Michiyo Yamakawa, Keiko Wada, Masahiro Hayashi, Takayuki Ezaki, Yuma Nakashima, Chisato Nagata, Yoshio Sumoto
Milk and dairy product intakes, intestinal bacteria, and respiratory infections in children of elementary school age and older in Japan
Nutrition (Burbank, Los Angeles County, Calif.)
purpose study establish minimal number days monitoring required accelerometers assess usual physical activity childrena total 381 students 189 192 f wore csa 7164 uniaxial accelerometer seven consecutive days examine agerelated trends students grouped follows group grades 13 n 92 group ii grades 46 n 98 group iii grades 79 n 97 group iv grades 1012 n 94 average daily time spent moderatetovigorous physical activity mvpa calculated minutebyminute activity counts using regression equation developed freedson et al 1997compared adolescents grades 7 12 children grades 1 6 exhibited less daytoday variability mvpa behavior spearmanbrown analyses indicated 4 5 monitoring would necessary achieve reliability 080 children 8 9 monitoring would necessary achieve reliability 080 adolescents within grade levels 7d monitoring protocol produced acceptable estimates daily participation mvpa r 076 071081 087 084090 compared weekdays children exhibited significantly higher levels mvpa weekends whereas adolescents exhibited significantly lower levels mvpa weekends principal components analysis revealed two distinct time components mvpa day children early morning rest day three distinct time components mvpa day adolescents morning afternoon early eveningthese results indicate 7d monitoring protocol provides reliable estimates usual physical activity behavior children adolescents accounts potentially important differences weekend versus weekday activity behavior well differences activity patterns within given day