Review Article, J Athl Enhanc Vol: 7 Issue: 2

Comparison of Nutrient Intake between Japanese Female Elite and Collegiate Karate Players

Oda K¹, Miyahara K¹, Matsuo K¹, Kawano K¹, Kikuchi R¹, Tai K², Iide K³, Yoshimura Y⁴ and Imamura H^5*

¹Department of Health and Nutrition, Faculty of Health Management, Nagasaki International University, Japan

²Department of International Tourism, Faculty of Human Sociology, Nagasaki International University, Japan

³Department of Physical Education, International Pacific University, Japan

⁴Department of Food and Nutrition, Beppu University, Japan

⁵Graduate School of Health Management, Nagasaki International University, Japan

*Corresponding Author : Hiroyuki Imamura
Graduate School of Health Management, Nagasaki International University, 2825-7 Huis Ten Bosch, Saseboshi, Nagasaki 859-3298, Japan
Tel: +81-956-20-5838
E-mail: himamura@niu.ac.jp

Received: April 11, 2018 Accepted: May 14, 2018 Published: May 21, 2018

Citation: Oda K, Miyahara K, Matsuo K, Kawano K, Kikuchi R, et al. (2018) Comparison of Nutrient Intake between Japanese Female Elite and Collegiate Karate Players. J Athl Enhanc 7:2. doi: 10.4172/2324-9080.1000290

Abstract

Keywords: Dietary assessment; Body composition; Karate; Female

Introduction

Karate is one of the most popular martial arts practiced both in and outside of Japan and will make its first appearance as an Olympic sport at the 2020 Summer Games in Tokyo, Japan [1]. Traditional karate training consists of practice in basic techniques, kata, and sparring. Basic techniques such as punching, kicking, blocking, and striking are practiced either in a stationary position or with body movement in various formal stances. Kata are set forms in a pre-established sequence of defensive and offensive techniques and movements. Sparring is the execution of defensive and offensive techniques while freely moving against an opponent. In addition to traditional karate training, many competitive practitioners cross-train using strenuous running and weight training programs to increase endurance, muscle development, and power.

The American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine (ADA, DC, and ACSM) [2] state that athletic performance and recovery from exercise are enhanced by optimal nutrition. The living environment of collegiate karate athletes (collegiate athletes) may be different compared to karate athletes in the national team (elite athletes). Factors such as the class and training schedules, whether they are living in a dormitory, have facilities for food preparation, and access to grocery stores influence when athletes are able to eat, as well as the type and quantity of food consumed [3]. Although the nutrient intakes of elite [4] and collegiate athletes [5,6] have been reported, these studies could not be compared directly because dietary information was collected using different methods; 1 study [4] used a Food Frequency Questionnaire (FFQ), while the other 2 studies [5,6] used a 3-weekday diet record.

Most published data on the physical and physiological profiles of karate athletes is based on studies of male athletes [7] and data on female athletes is rare. The purposes of this study were: 1) to collect baseline data on nutrient intake in order to advise athletes regarding nutrition practices that may enhance performance, and 2) to compare nutrient intake between elite and collegiate female karate athletes.

Material and Methods

The study protocol received approval from the Ethics Committee of the University. Informed consent was obtained from each subject.

Subjects

Thirty-five female black belt karate athletes volunteered to participate in this study. They were divided into 2 groups: 20 elite athletes and 15 collegiate athletes. The athletes competed in sparring or kata competitions from April to December. Regional tournaments are held from April to July, and national, international, and/or world tournaments are held from September to December. The elite athletes participated in a 3-day training camp once a month from May to August, so all anthropometric measurements and dietary information were obtained at the site of the training camp, which was considered representative of physiologic status during training for the next competition. The collegiate athletes were recruited from one university. Practice was usually for at least 90 min, 3 days per week, (Tuesday and Thursday evenings and Saturday morning), and the athletes were national level collegiate competitors in Japan.

Measurements and dietary information

Weight and height were measured to the nearest 0.1 kg and 0.1 cm, respectively. The Body Mass Index (BMI) was calculated as weight/height² (kg/m²). Biceps brachii, triceps brachii, subscapular, and suprailiac skinfold thickness were measured with Harpenden calipers on the right side of the body, with the subject in a standing position. The mean of 3 consecutive measurements was used to calculate the body density [8], percent body fat (%Fat), and Lean Body Mass (LBM) [9].

All subjects were interviewed by experienced dietitians using the FFQ, which is based on 29 food groups and 10 types of cooking, to estimate the energy and nutrient intakes of each subject over the previous 1 to 2 months [10]. The FFQ was validated by a comparison with weighed dietary records for 7 continuous days [11]. From the FFQ, the mean daily intake of total energy and nutrients was calculated according to the Japanese Foodstuff Composition Tables [12]. Each athlete was also questioned as to whether or not they were using a nutrient supplement or on a diet. The Estimated Energy Requirement (EER) for athletes was calculated according to the following formula [13]: 28.5 (kcal/LBM (kg) × PAL, where PAL is the physical activity level. The macro- and micronutrient intakes were compared using the Dietary Reference Intakes (DRIs) in Japan [14]. However, because the DRIs for Japanese were prepared for healthy individuals, the joint position stand of ADA, DC, and ACSM [2] was also used to evaluate macronutrient intakes. Micronutrient intakes less than the Estimated Average Requirement (EAR) or Adequate Intake (AI) were classified as inadequate [3].

