Tracking of physical activity in pubertal boys with different BMI over two-year period

We examined the tracking of physical activity (PA) measured by accelerometers and subjective self- and parental reports in normal weight and overweight and obese pubertal boys over two-year period. In total, 156 boys with mean (±SD) age of 11.53 ± 0.76 at baseline and with mean age of 13.94 ± 0.74 at 2 year follow-up were studied. At baseline and approximately two years later, the boys completed self-report questionnaire and wore an accelerometer for seven consecutive days. On the basis of first year assessment’s body mass index (BMI), the children were grouped as normal weight and overweight and obese groups according to BMI cut-offs. Tracking correlations of objectively measured PA and subjectively measured PA were fairly similar across the 12–14 year-old-boys weight groups over two year period. Tracking correlations of objectively measured PA and subjectively measured PA were not significantly different over two-year period between both BMI groups. The results of the study show that pubertal boys objectively measured PA decreased over two-year period and so the boys started to be less active in their pubertal period.     

Participation in sports in childhood and adolescence and physical activity in adulthood: A systematic review

ABSTRACT

The aim of this study was to systematically review the literature to verify the association between participation in sports (PS) in childhood and adolescence and physical activity (PA) in adulthood. A systematic search was conducted in the following databases: Medline (PUBMED), Web of Science, Scopus, and SPORTDiscus, LILACS and SciELO. All steps of the process followed the recommendations of the PRISMA FlowDiagram. After all the steps of the process, 29 articles were included for analysis. In general, only three of the studies analyzed found no relation between PS in childhood and adolescence and PA in adulthood. However, a positive relationship was found to be weak in only 7% of the studies, a moderate relation in 62% of the studies, and a strong relation in 21%. It was found that higher weekly frequencies of PS; persistence of at least three years of PS and, finally, the highest level of practice and/or competition reached were related to higher levels of PA in adulthood. Thus, it can be concluded that there is a positive association considered moderate to strong between PS in childhood and adolescence and PA in adulthood.     

Tracking and explanation of physical activity in young adults over a 7-year period

Tracking and explaining physical activity in young adults was investigated in a 7-year longitudinal design. From a representative sample of 980 respondents at baseline (M age = 21 years), 172 respondents, comprising 18% of the original sample, completed psychosocial questionnaires and were interviewed at home to assess their level of physical activity at follow-up. Psychosocial variables were grouped into four groups: social variables, self-efficacy, perceived benefits, and perceived barriers. Drop-out analyses showed no major differences between the baseline and follow-up samples. The aims of the present study were: (a) to investigate tracking in physical activity and psychosocial determinants over a 7-year period, and (b) to examine baseline determinants and change in determinants in predicting physical activity change in men and women. No significant tracking of physical activity level was found for men. For women, moderate tracking scores were found for total energy expenditure and moderate-intensity energy expenditure (r = .34 and .41, respectively). There was higher tracking in psychosocial determinants than in physical activity. Relatively high tracking scores for perceived benefits and barriers suggest that cognitions related to physical activity are more stable than the behavior itself. Although baseline psychosocial variables were poor predictors of physical activity change, determinants'change scores accounted for 16-19% of the variance in physical activity in men and 7-24% in women. Significant predictors were different for men and women. Present results can inform the design of physical activity interventions for these populations.     

Screen time and moderate-to-vigorous physical activity changes and displacement in adolescence: A prospective cohort study

Background: This paper determines longitudinal changes in the time Spanish adolescents devote to moderate-to-vigorous physical activity (MVPA) and screen media activity (SMA). Moreover, it examines the displacement hypothesis between time spent on SMA and MVPA.

Methods: A cohort of 755 adolescents participated in a prospective cohort study over a three-year period. Repeated measures ANOVA to highlight interaction effects among all variables and Structural Equation Modeling (SEM) techniques were employed.

Results: Age and gender-related variations in longitudinal changes in time spent on MVPA and SMA evolved in the inverse direction (decreased on MVPA/increased on SMA) according to the ANOVA. The potential displacement between time spent on SMA and MVPA from Wave I to Wave II was analysed via SEM. The first model, estimated in the overall sample, showed no evidence for the displacement hypothesis. Subsequently, a multigroup sequence of panel models was performed and a partial displacement was observed only in boys. Hence, boys who spent more time on SMA were more likely to devote less time to MVPA three years later.

