use of IV hydration pre-game is common practice, especially for athletes known to have issues with dehydration. Whether this is ethical or not is its own and final debate against IV hydration as a pre-exercise hyper hydration technique.  

More importantly, however, there’s a very specific reason why normal saline is generally infused and not ingested orally. That reason is because it’s nearly impossible for someone to rapidly ingest a large volume of normal saline because of it’s taste and because of the irritation caused by the large chloride concentration. Anyone willing to drink a liter or more of a normal saline solution would likely end up feeling nauseous and vomiting. It’s that bad, so we’ve been told by our local ER doctors. Our experience with athletes has always been that when too much sodium chloride or table salt was put in solution, the chloride could be a major irritant. That said we never experienced problems with sodium chloride when it was paired with real food. It’s a funny thing but perhaps a sign that we are not yet smarter than nature when drinking a bowl of salty soup is soothing while a saline solution with the equivalent amount of salt is not. Go figure.

Based on all of this, we formulated our Hyper Hydration Mix to have the same osmolarity and sodium concentration as blood at 3.5 grams per liter. But, instead of using sodium chloride, we paired the sodium in our solution with citrate, which is essentially a neutralized fruit acid or citric acid, the primary ingredient in lime juice. One of the major benefits of using sodium citrate instead of sodium chloride is that sodium citrate is very easy on the gut. The second benefit is that citrate, unlike chloride ion, can be consumed as a substrate or fuel source for energy creating metabolic pathways, specifically as a metabolite in the Citric Acid Cycle (aka, Kreb’s Cycle), a critical pathway for the conversion of sugar and fat into energy. Finally, sodium citrate is a very strong buffer. When it comes to the control of our body’s acidity level (i.e., acid-base balance), increasing positively charged sodium ions and decreasing negatively charged chloride can actually help to buffer or make the body less acidic – an idea known as the “Strong Ion Difference.” Ultimately, this buffering capacity may have positive consequences during intense exercise, especially in the first 5 to 10 minutes, though the performance literature supporting this is mixed. 

 Beyond the use of a large quantity of sodium citrate instead of sodium chloride, our Hyper Hydration Mix is also paired with a small amount of cane sugar and glucose. Water movement across the small intestine can be facilitated by the co-transport of sodium and glucose, where the pairing of 1 glucose molecule to every 2 sodium molecules allows the movement of 210 water molecules across the intestine via a specific sodium-glucose transporter. This co-transport is in addition to the passive movement of water across the intestine via osmosis. Because of this mechanism, we added enough glucose to the formula so that every sodium molecule could be used to maximize the movement of water into the body.

Finally, we struggled to make this high sodium drink palatable. The answer finally came to us in the form of a mango, or more accurately, in the form of many mangos. Putting aside the science hat for a moment and considering the problem from a culinary perspective, we realized that many cultures use mango to cut the saltiness of a dish. To our happy surprise, it worked. But, it took a lot of mangos. The total number of mangos, not the science, is the real secret behind the formula, so we’ll keep that to ourselves for now. Just know that it’s the most expensive ingredient in the entire product. In fact, you’re not really buying a lot of sodium, you’re buying a lot of mangos. Still, with the lower sugar and the extremely high sodium content, there’s no way that we could ever make this product taste even close to our line of Exercise Hydration Mixes. Compared, however, to normal saline and many other sports drink on the market, we feel pretty good about where we landed, especially since we were still able to solve the problem at hand with a bare minimum all-natural approach.

Based on the number of total mango molecules, sodium molecules, and sugar molecules, we pretty much had to stop there to keep the drink isotonic at 280 mOsm/L. Although, we tried throwing more ingredients in the mix, experimenting with different levels and types of sodium salts, percentages of carbohydrate, and fruits we found that the less is more approach worked the best. For example, any more sodium or additional ingredients and we risked making a solution with too high of an osmolarity which could result in significant gastro-intestinal distress and even diarrhea. In contrast, any less sodium than what’s found in blood and we wouldn’t maximize the amount of fluid retained in the vascular space before the kidneys would filter the excess water because of changes in blood pressure or sodium concentration. 

In the end, this product is intended for one specific purpose – to maximize hydration before an event that’s about to punish the participant with a heavy dose of dehydration.  Our solution was to create a product that increases the total sodium and water reserve within the body. Not only is this useful for athletes who know they won’t be able to drink enough to match their sweat losses, it’s also been extremely useful for athletes who know that they lose more sodium that our Exercise Hydration Mix provides them. Ultimately, dehydration is about a loss of both water and sodium and our Hyper Hydration Mix helps athletes to maintain both.  And since it’s sometimes hard to get a handle on how much sodium or water you’re about to lose, then sometimes the simplest solution is to just start with more of what you know you’re going to lose and that you know you can’t afford to lose.

Concerns with the Solution:

What’s ironic about all of this is that the high sodium content that forms the basis of our solution for extreme sweat rates is also the biggest single risk and problem with the solution. At 1700 mg for a single 500 ml serving (3.5 gram per liter), our Hyper Hydration Drink Mix is inappropriate for casual exercise use. A single serving, is similar to the amount of sodium that you’d find in two slices of Pizza Hut Supreme pizza (1720 mg Na+) or six slices of bologna (1850 mg Na+), or two cups of miso soup (2000 mg Na+).  Despite the fact that all of the foods listed above are commonly consumed and thought of as safe, like our Hyper Hydration Drink Mix, they can lead to the potential for an unsafe increase in blood pressure, especially in physically inactive individuals.  Thus, our biggest concern is that someone who is not healthy or is not intending to use the product mistakenly uses it, putting an inadvertent strain on their cardiovascular system. 

Beyond the potential for an elevation in blood pressure, there’s also the risk that sodium sensitive individuals who don’t lose a remarkable amount of sodium in their sweat or who are already adequately hydrated will experience bloating and excessive water retention with the product. For most in this category this will lead to a little discomfort and the knock to their vanity from not looking as ripped or vascular. At some point, the excess fluid will be relieved by excess urination, which in and of itself can be a hassle or concern, especially if occurring in the middle of a workout or ride.

Another concern is that because our Hyper Hydration Drink mix already has a very high sodium concentration and osmotic pressure equal to blood, if very sweet or salty drinks and foods are paired with the product, especially in the presence of a lot of caffeine, then there is a risk that the combined osmotic pressure could overwhelm a person’s gut and cause diarrhea. So it’s important that the drink is used by itself on a relatively empty stomach.

For some, a real valid concern is that they won’t enjoy the taste. If that’s the case, we’d suggest not using it and trying to drink 2-4 bowls of miso-soup right before a grueling event with minimal access to hydration.

