Let us understand carbohydrates, which are known as the powerhouse nutrients. The demand for carbohydrates becomes more specific and augmented for runners, as endurance exercise demands for a consistent supply of energy to maintain stamina and deter fatigue.
Carbs and calories
The food we eat is broken down in order to produce energy for various functions of the body, which are known as calories, or more generally kilocalories. Foods contain different nutrients such as carbohydrates, proteins and fats, which provide varied amounts of energy as mentioned in the table below.1
Although fats provide more energy, carbohydrates are known as the preferred fuel source of the body. This is because fat digestion and absorption takes place relatively slowly, whereas carbs are broken down into small molecules known as glucose and are quickly absorbed by the body to be used as fuel, especially during intense physical activities. Therefore, they help the athlete in performing better by providing energy for longer durations, thereby reducing fatigue.1
What are glycogen reserves?
Glycogen is the storage form of glucose, produced by the breakdown of carbohydrates in the body. Glycogen in the body is stored in the liver and muscles, which is released when the body’s glucose levels drop, which occurs during or post a long training activity or exercise. Depletion of these glycogen stores, during prolonged activity or long runs, lead to fatigue and decreased performance levels. Thus, carbohydrate intake needs to be planned well, in order to avoid a sudden decline in the glycogen stores during the activity when glucose availability is limited
Carbohydrates are present in almost all foods. For ease of understanding, carbohydrate sources have been classified as those rich in other nutrients, those low in other nutrients and those rich in fat.2
The sources that are rich in carbohydrate and other nutrients include breads and cereals, grains (e.g., pasta and rice), fruits, starchy vegetables (e.g., potato and corn), legumes and sweetened low-fat dairy products. These are easily absorbed and digested in the system, thereby helping in increasing the blood glucose levels quickly.2
The sources that are rich in carbohydrates and low in other nutrients such as soft drinks, lollies and carbohydrate gels should not form the main constituent of your diet; however, it can be taken around the event when you would need a quick energy kick. They give ‘empty calories’ as the term suggests calories with lesser amount of other vital nutrients.2 The sources that are rich in carbohydrate and fat are loaded with calories and are difficult to digest. These are best avoided during the runs. Some examples are pastries, cakes, chips and chocolates.2
In addition to these food sources, protein supplements can also help scale up the protein intake. It is best to consult a nutritionist for further guidance. Also, make sure you read the food labels to understand the protein contents in the product you buy.11
Getting the quantity of carbohydrates from the right sources before, during and
post the run can help you fuel up your stores and help support your performance for the marathon.
1. Briggs D, Wahlqvist M. Food Facts: The Complete No-Fads-Plain-Facts Guide to Healthy Eating. Melbourne, Australia: A Visionary Voyager Electronic Publication; 1998.
2. AIS Sports Nutrition. Carbohydrate - The Facts. Bruce, Australia: Australian Sports Commission; 2014.