Conclusion: This study confirms the opposite trend on the time spent on MVPA and SMA over a three-year period, being clearly higher in SMA. Further SEM analyses reveal a deferred displacement hypothesis between SMA and MVPA only in boys. This partial gendered displacement may be linked to the different uses adolescents make of screen media. The incursion of new technological devices (smartphones or tablets) and their wide range of possibilities for social networking or gaming could explain this displacement     

Bidirectional cross-sectional and prospective associations between physical activity and body composition in adolescence: birth cohort study

The aim of this study was to investigate the cross-sectional and prospective associations between physical activity and body composition in adolescence. This is a prospective study, including 4,103 adolescents belonging to the Pelotas (Brazil) 1993 birth cohort, who were followed up at the mean ages of 11.3 and 14.7 years. Subsample analyses included 511 individuals with accelerometry and deuterium dilution data at 13.3 years. Sum of skinfolds at age 11.3 years was highly correlated with skinfolds at age 14.7 years (rho = 0.74, P < 0.001). More than 85% of participants remained in the same quintile or changed by not more than one quintile during the 3.4 year period. Tracking of physical activity was considerably lower, although still significant; the correlation was 0.24 (P < 0.001) and 61.4% of the adolescents moved one or less quintiles. In fully-adjusted models, no significant cross-sectional or longitudinal associations were found between physical activity and body composition, neither in boys nor in girls. These null results were confirmed in the 511 individuals with accelerometry and deuterium data. We provide evidence of tracking of physical activity and particularly body composition during adolescence. Our results do not support the hypothesis that physical activity and fatness are strongly related in adolescents.     

Children's physical activity and physical self-perceptions

The aim of this study was to determine the relationship between physical self-perceptions and physical activity in Canadian school children aged 10–14 years. The sample consisted of 220 boys and 246 girls in grades 5–8. Physical activity was assessed by 7-day recall using the Physical Activity Questionnaire for Older Children. Selfperceptions of physical conditioning, sports competence, strength, body appearance and general physical selfworth were measured by the Physical Self-Perception Profile (PSPP). We found that boys were more physically active than girls and had higher perceptions of sport competence and strength. All PSPP scales were significantly correlated with physical activity in both boys and girls. Structural equation modelling procedures found the hierarchical PSPP model provided a good fit to the observed data, with little evidence of diff erences between the sexes. Analysis of five alternative structural models of the relationship between the PSPP and physical activity found the most parsimonious model to have significant pathways from both physical conditioning and sport skills to physical activity. Models for the sample as a whole, for boys and for girls were similar, accounting for an R 2 of 0.27–0.29 for physical activity. Our results demonstrate that physical self-perceptions, especially physical conditioning and sport skills, are significant correlates of activity in this population.     

Gender and ethnic changes in physical work capacity from childhood through adolescence

This study determined gender and ethnic differences in physical work capacity (PWC170) of 8-16-year-old American youth as they progress from elementary to high school. A multicohort group of 2,540 youth participated 50.4% girls (21.4% African Americans, and 78.6% Caucasians). PWC170 was predicted from cycle ergometer testing six times over a 7-year period. The absolute PWC170 of girls stabilized in early adolescence, while boys increased with each trial. The PWC170 relative to body weight of girls decreased steadily, whereas the boys remained stable. African Americans had greater absolute PWC170 values than Caucasians (p = .0001). The relative PWC170 was lower for African American girls than Caucasian girls (p = .0001), but there were no ethnic differences for boys (p > .05). Although correlations and grouping suggested moderate tracking; girls with high relative PWC170 tended to migrate to lower levels as they aged, where as high-peforming boys maintained their PWC170 as they aged.     

