A Multi-Level Analysis of the Effects of Epoch Length on the Estimates of Children’s Moderate to Vigorous Physical Activity

Using an ActiGraph GT3X+accelerometer,the study examined the effects of different epoch lengths on children’s moderate to vigorous physical activity(MVPA).The study also tested how different MVPA levels influence the relationship between epoch length and MVPA.The participants included third(n=28)and fourth grade(n=35)students.The third graders participated in a physical education class while the fourth graders were engaged in an active video game(AVG)class.Data were downloaded using six different epoch lengths.MVPA estimates were determined by five different cut points.Multi-level analyses were used to analyze the data.Results showed that when lower cut points were used,MVPA was positively related to epoch lengths,and this relationship was stronger when the MVPA level was higher.When higher cut points were used,epoch length was negatively related to MVPA,and this relationship was stronger when the MVPA level was lower.This study revealed that different epoch lengths generate various estimates of MVPA,and the relationship between epoch length and MVPA is affected by MVPA levels.

Association of Physical Activity, Screen Time and Sleep with Depressive Symptoms in Adolescents

Little is known on the association between movement behaviors including physical activity(PA),screen time(ST)and sleep(SLP)with depression in adolescents.This study aimed to explore the associations of PA,ST and SLP with depressive symptoms in adolescents.A total of 1,331 middle school students participated in this survey and provided valid data pertaining to the study variables.Self-reported questionnaires were used to collect information on participants’sociodemographic parameters.The Health Behavior in School-aged Children Questionnaire was used to assess the PA(days for moderate to vigorous PA),ST(daily hours of ST)and SLP(daily hours of SLP).Study participants’depressive symptoms were assessed using the Children’s Depression Inventory.Generalized linear models were used to estimate the associations of PA,ST and SLP with depressive symptoms.Of all the 1331 study participants,boys accounted for 51.31%and percentage of 7th,8th and 9th graders were 52.44%,23.22%and 24.34%,respectively.After controlling for sex,body mass index,grade,ethnicity,residence,siblings,perceived family affluence,father and mother educational level,only ST was positively associated with depressive symptoms(beta=0.17,p=0.005).This study suggests that excessive ST would be detrimental to depressive symptoms in adolescents.It may be effective to reduce ST for depression intervention or prevention.Future studies are encouraged to use an improved study design to confirm or negate this study’s researchfindings.

Associations among children's situational motivation,physical activity participation,and enjoyment in an active dance video game

Purpose:The purpose of this study was to examine the relationships between children's situational motivation and physical activity(PA)levels in a Dance Dance Revolution(DDR)program,and perceived PA enjoyment.Methods:A sample of 215 elementary children participated in a weekly 30-min DDR program.Children's situational motivation toward DDR(intrinsic motivation,identified regulation,external regulation,and amotivation)was measured,followed by the measurement of their accel-erometer-determined moderate to vigorous PA(MVPA)in DDR.Children then reported their PA enjoyment.Results:Only intrinsic motivation was positively related with children's MVPA in DDR and PA enjoyment.However,other motivational beliefs were not significantly related to MVPA and PA enjoyment.Regression analyses further suggested intrinsic motivation was the significant predictor for MVPA and PA enjoyment.Conclusion:Children who experienced fun and learned new things when playing DDR reached high PA levels in DDR,as well as developed generalized feeling states of enjoyment.

Physical exercise,Sedentary Behaviour,Sleep and Depression Symptoms in Chinese Young Adults During the COVID-19 Pandemic:A Compositional Isotemporal Analysis

Numerous studies links movement activity(e.g.,physical activity,sedentary behavior[SB],and sleep)with mental health or illness indicators during the COVID-19 pandemic;however,research has typically examined time-use behaviors independently,rather than considering daily activity as a 24-hour time-use composition.This cross-sec-tional study aimed to use compositional isotemporal analysis to estimate the association between reallocation of time-use behaviors and depression symptoms in young adults in China.Participants(n=1475;68.0%of female;20.7[1.60]years)reported their time spent in moderate to vigorous physical activity(MVPA),light physical activ-ity(LPA),SB,and sleep.Replacing SB with sleep,LPA,and MVPA at 5,10,or 15 min was significantly associated with lower estimated depression symptoms scores.For example,adding MVPA from SB at 15 min was associated with lower depression symptoms scores(estimated difference:-0.13[-0.17,-0.09]).The associations between reallocation of time use behaviors with depression symptoms scores were slightly differentiated.Our results emphasize the importance of increased MVPA and decreased SB as well as their mutual replacements for lowering the risks of depression symptoms in young adults during the COVID-19 pandemic.Our results can inform policy to develop effective plans and strategies for mental health promotion.