Statistical analysis

SPSS statistical software 22.0J (Chicago, IL) was used to analyze the data. Descriptive statistics included means and SD. Because sample size in each group was small, non-parametric statistics were used. The mean differences between the elite and collegiate athletes were analyzed by non-paired Mann-Whitney U test. A two-sided p<0.05 was considered statistically significant.

Results

Eight of the 20 elite athletes and 9 of the 15 collegiate athletes were on a diet. Most athletes practiced a healthy diet such as eating more salad, avoiding overeating, eating fewer sweet snacks and less fat, and eating less, but well balanced food. One elite player and 1 collegiate player, however, answered to eating less protein and/or carbohydrates. No athletes took supplements. In each group, when the athletes on a diet were compared to the athletes not on a diet, the mean physical characteristics and nutrient intakes were very similar; e.g. energy intakes for elite athletes were 2592 ± 621 kcal vs. 2629 ± 635 kcal, respectively and for collegiate athletes were 1464 ± 350 kcal vs. 1430 ± 398 kcal, respectively (data not shown in tables). Thus, in the following tables, we only show the added mean values in each group and compare the mean values of elite and collegiate athletes.

The characteristics of the subjects are shown in Table 1. The elite athletes showed significantly higher mean karate experience, age, and LBM and significantly lower %Fat and fat mass than the collegiate athletes. There were no significant differences in body height, weight, and BMI (Table 1).

Table 1: Characteristics of the subjects.

The energy and nutrient intakes and diet compositions (percentage of energy from carbohydrate, fat, and protein) of the subjects are shown in Table 2. The elite athletes showed significantly higher energy intake and higher intake of other nutrients than collegiate athletes. There were no significant differences in diet compositions between elite and collegiate athletes.

Table 2: Nutrient intake of the subjects.

The micronutrient intakes expressed as percentages of the Japanese EAR or AIs are shown in Table 3. The micronutrient intakes of the elite athletes were all above 100% of the EAR or AIs, whereas the collegiate athletes showed micronutrient intakes below 100% of the EAR or AIs for potassium, calcium, magnesium, phosphorus, iron, vitamins A and C (Table 2).

Table 3: Nutrient intakes expressed as a percentage of the Estimated Average Required �?�?EAR�?�?and Adequate Intake (AI).

Foodstuff intake is shown in Table 4. The elite athletes showed significantly higher mean intakes of green vegetables, other vegetables, soybeans and soybean products, meat, eggs, milk and dairy products, fruits, beverages, and fats and oils than the collegiate athletes.

Table 4: Foodstuff intake of subjects (g).

Discussion

Anthropometric data

Although there were no significant differences in the mean body height, weight, and BMI between elite and collegiate athletes, the elite athletes showed significantly higher mean LBM (45.5 ± 5.2 vs. 40.6 ± 3.8 kg, respectively) and significantly lower %Fat (20.8 ± 2.8 vs. 26.6 ± 3.4%, respectively) and fat mass (12.0 ± 2.5 vs. 14.9 ± 3.1 kg, respectively) than the collegiate athletes. The mean %Fat of the elite athletes was also lower than the values reported for Japanese female highly competitive (24.1 ± 5.5%) [5], and competitive collegiate karate athletes (23.9 ± 4.1%) [15], but was higher than the value reported for Botswanan female national karate athletes (18.6 ± 3.2%) [16].

Nutrient intake

The ADA, DC, and ACSM [2] state that low energy intake can result in loss of muscle mass, menstrual dysfunction, an increased risk of fatigue, injury, and illness as well as a prolonged recovery process. The mean energy intake for the elite athletes (2614 ± 613 kcal) was not different from the EER for female athletes (2525 ± 229 kcal), whereas the energy intake for the collegiate athletes was approximately 800 kcal below the EER (2261 ± 199 kcal) [13]. The low energy intake in the collegiate athletes may be a result of under-reporting, which is a recurrent problem in determining nutrient intake. The doubly labeled water technique is the gold standard for measuring energy expenditure by which energy intake data are evaluated. According to a review article by Livingstone and Black [17], in using the doubly labeled water technique, the majority of self-reported dietary intakes are biased towards underestimation of energy intake. The mean magnitude of the underestimation was 20%. In the present study, even if the mean energy intake for collegiate athletes was increased by 20%, the value would still be approximately 500 kcal lower than the EER.

It is stated that carbohydrate recommendations for athletes range from 6 to 10 g•kg^-1•bw^-1 to maintain blood glucose levels during exercise and to replace muscle glycogen [2]. According to these standards, the mean carbohydrate intake of the elite athletes was marginal (6.1 ± 2.0 g•kg^-1•bw^-1) and that of the collegiate athletes was low (3.7 ± 1.0 g•kg^-1•bw^-1). Many studies reported that athletes from various sports may not consume enough carbohydrates to meet current performance recommendations [18-21].