Children's physical activity and physical self-perceptions

The aim of this study was to determine the relationship between physical self-perceptions and physical activity in Canadian school children aged 10-14 years. The sample consisted of 220 boys and 246 girls in grades 5-8. Physical activity was assessed by 7-day recall using the Physical Activity Questionnaire for Older Children. Self-perceptions of physical conditioning, sports competence, strength, body appearance and general physical self-worth were measured by the Physical Self-Perception Profile (PSPP). We found that boys were more physically active than girls and had higher perceptions of sport competence and strength. All PSPP scales were significantly correlated with physical activity in both boys and girls. Structural equation modelling procedures found the hierarchical PSPP model provided a good fit to the observed data, with little evidence of differences between the sexes. Analysis of five alternative structural models of the relationship between the PSPP and physical activity found the most parsimonious model to have significant pathways from both physical conditioning and sport skills to physical activity. Models for the sample as a whole, for boys and for girls were similar, accounting for an R2 of 0.27-0.29 for physical activity. Our results demonstrate that physical self-perceptions, especially physical conditioning and sport skills, are significant correlates of activity in this population.     

Quantifying physical activity in first-through fourth-grade physical education via pedometry

The aim of this study was to determine pedometry steps per minute (SPM) cutscores that accurately quantify physical activity (PA) time in first- through fourth-grade physical education. A total of 257 participants were grouped in two data pools, first- and second-grade (n = 126), and third- and fourth-grade (n = 131). Systematic observation was the PA criterion instrument and pedometry was the predictor instrument. Correlations between physical activity measures were strong (r = .82-.89, p < .01). Ten min of PA and 33.33% of the lesson time engaged in PA within a 30-min class can be quantified by 61-63 SPM for first- and second-grade, and 58-61 SPM for third- and fourth-grade. IN CONCOLUSION: (a) SPM values were a valid indicator of students achieving or not achieving PA criteria, and (b) pedometry is a valid and practical tool for physical activity surveillance within physical education.     

Pedometer-assessed physical activity in young adolescents

The purpose of this study was to evaluate the physical activity (PA) patterns of children. Forty-four 7th-grade students (19 boys, 25 girls) recorded pedometer data for 2 consecutive weeks. Separate 2 x 3 repeated measures analyses of variance were used to examine differences in total steps/day between boys and girls and between after-school activity participants and nonparticipants. The relative contribution of physical education (PE) and after-school activity (ASA) to weekday steps/day was evaluated as a proportion, for example (steps taken in PE class/total daily steps taken on a PE class day) * 100. The total sample mean was 11,392 steps/day, SD = 4112; for boys, M = 12,490 steps/day, SD=3910, versus girls, M = 10,557 steps/day, SD=4142; F=(1, 42) 4.365, p = .043. The sample population averaged 2046 steps, SD=945, during PE class; boys=2379 steps, SD=1115, versus girls=1782, SD=703; t (42) = 2.15, p = .038, d = .65, which represented 18% of the total steps/day on PE days. In comparison, the participants accumulated an average of 5366 steps, SD=2590; ASA for boys=5897 steps/day, SD=2738, versus girls=4963 steps/day, SD=2450; t (42) = 1.190, p = .241, d = .36), representing 46% of the steps/day on all weekdays and 47% of the total on PE days. Expressed as a rate, the sample population took 45.5 steps/min (SD=21) during PE class and 13.1 steps/min (SD = 4.7) in ASA on all weekdays. The relative stability of day-to-day behavior in youth is a preliminary finding but noteworthy. Although the absolute contribution ofPE class to daily PA was less than ASA (i.e., 18 vs. 47%, respectively), the importance of the condensed contribution in class was evident when these two activities were expressed as rates (i.e., steps/min). These data indicate that youth involved in ASA accumulated a greater number of steps on all days, weekend days, and health education days when compared to youth not involved in ASA.     

Familial aggregation in physical activity.