Finally, some athletes that we worked with were concerned that the extra water weight would hurt their power to weight ratio. While too much fuel on a helicopter can definitely keep it from flying, when it comes to performance in very intense and hot situations, despite the increase in water weight, it’s unlikely that there would be any hit to that all too precious power to weight output. If anything, the improvement in cardiac output will likely enhance performance, especially relative to competitors who are more dehydrated late in a race or event.

Practical Advice on Experimenting & Usage of Hyper Hydration:

Like most ideas concerning training and nutrition, we are all individuals and responses will vary from person to person. As a generic recommendation, we advise the following directions for use:

  1. Only use our Hyper Hydration Mix before situations where you know you are about to experience intense exercise that will elicit extremely high sweat rates. If you use it before a casual training ride with your buddies, for example, you’ll likely just end up holding up the ride because you’ll end up needing to urinate frequently throughout the ride.
  2. Only use our Hyper Hydration Mix if you are healthy enough to experience intense exercise in situations that will elicit extremely high sweat rates. Consult with your health care professional if you have any questions or concerns about this.  
  3. Start by drinking 1 to 2 servings (1 serving =’s 1 packet mixed with 500 ml of water) about 30 minutes prior to exercise, finishing about 10 minutes before the start of exercise. A good starting point is to goal to consume a total of 10 ml per kg of body weight before exercise.

Based on these generic recommendations, the athletes we have worked with to develop this product have adopted varying personal strategies for the use of the product. Many find that it’s helpful to “top themselves off” the morning of an event by drinking 1 to 2 servings of Hyper Hydration Mix a few hours before competition. If they are already dehydrated from training or the previous days competition, they’ll tend to hold most of the extra fluid they consume and not urinate a lot of it away. If, however, they are adequately hydrated, then using the drink in the morning gives them time to urinate any excess fluid away before competition.

Other athletes have reported that they have good success when they begin using the Hyper Hydration Mix the day or night before a very important event as part of their taper.  While simply increasing their water and dietary sodium intake might work equally as well, for some using our Hyper Hydration Mix is a simple and convenient way to bolster their water and sodium reserves. That said, it’s by no means the only way. In fact, we’ve found that some athletes simply use our product because they are unsure of where they are with respect to their hydration status on any given day. One way to get to know where your hydration stands is to get familiar with your morning body weights as well as the changes in body weight caused by training or competing in different environments. Large or sudden drops in weight are likely due to dehydration.

For athletes, who know that they are adequately hydrated, they have found that our Hyper Hydration Mix becomes more effective when they consume it closer to the start of exercise. This is because if they drink too far out from exercise, the sudden increase in blood pressure simply causes them to urinate most of the extra water away. By waiting until just before exercise, blood flow is redirected away from their kidneys while sweating begins to pull away the excess water and salt reserve. This typically creates the biggest increase in performance relative to their non hyper-hydrated competitors. That said, it only works in very hot environments and for very intense bouts of exercise or competition.

The most important thing to remember is that our Hyper Hydration Mix has very specific use parameters. It’s not a drink anytime sports drink and needs to be used carefully and sparingly with real attention to how you feel and respond. Everyone is different and what works for one person may not work for you. Be willing to experiment and test and above all else use common sense. Less is often more, especially with a product that already has more in it. 

Posted in Science

What's in a Calorie? Do they make you Fat?

Posted on July 16, 2013 by Allen Lim, PhD | 1 Comment

I asked my little nephew the other day if he knew what a calorie was and he quickly replied, “It’s what makes you fat.” I didn’t know if I wanted to laugh or cry. While he was technically correct and his response was unknowingly witty and oddly in tune, I also realized that I might have exposed him to too many pro cyclists and that a three year old shouldn't be concerned about his power to weight ratio. I tried to explain that calories don’t make you fat on their own, but eating more calories than you need can. He didn’t seem to really care about what I was saying so we went back to the more constructive task of tearing up pieces of paper for no particular reason.

Still, his answer got me thinking about whether any of us really understand calories. For whatever reason, one of the most commonly asked questions I get asked when I’m at a bike race is; “Hey Al, how many calories do these riders eat?” I’m so sick of hearing that question that my knee jerk response is always something dry like, “A lot more than you.” But, If I’m in a particularly good mood, I might slowly and critically look the person up and down, and respond in a matter of fact albeit facetious tone; “Obviously less than you.”  That answer always seems to leave them even more confused.

So to set the record straight, let’s get some facts on the table:

1.     A calorie is a unit of measure for energy just like a centimeter or an inch is a unit of measure for distance.   Specifically, one calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius, whereas 1 Calorie with an upper case “C” is equal to 1 kilocalorie or kcal (i.e., 1000 calories), which is equal to the energy needed to raise the temperature of 1 kilogram (1000 grams) of water 1 degree Celsius. In the United States, food is always represented using the upper case “Calories” instead of Kcals because smart people out there felt that Americans couldn’t handle using the “kilo” or “k” designation. That’s the equivalent to making “Grams” with an upper case “G” synonymous with “kilograms” or “kg.” Everyone else just uses “kcals” or “kilocalories.”

2.     I’m not saying you’re fat and I’m very sorry for what I said earlier. Maybe we’re all just affected by misguided societal ideals. Know that if you just focus on your health and happiness the way you look is beautiful to me. In fact, I made you a Christina Aguilera iTunes mix. Listen to that first song because “You are beautiful, in every single way.”

3.     Energy can take on many forms from the mechanical work done by a lever or machine, the heat given off by a fire, the radiation given off by a nuclear reactor, and even the sound of a tree falling in the woods that no one hears. In the end, energy is what allows us to exist, to move, and to be something other than a cold inanimate blob of silent nothingness.

4.     Really, you’re not fat. Well, okay maybe you could lose a few pounds, but we could all lose a few pounds. We cool?

5.     In effect, a calorie is a way to measure heat or the heat that something gives off when it’s burning. To measure the calories or energy in food, scientists literally put a measured quantity of that food in something called a bomb calorimeter and using a whole lot of pressure and oxygen, light a match to detonate that food. The heat given off by that explosion is measured in calories and everyone is happy because they got to blow something up in a lab (lab work is not always so exciting).

6.     I’m not fat either. I’m just an athlete with extra (okay a lot of extra) fuel.

7.     It’s convenient to represent the energy in food using calories (i.e., as the heat food gives off when we burn it), because when our bodies metabolize food we are literally “burning” that food to create heat, potential energy in the chemical bonds of adenosine triphosphate (ATP), and mechanical work when the ATP is broken.  In addition, both processes require the use of oxygen. Thus, we can quantify energy by either measuring the heat given off by a chemical reaction or by the oxygen consumed in that reaction. 

