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Diego Augusto Santos Silva, Katie E. Gunnell and Mark Stephen Tremblay

Background: This study aimed to examine the factor structure of responses to the Portuguese version of questions related to screen time–based sedentary behavior among adolescents. Methods: This cross-sectional study with a sample of 1083 adolescents aged 14–19 years was conducted in Brazil. The sample was randomly divided into 2 groups for an exploratory factor analysis and for a confirmatory factor analysis. Screen time was investigated by a Portuguese version of questions about time sitting in front of television, computer, and video games on weekdays and weekends. Results: Scree plots showed 2 factors with eigenvalues above 1. One factor was formed by items about television and computer use, and the other factor was formed by items about video game use. The exploratory factor analysis with 2 factors resulted in factor loadings above .60. A second model with 1 factor was estimated and resulted in factor loadings above .55. A confirmatory factor analysis was estimated based on the 2-factor exploratory factor analysis and goodness-of-fit statistics were adequate. Confirmatory factor analysis with 1 factor had goodness-of-fit statistics adequate. Conclusions: The Portuguese language version of self-report screen time had 2 possible factor solutions, and items demonstrated good factor structure with reasonable reliability making it suitable for use in the future studies.

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Anders Raustorp, Peter Pagels, Cecilia Boldemann, Nilda Cosco, Margareta Söderström and Fredrika Mårtensson

Background:

It is important to understand the correlates of physical activity (PA) to influence policy and create environments that promote PA among preschool children. We compared preschoolers’ PA in Swedish and in US settings and objectively examined differences boys’ and girls’ indoor and outdoor PA regarding different intensity levels and sedentary behavior.

Methods:

Accelerometer determined PA in 50 children with mean age 52 months, (range 40–67) was recorded during preschool time for 5 consecutive weekdays at 4 sites. The children wore an Actigraph GTIM Monitor.

Results:

Raleigh preschool children, opposite to Malmö preschoolers spent significantly more time indoors than outdoors (P < .001). Significantly more moderate-to-vigorous intensity physical activity (MVPA) was observed outdoors (P < .001) in both settings. Malmö children accumulated significantly more counts/min indoors (P < .001). The percent of MVPA during outdoor time did not differ between children at Raleigh and Malmö.

Conclusion:

Physical activity counts/minutes was significantly higher outdoors vs. indoors in both Malmö and Raleigh. Malmö preschoolers spent 47% of attendance time outdoors compared with 18% for Raleigh preschoolers which could have influenced the difference in preschool activity between the 2 countries. Time spent in MVPA at preschool was very limited and predominantly adopted outdoors.

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Jamie Lau, Lina Engelen and Anita Bundy

Background:

After-school hours provide an opportunity for physical activity (PA). Parental perceptions influence children’s PA. The aims were to: compare parents’ perceptions of children’s PA with objectively measured PA; shed light on PA during after-school hours; and compare two electronic devices for collecting data.

Methods:

Twenty parent-child dyads participated. Children (5–7 years, mean 6.25 ± 0.64) wore Actical accelerometers; their parents responded to activity diaries on electronic devices. Data were collected twice for 4 consecutive weekday afternoons (15.30–19.00).

Results:

While parents perceived their children to be quite active, children were, in fact, largely inactive. Parents’ responses compared with accelerometer data yielded moderate correlations (r = .44, p < .01). Two thirds of parents’ responses were overestimations. Boys were physically more active than girls and had higher PA outdoors than indoors. Girls’ PA remained similar indoors and outdoors but parents did not perceive the similarity. Both electronic devices produced similar results and compliance rates.

Conclusion:

Parents consistently over-reported their children’s PA. Findings have implications for initiatives to increase PA. If parents perceive their children as very active, they may lack motivation to promote PA. Parents’ limitations as proxy reporters aside, the similarity of results yielded by the two electronic devices suggests that the choice is a matter of researcher preference.

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Amanda Louise Lewis and Frank F. Eves

Background/Objective:

While point-of-choice prompts consistently increase stair climbing, experimental comparisons of message content are rare. Here, the effects of 2 messages differing in complexity about the health outcomes obtainable from stair climbing were compared.

Methods:

In a UK train station with 2 independent platforms exited by identical 39-step staircases and adjacent escalators, observers recorded travelers ascent method and gender from 8:00 A.M. to 10:00 A.M. on 2 weekdays during February/March 2008 (n = 48,697). Baseline observations (2-weeks) preceded a 3-week poster phase. Two posters (594 × 841mm) that differed in the complexity of the message were positioned at the point-of-choice between ascent methods, with 1 placed on each side of the station simultaneously. Logistic regression analysis was conducted in April 2010.

Results:

Omnibus analysis contained main effects of the intervention (OR = 1.07, CI = 1.02–1.13, P = .01) and pedestrian traffic volume (OR = 5.42, CI = 3.05–9.62, P < .001). Similar effects occurred for complex (OR = 1.10, CI = 1.02–1.18, P = .01) and simple messages (OR = 1.07, CI = 1.01–1.13, P = .02) when analyses controlled for the influence of pedestrian traffic volume. There was reduced efficacy for the complex message during busier periods (OR = 0.36, CI = 0.20–0.66, P = .001), whereas the simple message was immune to these effects of traffic volume.

Conclusions:

Pedestrian traffic flow in stations can influence message effectiveness. Simple messages appear more suitable for busy sites.

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Mareesa O’Dwyer, Stuart J. Fairclough, Nicola Diane Ridgers, Zoe Rebecca Knowles, Lawrence Foweather and Gareth Stratton

Background:

Identifying periods of the day which are susceptible to varying levels of physical activity (PA) may help identify key times to intervene and potentially change preschool children’s PA behaviors. This study assessed variability of objectively measured moderate-to-vigorous physical activity (MVPA) during weekdays and weekend days among preschool children.