The purposes of this study were to (a) examine the stability and consistency of the Caltrac accelerometer (Hemokinetics, Madison, WI) and an activity record to assess physical activity in children and adults (Experiment 1), and (b) to determine if there is a relationship between parents and their children in physical activity level (Experiment 2). Thirty 5-9-year-old children and their biological parents wore Caltrac accelerometers for three consecutive days (including one weekend day). At the same time, parents completed a Caltrac Activity Record (CAL REC) for themselves and their child. Dependent variables were counts per day for the Caltrac and minutes of light activity and activity for the CAL REC. Between-day correlations for the Caltrac ranged from r = .73 to .87 for the parents (p less than .001) and from r = .38 (p less than .04) to .79 (p less than .001) for the children. An analysis of variance with repeated measures indicated no significant differences for the Caltrac between days for parents and children. Between-day correlations for CAL REC ranged from r = .67 to .91 (p less than .05) for parents and r = .36 to .72 (p less than .05) for children, and there were no significant differences between days. In Experiment 2, chi 2 analyses were used to examine familial resemblance in physical activity. Using the Caltrac, familial resemblance occurred in 67% (father and child) and 73% (mother and child) of the families. Using the CAL REC, familial aggregation was present in 70% (father and child) and 66% (mother and child) of the families.(ABSTRACT TRUNCATED AT 250 WORDS)     

论体力活动与学校体育

深入探讨了体力活动的定义、理论意义，体力活动在学校体育中的理论地位以及体力活动的相关知识和技能对学生体育实践的意义，以引起学校体育工作对这一概念的重视。     

Impact of physical activity domains on subsequent physical activity in youth: a 5-year longitudinal study

This study evaluates how domains of physical activity (PA) in youth predict later PA and assesses factors influencing changes in sports participation. Young people from the Children’s Sport Participation and Physical Activity study (n = 873; baseline age 10–18 years; 30.4% male) completed self-report surveys in 2009 and 2014. In a multiple linear regression analysis, participation frequency in club sport (β = 0.18) and extracurricular sport (β = 0.13) significantly predicted PA 5 years later, adjusted for age, sex and urban/rural classification (P < 0.01). Overall, rates of regular (at least once per week) youth sports participation were high (males 79.3–85.5%; females 74.8–83.2%). Uptake and dropout of specific sports varied widely. Despite high levels of migration into and out of Gaelic games, they remained popular at follow-up. Weight training was the only sport that increased in both sexes (P < 0.05). Fitness, friends and enjoyment were top motivations for taking up a new sport. Other commitments, a lack of interest and time were important factors leading to sports dropout. PA promotion strategies should include youth sport, take into consideration what sports are attractive to young people and address reasons for uptake and dropout.     

A prospective study of pedometer-determined physical activity and physical self-perceptions in children

There have been limited prospective studies investigating physical activity and physical self-perceptions in children. In this investigation, mean steps/day did not significantly change from late elementary to junior high for either boys or girls; however; boys accumulated more steps both at baseline and follow-up. Physical self-perception measures were significantly related to changes in steps/day and accounted for 21% (15% adjusted) of the variance after controlling for demographic/biological variables, R2 change = .21, adjusted R2 change = .15, F (5,88) = 4.66, p < .001. Sport competence emerged as the most important predictor t (88) = -3.76, p < .001, and was inversely related to physical activity change. The lack of opportunities to participate in sport activities normally found at the onset of adolescence may help explain this unexpected result.     

The influence of self-determination in physical education on leisure-time physical activity behavior

Using a multitheory approach, this study was designed to investigate the influence of urban adolescents' perceived autonomy and competence in physical education on their physical activity intentions and behaviors during leisure time. A transcontextual model was hypothesized and tested. Urban adolescents (N=653, ages 11-15 years) completed questionnaires assessing relevant psychological constructs and moderate to vigorous physical activity and then had their cardiorespiratory fitness assessed with the Progressive Aerobic Cardiovascular Endurance Run (PACER) test. Based on our structural equation modeling analyses and fit indexes, the transcontextual model adequately fit the data. We concluded that the two theoretical frameworks--SDT and theory of planned behavior--can be integrated to provide an enhanced understanding of the influence of physical education on leisure-time physical activity. The results revealed that perceived autonomy and competence in physical education are interrelated and function as a whole for enhancing leisure-time physically active intentions and behavior.     

问卷调查在体育科研中的应用

目前,误用和错用问卷调查及统计学数据处理的现象时有发生。就问卷的设计、受试者选取、问卷的发放回收及数据处理的统计学方法的选用等方面作了阐述及说明,以期达到正确使用并更好提升问卷调查在体育科学研究中应用之目的。