Effect of eating rice balls (Onigiri) as a supplementary food after training in college student middle-distance track and field athletes on subjective fatigue after exercise and after the next day

Background and objectives: Cooked rice is one of the foods whose main ingredient is α-starch, which is one of the polysaccharides, and Japanese people prefer to eat as "rice balls (Onigiri)". Elite athletes also eat "Onigiri" for important competition and recovery on site, but few studies have objectively measured the effect of "Onigiri" on after exercise recovery from fatigue. In this study, we compared the effect of eating "Onigiri" as a supplementary food after training within 30 minutes subjective fatigue and hunger from the next day onwards, and compared it with physiological data, aimed to verify the effectiveness of "Onigiri". Methods: The subjects were 7 male college student middle-distance track and field athletes, were participated in the experiment that take supplementary food (Onigiri) immediately after training and the control that don't take anything (control group) by crossover trial method. "Onigiri" was prepared as follows so that the intake of carbohydrates was 1.1g/kg of body weight: omelet and ham in Energy:384-465kcal, Carbohydrate:62.2-80.0, Protein:12.6-13.8g, Fat:7.7-7.8. All subjects ate lunch 2 hours after the end of training. For 3 days before and after training, changes in blood glucose levels were observed using a continuous glucose monitoring (CGM), and dietary surveys were also conducted. Furthermore, we surveyed the physical condition, subjective fatigue and hunger questionnaire. Results: In changes in blood glucose levels was higher the control group than the experiment at 3:00, 4:00, and 5:00, and tended to be higher the control group than the experiment at 6:00 and 7:00 from bedtime to early morning on the day after training. They were observed significant interaction. In the subjective fatigue questionnaire after training, "fatigue" was higher the control group than the experiment, and "hunger" was tended to be higher the control group than the experiment. Conclusions: In this study, "Onigiri" may affect glucose metabolism and may be a suitable food as a portable supplementary food after training. In the future, it will be necessary to conduct comparative experiments and laboratory experiments to investigate in detail whether "Onigiri" has psychological factors such as preference as factors that affect subjective fatigue.