en فيزيولوژی ورزشی و شاخه‌های وابسته بدان Sport Physiology and its related branches مقاله اصیل Original Article <div style="text-align: justify;"><strong>Background.</strong> Athletes&#39; poor understanding of sports nutrition could place their health in danger, degrade their performance, and have an impact on their lean body mass and energy levels.<br> <strong>Objective. </strong>The research study aims to study the perception of Thai national youth athletes regarding nutrition understanding and the relation between endurance, power, and mixed sports and believing in the food selection before, during, and after the competition.<br> <strong>Methods. </strong>The quantitative research was used with 216 respondents divided into three categories (Endurance Sport, Power Sport, and Mix Sport) which consisted of the Thai national youth athletes for each category in Thailand, and analyzed by the descriptive statistics, and the chi-square test by using SPSS.<br> <strong>Results. </strong>The result of the chi-square test between the athlete samples of endurance, power, and the mixed sport and believing in the food selection before the competition found that by having the correlation efficiency (Chi-Square: c2) = 1241.381, DF=32, and the p-value were 0.01. During the competition found that the food selection was related to the sports categories by having the correlation efficiency (Chi-Square: c2) = 485.438, DF=26, and the p-value was 0.01, and after the competition found that the food selection was related to the sports categories by having the correlation efficiency (Chi-Square: c2) = 718.997, DF=30, and the p-value were 0.01.<br> <strong>Conclusion. </strong>The result of this research may be applied as important information for developing an effective guideline for Thai national youth athletes in the future.</div> Sports Nutrition, Perception, Athlete, Nutritionist. 0 0 http://aassjournal.com/browse.php?a_code=A-11-1332-6&slc_lang=en&sid=1 Saowalee Kaewchuay saowalee.kae@mahidol.ac.th 100319475328460013264 0009-0001-6067-0167 No Faculty of Social Sciences and Humanities, Mahidol University, Salaya, Nakhon Pathom, Thailand Anantachai Inthiraj anantachai.in@ssru.ac.th 100319475328460013265 0009-0001-6877-0664 No College of Allied Health Sciences, Suan Sunandha Rajabhat University, Thailand Oam To-aj oam.deto@gmail.com 100319475328460013266 100319475328460013266 Yes Faculty of Social Sciences and Humanities, Mahidol University, Salaya, Nakhon Pathom, Thailand