Why avoid energy gels?

An article published this week on the Bike Rumor website has sparked several reactions in the sports nutrition industry. Since the article's publication, BikeRumor has released a few retorts that were sent to them afterward. ( http://www.bikerumor.com/2014/06/02/rebuttal-why-athletes-should-use-gels/ )

Here is a summary of this controversial article whose author, *Stacy Sims, MSc, PhD, is herself a triathlete and co-founder of the firm OSMO Nutrition .

When we examine some of the biggest concerns faced by endurance athletes, the balance between nutrition and fluid intake to maintain optimal performance and delay fatigue during an activity without suffering gastrointestinal disturbances is at the top of the list. Studies show that 45 to 50% of endurance athletes are affected by various gastrointestinal symptoms. Ranging from mild to severe, these symptoms can be linked to more than one factor. The physiological response to effort is complex and varies from one individual to another, so the fuel (mainly carbohydrates) and fluids absorbed during exercise can be beneficial or, conversely, harmful to the athlete.

PHYSIOLOGICAL PERSPECTIVE:

When exercise is intense and/or when dehydration causes hypovolemia (a decrease in blood volume in the body's venous network caused by water loss due to sweating), exercise induces changes in blood circulation, as blood passes from the gut to working muscles. This results in an increased secretion of certain hormones and a decrease in absorption by intestinal cells. The combination of these factors induces diarrhea, intestinal cramps, gastric discomfort (stomach pressure or "sloshing" sensations) and can even lead to stomach and colon bleeding, which explains why some people find blood in their urine and stool after particularly difficult events. The use of non-steroidal anti-inflammatory drugs (NSAIDs, aspirin) can aggravate bleeding and interferes with water balance in the kidneys (which tends to exacerbate the problem of dehydration).

Anxiety, often present in athletes as important competitions approach, is another factor that tends to induce gastrointestinal symptoms, but there appears to be a difference in these symptoms based on gender. Women have an increased risk (5 times greater than men) of diarrhea, intestinal cramps, and associated pain. Men, on the other hand, tend to have a higher risk of vomiting and nausea. Fructose intake would contribute more to dehydration in women.

The use of energy gels during activity is most often THE solution advocated by athletes to provide them with a quick source of energy from sugars. Although practical, this solution is, according to Stacy Sims*, the author of the study cited here, one of the most detrimental fuel sources for performance.

GLOBAL NUTRITIONAL SCOPE

In a standard gel, the calorie content ranges from 100 to 120 kcal per serving (typically 33 to 40g of sugar), which includes glucose and fructose, a little sodium, potassium, flavorings, and preservatives. Most usage instructions state that a gel should be consumed with water (2 to 4 oz). This is where it starts to get complicated...

In simple terms, a gel is a concentrated carbohydrate: a solution of at least 73% (73g of CHO (carbohydrates) per 100 ml). By recommending water, manufacturers aim to reduce the concentration of this solution. Why? Simply put, the concentration and carbohydrate content affect gastric emptying. Due to its concentrated nature, a gel will sit in the stomach and increase osmotic pressure (related to absorption), drawing water into the stomach to effectively decrease this pressure and allow the solution to flow into the small intestine, thus depriving the body of the necessary water volume for proper blood system function, particularly when the body is subjected to significant effort. This is the first step towards what the author calls "effective dehydration."

Another aspect is the combination of different sugars whose absorption rate varies. For example, glucose is absorbed by the intestine more quickly. Fructose, being slower to absorb due to less efficient transport mechanisms, tends to remain longer in the intestinal space and cause an increase in pressure, thus leading to the unpleasant feeling of bloating, gas, diarrhea, and general gastrointestinal discomfort.

To counter these negative effects, manufacturers notably use maltodextrin, a polysaccharide composed of glucose blocks. Because maltodextrin is a long chain of glucose molecules, it results in a faster gastric emptying rate. However, there is a catch to this solution because maltodextrin is not completely broken down in the stomach but continues into the small intestine. Thus, the multi-chain glucose molecules that make up this compound end up creating the same environment in the intestines as fructose does in the stomach. It's clear that this solution will only have shifted the problem...

Glucose molecule

HER CONCLUSION:

Why shouldn't gels be used? First, because this concentrated carbohydrate, once in the body, ends up in the intestine and will slow gastric emptying due to water retained in the stomach to facilitate absorption. Secondly, they are generally composed of Maltodextrin and fructose, two types of carbohydrates that create a significant hyper-osmotic environment in the small intestine. Both, in addition to causing the inconveniences listed above, will deprive muscles and blood of the water necessary to maintain performance.

Knowing that the natural fluid loss during exercise is difficult to reduce and that it is essential to maintain the necessary volume of water in the body to meet the essential needs for perspiration and proper muscle function, why would one want to ingest a product that accelerates dehydration and risks causing gastrointestinal problems?

Translated and summarized from: PHYSIOLOGY AND NUTRITION: WHY NOT GELS? Posted by Stacy Sims on May 9, 2014, on http://www.bikerumor.com

http://www.bikerumor.com/2014/05/09/physiology-and-nutrition-why-not-gels/

** Stacy Sims, MSc, PhD, served as an exercise physiologist and nutrition scientist at Stanford University specializing in recovery and nutritional adaptations for health, body composition, and maximizing performance. During the past decade she has worked as an environmental physiologist and nutrition specialist for top professional cyclists and triathletes, ultra-endurance athletes, the Garmin/Slipstream Pro Cycling Team, USA Cycling Olympic Team (BMX and women’s track cycling), Team Tibco, Flying Lizard Motorsports, and Team Leopard-Trek, among others. She competes as a Cat 1 road cyclist and elite XTerra triathlete and is co-founder of OSMO Nutrition.