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  Last updated:4/24/2019


Sport drinks both help toavoid dehydration while exercising, as well as supplement your internal energy stores (glycogen) for endurance events - over 2 hours in length. Although they provide some electrolytes, it is questionable if they are helpful aside from minimizing the risk of hyponatremia when riding in severe conditions of high heat and humidity when large volumes of fluid are being ingested.

Commercial sports drinks are the easiest, but are pricey. If you are interested in the Caloric supplement component, you can save a few dollars by purchasing a complex carbohydrates in a health food store and mixing it at home with the flavor of your choice or use it to supplement a current favorite drink. Maltodextrin is a corn starch molecule which has been broken down into glucose polymers (chains of glucose molecules). When added to water or other drinks, it increases the energy content without the disadvantage of an overly sweet taste and a highly concentrated solution which may delay gastric emptying. It may be useful as a post ride supplement, but does not provide any advantages to breads, cereals, grains, etc. as a regular daily energy source. Directions are usually available from the container, but can vary from 1/2 cup in 8 pounces to 3/4 cup in 32 ounces. You may need to experiment to find the best concentration for your personal physiology.

A 16 ounce water bottle (480 cc) of a 7% sugar solution at 4 Cal per gram of carbohydrate will contain about 136 Calories. If you add 1/2 cup of Carboplex (a commercial maltodextrin) you will add another 220 Calories almost tripling the energy density (concentration) of your drink with minimal chances of nausea or other side effects.

The risk from pushing the sugar (fructose, glucose, complex carbohydrates) content of drinks is the development of GI side effects, specifically gas and bloating, thought to be the result of a saturation of the sugar transport proteins in the small intestine. This suggests an upper limit, or maximum, of glucose (or fructose) absorption per minute with any excess sugar not absorbed passed on into the colon where bacteria ferment it, producing gas as one product of that metabolism.

There are at least two transport proteins in the small intestine - one for glucose and another for fructose. Both can be overloaded as they have an upper limit to the rate of absorption of their target monosaccharide. Knowing this, we can formulate a drink which can be used to an athlete's advantage. A drink containing a combination of both glucose and fructose will increase the total grams of carbohydrate per minute, and thus Calories per minute, potentially available to the exercising muscle compared to a drink containing an equal number of total Calories of either individual sugar.

The older literature (pre 2010) suggested that the addition of protein to a CHO mixture of glucose and fructose would increase the rate of CHO absorption - both in supplements taken while exercising as well as in post exercise recovery drinks. A review of 26 studies, published in 2014 concluded: "When carbohydrate is delivered at optimal rates during or after endurance exercise, protein supplements appear to have no direct endurance performance enhancing effect. " And in addition, they expanded that conclusion to include supplements while riding as well as in the post ride recovery period: "...when carbohydrate supplementation was delivered at optimal rates during or after exercise, protein supplements provided no further ergogenic effect, regardless of the performance metric used." My conclusion is that protein combinations might be considered based on taste alone. That is you cannot tolerate sugary drinks (ingest the ideal amount of carbohydrate per hour). An alternative strategy is the use of complex carbohydrates toincrease carbohydrate Calories in a drink that is not as sweet tasting.

A review of individual studies on fructose/glucose mixtures shows ratios (glucose:fructose) of 1:1 to 3:1. I assume that these ratios were chosen based on both palatability and minimizing intestinal side effects of cramps and gas. What is the best ratio and concentration if we are going to design an "ideal" drink? I suspect it is different for each of us and also that the numbers in the meta-analysis are on the low side (I say that as many studies have shown that concentrations of 10% seem to be well tolerated versus the 3 - 10% mentioned. And if you add 0.7 gm/kg/hr glucose and 0.2 gm/kg/hr fructose you will get 0.9 x 70 kg rider = 54 grams per hour - which is much less than the 1.75 gm minute x 60 minutes = 105 grams per hour mentioned as a maximum in a relatively recent review.) What we do know is that the upper limits for supplementation goes up with time - as the physiologists push the limits of their subjects. In 2004 it was 1.3 grams per minute and by 2010 has been pushed up to 1.75 gm per minute.

This meta analysis (a summary of multiple studies) gives us another way to identify the ideal amount and concentrations (3 - 10%) of fructose and glucose drinks that have been shown to be of benefit (ignorethe recommendation on protein based on the more recent 2014 review). As most researchers follow standard protocols (and what otheres have been done in the past), the unanswered questions is "did these studies pushed high enough concentrations" and thus are conservative recommendations.

