While Miles' pre-race meal may not have been ideal, at least according to contemporary standards, his unconventional approach underscored the ongoing importance of low-tech nutrition to athletic performance.
Without a doubt, advances in sports nutrition have enabled athletes to make tremendous performance gains, and high-tech, scientifically-derived products (such as bars, gels and sports drinks) are crucial to top race-day results; however, consider that, during long-course events, triathletes race from the early morning until, in many instances, well into the night. During this time, athletes will miss four to six regular meals and snacks -- all while the body churns through up to 500 calories per hour.
Thus, balanced, well-planned nutrition is required to make up for these missed meals and provide the fuel needed for a race-day effort. To supplement their intake of bars, gels and sports drinks (which typically constitute the core of most athletes' race-nutrition plans) and provide some culinary variety, many athletes turn to low-tech solutions.
So how do you fuel up effectively to sustain a long, intense effort?
Carbohydrates: It's not practical or necessary to eat as many calories as you're burning as long as you're well trained and have topped up your glycogen stores before the race. During an endurance event, your body will burn a mixture of fat and glycogen for energy. The glycogen comes both from your body's stores and from the carbohydrates you consume during competition.
How much glycogen you use, and how many grams of carbohydrates you require to supply your energy needs, depends largely upon your intensity.
The higher the intensity of exercise, the more difficult it is to eat and digest food; for this reason, it's important for athletes to know the pace and caloric-consumption rate they can sustain for the total amount of time they're on the course.
As a general rule, you should aim to consume one gram of carbohydrate per kilogram of body weight per hour during Ironman racing. For example, a 70-kilogram athlete needs 70 grams of carbohydrate per hour; this can come from drinks, bars, gels and real food.
Fat: Fat consumption should be kept to a minimum during an Ironman. Although most of your energy does come from fats at Ironman race intensity, your body stores more than enough fat to supply this energy. The limiting factor in Ironman performance is carbohydrate availability, so carbs should be your primary nutrition focus.
Also, any fats you consume will tend to slow digestion and metabolism; therefore, food choices need to be ultra-low fat and high in carbohydrates so sugars can get into the bloodstream as quickly as possible without extra caloric expenditure.
Protein: As with fat, most of the protein used for energy during exercise is already in the body when you begin your race. That said, some studies have indicated that protein consumption during exercise can boost endurance, not so much by providing a direct energy source as by reducing muscle damage.
Sodium: Athletes need to ingest sodium to replace what's lost in sweat and to help with hydration. An athlete can replace 500 to 700 mg of sodium per hour with salt tablets and salty foods.