Fuel Your Performances

The start of a series.

Using acute and chronic strategies to manipulate carbohydrate and fat versus one-time macronutrient prescription for endurance training have been useful for enhancing performance among athletes. 

DEFINITIONS AND EXPLANATIONS ARE NECESSARY IF RESEARCHERS, SCIENTISTS, COACHES, AND ATHLETES ARE GOING TO BENEFIT FROM MANIPULATING FUEL AVAILABILITY IN SPORT. KNOWING ALL AVAILABLE OPTIONS, THEIR HIGHLIGHTS AS WELL AS THEIR LIMITATIONS WILL ALLOW THE SPORTS NUTRITION COMMUNITY TO UNDERSTAND WHICH METHODS TO CONSIDER WHEN FUELING PERFORMANCE. 

Using nutrition as a way to strategize enhancements in performance might provide you with an edge over the next competitor. Understanding the science of the various fueling strategies might help you experiment with you or your athletes metabolically preferred fuel source.

Today I’m looking at the chronic and acute diet strategies used to fuel athlete performance. What I love most is being able to relay the clear and concise definitions of each of these nutrition strategies, so you can understand which chronic and acute approach may best fit your health and performance goals!

Over the course of the next couple months I am going to unpack the fine details of each of the chronic and acute nutrition strategies listed below. Stay posted! Contact me if you’d like to work on your own plans to fuel your performance pursuitS.

CHRONIC STRATEGIES

The athlete may not be aware, but their diet generally mocks one of the chronic strategies listed below. Some athletes focus their performances with a heavy emphasis of carbohydrates as fuel sources while others more recently have chosen to center their diets around higher intakes of fat. Ultimately how you choose to fuel can affect your performance. Below are some listed strategies on chronic diet types chosen among athletes.

Carbohydrate Focused Fueling

High Carbohydrate Diet

  • Use percentages, absolute values, or weight-based recommendations to provide one-time carbohydrate prescriptions. 

  • This concept does not consider the ever-changing energy needs based on muscle mass, intensity, and volume. 

High Carbohydrate Availability Diet

  • Carbohydrate prescriptions are adjusted to meet the athlete’s daily training sessions and often consider carbohydrate needs before, during, and between sessions. 

  • This often requires guesswork and trial and error with the athlete. During high-volume training, unfortunately even high carbohydrate intakes will not meet needs and leave the athlete with low availability. 

Periodized Carbohydrate Availability Diet 

  • Carbohydrate intake will vary depending on the session and the goals within the periodization cycle to take advantage of the adaptation desired for the training period. Athletes can vary between “train high” (sufficient carbohydrate availability) and “train low” (insufficient carbohydrate availability).

  • Sub elite athletes have found benefits from this strategy over a 3 and 1 week period. 

Fat Focused Fueling

Non-ketogenic Low Carbohydrate High Fat diet 

  • Chronic low carbohydrate availability to improve fat oxidation by the muscles; 15-20% of energy from carbohydrate; 15-20% of energy from protein; 60-65% of energy from fat

  • Reduces mitochondrial respiration, which causes fat oxidation within the body and subsequently decreases exercise economy for the athlete.

Ketogenic Low Carbohydrate High Fat diet 

  • Restricted carbohydrate and protein intake, 5% and 15% of energy needs respectively, to achieve higher fat oxidation during exercise. 

  • Should not be encouraged when higher intensity performance is required.

  • The lack of food variety may limit micronutrient and fiber requirements, so careful planning is suggested.  

 

ACUTE STRATEGIES OF CARBOHYDRATE MANIPULATION

Listed below are a number of acute strategies used to further enhance adaptations to endurance exercise on top of the athlete’s general chronic nutrition intake.

Train High (glycogen) 

  • Muscle glycogen is adequate to fuel the current training bout due to fueling strategies used after previous training session. 

  • This strategy is recommended when sport and training require movement that focuses on quality, intensity, and proficiency. 

Train High (exogenous Carbohydrates)

  • Supplying exogenous carbohydrate for muscle fuel economy; may be adapted when there is low muscle glycogen from high volume training and planned when introduced in periodized nutrition plans or ketogenic diets. 

  • Upregulates absorption of carbohydrate in the stomach to fuel the working muscles. 

  • Athletes on a chronic ketogenic diet may benefit from this strategy to ensure adequate carbohydrate usage by stomach and muscles is not lost, but it is not understood how often this can be implemented before diminishing ketosis. 

