The night before the world-renowned Patriots’ Day Run (aka, “Boston Marathon”), the thousands of marathoners who convene in Boston typically prime themselves by “carbo-loading.” The legendary meal of choice is most often pasta—the classic, complex-carbohydrate concoction. Carbo-loading has assumed near-mythic status as a prerequisite to marathoning success—the way to prepare for challenges requiring over-the-top endurance.

The basics of this classic marathoner meal have changed little over the years. However, nutrition science and ingredient technology have advanced to where the complexity of the repast is in more than just the carbohydrates consumed.

A variety of carb flavors and types, as well as proteins and other bolstering ingredients, are typified in the marathon dinner. But the science of the endurance meal is leveraging new and innovative concepts and ingredients. The goal is to enable not just athletes, but anyone who requires sustained energy to get through the day to wring the most energy out of every muscle at the beginning of a routine, through to the moment it ends, and even beyond. Some of the latest advances in ingredient development weren’t even possible just a few years ago.

Glucose is the primary fuel of the body and brain. During exercise, glycogen, the storage form of glucose, is converted back to glucose and used for energy. The ability to sustain prolonged, vigorous exercise is directly related to initial levels of muscle glycogen. The body stores a limited amount of carbohydrate in the muscles and liver.

If an event lasts for fewer than 90 minutes, the glycogen stored in the muscle is enough to supply that needed energy. For these relatively short bursts of needed energy, extra carbohydrate will not help any more than adding gas to a half-full tank will make the car go faster.

For events requiring heavy work of more than 90 minutes, a high- carbohydrate diet, especially eaten two to three days before the exertion, allows glycogen storage spaces to be filled. Long-distance runners, cyclists, cross-country skiers, canoe racers, swimmers, and soccer players all have reported benefits from a pre-competition diet where 70% of the calories come from carbohydrate.

Question of Balance

Carbohydrates not only provide energy for endurance; the correct form of carbohydrate will support long-term energy needs by attenuating the body’s metabolism of glucose. While complex carbs are perfect for storage, some smaller fractions (specifically certain disaccharides and oligosaccharides) also demonstrate a unique ability for slow digestion. Yet, they demonstrate strong versatility in formulations.

One particular carbohydrate, the disaccharide isomaltulose, has proven very popular with endurance product formulators. Like sucrose, isomaltulose is composed of glucose and fructose. This chemical similarity to table sugar means it can function nearly the same as sugar in foods and beverages, and it delivers the taste factors that help formulators match favorite flavors in products. However, its two component molecules are bound together differently, putting the body to work at digesting it and, thus, releasing its glucose slowly into the bloodstream.

As a digested carbohydrate, isomaltulose still provides 4kcal/g, so it is not a low-calorie sweetener. But by releasing its glucose so slowly and over a sustained period of time, less insulin gets released at once, so a low blood glucose-response ensues. The body reflects this steady influx by exhibiting fewer peaks and valleys of energy. Moreover, fat oxidation increases, allowing the body to burn that energy source as well, and without leading to a crash, which can happen when glucose stores are exhausted quickly.

Some carbohydrates that are known for health benefits such as protection against cardiovascular disease, certain cancers, and obesity, also have drawn attention for providing long-haul energy support. Resistant starch (from high-amylose corn, wheat, potatoes, barley, and other sources) and waxy starches (from corn, tapioca, and potatoes) exhibit an ability to improve carbohydrate oxidation rates and better balance serum glucose and insulin response during extended exercise (specifically, cycling). They also can improve response of the peptide hormone glucagon, which converts glucose stored as glycogen into the bloodstream.

Potatoes and other tubers, when slow-cooked, also are among the best sources for building glycogen stores in the body.

“There’s a reason these carbohydrates are the staples of pre-contest meals,” says Mark Anthony, PhD, adjunct professor of natural sciences at St. Edwards University in Austin, Texas. “One always hears about bars and drinks for energy and sports performance, but often ignored is the energy value of low-heat-prepared carbohydrates from root vegetables.”

Anthony notes that roots and tubers typically are enjoyed in something like a soup, where the dominant source of energy comes in the form of a boiled starch. “It would be forward thinking for a processor to market a soup as source of long-term energy,” he remarks. “But at least the incorporation of, for example, potato starch derived from boiling or steaming—as long as it’s still in its long-chain polymer form—could make a great addition to a sports endurance beverage.”