8.     I said I was sorry.

9.     A power meter like the CycleOps PowerTap measures mechanical energy or work by measuring the amount of physical force applied to the rear hub and the distance that hub travels or spins. Mechanical energy is measured in Joules, which is different than a calorie. One calorie is equal to 4.186 joules or roughly 4 joules per calorie. The human body, however, isn’t perfectly efficient, meaning only a fraction of the calories we burn while riding a bike gets turned into mechanical work or joules that moves the pedals. Most of those calories we burn are wasted as heat lost to the world. Specifically only about 1 out of every 4 calories we burn gets converted to joules or useful work. Since the conversion of joules to calories is roughly 4 joules to 1 calorie, the two cancel one another out, such that 1 joule of work measured by a power meter is roughly 1 calorie burned by the body. On a power meter, work is normally given in kilojoules or kj’s so 1000 kj’s of work is equal to about 1000 kilocalories or kcals which by US convention is equal to 1000 Calories (with an upper case “C”) of food. By measuring someone’s exact efficiency in the laboratory we can get a pretty good estimate of the calories they burn when riding with a power meter in the field. This is how we measure and know how many calories riders burn when they compete in races like the Tour of California. Long story short, if their power meter says they did about 3500 kilojoules or kjs, they’ve burned a little over 3500 Calories or kcals.

10.  The CDC reports that 35.7 percent of Americans are obese. Obesity itself is closely associated with heart disease, stroke, type-2 diabetes, and certain types of cancer, making obesity the leading cause of preventable death. In 2008, the US spent $147 billion dollars on medial costs related to obesity and on average the medical costs for people who are obese are $1,429 higher than those who are normal weight. Those costs continue to climb.

11.  A typical professional cyclist who weighs on average 154 lbs will burn 700 to 900 Calories per hour during a typical stage of the Tour of California. At 3 to 6 hours a day that’s a range between 2,100 to 5,400 Calories with an average day coming in at 3,500 Calories on the bike. Add an additional 2000 to 2500 Calories for daily living and resting metabolic rate and on average a pro-cyclist will consume between 5,000 to 7,000 Calories per day.  An average person may only need 1,500 to 2,500 Calories per day to maintain a normal weight.

12.  There are 3,500 Calories in 1 pound of fat. Just in case you were wondering.

My nephew, Kian, at 3 years years old, ripping his 12" mountain bike on the trails:


Posted in Science

Exercising in the Cold of Winter by Allen Lim

Posted on January 31, 2013 by Allen Lim, PhD | 1 Comment

So far, every time I’ve gotten on a plane this year, I’ve flown to somewhere colder than where I was previously. I started the year in Los Angeles, leaving LAX at a nice balmy 70˚F, before heading back home to Colorado where temperatures were a cold but manageable 40˚F. Unfortunately, things started really getting tough when I headed out to spend the week in Verona, Wisconsin for the Cyclocross National Championships, where we brought the Skratch Lab’s kitchen trailer to cook for racers and spectators. I knew it was going to be cold heading out, but working in 20 to 30˚F temperatures all day was a harsh reminder of all of the challenges and risks associated with exercise and exposure in sub-freezing temperatures.

While I’ve spent a large part of my career thinking about how to improve performance in hot weather conditions, the reality is that humans are extremely well suited to cope with the heat. When it gets hot, we easily and effectively redirect blood flow to help dissipate heat to the skin, we sweat to help cool that skin, we make quick hormonal adaptations that increase our ability to hold and store water, and we become more efficient at this whole process the more we are exposed to the heat. 

In stark contrast, humans have very few and fairly unsubstantial responses to the cold. Blood vessels can clamp down to help keep warm blood at the core, we might shiver to increase our metabolic rate, and for some individuals, after consistent exposure to the cold an increase in the core temp during exercise or an input of heat into the core can cause blood flow to increase to the hands and feet helping to keep the extremities warm despite the cold – something known as the “Hunter’s Reflex.”  These responses, however, do little to actually keep us from losing precious body heat. Unlike some animals, our fur is limited and we can’t just burn fat to create heat, so our only real option for preventing hypothermia or other cold weather related injuries like frostbite or exercise-induced bronchoconstriction depends on our behavior and technology.

When we exercise in the cold, we might be creating extra heat, but the combination of sweat, movement, and an increased ventilation rate can create some real problems. Ironically, one of those problems is the loss of even more heat and the risk of getting too cold once we stop exercising because of excess moisture from sweat. In fact, Eric Larssen, who we supported on his recent attempt to ride to the South Pole, faced temperatures in Antarctica that were so cold that he had to find an exercise intensity that was just hard enough to keep his bicycle moving, but easy enough that he would minimize any sweat production or risk freezing when he stopped.

That extra heat production from exercise and the ease at which we can lose that heat in the cold also puts extra strain on our fuel stores. In particular, when exercising in the cold, we preferentially rely on carbohydrate in the form of stored glycogen. A lot of that is due to an increase in our fight or flight response – activation of our sympathetic nervous system that works in the background without conscious attention to keep us charging under stress. Cold as a basic stress causes our sympathetic nervous system to light up which can cause us to waste precious energy, especially carbohydrate, making it a lot easier to bonk or hit the wall in the cold. Despite having ample fat stores available to us, once we run out of carbohydrate, we risk becoming hypoglycemic (low blood sugar). Since our nervous system and brain rely solely on glucose (i.e., sugar or carbohydrate) we can get really loopy when that happens. While becoming hypoglycemic at any temperature is bad enough, becoming hypoglycemic and hypothermic can be even worse since in and of itself, hypothermia can also lead to a host of issues like confusion, apathy, irritability, and cardiac arrhythmias. Thus, making sure we have plenty of food available, especially simple sugar, can be a lifesaver when it’s cold or when we get cold.

            This increase in sympathetic tone can also result in something known as cold diuresis. Essentially, when we’re cold or exposed to the cold we pee – a lot. As our sympathetic tone increases, it causes our blood vessels to stiffen which increases our blood pressure. At the same time, the cold causes blood vessels in our skin and periphery to constrict which drives more blood to our central blood volume further increasing blood pressure. This ultimately causes our kidneys to respond by pushing out dilute urine into our bladder and inadvertently dehydrating us even if we previously drank enough.

Another issue is that cold air is extremely dry air, which can damage our delicate lungs which function best when the air we breathe is brought up to 100% humidity and to body temperature (37.0˚C / 98.6˚F).  This is easily done at warm temperatures, but at a given relative humidity, the colder the temperature the less water the air holds. As an example, at 100% relative humidity, there is 44% less water in the air from 0˚C compared to 10˚C (5 grams of water per liter of air versus 9 grams of water per liter of air). So when people say “it’s too cold to snow” it probably is too cold to snow since the air can’t hold the moisture. The net result is that as the temperature drops, we lose more water and heat through our lungs to humidify and heat the air we breathe. Specifically, depending upon the humidity, at 0˚C (32˚F), we can lose anywhere from 20-30% more water through our lungs compared to 20˚C (68˚F), and from 40-50% more water compared to when the temperature is at 30˚C (86˚F).


