An exploration of low carbohydrate dietary intake in endurance athletes: prevalence, knowledge and the potential effect on bone health and remodelling

Background

Low carbohydrate (CHO) diets in endurance athletes have gained attention for potential benefits in supporting metabolic adaptation and body composition. However, recent evidence suggests these diets might negatively affect bone health due to low energy or CHO availability. This thesis examines the prevalence of low CHO diets among elite endurance athletes and their potential impact on bone injuries and remodelling. It also explores athletes’ knowledge and application of dietary recommendations in this regard, and investigates education using online media as a means to improve both.

Approach:

Three studies were conducted to provide practical outcomes for the Sport Ireland Institute and contribute to scientific literature. The first study uses a bespoke questionnaire to assess the prevalence of low CHO intake and fasted training, and their association with bone injuries. The second study evaluates if an online nutrition education programme can improve nutrition knowledge among adolescent endurance athletes. The third study investigates if the macronutrient composition of a pre?exercise meal affects bone remodelling responses to exercise.

Findings:

A 28% prevalence of low CHO intake was reported, with athletes showing varying understanding of low CHO diets. A higher prevalence of fasted training use (38%) was identified in this cohort and there was a significant association between this use and bone injury incidence. Those who use fasted training were 1.61 times more likely to have suffered a bone injury in their career versus those who had never used it. A potential deficit in understanding of nutrition and sports nutrition guidelines was also identified in this study. Adolescent athletes scored 55 ± 6.2% on the Nutrition for Sports Knowledge Questionnaire (NSKQ). An online education program improved scores to 62.9 ± 9.1%, retained at 64.1 ± 6.6% after 8 weeks, despite poor engagement. Many athletes did not meet sports nutrition recommendations, under consuming CHO and overconsuming protein, potentially leading to energy deficits. Pre-exercise meals high or low in CHO showed no significant differences in bone resorption and formation markers.

Conclusion:

Low CHO diets are a controversial topic with potential for misunderstanding among athletes and coaches. Nutrient intake should be periodized according to training and competition demands. Effective communication of nutrition guidelines is crucial in the modern, online media-based world. The impact of low CHO diets on bone health and bone remodelling in endurance athletes warrants investigation due to the high incidence of injuries and poor bone health in this group. No significant differences in bone remodelling were found with short-term low CHO diets, but prolonged low CHO or low energy availability (LEA) may negatively affect bone mass and health.