Keep it Running

For continuous activities of three to four hours, glycogen stores in the muscles and liver must be at a maximum to minimize fatigue. Also, maintenance energy is crucial. Consumers needing to keep their engine running at speed do best when taking additional carbohydrate during the event, in the form of carbohydrate solutions. The current recommendation from sports nutritionists is a 6-8% glucose solution.

Manufacturers leverage innovative concepts and ingredients to develop products that enable athletes, weekend warriors, and overworked but active everymen to wring the most energy out of every muscle—from  the beginning of a routine to the moment it ends and beyond. The most common sources of energy are supplemental foods and beverages, from sports drinks to shots, bars, and gels.

“Today, on the bar side particularly, there’s a lot more usage of what we call natural and authentic ingredients than previously available,” says Matthew Roberts, PhD, chief scientific officer for NBTY Inc., a nutritional supplement manufacturer and distributor. Roberts notes that, due to advances in processing, especially in the cutting stages and in managing heat conditions, it’s possible to get the active ingredients into a bar form and keep them from losing efficacy or organoleptic characteristics over a longer shelflife.

“That makes a wider selection of effective ingredients available for athletes and other consumers,” says Roberts.

Roberts further notes that all the macro-ingredients contribute to good endurance nutrition. “Carbo-loading is the age-old mantra of endurance athletes. But, as the sport or endurance events get longer, there are better alternatives. Runners, for example, try to get up to 65% of their diet in carbohydrates for optimal carbo-loading, which delivers about 2g of glycogen per pound of muscle tissue. That level of glycogen in the muscle and in the liver could really augment your performance for a couple of hours. However, if you’re in an iron-man competition or a triathlon, that really isn’t enough.”

Other macronutrients have to come into play for maximum muscle efficiency, according to Roberts. “Lipid stores also must be built up for longer events. As competition gets fiercer and events get longer, some things become disproportionately important,” he says. “This is when a variety of proteins, carbohydrates, and electrolytes becomes critical.”

All exercise or exertion breaks down muscle tissue, and exertion over a long period accelerates the body’s need to engage in muscle replacement while catabolism is occurring. (See “Muscle to the Max,” PF, January 2016.) While carbohydrates and electrolyte balance are important, protein is becoming a key endurance ingredient.

“Carbs alone don’t cut it,” says Susan Mitmesser, PhD, head of nutrition and scientific affairs for NBTY Inc. The company makes the Met-Rx and Met-Rx Prime sports and endurance product lines. “Research is showing that a nice mix of proteins is beneficial in that pre-workout. A balanced mix helps the body build up glycogen stores, which then helps the body recover better from muscle breakdown during events.”

The successful endurance product also must deliver a positive nitrogen balance. “Amino acids found in proteins contain nitrogen,” states Mitmesser. Endurance training breaks down protein-containing structures in the muscle, resulting in lost nitrogen. If the loss of nitrogen exceeds what is consumed through food or supplements, the result will be a negative nitrogen balance. It’s important to sustain enough protein in the diet to maintain a positive nitrogen state.”

Mitmesser explains the company’s criteria for selecting ingredients. “It’s important to focus both on fast-digesting protein and slow-digesting protein to serve two parallel objectives,” she says. “For products stressing endurance, whey is ideal as an ingredient to deliver faster-digesting protein, while casein is ideal for slower-digesting protein. For carbohydrates, the need is for both simple and complex. And electrolytes need to be continued throughout the day, regardless of activity level, to ensure proper hydration.”

Peppy Combo

Some supplement powders include one of the oldest ingredients for providing a long flush of energy: caffeine. While energy from alkaloids is, of course, indirect—in that alkaloids merely stimulate the body to burn its energy stores—there is no doubt caffeine and its relatives can be helpful in a pinch.

However, formulators are developing more complex mixes of nutraceutical blends that include caffeine in balance with other ingredients that temper the stimulants and provide a steadier energy flow. Bluebonnet Nutrition Corp.’s Extreme Edge line of pre-workout formulas contain simple carbohydrates in conjunction with amino acids, specifically arginine, lysine, and BCAAs. The line also contains what Trisha Sugarek-MacDonald, senior director of R&D for Bluebonnet, calls “responsible amounts of caffeine to spur the body into action—not just physically, but mentally.”