At rest, when our ventilation rate is only about 5 liters of air per minute, the amount of water we lose through our lungs is fairly insignificant - about 10.5 ml of water per hour at 0˚C and 6.5 ml of water per hour at 30˚C. But this small amount can become a really big deal when we are exercising and ventilation rates can be as high as 100 to 150 liters of air per minute. At a ventilation rate of 100 liters per minute, we can lose as much as 211 ml of water in an hour at 0˚C through our lungs versus 132 ml of water in an hour at 30˚C. This difference isn’t trivial since in many cases, our lungs can’t actually keep up with this differentially and the air we breathe isn’t fully brought up to temperature and humidity in the lower airways. This can lead to inflammation, damage to our airway structure, and a higher prevalence of exercise-induced bronchoconstriction and asthma in the cold winter season – something that can be worsened by dehydration or inadequate fluid replacement in the cold.

 The question, however, is if all of this actually adds up to real dehydration in cold weather. While there are obvious risks of not getting adequate fuel and hydration in the cold and while there is a good rationale for how one might be at risk for becoming dehydrated in cold environments, there’s not too much research on hydration status in cold temperatures. This may be due to the fact that it’s not actually a problem and not something that we either worry about or study. But, that lack of attention may also be a problem in and of itself. In fact, in a recent study examining hydration status and sodium balance in a group of junior women’s soccer players in a cool environment, the players did not drink enough or consume enough sodium despite very low sweat rates (Gibson, et al. 2012). In another study, that examined water turnover and core temperature on Mt. Rainier, researchers found that hydration demands during the ascent in a group of seven novice climbers was elevated and that the climbers lost a significant amount of fluid despite not showing an elevation in core temperature (Hailes, et al. 2012). In both situations, dehydration occurred despite a lack of a heat stress and perhaps because of a lack of drive to drink due to the cold. Because, even a small amount of dehydration can hurt performance (Yoshida, et al. 2002), it stands to reason that staying focused on hydration, even in the winter, can help improve one’s performance.

With all of this in mind, it’s obviously important to first and foremost do everything you can to stay warm when temperatures are cold. For the most part, much of this comes down to our behavior – to being prepared and having the right gear if you’re planning to head out and exercise in the cold. Investing in the right clothing is obviously the first place to start – a high quality and tight wicking base next to the skin, an insulting wool over that, high loft materials for extra warmth as another layer of defense, and a final barrier to stop the wind on top. Add to that gloves, a good neck gaiter, something to cover your face and create a barrier to help maintain moisture lost through breathing, good head protection and booties to keep your feet warm.  Also, instead of putting air activated toe and hand warmers around your feet and hands, try putting them next to your chest and see if that “Hunter’s Reflex” works for you.

Beyond the right clothing, it’s just as important to focus on your food and hydration in the winter as it is anytime of the year with some subtle differences. First and foremost, realize that your need for carbohydrate at any given intensity is probably going to be higher when it’s cold. So don’t forget to eat and to bring those simple sugars outdoors with you. Next, just because you may not sense that you are losing a lot of fluid or you may not feel that you need to drink, making sure you stay on top of your hydration, especially with something warm. It’s a lot easier to keep your core temperature up from the inside out than it is from the outside in, so having an insulated bottle and keeping some warm hydration product can be a small but significant thing. This is one of the main reasons we decided to develop our Apple and Cinnamon exercise hydration drink mix. We wanted something that would taste good hot and that would remind us to bring something hot out with us that had some calories and electrolytes in it for exercising in the cold.

Finally, use common sense. Sometimes it’s best to just stay indoors and go to the gym, get on a treadmill, or ride the trainer. Be smart out there and use your head. In cold weather, it’s really our best tool.



For more on the topic, check out the references below:


Gibson, J. C., Stuart-Hill, L. A., Pethick, W., & Gaul, C. A. (2012). Hydration status and fluid and sodium balance in elite Canadian junior women’s soccer players in a cool environment. Appl Physiol Nutr Metab, 37(5), 931-937.


Hailes, W. S., Cuddy, J. S., Slivka, D. S., Hansen, K., & Ruby, B. C. (2012). Water turnover and core temperature on Mount Rainier. Wilderness Environ Med, 23(3), 255-259.


Kippelen, P., Fitch, K. D., Anderson, S. D., Bougault, V., Boulet, L. P., Rundell, K. W. et al. (2012). Respiratory health of elite athletes - preventing airway injury: a critical review. Br J Sports Med, 46(7), 471-476.


Marek, E., Volke, J., Muckenhoff, K., Platen, P., & Marek, W. (2013). Exercise in cold air and hydrogen peroxide release in exhaled breath condensate. Adv Exp Med Biol, 756, 169-177.


McMahon, J. A., & Howe, A. (2012). Cold weather issues in sideline and event management. Curr Sports Med Rep, 11(3), 135-141.


Sue-Chu, M. (2012). Winter sports athletes: long-term effects of cold air exposure. Br J Sports Med, 46(6), 397-401.


Yoshida, T., Takanishi, T., Nakai, S., Yorimoto, A., & Morimoto, T. (2002). The critical level of water deficit causing a decrease in human exercise performance: a practical field study. Eur J Appl Physiol, 87(6), 529-534.


(2011). Update: cold weather injuries, U.S. Armed Forces, July 2006-June 2011. MSMR, 18(10), 14-18.

