The Effects of Exogenous Ketosis on Ultra-endurance Recovery and Performance

Exploring the Role of Intermittent Exogenous Ketosis on Physical and Mental Fatigue During Ultra-endurance Performance

The study aims to investigate the effects of post-exercise and pre-sleep ketosis via oral ketone ester supplementation on physical and mental recovery during a multi-day cycling stage race.

Ultra-endurance events are becoming increasing popular. Participation in the multi-day events adds a lot of physical and mental strain on the body, while the athletes are still required to perform. Without appropriate recovery the athletes are at increased risk of overreaching, injury, or illness.

Therefore, the purpose of the study is to create a better understanding of the exercise fatigue experienced during ultra-endurance performance and the role intermittent exogenous ketosis (IEK) plays in reducing the amount of fatigue to maintain performance during multi-day racing and lower the risk of injury and illness.

Participants will first compete in a 8-day simulated stage race performed on taxc trainers and then we will conduct a field study during the Absa Cape Epic a 8-day mountain bike stage race. Immediately following each stage and 30-mins before bed the participants will consume either a ketone ester and taste-match placebo drink. During the race the following variables will be measured; hydration status, weight change, activity readiness, and nutrition intake. Cognitive function will be assessed on day 2, 4 and 8 of racing. One day before and one day after the race the participants will report to the lab to assess basal metabolic rate, stress via questionnaires, appetite, cognitive function, muscle biopsies, venous blood samples, mechanical efficiency and 30-min Time Trial.

Inclusion Criteria:

• have been cycling consistently for at least 1 year before entry into the study
• have been cycling for a minimum of 7 hours per week for the 6 months leading up to the study
• additional for the field study: valid entry to the 2025 edition of the Absa Cape Epic
• non-smoker

Exclusion Criteria:

• Do not follow a ketogenic diet or low-carbohydrate diet
• Have any metabolic or auto-immune disease that will influence their metabolism
• Take medication or supplements that is known to affect ketone supplement metabolism
• suffering from a recurring injury or illness from which they have not fully recovered that is a contr-indication to perform high-intensity exercise
• Unable to finish each stage
• Women: if they are pregnant or breastfeeding