[Effects of different fat-tocarbohydrate ratio in crosscountry skiers on time "until exhaustion" and competitive...

In elite sports, studying the role of macronutrients in providing energy during physical activity is a vital area of research for achieving high performance. The aim of the present study was to analyze the correlation between performance indicators (VO2max, test time, and Russian Cross-Country Skiing Federation rating score) and the levels of carbohydrate (normal or below normal) and fat (normal or above normal) intake in elite athletes.

A retrospective longitudinal analysis of data from cross-country skiers (n=46, male, age 19.7±4.8 years) collected during the preparation period from 2014 to 2017 was performed. Energy intake was evaluated using the 24-hour recall method for 3 days. Performance indicators and energy expenditure were measured by indirect calorimetry in a test to failure.

Relative energy intake of the athletes on typical training days was at the lower limit (47±12 kcal/kg day). Analysis of the actual diet showed a non-optimal ratio of carbohydrates (388±121 g/day) and fats (132±40 g/day) in the diet of the majority of the athletes. The association between carbohydrate and fat consumption levels with performance indicators demonstrated the leading contribution of carbohydrates to energy supply during submaximal and maximal physical performance. Adequate carbohydrate intake (more than 350 g/day) increased the duration of exercise testing time to failure by 13% (p=0.004) and, accordingly, the level of carbohydrate consumption can be considered as a marker for predicting athletic performance. The revealed direct correlation between high points in the Russian Cross-Country Skiing Federation rating and total testing time (ρ=0.53; p=0.008), as well as excess fat intake (ρ=0.51; p=0.021), indicate the participation of fats in the energy supply of competitive performance.

The ratio between fat and carbohydrate intake (37:49%) among the examined cross-country skiers does not meet recommended levels and is insufficient to cover their energy expenditure, which may be accompanied by a decrease in performance during the competition period. The results of this study can be applied to optimizing athletes' actual dietary intake and improving their physical qualities.