Sugarek-MacDonald points out that, in addition to energy and sharp mental focus, the mix also provides beta-
alanine to help “increase the concentration of carnosine in the muscles, preparing them for extreme performance, while decreasing fatigue.”

Extreme Edge Carbo Load combines such complex carbohydrates as waxy maize, steel-cut oats, brown rice, and maltodextrin.

“These are important, because when you’re refueling the body, you want carbohydrate sources that don’t just temporarily spike blood glucose levels but are steady and provide the cells with ample energy to go the distance,” says Sugarek-MacDonald. Extreme Edge Carbo Load also contains alphalipoic acid, cinnamon, and chromium. “These support glucose and insulin activity so that athletes can avoid the dreaded blood-sugar nosedive,” she adds.

Athletes benefit the most from the amount of carbohydrate stored in the body, notes Sugarek-MacDonald. “In the early stages of moderate exercise, carbohydrates provide 40-50% of the energy requirement, and carbohydrates yield more energy per unit of oxygen consumed than fats,” she explains. “Because oxygen often is the limiting factor in long-duration events, it is beneficial for the athlete to use the energy source requiring the least amount of oxygen per kcal produced. As work intensity increases, carbohydrate utilization increases.”

Macro Micro

Adding vitamins and minerals to an endurance product’s ingredient profile is critical. “Research shows that female long-distance runners, in particular, have a decreased absorbability and retention of iron in their bodies,” says Mitmesser. “That can lead to a lot of metabolic interruptions, since iron is critically involved in metabolism and muscle breakdown. Deficiencies can result in more wear and tear on muscle fibers.”

Iron is vital, particularly for active women—in sports or otherwise. “There’s an increased risk of muscle tears and muscle breakdown in females who are iron deficient,” Mitmesser adds.

B vitamins also are an important component of an added vitamin-mineral ingredient profile, for both men and women. “Many long-endurance athletes have lower stores of many of the B vitamins, in particular B6 and B12. Because endurance athletes burn complex carbohydrates, they also need fiber in their supplements, as well as vitamin D. As a consequence of the demands on the body, vitamin D has been shown to be less bioavailable.” So it, too, must be added for both men and women participating in endurance athletics.

Since vitamin D is strongly involved in bone mineralization, a vitamin D deficiency can lead to stress fractures caused by the re-occurrence of pounding on the joints and bones in athletes and active persons, says Mitmesser. “Vitamin D has to be in that vitamin-mineral ingredient profile.”

Gummy products are popular nutrient-delivery formats for micronutrients, because they can be consumed easily, virtually anywhere, and even on the run—literally or figuratively. Key ingredients are chlorides—electrolytes that help in hydration—delivered in the form of both sodium chloride and potassium chloride.

“Gummies are easily consumed and fast-digesting,” says Mitmesser. “When muscles are well-hydrated, athletes and other active consumers have an adequate balance of electrolytes and their muscles react better.”

NTBY’s Met-Rx Prime product delivers high-fiber and high-protein, for a positive nitrogen balance, as well as flax seed. Flax is a key ingredient delivering omega-3 fatty acids. One study, published last December in PLoS One, was among the latest of many providing evidence to suggest omega-3 fatty acids could help increase both resting and exercise metabolic rate.

“There is significant evidence showing that omega-3s are quite helpful to athletes from a performance perspective,” Mitmesser adds. The Prime bars contain 400mg of omega-3, in addition to being free of artificial growth hormones, sweeteners, flavors, or colors.

Up and Coming

Nutrition that enables athletes to perform well can come from many sources. For White Wave Foods Co.’s Vega brand, the nutrition focus is on plant-based nutrition. A key ingredient in some of the company’s Performance products is the humble date.

“Dates are a whole-food sweetener and are minimally processed and more nutrient-dense,” explains Emma Andrews, innovation specialist for the company. “They are a glucose-rich source of functional fuel. While the glucose from the dates is rapidly digested for quick energy gain, dates also provide the antioxidant vitamins A and C to support inflammation management.”

Because of these characteristics, both the Vega Sport Energy Bar and Endurance Gel products are made with whole dates as a primary ingredient. The bar also contains organic agave, dried cherries, dried apples, and coconut palm sugar.