Train High (glycogen and exogenous Carbohydrates)

  • Muscle glycogen and exogenous carbohydrate are sufficient for training to support exercise and offset any reactions to low carbohydrate availability.

  • Most recognized strategy used for performances and should be periodized when adequate carbohydrate intakes are necessary for higher volume and intensity training sessions and events. 

Recover High

  • Ingestion of hourly intakes of 1g/kg carbohydrate for about 4 hours after session completion to refuel muscle glycogen for additional training bout to be completed in subsequent hours.  

  • When practicing fueling for optimal performance, some may need to implement this strategy ahead of time if low energy availability is typically a problem for the athlete. The idea is to ensure optimal glycogen resynthesis on day of the competition or event. 

 Pre-Session Fueling

  • Carbohydrate intake 1-4 hours prior to training when fuel sources have been limited; this may help to restore any decreased muscle glycogen stores from previous training bouts or to restore liver glycogen from fasts. 

  • In some instances, carbohydrate intakes during these times may release too much insulin. Too much insulin can cause over oxidation of carbohydrate (limit other fuel sources like fat) which may lead to quick depletion of carbohydrates before competition or an event or even hypoglycemia (low blood sugar). 

Train Low (glycogen)

  • Training with low muscle glycogen based on performance needs; can be managed in training as a second session completed without replete glycogen stores.

  • Places a greater metabolic stress and response to training. Chronic implementation during training can result in a net increase in workload of oxidative enzyme proteins, increased lipid metabolism, and potentially improve performance. 

  • The stress created by this acute fueling strategy may put athlete’s at risk for illness and injury.

Train Low (fasted) 

  • Training with low liver and muscle glycogen due to prolonged fasts (>6 hrs) and no carbohydrate during activity for sessions lasting 45-60 minutes to alter metabolic efficiency. 

  • Increases the utilization of AMPK and muscle fueling pathways to transport fuel sources as well as increase uptake of the substrates. 

  • The research is more limited on fated training, but current research shows limited promises for this strategy to enhance performance. 

Train Low (glycogen and fasted) 

  • Training on below threshold glycogen levels and low levels of liver glycogen, which is thought to provide the most metabolic stress during training. 

  • This should be strategically planned if undertaken by an athlete, so that all negative effects are taken into account to reduce the chances of injury and illness. 

Ketone-Supplemented Training Session 

  • Using (ester) ketone bodies during and after exercise to potentially take advantage of an additional fuel source during training.

  • This strategy may result in GI side effects that can impair performance. 

Recover Low/Sleep Low

  • Restricting carbohydrate after training session either in between sessions throughout the day or failing to replace carbohydrates after an evening workout before going to sleep. Protein intake does not diminish the effect of this strategy.  

  • Free fatty acid utilization is encouraged due to decreased carbohydrate availability following training, which may help to increase adaptive responses to training sessions. 

  • Factors which influence this strategy include overall glycogen depletion, training performed, and when the next planned training session. If not considered the athlete may have diminished immunity, subsequent training capacity, and negative rates of bone turnover.  

Classic Carbohydrate Loading

  • Maximizing glycogen stores for longer training events by beginning the athlete on a 3 days of a low carbohydrate diet (10-100g/day) followed with training to deplete glycogen. This is then followed with 3 days of a carbohydrate rich diet consisting of (500+ calories/day) with tapered training. 

  • Has the potential to double glycogen stores, which were depleted (in moderately trained individuals) and may improve running performances in larger volume races (30-40 km). 

  • Athletes in weight class sports or where body composition is emphasized may want to consider the 1-3% increase in body mass associated with this strategy. 

Contemporary Carbohydrate Loading 

  • Carbohydrate intakes of 10-12 g/kg for 36-48 hours prior to training paired with tapered training to enhance muscle glycogen usage in longer training events. 

  • The athlete must achieve optimal energy intakes to benefit from enhanced glycogen storage. 

Resourced from: Burke, L.M., Hawley, J.A., Jeukendrup, A.E., Morton, J.P., Stellingwerff, T., & Maughan, R.J. (2018c). Towards a common understanding of diet-exercise strategies to manipulate fuel availability for training and competition preparation for endurance sport. International Journal of Sport Nutrition and Exercise Metabolism, 28, 451–463. 

 

Valerie Wright