Posted in Science

Five tips for better fueling during endurance sports

Posted on August 19, 2012 by Skratch Labs | 0 Comments


1. Eat & Drink Early & Consistently—One of the biggest mistakes riders make is forgetting to eat and drink early and consistently throughout the day. While this is plain common sense, it‘s often disregarded on ride day—a mistake that can spell disaster no matter how well trained or prepared you are.
As a general rule, you need to replace at least half the calories you burn each hour, and you need to begin replacing those calories in the first hour if you’re going to be out for more than three hours. On a flat road without drafting, the average cyclist will burn about 200-300 Calories at 10-15 mph, 300-600 Calories at 15 to 20 mph, and 600 to 1,000 Calories at 20 to 25 mph.
Regarding hydration, on a hot day your fluid needs may be as high as 1 to 2 liters an hour. The best way to get an appreciation of how much fluid you might need is to weigh yourself before and after a workout. The weight you lose is primarily water weight, where a 1-pound loss is equal to about 16 ounces of fluid. As a general rule, try not to lose more than 3 percent of your body weight over the course of a long ride.
2. Try Eating Real Food—While there are plenty of pre-packaged sports bars and gels touting their ability to improve one’s performance, it’s important to realize that real food can work just as well if not better than expensive, engineered nutrition. A regular sandwich, a boiled potato with salt, a banana and a ball of sushi rice mixed with chocolate or some scrambled eggs can all give you the calories you need without upsetting your stomach the way a lot of sugary gels or sports bars can. In fact, while coaching teams at the Tour de France, the riders I worked with used real food as their primary solid fuel source, because it just worked better. Most of the recipes for these foods can be found in “The Feed Zone Cookbook” that I wrote with Chef Biju Thomas to promote healthful, real-food eating.
3. Don’t Just Drink Water—When we sweat we lose both water and valuable electrolytes. Those electrolytes include sodium, chloride, potassium, magnesium, and calcium. Of these electrolytes, the vast majority (about 90%) of that loss is sodium chloride. But it’s sodium that plays a critical role in almost every bodily function. Thus, when sodium is lost through sweat, drinking only water can further dilute the concentration of sodium in the blood, leading to a condition called hyponatreamia, which can lead to a host of problems ranging from a drop in performance to seizures and even death. The amount of sodium that we lose in sweat is highly, variable ranging anywhere from 250 to 1100 mg per half liter (16.9 ounces). Because of this large range, it’s always better to err on the side of more salt than less salt, especially if you tend to see more white streaks of salt caked on your workout clothing compared to others or if you crave salt after a sweat filled workout. Unfortunately, most sports drinks contain too much sugar, not enough sodium, and an excess of artificial ingredients, which caused many of the riders I worked with to become sick during long days on the bike. For that reason, we developed an all-natural sports drink using less sugar, more sodium and flavored only with real fruit. Outside of using a sports drink with more sodium, also consider eating salty or savory foods on your ride rather than just sweet foods.
4. Learn What you Need in Training—Ride day is not the day that you want to be experimenting with yourself. So try different hydration and feeding strategies during training well before the big day. As an example, simply weighing yourself on a long training ride before your big event can give you valuable information to optimize your hydration for that event. Likewise, taking the time to prepare your own foods or trying different products beforehand and then writing out a specific game plan for your drinking and feeding needs can go a long way to making sure you don’t make any mistakes on ride day.
5. Come in Well-Fed and Well-Rested—While proper training is obviously important, making sure you are well rested coming into an event is sometimes even more critical. You can’t cram training, so as you approach the big day, make sure you are getting plenty of sleep and aren’t killing yourself in training the week leading into your event. Just sleeping an extra hour each night the week before your event can significantly improve your performance. Finally, adding extra carbohydrate to your diet, and making sure you get plenty of calories the week before your event, will assure that your legs are fueled and ready to go.

Posted in Science

Hydration Science and Practice

Posted on May 03, 2012 by Skratch Labs | 0 Comments

Less is More:

    Two frequently asked questions that we get are 1) why our Exercise Hydration Mix is only 80 Calories per 500 ml (16.9 ounce) serving and 2) how to get more calories in during long endurance events with our relatively low calorie sports drink.

    The short answer to the first question is that our Exercise Hydration Mix is only 80 Calories per serving because it is our experience that a 4% carbohydrate solution (4 grams of carbohydrate per 100 ml or 20 grams per 500 ml at 4 Calories per gram) is the highest concentration of carbohydrate that we can have in our drink while still optimizing water or fluid transport across the small intestine.

    I’ll get to the science of it all below for those who are interested, but for those who aren’t, the bottom line is that in practice, when athletes I’ve worked with used solutions that were concentrated with too much carbohydrate (regardless of type of carbohydrate), most experienced gut rot – that bloated, sick, less than fresh, I don’t want to drink anymore, stomach upset that is a problem common with many sugary sports drinks and gels – a problem that motivated the development of our line of anti-gut rot hydration products.  

    The answer to the second question is that if you need more calories to meet your energy demands during a long workout, what I’ve observed amongst Grand Tour riders, who require and consume more calories while competing than almost any other group of athletes in the world, is this - that for the same amount of energy, eating real food that forms a bolus in the stomach and slowly trickles into the body always works better than trying to drink that fuel or energy in a solution.

The Details:

    So how does a lower calorie drink help to prevent gut rot? To understand that, you need to know a little bit about how water gets transported into our body. In short, water can be transported across the small intestine passively through a process called osmosis or co-transported with sodium and glucose.

Osmosis & Semi-permeable Membranes: 

    Osmosis is the movement of a particular fluid from an area of low concentration to an area of high concentration across a semi-permeable membrane. A semi-permeable membrane allows the fluid but not certain molecules to pass through it.  When a membrane keeps certain molecules from crossing it, differences in concentration can exist on either side of the membrane. As a result, any fluid that can pass through the membrane will move from the side with the lower concentration of molecules to the side with the higher concentration to create equilibrium through the process of osmosis. Examples of semi-permeable membranes include the walls that form each of our body’s cells, the thin layer of film that is visible when you crack an egg, and our small intestine, which is the primary gateway that water uses to enter our body.

    With this in mind, one very important idea is that the inside of our belly or gastrointestinal tract, where we stuff our food and drink into via our mouths, is not the inside of our body. In fact, the GI-tract is simply a tube within our body that is open to the exterior world at our mouth and anus. The GI-tract, not only digests and processes the food we eat, it acts to selectively transport fluid and nutrients from the outside world (which is the inside of the belly) into our body primarily at the small intestine.

    While the small intestine can actively transport nutrients like sugars, amino acids, and electrolytes, it also acts as a semi-permeable membrane where water flux is strongly influenced by osmosis. This means that if you drink a solution with a greater concentration than your blood or bodily fluids, water will flow out of your body into your belly through osmosis to dilute that concentrated solution unless the molecules or ingredients in that solution are permeable to your small intestine or unless those molecules can be quickly and actively transported to the other side to help pull water along.

    Said another way, if your sports drink is “thicker” than blood, then water will flow out of your blood stream into your gut, effectively dehydrating and bloating you, especially if the concentration is so high that active transport of solutes or particles in the solution can’t keep up with the initial water flux. Ultimately, drinking a solution with a very high concentration of anything (e.g., gels) is like throwing a lot of junk down your sink’s garbage disposal and not having either enough water or a strong enough motor to keep the drain open.  


