PROS: Convenient mode for consuming a concentrated dose of energy (calories) and carbohydrate; star as prerace meals or post-recovery drinks due to low fiber and higher energy content; typically a well-tolerated option for ultra-endurance athletes.
CONS: Can lead to digestive problems and dehydration when consumed during moderate-to-high intensity exercise; energy-dense beverage can contribute to unwanted weight gain if routinely consumed in place of meals or snacks.
With practice an energy bar can be easy to carry, chew and digest while running. Unless you'll be on the move longer than four hours, however, choose varieties that obtain most if not all of their calories from carbohydrate (70 percent or more). It's only during longer hauls that the body has time to actually digest and assimilate the fuel from other sources.
PROS: Wide variety of flavors and textures to choose from; travel well; welcome alternative to sweet-tasting drinks, gels, chews and blocks; another option for meeting higher energy requirements of long-distance runs.
CONS: More difficult to chew and digest than liquids, especially when you're fatigued; must take with ample fluid for proper digestion; solids can take much longer to boost blood sugar levels than liquids.
Ultra runners can be seen refueling with everything from sports drinks and energy gels to sandwiches, fried chicken and pizza. Ditto for walkers and back-of-the pack marathon runners who often rely on real food for fuel, such as candy, dried fruit or pretzels. The longer duration and slower pace (lower intensity) allows these athletes to profit from consuming real food despite the extra time required to convert energy into fuel the body can use.
PROS: Helps fight "flavor fatigue" common when consuming only sweet-tasting sports foods; allows athletes to meet the high energy demands of prolonged ultra running; can be mentally uplifting or rewarding.
CONS: Protein, fiber and fat in real foods can slow absorption and digestion time and increase potential gastrointestinal problems; more complicated logistics of carrying and consuming while on the move.