For those of you that are adventuresome and interested in designing your own personalized supplement, these articles give you a place to start - and your only risk with pushing the limits on concentration will be the short time GI side effects.

A word of warning about overdoing it with sports drinks. The American Academy of Pediatrics has released a position paper on sports and energy drinks pointing out the risks of over stimulation (for caffeine containing drinks) and obesity (from the extra carbohydrate Calories) when they are used OUTSIDE of exercising. This is especially a hazard for adolescents and preteens.

But excess sugar (beyond that needed to support the Caloric needs of exercising) is a risk to adults as well. Recent work suggests that excess fructose in sports drinks might be harmful. Why are pre diabetes (and diabetes) so much more common now than 50 years ago? Epidemiologic studies have suggested an association with the increasing use of fructose sweeteners after WWII (the 1950s and beyond). Now we have a study suggesting that fructose specifically activates a liver enzyme that then causes a) resistance in the liver to the effects of insulin as well as b) increases the production of additional glucose from the liver cells - a positive feedback loop. And in essence a prediabetic state.

(As an aside, I've had an interest in metabolic syndrome - the clinical triad of a) glucose intolerance, b) fat accumulation in the liver, and c) high blood pressure. I pulled together some background as well as a diet that made sense to me. It also qualified as a healthy diet approach for all of us. Here's the link.)

How does this relate to cyclists and other athletes participating in endurance activities?

Bottom line for me? I try to avoid fructose as much as possible feeling its potential risks outweigh any small benefits in carbohydrate replacement.



There have been some encouraging studies on the use of glycerol to minimize the negative impact of dehydration on performance. For those interested in a commercial product, try the internutria website.

Lactic acid has always been considered a by-product of metabolism , and something to be eliminated from the muscles as quickly as possible. Yet a recent study looked at lactate as a possible energy source and demonstrated that it is actually metabolized more quickly than glucose. We may see more drinks with lactate as a fuel source coming soon.

Except under extreme conditions, electrolytes (particularly sodium chloride or salt) do not need to be replaced along with fluids.


Let's review the facts. It's well documented that you can:

  1. exercise longer
  2. more intensely
  3. and recover faster
using oral glucoes supplements to prevent glycogen depletion during vigorous exercise. Sports drinks offer us an easy solution, but fruit juices may be better. This interesting article (and referenced study) suggests the way those carbohydrates are packaged may add additional benefits.

The Calories/minute of oral carbohydrate your digestive system can deliver to exercising muscles is limited by the rate at which they can be absorbed from the small intestine into the bloodstream. Two simple single molecule sugars (glucose and fructose) are absorbed by special carrier proteins called carbohydrate transporters. Each of these simple 6 carbon sugars has its own unique carbohydrate transporter. As each transporter can be "maxed out", sugar absorption into the bloodstream can be increased (by as much as 65 percent) by replacing exercise Calories using a drink, or bar, made of 2 different sugars compared to glucose alone.

Comparing two drinks, equal in energy density (calories per ounce), those with fruit sugars (sucrose = glucose plus fructose) provide the muscles more carbohydrate calories per minute than those based on glucose alone, presumably the end result of taking advantage of the 2 separate sugar transport pathways in the digestive tract. (Reference 1, Reference 2)

Sports drinks based on maltodextrin (a starch from rice, corn, potato and whole grains) which is a starch composed of a chain of multiple glucose molecules, is no better than glucose alone. However drinks that contain both maltodextrin AND fructose are similar to drinks based on sucrose (the dischaddaride of glucose and fructose).

In addition to their fructose benefit, fruits (and their juices) contain antioxidants and other nutrients absent from sports drinks. Sports drinks responded to this criticism by adding multiple "natural" ingredients. But as well critiqued in this blog they have their own set of potential side effects.

The bottom line is although sports drinks are an easy solution, but are not all equally effective. Avoid those based on glucose alone and see if you can find one containing both glucose and sucrose/fructose. And move those with the lowest number of ingredients (additives), caffeine is OK, to the top of your preference list. And don't ignore the potential of fruit juices and whole fruit which can be as effective, if not better, than using a sport drink based on glucose alone. Here is a link with natural smoothie recipes to get you started.


Whichever drinks you decide on, I'd encourage you to avoid the current "energy drink" fads - Red Bull and Monster.

Energy bars (the original Clif Bars for example) and gels started off as a convenient source of carbohydrate energy for aerobic muscle metabolism while on the bike. Then the black magic of "additives" was applied and we ended up with energy drinks such as Red Bull and Monster.