    Given that we don’t want to clog our drain, it’s critical that we also understand what determines the osmotic pressure or force that a solution exerts. Simply, osmotic pressure is a function of the total number of molecules (solute) that end up dissolving into a fluid (solvent) to form a mixed solution. This osmotic force or “thickness” can be measured as that solution’s osmolality.  Thus, if you want to ensure that what you drink is easily absorbed into your body, then in theory the osmolality of that drink needs to be less than the osmolality of blood or plasma, assuming that osmosis is the only mechanism for water transport (more on this in a bit). 

    Depending on one’s hydration state, blood osmolality can range anywhere from 275 to 295 milliosmoles per kg of water. Our exercise hydration drink has an osmolality of 280 to 285 milliosmoles per kg of water, primarily because of the lower concentration of carbohydrate that we use, which is our main ingredient.

    It’s important, however, to realize that a solution’s osmolality is affected by all of the molecules that enter into solution. This means that the osmolality of a sports drink is determined not just by the amount and type of carbohydrate in the solution but by all of the ingredients in that solution, from the electrolytes to ingredients like preservatives, artificial sweeteners, flavoring agents, and even food colorings. This is a key reason why we do not add superfluous ingredients to our hydration products. This is also why gels and heavily concentrated carbohydrate solutions that are already dissolved in water can exert a greater osmotic force than a bolus of real food even when matched for calories. And while we intentionally designed a drink with an osmolality that favors the passive movement of water into the body, the favorable osmotic gradient of our drink relative to the body is not the only factor that helps to help optimize hydration and prevent bloating.  

Co-Transport of Water with Sodium and Glucose:

    Water can also move into the body through channels known as SGLT1 transporters that actively transport sodium and glucose across the small intestine. These channels use energy to move 2 sodium ions and one glucose molecule into the body. As this happens, 210 molecules of water also move across, effectively getting a free ride into the body as sodium and glucose pay a toll to gain entry. While this seems like a lot of water relative to sodium and glucose, this gateway is rate limited or locked by the availability of sodium and glucose. Crunching the numbers, to move 1 liter of water across the gut through this mechanism, just over 12 grams of sodium and close to 48 grams of glucose (a 4.8% glucose concentration) would be needed.  This is one reason why oral rehydration solutions used to treat diarrheal diseases contain grams, not milligrams of sodium in them along with some sugar or glucose to help take advantage of this route.

    Because our exercise hydration drink contains significantly more sodium (310 mg per ½ liter or 16.9 ounces) than other sports drinks to help replace the sodium we lose in our sweat as well as plenty of glucose, a relatively greater, albeit still very small, amount of water (25 ml) can be theoretically co-transported through the active transport of sodium and glucose. In theory, the active transport of sodium itself along with other molecules like glucose also creates a more favorable concentration difference for the flow of water into the body by osmosis. That all said, starting with a sports drink with a concentration that is too high and without enough sodium or salt makes this a real uphill battle despite active transport systems that might help to facilitate water transport. This significantly increases the risk of stomach problems especially over the course of a really long day since water flow is still primarily dependent on osmosis.  

Water Alone Can Kill You:

    All of this may lead people to think that if hydration were the primary goal then just drinking water would be the quickest and most effective way to hydrate. In fact, because water can be transported passively along its osmotic gradient and also co-transported with sodium and glucose, having some salt and sugar in a drink solution that is hypotonic (less concentrated) or even isotonic (same concentration) compared to blood would actually be the fastest way to hydrate. While drinking water alone is just fine if you’re sitting around or having dinner at home, drinking water alone is not fine if you’re trying to rehydrate when you’re sweating or have some illness or hangover that results in diarrhea or vomiting. In fact, drinking water alone when we are exercising can be risky since we can lose an appreciable amount of sodium in our sweat (400 to 800 mg per liter of sweat) and if we don’t replace that sodium then an influx of just water can dilute the sodium in our body.  This can lead to a scenario called hyponatremia, which include symptoms like headache, confusion, a drop in performance, fatigue, nausea, vomiting, irritability, muscle spasms, seizures, coma, incontinence, and in some very rare cases death. 

Eat Real Food:

    This of course, leaves us with the final question – if our goal is not hydration, but calorie replacement during heavy exercise, how do we get enough calories in our body if we don’t drink those calories? While the simple answer is to eat solid and real food, the type of food matters and there is, of course, a lot of individual difference in how people process and deal with different foods. So despite this general piece of advice, it’s still important to experiment and stick with foods with minimal ingredients and that are low in fiber during exercise.

    Still, the basic concept is this – that when we chew something and it forms a bolus that enters our stomach, as that bolus or mass is broken down and liquefied by acid in our stomach, the entrance of those calories and nutrients into the small intestine, where nutrients are absorbed into the body, is paced. So instead of having a huge influx of a highly concentrated fluid with a high osmolality that can disrupt water absorption into our small intestine, we have a slower but steady influx of reduced chyme (partially digested food, water, acid, and digestive enzymes) that the small intestine can then actively transport into the body at a rate that doesn’t overwhelm the gut. The simple analogy is instead of trying to get 200 cars onto a highway all at once and causing a big traffic jam, eating solid food helps to allow a steady stream of cars or calories onto the highway in a way that keeps traffic flowing.

    That all said, the addition of any calorie source whether it is in liquid or in solid form creates a net osmotic pressure once it arrives in the small intestine. Managing this flow of both energy and hydration is ultimately the key. With that in mind, the real question to ask yourself is how quickly are you losing sweat and valuable water versus how quickly are you burning through available fuel?

Hydrate First & You May Not Need to Eat:

    The reality is that in the heat, we can lose fluid at a much faster rate than we burn through fuel. And in the same way that we can live for weeks without food but only days without water, our physical performance can drop immediately and appreciably when we become dehydrated despite having ample untapped fuel supplies in the form of glycogen and fat stores on board.

    To put this into some real numbers, let’s do a rough comparison of a very fit “amateur” cyclist riding at 150 watts versus a “professional” riding at 250 watts for 5 hours. At these intensities, the rider pedaling at 150 watts is burning about 594 Calories per hour while the one pedaling at 250 watts is burning about 990 Calories per hour. At these intensities, a very conservative sweat rate at a temperature of 75 to 80 degrees Fahrenheit might be about 1 liter per hour at 150 watts or 2 liters per hour at 250 watts. Because sweat rates can vary greatly depending upon the temperature, humidity, cloud cover, exercise intensity, fitness level, and body size and shape the best way to measure sweat rate is to weigh yourself before and after exercise, realizing that a 1 kg drop in body weight is equal to about 1 liter of sweat loss (1 pound loss is equal to 15.3 ounces of sweat). So these sweat figures, while a guess, are in the range of what I’ve measured in the field. 

