This is the first study of its kind to assess the association of nutrition knowledge, practice, and nutrient intake and supplementation use with athletic performance among Taekwondo players in Nepal. Good nutritional knowledge, practice, and adequate nutrient intake are considered a crucial component that contributes to a basic part in enhancing athletic performance among athletes [26].
In this study, based on the correct response of the nutrition knowledge and practice score, the study participants exhibited a relatively low level of nutrition knowledge and practice compared to previous findings, a study conducted by Folasire OF et al (2015) and Abbey et al (2017), where less than half (42.8%) and (35%) had poor nutritional knowledge [20, 27]. However, our result is in line with the other studies report where overall nutrition knowledge scores were low [9, 28]. Optimum nutrition knowledge is an essential factor for promoting athletic success to the sportsperson [8, 9]. Inadequate nutrition knowledge can have a serious impact on the nutritional status and performance of athletes [10]. The study conducted by Walsh et al (2011) showed that nutrition knowledge and attitudes affect eating habits and inadequate nutritional knowledge may contribute to poor dietary behaviors [11].
This study revealed that those athletes who had poor nutrition knowledge were found to have poor nutrition practice scores. These findings were found similar to previous results where the correlation between nutrition knowledge and practice score of athletes were found statistically significant [20, 29]. The prevalence of supplement use in the current study was found to be lower than that reported in other studies [8, 13]. Overall, 7.17% of Taekwondo players in our study used some form of supplements. Likewise, Muwonge H et al (2017) also reported the prevalence of supplements used was 13.4% [30], which is also low compared to previous study findings [8, 13, 31]. The professional TKD players may readily use nutritional supplements mainly to maintain their health and improve athletic performance. The possible explanation for these findings could be that the assessment tools for supplements use adopted by the current study may have underestimated the true prevalence of supplements use in these populations.
In this study, a total energy intake, protein, fat, calcium, and iron were significantly lower than the corresponding RDA except for carbohydrates intake. Every athlete including TKD players needs adequate calorie from the diet in terms of optimum quality and quantity before, during, and after exercise for improved athletic performance [2]. Likewise, adequate nutrient intake and good nutrition knowledge have been recognized as key factors that play an important role in improving the athletic performance in terms of improved quality of training and speedy recovery from injury in athletes. The median carbohydrate intake of the participants was 71.4% in this study. This is only equivalent to 100% of RDA's recommended value for athletes within this population. This result is consistent with results from Wierniuk et al (2013) and Ali A et al (2015) findings [10, 32]. Carbohydrate is essential not only as a source of energy but also protects the protein from being exploited as an energy source [33, 34]. Inadequate intake of carbohydrates increases the risk of injury and exaggerates deterioration of athletic performance [28, 34]. Thus, carbohydrate intake before, during, and after exercise should be scaled up according to the characteristics of the event. Even small amounts of carbohydrate solution like mouth-rinsing without swallowing, increase athletic performance through the central nervous system [33].
The median protein intake of the participants was 13.28%. The protein intake was found to be inadequate in this study, only meet 58% of corresponding RDA for athletes within this population. Inadequate protein consumption can have serious health problems in athletes such as inability to maintain proper body function and declining sports performance [7]. A previous study depicted that a protein intake of 1.4-2.0 g/kg body weight can improve body adaptability to intensive physical activity [35]. Adequate protein intake is a key role in the overall exercise training program, required for a proper and speedy recovery from injury, bolster immune function, and the growth and maintenance of lean body mass [35].
The median fat intake was found to be low (15.85%) in this study, which is only equivalent to 61% of RDA recommended value for athletes within this population. This finding is inconsistent with other findings, where the fat intake was found to have higher than RDA [28, 32]. Fat is an essential component of a balanced diet, providing energy, optimum elements of cell membranes, and facilitation of the absorption of fat-soluble vitamins [36].
The median energy intake in these participants was 2367.86 kcal/day, which is lower than the corresponding RDA, which is slightly lower than reported in the previous study in Indian Taekwondo athletes, with mean energy intakes 3129 ± 518.95 [4]. According to the Nutrition and Hydration Guidelines set under the collaboration of Indian Life Science Institute, National Institute of Nutrition and Sports Authority of India, weight division game such as TKD is categorized under Group-IV sport event which demands a minimum 3600Kcal of daily calorie, 65%, 15%, and 20% should be yield from carbohydrate, protein, and fat respectively [37].
The median intake of micronutrients: calcium (416 mg) and iron (7 mg) were below the RDA, which can meet only 47% and 32% of RDA value for athletes within this population. These findings are in line with the results from the other studies [4, 28], where their results also below the RDA. Adequate intake of iron, which is necessary to carry oxygen and maintaining energy production, is important for especially female athletes during the high-intensity exercise [38]. Likewise, a sufficient amount of calcium-rich diet contributes to bolster bone mineral density and prevent injury risk [28].
Anthropometric characteristics like height, weight, and BMI were significant positive correlation with athletic performance. These results are consistent with previous studies where they reported that handgrip strength had a strong correlation with various anthropometric characteristics [19, 20]. In this study, results indicated a significant relationship between NK score and athletic performance. Various previous studies were reported that nutrition knowledge was positively correlated with athletic performance [11, 20, 29]. Higher nutrition knowledge to the athletes, better the player's attitude and practice towards a sport-enhancing diet, resulting in athletes can perform a better athletic performance [29]. Likewise, total energy and fat intake were significantly positively correlated with handgrip strength of athletes. The previous study also reported that energy intake was positively associated with handgrip strength [20]. The most important component to optimize athletic performance through diet is to ensure the athlete is consuming enough calories to maintain positive energy balance [6, 15]. However, it might be challenging to meet the energy needs of athletes with a high volume of intense training. Insufficient energy intake can result in weight loss, especially lean muscle mass, injury, illness, increased prevalence of overtraining syndrome, and ultimately decreased exercise performance [39]. Moreover, in linear regression analysis, the DHGS were positively associated with training hours per day, BMI, NK score, and energy intake. These results are consistent with the findings from the study conducted by Folasire OF et al (2015). For better athletic performance by athletes, an adequate energy balance is needed, where energy balance occurs only when energy intake such as foods, fluids, and supplement products are equals energy expenditure [7]. Energy expenditure for various exercise is dependent on the duration, frequency, intensity of the exercise, sex, age, body size of the athletes. The more energy used in the exercise, the greater calories required to achieve energy balance [36].
Our study had a few limitations. The sample size used in this study was confined to Taekwondo players, thus we cannot generalize the findings to all types of sports., There are slight differences in nutritional requirements depending on the type of sports. We used a 24-hour dietary recall method which can underestimate true nutrient intake. Also, single 24-hr recall cannot identify within and between-person variations. Although other minerals and vitamins play a key role in human health and nutritional status, we included only calcium and iron as micronutrient intake. Since the information was collected through face-to-face using semi-structured questionnaires, response preference to some nutrition issues may lead to social desirability bias. Despite the mentioned limitations, our study has some strengths. Our study included an analysis of the correlation between nutritional knowledge, practice, and nutrient intake with athletic performance. This data provide insight into the potential factors influencing athletics performance which helps in forming the basis of targeted nutrition education programs. Since the majority of the national Taekwondo clubs located in Kathmandu Metropolitan City, the study sample is highly representative as it included all levels of players including the national level Taekwondo players of Nepal. The results of this study can be utilized in planning the health and development of Taekwondo players in Nepal and pave the way for the nutritional policy of other athletes as well. This study has also set the background to conduct further study to explore the determining factors for the nutritional knowledge and practices among Nepalese athletes.