Do these energy drinks improve performance? When compared to an carbohydrate equivalent (equi-caloric) caffeine/glucose drink - NO

Are you risking more than your wallet? Are they potentially harmful? - YES.

They not only lead to an immediate increase in blood pressure, but also have been linked to cardiac arrhythmia and sudden death. This interview from provides additional insight into the reasons for their negative cardiovascular effects.

Plus they can increase inflammatory blood markers such as C-reactive protein. This chronic inflammation will injure normal tissues. And when monitored over time, groups with elevated C-reactive protein levels have been shown to have higher rates of diabetes, cardiovascular disease, and cancer.


Q. I currently average about 225 to 250 miles a week with a metric century or a full century on the weekends (and 1 or 2 rest days and recovery ride during the week). I have been weighing myself before rides and after and its a little alarming, on average I lose about 4-6 pounds on every ride I take! I just completed a 70 mile with 3 big climbs, in 4:00:59, when I started I weighed 148 lbs when I finished I weighed 142 lbs! I Drank 4 24 ounce water bottles with Gatorade Endurance formula, had two Gels and a cliff bar (oh yeah and had a cliff bar to start for Breakfast at 6am). I drank so much I feel a little gassy toward the end and did not feel better until i burped many times. Is this weight loss normal for a rider my size? Our average temperature in Phoenix when I ride is 92-95, with a little humidity in July-Aug (30-50%); should I be alarmed? Do I need to rethink my whole hydration plan for the whole ride? - C.H.

A. When you lose weight on a ride, you can assume it is water weight - so you were 6 pounds or a quart and a half behind in fluids (a quart or 4 cups = 2 pounds)at the end of the ride. (In ounces, that is 16 x 6 or 96 ounces.) That is 4% of your body weight - which will impact your performance. The bottom line - you do need to rethink your hydration plan.

Over the four hours, you drank 96 ounces or 24 ounces per hour. I think that is about the maximum you can take in per hour (and empty from your stomach). But you may get some additional benefit by drinking 20 oz of cool water 2 hours before exercise and another 8 to 16 ounces 30 minutes before exercise to assure that you are fully hydrated when you start. You might consider trying other sports drinks as sometimes one will agree with your physiology better than another and thus empty a bit more quickly from your stomach. Other strategies would include proper clothing (white to reflect the heat), and I'd also think about switching to a completely liquid diet for the few hours before and during the ride - even the cliff bar may be enough to lengthen gastric emptying time and contribute to the bloated feeling.

Q. Do you know of any recipes for sugar free sports drinks?? My daughter is rotting her teeth, partly because of the dehydration from running, and partly because of sports drinks.? We'd like to mix up something ourselves. - T.

A.There has been ongoing speculation as to the acids in sports drinks as one of the reasons for the increasing incidence of cavities (caries) in athletes. One study from England suggested that although sports drinks might be more damaging than colas, lemon tea was even more so. The most recent review articleI could find, from 2005, identified only a single study supporting the idea that sports drinks might be harmful to the athlete. The review article noted that the real culprit might be poor saliva formation, aggravated by dehydration and mouth breathing in cyclists. Here is the perspective of my son, a practicing dentist - with a few thoughts on prevention.

Sports drinks provide:

  1. Water - dehydration reduces saliva production, so drinking is key to keeping the mouth moist (with cyclist's tendency to mouth breath) and restoring a more normal pH.
  2. Palatability (which helps maintain adequate re-hydration) - any flavoring will do. Flavored waters (may are commercially available) would work just as well. But after 2 hours a cyclist may start to run out of carbs.
  3. Electrolytes (salt being the most common, then perhaps potassium) - but unless one is running 5 hour marathons, probably not a big deal.
  4. Carbohydrates - to replace glycogen stores and what is being metabolized, but only become important after two hours of continuous exercise. These liquid carbohydrates may be a contributor, along with a dry mouth, in promoting dental disease. A complex carb theoretically might be less of a problem (Carboplex) but anything with simple glucose or sucrose is going to leave a sugar film on the teeth to aid the bacteria which cause decay.

Bottom line? If you are cycling less than 2 hours, water is usually enough (perhaps flavored). If supplements are needed, energy bars may be better for than a sport drink as there is less residue on the teeth (to aid bacterial growth and cavity formation) and no damaging acidity. And finally, consider chewing gum while riding to stimulate saliva production, and brushing immediately after a ride.

Questions on content or suggestions to improve this page are appreciated.

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