    With that disclaimer on sweat rate, if the first priority for these riders is to hydrate, then the rider pedaling at 150 watts would need to drink 1 liter each hour while the rider pedaling at 250 watts would need to drink 2 liters an hour. Assuming that they are using our 80 Calorie Exercise Hydration mix in each ½ liter or 500 ml bottle (though I realize that most cycling water bottles are about 650 ml or 22 ounces) then over the course of 5 hours, if a rider were to actually drink to match their sweat rate, then the rider at 150 watts would be taking in 160 Calories an hour from their drink mix, while burning 594 Calories an hour. In contrast, the rider at 250 watts would be taking in 320 Calories from their drink mix while burning 990 Calories each hour.

    At first glance it’s obvious that the calories coming from the drink mix aren’t enough to match the rate of energy expenditure. But this simple glance doesn’t account for the carbohydrate we have stored in our muscles and liver or our ample stores of fat. Assuming that for each rider 20% of the calories are derived from fat and the rest from carbohydrate and also assuming that the amateur has 1500 Calories and the professional cyclist 2500 Calories stored as glycogen, then the requirements each hour for a 5-hour ride change. Doing the math, if we account for stored glycogen and fat, the amount of energy needed per hour for the amateur cyclist would be 175 Calories per hour while the professional would need 292 Calories per hour. While the amateur would be a little off consuming only 160 Calories an hour from their drink mix alone to meet their 175 Calorie need, the professional would actually be fine consuming 320 Calories an hour from their drink mix alone to meet their 292 Calorie need.

    While I’m not advocating that our drink be used as the sole source of energy, in many cases if our drink at 80 Calories per bottle is used to replenish all of our actual hydration requirements then our energy needs would come pretty close to being met depending upon the situation. In effect, because a lower calorie solution has the potential to empty at a much faster rate than a high calorie drink, energy needs can be made up for by the ability to drink a higher volume of fluid, which ultimately ensures proper hydration.

    In reality, I know very few riders who actually keep pace with their sweat rate. At best, if they keep their weight loss due to dehydration to less than 3% of their body weight then they are doing quite well. After a 3% weight loss there are significant performance declines so trying not to lose 4.5 pounds for a 150-pound rider or 6 pounds for a 200-pound rider is critical. Because of this eating some food consistently and from the onset of a ride or competition is critical. As a general rule of thumb, I recommend that beyond a 2 to 3 hour ride that athletes make it a goal to replace at least half the calories they burn each hour. In most cases, if an athlete is staying hydrated (less than a 3% loss in body weight) then about 75% of that energy might come from their energy drink while the rest might come from real food. For a hard working professional this might mean that in a race at an average energy demand of 800 Calories an hour that the athlete needs to eat about 400 Calories each hour or 100 grams of carbohydrate. Typically, 300 of those Calories can be brought in through 3 to 4 bottles an hour, while the final 100 Calories can be eaten. While I’ve had riders try and just drink the entire 400 Calories in one bottle and then take in plain water, this method usually wreaks havoc on their gut and prevents them from getting adequate sodium. Ultimately, the bottom line is that it is as important to think about hydration as it is to think about fuel and that if done right, you don’t need an appreciable amount of calories in each bottle to meet the needs of both.

The Egg Model:

    In the video linked to this article, I demonstrate an extremely simplified model of osmosis using a raw egg with its shell removed by soaking the egg in standard cooking vinegar for about a day and a half. The vinegar literally cooks the shell off and stiffens the very thin membrane surrounding the egg leaving a completely raw egg that feels like a delicate water-balloon.

    Since that thin membrane is permeable to water but not larger molecules like sugar, it’s, in theory, a great way to demonstrate osmosis. And in theory, if you soak that raw egg in a solution that has a concentration that is greater than the inside of the egg, water will flow out of the egg. Likewise, if you soak that raw egg in a solution that has a concentration that is less than the inside of the egg then water will move into the egg.  

    So in this particular model, the glass jar is meant to represent the inside of our small intestine while the interior of the egg is meant to represent the inside of our body. Finally, the thin semi-permeable membrane surrounding the egg separates the inside of the body or egg from the solution or outside world that the egg is floating in. If the egg is bathed in a solution that hydrates it, then the egg will gain weight. On the other hand, if the egg is bathed in a solution that dehydrates it, then the egg will lose weight.

    With all of this in mind, and despite not knowing the exact osmolality of a raw chicken egg soaked in vinegar, I wanted to see if soaking that raw egg in our Exercise Hydration Mix would hydrate or dehydrate the egg compared to higher calorie solutions. Initially, I wanted to compare our drink at 80 Calories to three other solutions at 160, 280, and 400 Calories. Unfortunately, I busted one of the eggs and had to settle with comparing 80 Calories of Skratch (4% carbohydrate solution) against 160 Calories worth of a gel product (8%), against 400 Calories of a maltodextrin solution (20%), all mixed in 500 ml of water over the course of 2 hours.

    To measure the hydration state, I weighed the eggs on a precision digital scale before soaking them and after soaking them to see if there was a positive or negative shift in water.  About an hour and a half into the experiment, I got impatient and wanted to see what was happening. At this point, the egg soaked in our 4% Exercise Hydration Mix from Skratch went from an initial weight of 107.52 g to 113.44 g, our egg in the 8% solution went from 94.32 g to 93.75 g, and our egg in the 20% solution went from 92.80 g to 86.15 g in just 1 hour and 35 minutes.

    Thus, our Skratch egg gained + 5.5% in water mass, the egg in an 8% solution lost - 0.6% of its water mass, and the egg soaked in the 20% solution lost - 7.1% of its water mass. What’s interesting is that over the course of 24 hours, our Skratch egg stayed at virtually the same weight demonstrating that it hydrated quickly and achieved equilibrium with the solution. In contrast, the egg soaked in the 8% solution continued to lose weight and lost a total of - 13.02% of its weight after 24 hours, while the egg soaked in the 20% solution lost a total of - 36.61% of it’s weight after 24 hours.

    Obviously, this is a neat model for osmosis but it by no means represents the truly incredible and complex process of digestion or fluid and nutrient absorption during exercise. That being said, this little demonstration is a great example of the basic core of a scientific experiment – making a guess based on a sound theory and then testing it by making observable measurements that either prove or disprove your original theory.

    Despite it’s simplicity, this process is essentially how we developed our Exercise Hydration Mix. We took real athletes preparing for the Tour de France and poured different formulas down their throats as if their bellies were delicate eggs soaking in different solutions. Regardless of the theories or known or unknown physiological mechanisms behind them, we had some very simple bottom lines that we assessed – were the athletes able to get hydrated, did their stomachs bloat when we tried to keep pace with their hydration needs, did they like the taste, did they feel good or bad, and were they able to perform better. Because, available drink mixes did not satisfy our needs, we were strongly motivated to find something better. Through a lot of hard work and time, we ultimately did find something better and we continue to work to learn and improve.

