Like physical energy, mental energy is integral to optimal function. Here, we take a look at four energy sources.
We know matter is energy. Nowhere is this more pertinent than in the gym. Body mass is, crudely, energy realised. When we have more than the body needs, we gain weight, less and we lose it. Left to its own devices, in the absence of its favourite energy source glucose, the body will convert muscle into glucose through the process of catabolism and gluconeogenesis. While fat is the form of energy most readily stored as body fat, it’s the last in line to be liberated when dietary energy is in short supply. Fasted workout fiends beware: while unfed workouts make sense on paper, studies suggest that working out unfuelled can negate the higher fat burn percentage due to reduced intensity.
Carbs are the body’s go-to fuel for workouts lasting less than 40 minutes, so optimising intensity depends on either ready (just consumed) glucose or glycogen, which is how glucose is stored in muscles and the liver. That’s why many fitness pros recommend eating slow-release carbs pre-workout – think low-GI carbs such as sweet potato. Whereas simple carbs (sugar) prompt the pancreas to flood your blood with fat storage hormone insulin, complex carbohydrates regulate the rate of release, effectively reducing the chance that energy will be stored as body fat.
Often added to workout supplements, caffeine can promote endurance by reducing pain perception according to a study on the effects of caffeine on pain during exercise published in the International Journal of Sport Nutrition and Exercise Metabolism. Caffeine tolerance did not appear to reduce the effects of caffeine on pain perception during high-intensity exercise, researchers found.
Hitting the wall in a workout doesn’t always mean you’re out of fuel. Excess lactic acid build-up and increased tissue acidity can make your muscles feel fatigued (metabolic fatigue), but rather than meaning you’re on empty, it’s due to incomplete aerobic metabolism of glucose, which inhibits production of ATP and causes muscles to weaken. Intense exercise such as HIIT and metabolic circuits sharply reduce ATP and promote lactic acid build-up and increased tissue acidity. Supplements can mitigate metabolic fatigue and keep you moving for longer.