ABSTRACT
Phase angle, calculated as the arc-tangent of the reactance-to-resistance ratio in bioelectrical impedance analysis, represents skeletal muscle quality, and is suggested to be an indicator of sports ability and physical fitness. However, it is unclear whether phase angle is related to physical fitness in early childhood in Japanese subjects. The purpose of this study was to examine the cross-sectional relationship between physical fitness and bioelectrical impedance analysis-based phase angle in 6-year-old Japanese children. The subjects were 85 kindergarten students who participated in a physical fitness test and body composition assessment in 2017, 2018 or 2019, in the third year of kindergarten. Fitness tests included grip strength, standing long jump, and 25 m run. A multi-frequency composition analyzer was used for body composition analysis, and the phase angle of the left half of the body was acquired at 50 kHz. Statistical analysis was performed using a general linear model to calculate the regression coefficient of phase angle for physical fitness. Phase angle correlated significantly with the standing long jump and 25 m run. The regression coefficient (±standard error) of phase angle in the standing long jump in the fully adjusted model was 5.098 ±2.264 (p<0.05), and that in the 25 m run was -0.179 ±0.088 (p<0.05). There was no significant correlation between phase angle and grip strength. These results suggest that phase angle based on bioelectrical impedance analysis might be related to lower limb muscle function and running ability in 6-year-old Japanese children.
ABSTRACT
The aims were to investigate the changes in physical activity of university students after the COVID-19 emergency declaration was lifted, and to determine whether there were any differences in these changes between academic years. The subjects were 81 students attending university or graduate school in Kochi Prefecture who completed a baseline survey (May 2020). Analysis 1, included 51 subjects who responded to both the baseline survey and the retrospective survey (October 2020) on physical activity at 1 year prior. In Analysis 2, 71 subjects who participated in at least one follow-up examination (August 2020, November 2020) were included. The International Physical Activity Questionnaire – Long Form was used to assess physical activity and sitting time per week. Between October 2019 and May 2020, the total (-47.7%), vigorous (-59.3%) and moderate (-42.1%) physical activity decreased, and sitting time (+36.9%) increased. The interaction between the time of the survey and year of university (first-year, ≥second-year), analyzed using a generalized linear mixed model, on total, vigorous, walking physical activity and sitting time was significant. Especially, the estimate of least squares mean after inverse square root transformation of total physical activity in first-year students was higher in November 2020 (8192.4 METs·min/week) compared to baseline (3388.5 METs·min/week). Vigorous physical activity in first-year students was also higher in November 2020 (4773.3 METs·min/week) compared to baseline (1060.3 METs·min/week). The emergency declaration in April 2020 inhibited physical activity among university students, and the impact was particularly strong among first-year students.