: Trends in body mass index and physicalˆtness of Japanese university students over 26 years and the association between these parameters. Japan J. Phys. Educ. Hlth. Sport Sci. 58: 181 194, June, 2013 AbstractThe purpose of this study was to examine trends in the body mass index (BMI) and physical tness of Japanese university students over a period of 26 years and the association between these parameters. We retrospectively collected data on 17,514 students aged 18 19 years attending a university in the years 1984, 1986, 1990, 1991, 1996, 1997, and 2004 2010. The subjects were classiˆed into three body types on the basis of calculated BMI: underweight (BMI<18.5), normal (18.5BMI<25), and overweight (BMI25). We also calculated the physicalˆtness score on the basis of 4ˆtness-test results (hand-grip power, handball throwing distance, 50-m running time, and 20-m shuttle run count). The time of assessment was categorized into three periods: 1980s (1984 and 1986), 1990s (1990, 1991, 1996, and 1997), and 2000s (2004 2010). The association of physicalˆtness with body type and period was analyzed using 2-factorial analysis of variance. Descriptive statistics showed that over the 26-year period, moderately increases in the prevalence of underweight and overweight individuals were observed, and theˆtness score decreased for both sexes and all body types. A signiˆcant interaction between body type and period on physicalˆtness was observed in boys (P<0.05); underweight and overweight boys showed a greater decrease in physicalˆtness than normal-weight boys from the 1990s to the 2000s. These long-term data suggest that over 26 years, an increase in the prevalence of underweight and overweight individuals among university students resulted in a decrease inˆtness levels to a greater extent in boys.
The purpose of this study was to investigate the effect of rest periods on energy system contribution during interval swimming and whether the energy system contribution varied depending on the swimmer's specialty, such as swimmers who specialize in the 100 m or 200 m. Seven highly-trained male varsity swimmers performed three different tests: a 10-min continuous test (CON), 10 ϫ 1-min interval test with rest periods of 20 s (INT20) and 10 ϫ 1-min interval test with rest periods of 30 s (INT30). Swimming velocity during all tests was set to maintain a blood lactate of 4 mM determined by progressive swimming. The relative aerobic and anaerobic energy system contribution was evaluated from accumulated oxygen uptake and oxygen deficit. Aerobic energy system contribution in CON, INT20, and INT30 was 93.3 ± 1.1, 81.0 ± 10.4, and 67.4 ± 8.5%, and anaerobic contribution was 6.7 ± 1.1, 19.0 ± 10.4, and 32.6 ± 8.5%, respectively. There were significant differences (p < .05) in both aerobic and anaerobic energy system contributions between each test. The index derived from the ratio of swimming velocity of the best time between 100 m and 200 m correlated significantly (p < .05) to relative anaerobic energy system contribution during INT30. These results suggest that the energy system contributions during interval swimming are significantly affected by the difference of 10 s in the rest periods, and the contributions would vary depending on the swimmer's specialty.
Key Points:• This study focused on the effect of rest periods on energy system contributions during interval swimming. • Energy system contributions were significantly affected by the difference of 10 s in the rest periods. • Energy system contributions varied depending on the swimmer's specialty.
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