The Evolution of Fueling Science

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Fueling for endurance events hasn’t always been a dialed science. Maurice Garin, the first winner of the Tour de France in 1903, reportedly ate at pubs along the course to fuel himself to victory, while Canadian runner Tom Longboat received champagne during the 1908 Olympic marathon in London and unfortunately was not so lucky, as he was forced to drop out at Mile 19.  Fueling tactics in the past have ranged from alcohol and tea consumption to eating carbohydrates from everything from bananas to cake. 

It wasn’t until the 1980s that Brian Maxwell, a Canadian Olympic marathoner developed one of the first portable sports nutrition bars, otherwise known as Powerbar.  The nutrition bar gained popularity quickly and revolutionized the specialized sports nutrition products for runners. 

Flash forward to today’s trail and ultra races. Most runners are now trying to at least consume some amount of all three keys to a modern fueling plan—-fluids, electrolytes, and calories. 

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Hydration—Friend or Foe? 

While Gatorade sports drink was initially developed in 1965 for the University of Florida Gators football team, hydration science didn’t really take hold in the endurance community until the 1970s. Before the 1970s, runners were discouraged from taking in fluids during exercise and doing so was considered an act of weakness or was believed to cause a runner to slow down.  

As companies like Gatorade started to do more structured research, more advancements in hydration science were made.  In 1996, the American College of Sports Medicine started recommending that athletes should start drinking early and regularly to replace all of the fluids lost as sweat during exercise. This led to its own problems of athletes overhydrating and risking hyponatremia, the condition that happens when your blood sodium gets too low.  

Today’s viewpoints are trending towards recommending drinking to thirst for shorter-distance endurance events, while longer ultra-endurance events require a planned hydration strategy to avoid severe dehydration and electrolyte imbalances.  

The Evolution of Electrolytes

As Gatorade continued to develop its sports drink, sweat breakdown was studied more for its composition. Electrolytes like sodium, potassium, chloride, magnesium, and calcium play an important role in fluid balance, muscle contraction, and nerve signaling.  

Today, with advancements in sports science, techniques for measuring sweat rate and sodium sweat concentration have become more accessible. As athletes begin to understand their sweat composition even more, more personalized protocols can be developed for electrolyte replenishment using drink mixes, tablets, and supplements. 

Calorie Intake—gels, chews, waffles, and donuts, oh my!

Calorie and carbohydrate intake started becoming more popularized in the 1970s as sports scientists began to recognize the importance of taking in fuel during endurance events.  Whole foods like fruit, cookies, and other carb-rich snacks were the original choices for fueling.  Powerbar came about in the 1980s, and in 1993, GU Energy Labs was formed. GU’s goal was to create one of the first gels that provided a quick and easily digested energy source for athletes during exercise. 

While we know that it is not possible to replace all energy expended during training and racing, current science supports that a strong effort should be made to minimize calorie deficiencies. Calorie intake every hour should be personalized depending on the athlete, but it is not recommended to take in more than 200 calories per hour. Amounts of carbohydrate vs. fat intake are unique to the athlete’s goal races as well as gut tolerance and effort level. A minimum of 30 grams of carbohydrates is recommended every hour, and fats can make up the remainder of the calories. (Keep in mind that fats are digested much more slowly.)  Regardless, a higher tolerance of carbohydrate and fat intake is typically required to have a successful race. 

A key consideration to keep in mind with ultra fuel is the palatability of foods chosen for the fueling plan. Over time as fatigue sets in, runners may grow sick of sweet food options and crave things that are more salty or savory. When that happens, it’s important to identify what foods or supplements are viable so as to make sure there aren’t gaps in fueling during a race. 

It is advisable to include a mix of liquid calories, gels, and whole food options during trail and ultra events longer than three hours in duration. Logistics of carrying fueling options (including hydration and electrolytes) can be difficult to figure out, but with a little planning and testing, it can be done!

RELATED: The Evolution of Running Training Theory

Modern Ultramarathon Fueling

While runners in the past took a more unstructured “winging it” approach, we now know a whole lot more about what we should be including and consuming to support endurance performance goals. Technology and research in hydration, electrolyte, and calorie consumption has evolved to allow for athletes to develop their own individualized race fueling plans depending on race elevation, climate, and duration of target event. It is important to keep in mind that fueling science is ever evolving and what worked last year might not be the best choice for today.

It is known that fluid, electrolyte and calorie consumption during every hour of exercise, can help prevent a runner from the dreaded “bonk,” muscle cramping, and/or gastrointestinal distress—all of which can ruin your race day goals! Plus, because low blood sugar from inconsistent fueling can often lead to reduced mental acuity, consistent fueling can help your mind from going sideways and your thoughts from turning negative.

This is where the importance of planning, testing and implementing fueling strategies ahead of time allows for athletes to figure out what can work for their target races and lets their body adjust accordingly to products and amounts targeted. Every runner is unique and what works for one runner—a friend, a training partner or an elite athlete—might not work for you. 

Today’s trail and ultra-fueling still resembles a running picnic of options. Nowadays, though, it’s a more organized one with better and more effective fueling sources.


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