CARBOHYDRATES: THE DRIVING FORCE FOR OPTIMAL PHYSICAL & COGNITIVE PERFORMANCE
By Melinda Burris Willms
In this age of emphasis on being fit and trim, carbohydrates have gotten a bad rap. What you don’t often hear about carbohydrates is how essential they are for the body to do anything requiring energy, endurance, and focus. Of course, athletes in particular, need all of these things—at once.
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Carbohydrates are Fuel
Scott Christenson from Complete Track & Field makes the powerful declaration that carbohydrates are “the only fuel source the brain can operate with” making the human body reliant on an adequate store of carbohydrates to function properly.[i] While Christenson’s research focuses on studies demonstrating a positive correlation between high pre-competition glycogen supply and peak performance outcomes for cross-country runners, the findings can be extrapolated to effectively validate the importance of a proper diet that includes carbohydrates in proper proportions and at the right time in the training schedule to allow hurdlers and track athletes across the board to maintain adequate glycogen stores to ensure the highest level of execution in competition.
The body stores carbohydrates as glycogen in the muscles, the liver, and in the blood stream. The vast majority of carbohydrate that has been converted by the body to glycogen is stored in the muscles, but the body relies on all three stores to perform physical activity.[ii] Christenson’s findings support “a statistically significant correlation between the pre-exercise muscle glycogen stores and the length of time running can be performed at 75% of VO2 max.”[iii] (VO2 max refers to maximal oxygen uptake.) This shows a direct link between higher amounts of glycogen stored in the muscles and improved athletic endurance.[iv] Study participants who maintained a “mixed diet of 50%/50% carbohydrate” reached a muscle glycogen level of “106 mmoL/kg wet muscle weight” and this group was able to sustain running at a maximum rate of 75% VO2 for up to an hour and 15 minutes prior to their glycogen levels showing signs of depletion. The study compared muscle glycogen production and endurance levels between a group of subjects on low carbohydrate diets and another subject group on high carbohydrate diets and the results were telling. The low carbohydrate dieters, defined as consuming fewer than 10% of KCAL as carbohydrates, had very low levels of muscle glycogen, only 38 mmoL/kg. These participants were only able to maintain running for sixty minutes, at the same maximum rate of 75% VO2. In contrast, the high carbohydrate group, consisting of participants who derived in excess of 80% KCAL as carbohydrates, had high levels of muscle glycogen, 204mmoL/kg. This group was able to sustain the maximum rate of effort achieved by the other participants and persist for 170 minutes.[v] It is clear; the higher an athlete’s muscle glycogen production, the higher his or her VO2 rate, and consequently, the higher the athlete’s endurance level.
“Coaches often report that athletes who follow low-carbohydrate diets fatigue early and make more cognitive mistakes.”
—Sally Hara, MS, RD, CSSD, CDE
Sally Hara, a registered dietician with ProActive Nutrition, agrees that carbohydrates are the body’s go to fuel for anaerobic exercise. She explains that the body can’t utilize fat stores for energy because, “There isn’t enough oxygen available during anaerobic exercise to use the oxidative pathway necessary to use fat as a fuel.”[vi] Hara concurs with Christenson’s assessment that our brains need carbohydrates too. She notes, “Coaches often report that athletes who follow low-carbohydrate diets fatigue early and make more cognitive mistakes.”[vii] The take away is that athletes who do not consume enough carbohydrates are prone to underperformance because their bodies don’t have what they require to physically accomplish what is needed; while at the same time, their brains are also undernourished, making it impossible for the athletes to make smart decisions in competition.
Glycogen Production and Replenishment
Exercise depletes blood glucose levels and when the body senses a significant decrease it signals an increase in glucagon production to facilitate the release of glycogen stores in the liver. If glucose levels are very low, the body also releases cortisol to enable “the synthesis of glucose from free fatty acids and amino acids.”[viii] Several body systems are elevated following exercise ranging from “enzymes, blood flow, to receptors on the muscles cell, to hormone action.”[ix] This raised rate of production is at its highest during the initial 45 minutes immediately following exercise. It is this 45-minute timeframe that is crucial for eating the right foods, including carbohydrates, to replace the depleted stores of glycogen necessary to preserve endurance. It is also importance to rehydrate and to make sure your meal includes foods that will aid in muscle recovery.[x] Not eating immediately after training or competing can seriously affect your body’s ability to rebuild its glycogen stores. Christenson points out, “If the athlete delays carbohydrate consumption by two hours or more, glycogen synthesis will be reduced by 50%.”[xi]
This time of year, most athletes have two meets per week, with training concentrated on the longer, higher-stakes weekend meets. Training and competition will continue to intensify into May as high-schools compete in state championships and conference meets and college conference championships are held. As you factor diet into your competition game plan, keep it simple: make sure you consume enough carbohydrates to allow your mind and body to perform optimally, be mindful of your protein intake to facilitate tissue repair, and stay hydrated.