    While a myriad of arguments can be made for one idea or theory versus another idea or theory – for one product or philosophy versus another – the bottom line is that we are each our own scientific and real world experiment and that the best way to discover is to try for yourself. In the end, soaking your egg or gut in our drink may just not work for you or it may work better than anything you’ve ever tried. We believe that it’s the best while still working to make it even better. But you’ll never know until you stop reading all these ideas and just try.  

Just in case you’re interested though, here are some references to check out:

Gisolfi, C. V., Summers, R. W., Schedl, H. P., & Bleiler, T. L. (1992). Intestinal water absorption from select carbohydrate solutions in humans. J Appl Physiol, 73(5), 2142-2150.

Gisolfi, C. V., Summers, R. W., Lambert, G. P., & Xia, T. (1998). Effect of beverage osmolality on intestinal fluid absorption during exercise. J Appl Physiol, 85(5), 1941-1948. 

Gisolfi, C. V., Lambert, G. P., & Summers, R. W. (2001). Intestinal fluid absorption during exercise: role of sport drink osmolality and [Na+]. Med Sci Sports Exerc, 33(6), 907-915.

Grootjans, J., Thuijls, G., Verdam, F., Derikx, J. P., Lenaerts, K., & Buurman, W. A. (2010). Non-invasive assessment of barrier integrity and function of the human gut. World J Gastrointest Surg, 2(3), 61-69.

Hall, D. M., Buettner, G. R., Oberley, L. W., Xu, L., Matthes, R. D., & Gisolfi, C. V. (2001). Mechanisms of circulatory and intestinal barrier dysfunction during whole body hyperthermia. Am J Physiol Heart Circ Physiol, 280(2), H509-21.

Henkin, S. D., Sehl, P. L., & Meyer, F. (2010). Sweat rate and electrolyte concentration in swimmers, runners, and nonathletes. Int J Sports Physiol Perform, 5(3), 359-366. 

Hoorn, E. J., & Zietse, R. (2008). Hyponatremia revisited: translating physiology to practice. Nephron Physiol, 108(3), p46-59.

Jeukendrup, A. E., & Moseley, L. (2010). Multiple transportable carbohydrates enhance gastric emptying and fluid delivery. Scand J Med Sci Sports, 20(1), 112-121.

Lambert, G. P., Chang, R. T., Xia, T., Summers, R. W., & Gisolfi, C. V. (1997). Absorption from different intestinal segments during exercise. J Appl Physiol, 83(1), 204-212.

Lien, Y. H., & Shapiro, J. I. (2007). Hyponatremia: clinical diagnosis and management. Am J Med, 120(8), 653-658.

Noakes, T. D., Goodwin, N., Rayner, B. L., Branken, T., & Taylor, R. K. (1985). Water intoxication: a possible complication during endurance exercise. Med Sci Sports Exerc, 17(3), 370-375.

Noakes, T. D. (2007). Drinking guidelines for exercise: what evidence is there that athletes should drink “as much as tolerable”, “to replace the weight lost during exercise” or “ad libitum”? J Sports Sci, 25(7), 781-796.

Wright, E. M., & Loo, D. D. (2000). Coupling between Na+, sugar, and water transport across the intestine. Ann N Y Acad Sci, 915, 54-66.

Zeuthen, T., Belhage, B., & Zeuthen, E. (2006). Water transport by Na+-coupled cotransporters of glucose (SGLT1) and of iodide (NIS). The dependence of substrate size studied at high resolution. J Physiol, 570(Pt 3), 485-499.

Zeuthen, T. (2010). Water-transporting proteins. J Membr Biol, 234(2), 57-73.

Posted in Science

Why Sports Drinks are Important:

Posted on February 15, 2012 by Skratch Labs | 0 Comments

A Little Primer on the Logic Behind Sports Drinks:

1) You sweat whenever you are doing something that makes you really hot like working out or mowing the lawn in oppressive heat.

2) Sweat has fluid and electrolytes like sodium, potassium, magnesium, calcium, and chloride.

3) While all electrolytes are important to your body’s function and performance, sodium is by far the most important electrolyte, because a decrease in your body’s sodium concentration – something called hyponatremia – can have some extremely negative consequences that range the gamut from just not feeling well to seizures, excessive urination, incontinence (that’s when you soil yourself), and even death.

4) There is anywhere from 200 mg to 1000 mg of sodium in a liter of sweat (Our Exercise Hydration Mix contains 620 mg of sodium per liter).

5) Since sweat has both fluid and electrolytes in it, drinking water alone to replace the fluid you lose when you’re sweating can be really dangerous since this is the quickest way to decrease or dilute your body’s sodium concentration. So if you’re exercising and you find yourself peeing a lot and feeling really sick, you may be hyponatremic and you’ll need to rehydrate with something with a lot of salt in it or just eat salty foods with whatever your drinking.  

6) In theory, the best thing to drink when you’re sweating is your own sweat. But drinking sweat tastes gross. This is just my personal opinion cause I’ve tried it. Also, I’m pretty sure that if I gave someone a glass of sweat to drink that they’d be pissed and throw the glass at me. Finally, it’s hard to capture all the sweat you lose when you’re sweating unless you have one of those cool suits from the movie Dune that recycles your sweat and urine.

7) Sweat does not contain artificial colors, artificial flavors (or any flavoring agents for that matter), sugar, artificial sweeteners, preservatives or other strange ingredients that you need to take an organic chemistry class to figure out. 

8) Most sports drinks contain water, electrolytes, and some form of sugar to provide a small source of energy to help maintain blood sugar and fuel working muscle. Unfortunately, most sports drinks also contain artificial colors, flavoring agents, artificial sweeteners, preservatives as well as other strange ingredients that you need to take an organic chemistry class to figure out.

9) My experience is that most sports drinks don’t contain enough electrolytes, have too much sugar, and that all of the excess ingredients make people sick when they drink too much of it.  

10) Without the fruit, citric acid (i.e., lime), and sugar our Exercise Hydration Mix tastes just like sweat (Again, I’ve tried our mix without any fruit and it is nasty). But with a little bit of fruit, citric acid, and sugar our Exercise Hydration Mix tastes clean and light.  So here’s the plug - if you are sweating a lot and need something to rehydrate with that replaces what you lose in your sweat but you don’t want a bunch of excessive ingredients and you don’t want to drink your own sweat, give our Exercise Hydration Mix a try. And if you don’t think it’s better than your own sweat or the sports drink you get at the gas station, let us know and we’ll make it up to you. 

Posted in Science