Carrying enough food to keep you fueled during a run can be a challenge. How do you carry it? How much should you bring? And what should you eat?
Unlike carrying food on a bike, which are typically equipped with two bottle cages, running requires you hold your fuel.
You can hold a bottle in your hand, wear a fluid bladder on your back, or carry one larger bottle or multiple smaller flasks on a waist belt. But in each of these cases the fuel adds weight directly to your body and bounces up and down with you on every single stride.
Cyclists typically carry at least one full bottle of fluid to sip on during every ride. It's so convenient, why not? Runners are more likely to carry nothing to drink on all except the longest ones. Hauling fluid on the run is such an annoyance that most runners do it only when failing to do so is likely to result in severe thirst and compromised performance.
Given the discrepancy between cyclists and runners, one has to wonder: Are runners missing out on potential benefits of proper fueling by leaving their nutrition at home most days? The answer to this question may surprise you.
Recent science suggests that there's an actual advantage to training without supplemental fuel. The most effective strategy for workout fueling may be one where supplemental fuel is provided only during select runs (but not necessarily just long runs) in which maximizing performance is important.
Most sports drinks, energy gels and other ergogenic aids contain carbohydrate. The carbohydrate content of these products is the key to their performance-enhancing effects. Dozens of studies have demonstrated that consuming carbohydrate during endurance racing enhances performance 2 to 4 percent. So if you're a 4-hour marathoner with plain water, it's likely that you will be a 3:55 to 3:50 marathoner with a carbohydrate-containing sports drink.
In training, however, carbohydrate supplementation comes at a certain cost. When the muscles are consistently supplied with an extra source of carbohydrate during workouts, they burn less fat than they otherwise would. Over time, this attenuates the gains in fat-burning capacity that normally occurs with training.
Maximizing the fat-burning capacity of the muscles is especially important when you're training for longer events such as marathons because it reduces the likelihood of bonking in the latter miles. By acting as a kind of metabolic crutch, supplemental carbohydrate consumed during workouts sabotages this component of fitness.