“This variety of carbohydrate sources gives working muscles a blend of both high- and low-glycemic carbohydrates, for a combination of instant and sustained energy, benefiting an athlete immediately and over the duration of a workout,” adds Andrews. The performance products also have been formatted to make it easy to be consumed “on the fly,” during sustained activity.

Vega also uses omega-3 fatty acids in several of its products. The bar contains 1g of omega-3 from oil from the sacha inchi seed.

“Omega-3 fats are important for reducing inflammation and supporting immune function, which is less resilient during times of stress, such as periods of extended activity. Omega-3s also can help to sustain endurance, since they play a role in the absorption of muscle-sparing amino acids, such as branched-chain aminos that circulate in the bloodstream.” Andrews adds that these amino acids can help prevent muscle catabolism. “Muscle breakdown is common among endurance athletes and is not an effective way to improve strength-to-weight ratio—the ideal goal.”

Choline, too, has emerged as an important nutrient for helping the body generate energy for long periods. This relative of B vitamins is a key nutrient for the production of energy on a cellular level and throughout the body. As the building-block molecule for acetylcholine, it’s the primary neurotransmitter for neuromuscular action. All motor neurons excrete acetylcholine to activate individual muscular cells. Animal proteins (meat, eggs, dairy, seafood, poultry) all are good sources of choline. So, too, are nuts and legumes.

Gelling Out

Gels have become highly popular among active persons and athletes. Vega’s Sport Endurance Gel is an example of the genre, being a blend of high- and low-glycemic carbohydrates that includes rice dextrins and grape juice. They’re included as alternatives to maltodextrin, an ingredient that has been linked to digestive discomfort in some highly active consumers.

Some athletes report side-effects of maltodextrin ingestion that include indigestion, bloating, and acid reflux. “These conditions can impair nutrient and electrolyte absorption,” says Andrews.

Vega’s Energy Gel also contains an electrolyte blend of sodium, potassium, magnesium, calcium, and chloride. All are essential electrolytes that “stimulate what’s known as the ‘action potential’ within the nervous system,” explains Andrews. “This helps regulate muscle contractions and heart rhythm. The blend also contains antioxidants, vitamin C, and selenium to proactively replenish and replace what is lost in sweat.”

Since the Vega endurance gel is made primarily with whole foods and minimally processed ingredients, “it has a larger serving volume than gels made with refined sweetener sources like maltodextrin or glucose-fructose syrup,” notes Andrews. The texture also is more fibrous, so she points out that combining it with a fluid such as a beverage will “not only makes consumption easier, but also help digestion and absorption.”

Andrews also includes that, because of its texture, some consumers have used the gel as a jam alternative on toast before a long run or an endurance workout. “The orange zest flavor tastes especially like marmalade,” she says.


Originally appeared in the February, 2016 issue of Prepared Foods as Pace Yourself.

Formula One

There are hundreds of different sport endurance beverages on the market. All have some basics in common: They typically are an electrolytic solution slightly more acidic than water and using a simple carbohydrate—often sucrose or other simple sugar—in conjunction with sodium, as well as potassium.

An ideal sports drink with reasonable sodium amounts will be balanced at approximately 6 Tbsp. carbohydrate as sucrose and 1/3 tsp. salt per each quart of fluid. Using warm water or other liquid will allow better
solubilization. The salt translates into a sodium concentration of 650 mg/L. This small amount is good for marathon runners and those who engage in long workouts, since sodium is lost in through sweat.

Fire in the Belly

One hot ingredient for endurance energy is not so hot, even though it comes from chili peppers. Recent studies indicate compounds in chili peppers, especially dihydrocapsiate, could have the potential to boost metabo-lism and increase fat burning, while dampening fat deposition. Dihydrocapsiate is a capsinoid ingredient derived from sweet peppers. Unlike capsaicin, it doesn’t set the mouth on fire. Yet, once in the digestive system, the compound does bind to the same receptors (called TRPV1 receptors) that register spicy heat in the oral cavity.

And, like capsaicin, it still triggers the sympathetic nervous system, better known for the “fight or flight” response, essentially stimulating energy. Human and animal research shows that both compounds have the potential to boost metabolism and increase fat burning, while dampening fat deposition.