Nutrient intake and performance during a mountain marathon: an observational study

In order to study nutrient intake of amateur runners during a mountain marathon, compliance with recommendations, and association with performance, an intake of 42 participants in a Swiss mountain marathon was assessed by direct observation. Data on demographics, dietary preparation and race experience were obtained by questionnaires. Anthropometrical measures were performed before and after the race. Mean hourly intakes (SD) of fluid, carbohydrate, energy and sodium were 545 (158)ml, 31 (14)g, 141 (63)kcal [or 590 (264)kJ], and 150 (203)mg respectively. A third of the runners drank 600mlh−1 or more, 52% consumed less than 30gh−1 carbohydrates, 95% consumed less than 500mgh−1 sodium. Mean weight loss was 4 (1.5)kg; 30 runners (71%) lost over 3% body mass. Mean running time was 7h 3min (1h17min). Most participants failed to meet nutritional recommendations. None were at risk of overhydration. Body composition and race experience were correlated with performance, but not nutrient intake. Because experienced runners are well trained, fitter, and know better their personal needs during such a race, it is difficult to disentangle these associations. As causal relationship cannot be proven with this cross-sectional design, non-compliance with intake recommendations requires additional experimental research on the impact of nutrient intake on field performanc