Carbohydrates are key for a marathon
It’s the start of marathon and triathlon season, with races taking place almost every weekend from late August though November. With so many athletes training to compete in events that demand pushing their physical limits for hours on end, it’s time to discuss the subject no endurance athlete likes to bring up: hitting the wall.
For runners, the wall comes somewhere after the 32-kilometre mark. One minute you’re on pace, and the next you’re feeling like you’re pulling a piano behind you. The legs are heavy, your energy is sapped and your body is screaming to pack it in.
The wall isn’t to be confused with plain old fatigue or the discomfort associated with exercise that lasts several hours. It’s a phenomenon that hits any exerciser who runs out of the energy needed to fuel the working muscles.
That fuel is derived mainly from carbohydrates, which have a finite amount of storage space in the muscles. Once it’s depleted, the muscles find the next-best source of fuel, which is fat. The storage capacity for fat far exceeds that for carbs, but fat is a slowburning fuel that can’t supply the energy quick enough to keep a runner on pace.
While carbohydrates remain in plentiful supply, the muscles can maintain a running pace, but when fat is forced to take over as the primary source of fuel, the pace slows, often to a walk or a shuffle.
The solution is to saturate the muscles with carbohydrate.
Endurance athletes used to go through a complicated routine of depleting and storing carbohydrates 10 to 14 days before competing.
Thankfully, that technique has fallen out of favour, with most recommendations advising that runners eat a high-carbohydrate diet the week before an endurance event, effectively filling the muscles with as much stored energy as possible.