The recommended intake of protein for endurance and strengthtrained athletes ranges from 1.2 to 1.7 g•kg^-1•bw^-1 [2]. Tarnopolsky et al. [22], using the leucine kinetic and nitrogen balance methods, investigated the dietary protein requirements of strength athletes compared with sedentary subjects. They reported that the protein intake for zero nitrogen balance in sedentary subjects was 0.69 g/ kg body weight per day and for strength athletes was 1.41 g/kg body weight per day; with a safety margin of ± 1 SD, the suggested recommended intakes were 0.89 and 1.76 g•kg^-1•bw^-1 per day, respectively. Because many competitive karate athletes follow a strenuous weight-training program to increase muscle development and power, and sparring athletes spar quite often, which may cause muscular damage [6], highly competitive karate athletes may need 1.4 to 1.7 g/kg body weight per day of protein intake. From this assumption, the mean protein intake of the elite athletes was within the range (1.6 g•kg^-1•bw^-1), but was below it in the collegiate athletes (0.9 g•kg^-1•bw^-1).

It is stated that fat intake should range from 20% to 35% of total energy intake (%E) [2]. The mean fat intakes of %E for the elite and collegiate athletes (31.7 ± 7.8% and 28.2 ± 4.7%, respectively) were within the recommended range and were similar to the fat intakes reported in previous studies using highly competitive Japanese female elite [4] and collegiate karate athletes [5]. Similar results were reported in female athletes participating in various sports at a National Collegiate Athletic Association in the US [3,23]. On the other hand, a higher intake of fat was reported in elite female athletes (volleyball, middle distance running, ballet dancing, and swimming) in Greece [24], with mean fat intakes of %E 39.6%. Similar results were reported in female elite flat-water paddlers [25].

Regarding the micronutrient intakes, they were all above 100% of EAIs or AIs for the elite athletes, whereas the collegiate athletes were less than 100% for potassium, calcium, magnesium, phosphorus, iron, vitamins A and C. To increase mineral and vitamin intakes, the Ministry of Health, Labour, and Welfare in Japan [14] recommends the daily consumption of 200 g of milk and dairy products, 120 g of green vegetables and 230 g of other vegetables. The mean intakes of milk and dairy products in elite athletes were higher, while those in collegiate athletes were lower, than the recommendation. Although mean intakes of green vegetables and other vegetables in the elite athletes were significantly higher than collegiate athletes, mean intakes in both groups were lower than the recommendations.

Feedback

The results of the present study indicate that the elite athletes in general showed adequate energy and nutrient intakes, whereas the collegiate athletes showed inadequate energy, macro- and micronutrient intakes in terms of EER, current recommendations for carbohydrates and protein, EAIs or AIs for micronutrient intake. Thus, we advised the collegiate athletes to consume adequate energy for the heavy demands of training and competition, and to consume adequate protein to increase muscle development and power and to repair muscular damage. Although approximately half of the athletes in the present study were on a diet, most athletes practiced a healthy diet. However, 1 elite player and 1 collegiate player answered to eating less protein and/or carbohydrates. Thus, we emphasized the importance of consuming an adequate amount of carbohydrates and protein for the reasons mentioned above. To attain these goals, it is desirable to increase the amount of meals by increasing the intake levels of grains, vegetables, fruit, milk and dairy products, lean meat and fish.

One limitation of our study needs to be mentioned. Because the FFQ was developed to determine the most common food items for the population as a whole, its applicability for assessing the nutrient intakes of people whose eating patterns deviate considerably from those of the mainstream is limited. It is reported that the FFQ may overestimate at low energy intakes and underestimate at high energy intakes [26]. It is also reported that a 7-day dietary record increases the reliability of collected data [26]. However, the members of the national team were selected from many regions in Japan, so it is very difficult to instruct them in the procedure involved in accurately recording dietary intake. In the present study, FFQ was chosen because it is much less burdensome than the 7-day dietary record. Even with this limitation taken into consideration, it seemed worthwhile to collect dietary assessments of these athletes because the subjects in the present study were highly competitive in world and international competition, and the trends in Japanese highly competitive karate athletes’ dietary habits, which differ considerably from Western countries, could be shared with others interested in sports nutrition in the region.

In summary, the elite athletes showed significantly higher mean LBM and significantly lower %Fat and fat mass than the collegiate athletes. The elite athletes showed significantly higher energy intake and intake of other nutrients than the collegiate athletes. The elite athletes in general showed adequate energy and nutrient intake, whereas the collegiate athletes showed inadequate energy, macroand micronutrient intake. Thus, we advised the collegiate athletes to consume an adequate amount of carbohydrates and protein. To attain these goals, it is desirable to increase the amount of meals by increasing the intake levels of grain, vegetables, fruit, milk and dairy products, lean meat and fish.

Acknowledgements

This study was supported by grants from the Nagasaki International University.

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