Author(s): ISHIBASHI, A.1, UCHIZAWA, A.2,3,5, KONISHI, H.4, MAKINO, S.4, SAGAYAMA, H.5, Institution: TOYO UNIVERSITY, Country: JAPAN, Abstract-ID: 1063

INTRODUCTION:
Rugby union is a high-contact sport characterized by repeated high-intensity bouts and physical collisions. Given the physical demands of the sport, players aim to maximize their fat-free mass while maintaining a low body fat percentage. To develop optimal nutritional strategies that support these goals, an accurate understanding of athletes’ total energy expenditure (TEE) is essential. However, data regarding TEE and energy intake (EI) during a typical training week in elite male Japanese rugby players are limited. Therefore, this study aimed to investigate TEE and EI during a regular training period in elite male Japanese rugby players using the doubly labelled water (DLW) method and dietary records.
METHODS:
Measurements were conducted in ten elite Japanese male rugby players (forwards: n = 5; backs: n = 5) during the pre-season training period. TEE was assessed using the DLW method over 7 days, with a baseline urine sample collected prior to the oral administration of a bolus dose of hydrogen (²H) and oxygen (¹⁸O) stable isotopes. TEE was calculated based on the analysis of subsequent urine samples. Body composition was assessed using bioelectrical impedance analysis (InBody) on days 1 and 7 of the measurement period. Dietary intake was monitored throughout the measurement period using a 7-day dietary record.
RESULTS:
As a result, TEE was 4269 ± 386 kcal/d (forwards: 4460 ± 300 kcal/d; backs: 3982 ± 211 kcal/d), and TEE per body mass was 45.0 ± 4.4 kcal/kg/d (forwards: 42 ± 3 kcal/kg/d; backs: 48 ± 5 kcal/kg/d). EI was 3869 ± 378 kcal/d (forwards: 4052 ± 305 kcal/d; backs: 3565 ± 304 kcal/d), and EI body mass was 40 ± 5 kcal/kg/d (forwards: 43 ± 5 kcal/kg/d; backs: 43 ± 2 kcal/kg/d). TEE was significantly higher than EI (p < 0.01). In addition, a significant positive correlation was observed between body mass and TEE. (r = 0.78, p < 0.01).
CONCLUSION:
The TEE of professional male Japanese rugby union players is comparable to values of elite male English rugby players reported in a previous study1). The finding that EI was significantly lower than TEE, suggests that these athletes may have experienced an energy deficit during training season; however, the potential for underestimation in self-reported dietary records compared to the DLW method must also be considered. Future studies should examine differences during the competitive match period and between players with higher and lower body fat percentages.
1) Smith, D. R., King, R. F. G. J., Duckworth, L. C., Sutton, L., Preston, T., O’hara, J. P., & Jones, B. (2018). Energy expenditure of rugby players during a 14-day in-season period, measured using doubly labelled water. European journal of applied physiology, 118(3), 647-656.