Remember, check with your coach for the best dietary recommendations for you! Your coach knows your body type, your physical fitness level, your training regimen, and the demands of your particular competitive events, so he or she can give you advisement structured specifically for your physical and mental well-being as well as tips geared to assist you in reaching your full athletic potential. It is also always a good idea to consult your physician when starting a new nutritional plan to be sure you have no food or additive allergies or other conditions that should be considered when structuring your dietary plan.
Eat Well but Enjoy What You Eat
To thrive as an athlete, it is vital that you make sure you understand the basic principles of proper training techniques and proper nutrition. Armed with the correct information and a willingness to apply these fundamentals, athletes can improve their performance—physically and cognitively—and make smart choices that can help avoid or minimize injuries. It is important to find foods you like among the required food groups. Monotony makes any diet hard to stick to so be sure to try different combinations and flavors to increase your chance of success in getting the right calories at the right time.[xii]
1. Scott Christenson. “Carbohydrate Metabolism.” CompleteTrackandField (blog). Complete Track & Field, December 20, 2012, http://completetrackandfield.com/carbohydrate-metabolism/
2. Kristen Austin and Bob Seebohar. Performance Nutrition: Applying the Science of Nutrient Timing (Champaign, IL: Human Kinetics, 2011), 2.
3. Ibid.
4. Ibid
5. Ibid.
6. Marie Spano, “Postexercise Recovery — Proper Nutrition Is Key to Refuel, Rehydrate, and Rebuild After Strenuous Workouts.” Today’s Dietitian 15, no. 11 (2015): 18. http://www.todaysdietitian.com/newarchives/110413p18.shtml
7. Ibid.
8. Kristen Austin and Bob Seebohar, Performance Nutrition: Applying the Science of Nutrient Timing (Champaign, IL: Human Kinetics, 2011), 2.
9. Ibid., 157.
10. Ibid.
12. CTS Coaching Staff. “Three Nutrition Mistakes That Kill Performance.” Accessed Apr. 4, 2017. http://trainright.com/clearing-common-sports-nutrition-hurdles/
Bibliography
Austin, Kristen and Bob Seebohar, Performance Nutrition: Applying the Science of Nutrient Timing. Champaign, IL: Human Kinetics, 2011.
Christensen, Scott. “Carbohydrate Metabolism,” CompleteTrackandField.com. December 20, 2012.http://completetrackandfield.com/carbohydrate-metabolism/.
CTS Coaching Staff. “Three Nutrition Mistakes That Kill Performance.” Accessed Apr. 4, 2017. http://trainright.com/clearing-common-sports-nutrition-hurdles/
Spano, Marie. “Postexercise Recovery — Proper Nutrition Is Key to Refuel, Rehydrate, and Rebuild After Strenuous Workouts.” Today’s Dietitian 15, no. 11 (2015): 18. Accessed Apr. 4, 2017. Accessed http://www.todaysdietitian.com/newarchives/110413p18.shtml.
Bibliography
Austin, Kristen and Bob Seebohar, Performance Nutrition: Applying the Science of Nutrient Timing. Champaign, IL: Human Kinetics, 2011.
Christensen, Scott. “Carbohydrate Metabolism,” CompleteTrackandField.com. December 20, 2012.http://completetrackandfield.com/carbohydrate-metabolism/.
CTS Coaching Staff. “Three Nutrition Mistakes That Kill Performance.” Accessed Apr. 4, 2017. http://trainright.com/clearing-common-sports-nutrition-hurdles/
Spano, Marie. “Postexercise Recovery — Proper Nutrition Is Key to Refuel, Rehydrate, and Rebuild After Strenuous Workouts.” Today’s Dietitian 15, no. 11 (2015): 18. Accessed Apr. 4, 2017. Accessed http://www.todaysdietitian.com/newarchives/110413p18.shtml.
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