, swimming, and weight lifting are great most of the year, as part of low-key training months when your main goals are general fitness and injury prevention, but the heavy training month before a big race needs to be a month of living a little dangerously
-depleted state. Ever since carbohydrate-loading caught on decades ago, carbs have been the focus of nutrition advice for marathon runners. You can burn 2,300 calories on a 20-mile run, and the carb is the most readily converted fuel source, so it makes perfect
