Fueling For Training

I See Food in your Power File: Fueling Adequately for Training

A few weeks ago I hosted a webinar for USA Cycling on the Nutrition Care Process. I discussed how Registered Dietitians conduct nutrition assessments and how coaches can apply these concepts to identify nutrition-related issues in their athletes. The webinar inspired this article where I present a few cases where athletes were unable to complete their workout properly due to improper fueling. Improper fueling for endurance workouts is usually centered around inadequate carbohydrate consumption before and/or during the ride. Here are a few examples of cases where the athletes did not fuel well before and during their workouts. 

Ate for a 1hr ride, not a 5hr ride

During the first 1:10 of this ride, the athlete was able to sustain high tempo zones and also breach Vo2, indicating the athlete was fresh and fueled well going into the ride. The athlete then got a flat tire which had to be changed and stopped from 1:10-1:45. The athlete brought enough food for the first 2.5 hours of the ride but the stop extended the time to 3.5hrs when the athlete would next have access to fuel. During both climbs starting at 2:15 and 2:30 the athlete was able to ride at tempo for half of the climb but plummeted halfway up. The next food stop was not until 3:30. In this case you can see how the athlete was well fueled for a 1hr ride but their power indicates they were not sufficiently fueled for the last 3hours.

Fueled well for 3:40, not 4:20

This athlete was prescribed a 4.5hour endurance ride. While this athlete fueled well for the first 3:40 they were unable to consistently hold endurance zone2 for the rest of the ride. Their average watts dropped 10% and their heart rate dropped 5%. Humans have roughly 2000kcals of glycogen stored in their liver and muscles. If an athlete is not fueling well in training and supplying glucose to their bloodstream, their glycogen stores become more quickly depleted and performance significantly declines. In this athlete’s case for this workout, they were fueling during the ride but with not enough carbohydrates to meet the demands of the effort.

Depleted glycogen starting the intervals

This athlete was prescribed endurance for 1.5hrs and then intervals at tempo with sprints. The athlete successfully rode at a consistent zone2 pace for the first 1.5hrs of the ride. They were able to complete the first interval with consistent sprints but unable to complete the sprints in the second interval. They ended the second interval early and tried for another interval but again was not able to hit the sprints in the last interval. These ‘bursts’ and the tempo in-between are mainly anaerobic efforts which prefer glucose from the bloodstream. Glucose in the bloodstream either comes from intake (sugar in food and drink mix) or glycogen stored in the muscles and liver which is broken down into glucose and enters the bloodstream. While this athlete had enough glucose available to complete the endurance and first set of intervals, there was not enough there for the second 2 intervals. 

Fueling with enough carbohydrates is essential to effectively complete training rides and perform in races. If you are an athlete and are having a hard time completing workouts or breaching top end efforts in races, check in with your fueling and make sure you are eating enough carbohydrates before and during your rides. If you are coach and see athletes struggling to complete workouts or races like these, check in with them and make sure they’re optimally fueling to perform. Not sure what is optimal? Schedule a nutrition consult with me and let’s come up with a plan.

About the author: Kristen Arnold MS, RDN, CSSD is a level 2 USA Cycling coach as well as a Registered Dietitian (RD) specializing in sports nutrition and is a board Certified Specialist in Sports Dietetics (CSSD). With Kristen’s nutrition expertise and diverse experience in the sport of cycling as a racer and a mentor, she provides a comprehensive approach to her coaching. She works with athletes from the beginner to elite ranks in road, cyclocross, and mountain biking disciplines. Kristen is also a category 1 domestic elite road racer and seasoned mountain bike and cyclocross racer. Learn more about Kristen.

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