Athlete Health Concern: Fueling

By Emily Dickerson

Have you ever “bonked”? If so, you would likely know it. “Bonking” is a common concern for athletes, most notably for endurance athletes. When an athlete bonks they feel as if they have “hit a wall”, or as if their “legs feel heavy like lead”. The effects of bonking are often felt both physically and mentally. Symptoms of bonking include weakness, fatigue, confusion, disorientation, dizziness, hallucinations, and cognitive and emotional symptoms. Bonking occurs when muscles run out of glucose, the cell’s primary fuel source. Bonking is a symptom of hypoglycemia that results from insufficient fueling before and during exercise. Most notably seen in endurance athletes, bonking can happen to any person, in any state of insufficient fuel during exercise.

Should I fuel before I work out?

Absolutely. One of the biggest mistakes that a person makes is not eating prior to exercise. The body needs fuel to function, even more so to perform athletically. One of the worst things that we can do for our bodies is to exercise before eating breakfast. In providing no fuel to our body, the brain and red blood cells get preferential use of stored glucose, while the muscles have to use an alternate source of fuel, such as fat. Fat is harder to access for the body, requiring additional energy to gain glucose from a fat source. It also trains the body to store carbohydrates when it does receive them. Not only is this not a great thing for your workout, but it also affects for your ability to lose weight.

Fuel for our body during exercise mostly comes from carbohydrates, but some fat balanced with carbohydrates can also be used. Many athletes use carbohydrate dense gels, gummies, and sport drinks as fuel before and during exercise, but these are not the only fueling options. Whole foods options such as fruit and nuts are great sources of fuel during exercise as well.

It is best to fuel with sufficient time prior to working out. However, that is not always possible. Use the following algorithm to know how much and at what time to provide your body with the carbohydrates (aka glucose) needed prior to exercise.

Prior to exercise or an athletic event, fuel 1 to 4.5 g CHO (carbohydrates)/kg (body weight). Fuel with more carbohydrates the longer it is until competition:

  • 4 hours before ~ 4 g CHO/kg
  • 3 hours before – 3 g CHO/kg
  • 2 hours before – 2 g CHO/kg
  • 1 hour before – 1 g CHO/kg

Fueling during exercise or an athletic event is important. Begin soon after the onset and continue at regular intervals, often every 10-15 min. While exercising or during an athletic even, fuel using the following algorithm:

  • 1.0 – 1.1 g/minute
  • 60 – 70 g/hour

If this interests you and you would like to know more about athlete health, nutrition, and supplementation, please join Dr. Dickerson for her Athlete Health: Sports Nutrition, Nutrient Timing, and Supplementation community education class on Thursday, September 17th, 2015. The class will be held at Hillside Junior High from 6:30 PM to 8:30 PM.