Methods:

One hundred and eighty-eight children (aged 3 to 5 years; 53.2% boys) from a northwest English city wore uni-axial accelerometers for 7 consecutive days.

Results:

Higher levels of MVPA were recorded in boys, particularly those who attended preschool for a half day. Children who attended preschool for a full day engaged in 11.1 minutes less MVPA than children who attended for a half day. After-school hours were characterized by a decrease in activity for all groups. Patterns of activity during the weekend were smoother with less variability.

Conclusion:

This study identified discrete segments of the week, specifically afterschool and during the weekend, when preschoolers engage in low levels of PA. Higher levels of MVPA among children who attended preschool for less time each day suggests that the structured preschool environment is related to decreased activity. Consequently, there is a need for interventions in young children to focus on school and home environments.

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Au Bich Thuy, Leigh Blizzard, Michael Schmidt, Costan Magnussen, Emily Hansen and Terence Dwyer

Background:

Pedometer measurement of physical activity (PA) has been shown to be reliable and valid in industrialized populations, but its applicability in economically developing Vietnam remains untested. This study assessed the feasibility, stability and validity of pedometer estimates of PA in Vietnam.

Methods:

250 adults from a population-based survey were randomly selected to wear Yamax pedometers and record activities for 7 consecutive days. Stability and concurrent validity were assessed using intraclass correlation coefficients (ICC) and Spearman correlation coefficients.

Results:

Overall, 97.6% of participants provided at least 1 day of usable recordings, and 76.2% wore pedometers for all 7 days. Only 5.2% of the sample participants were involved in work activities not measurable by pedometer. The number of steps increased with hours of wear. There was no significant difference between weekday and weekend in number of steps, and at least 3 days of recordings were required (ICC of the 3 days of recordings: men 0.96, women 0.97). Steps per hour were moderately correlated (men r = .42, women r = .26) with record estimates of total PA.

Conclusions:

It is feasible to use pedometers to estimate PA in Vietnam. The measure should involve at least 3 days of recording irrespective of day of the week.

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Katja Borodulin, Anja Kärki, Tiina Laatikainen, Markku Peltonen and Riitta Luoto

Background:

Daily sitting time may be a risk factor for incident cardiovascular disease (CVD); however, this has not yet been extensively studied. Our aim was to study the association of total sitting time with the risk of CVD.

Methods:

Participants (n = 4516, free of CVD at baseline) from the National FINRISK 2002 Study were followed for fatal and nonfatal CVD using national registers. Participants underwent a health examination and completed questionnaires, including total daily sitting time.

Results:

During a mean follow-up of 8.6 years, 183 incident CVD cases occurred. Sitting on a typical weekday, at baseline, was statistically significantly associated with fatal and nonfatal incident CVD. The hazard ratios (with 95% confidence intervals, CI) for the total amount of sitting were 1.05 (95% CI, 1.00–1.10) in the age and gender adjusted model and 1.06 (95% CI, 1.01–1.11) in the fully adjusted model, including age, gender, employment status, education, BMI, smoking status, leisure time physical activity, use of vegetables and fruit, alcohol use, blood pressure or its medication, and cholesterol or its medication.

Conclusions:

Our findings suggest that total amount of daily sitting is a risk factor for incident CVD. More research is needed to understand the etiology of sedentary behavior and CVD.

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Peter Collins, Yahya Al-Nakeeb and Mark Lyons

Background:

Active school commuting is widely regarded as a key opportunity for youth to participate in physical activity (PA). However, the accurate measurement of the commute home from school and its contribution to total free-living moderateto- vigorous PA (MVPA) is relatively unexplored.

Methods:

Seventy-five adolescents (38 males, 37 females) wore an integrated GPS and heart rate device during after-school hours for 4 consecutive weekdays.

Results:

Active commuters were significantly more active (11.72 minutes MVPA) than passive commuters (3.5 minutes MVPA) during their commute home from school (P = .001). The commute home of walkers and cyclists on average contributed 35% of their total free-living PA. However, there was no significant difference in the overall free-living PA levels of passive and active commuters (P > .05). A total 92.7% of the youth living within 1.5 miles of the school actively commuted, compared with 16.7% of the youth who lived further away. Socioeconomic differences in commuting patterns were also evident.

Conclusions:

The findings highlighted the significant proportion of total free-living PA that was attributed to active commuting home from school. The study demonstrates the usefulness of utilizing GPS and heart rate data to accurately track young people’s after-school PA. Demographic influences and implications for future research are discussed.

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Maciej S. Buchowski, Leena Choi, Karen M. Majchrzak, Sari Acra, Charles E. Matthews and Kong Y. Chen

Background:

Environmental factors including seasonal changes are important to guide physical activity (PA) programs to achieve or sustain weight loss. The goal was to determine seasonal variability in the amount and patterns of free-living PA in women.

Methods:

PA was measured in 57 healthy women from metropolitan Nashville, TN, and surrounding counties (age: 20 to 54 years, body mass index: 17 to 48 kg/m2) using an accelerometer for 7 consecutive days during 3 seasons within 1 year. PA counts and energy expenditure (EE) were measured in a whole-room indirect calorimeter and used to model accelerometer output and to calculate daily EE and intensity of PA expressed as metabolic equivalents (METs).

Results:

PA was lower in winter than in summer (131 ± 45 vs. 144 ± 54 × 103 counts/d; P = .025) and in spring/fall (143 ± 48 × 103 counts/d; P = .027). On weekends, PA was lower in winter than in summer by 22,652 counts/d (P = .008). In winter, women spent more time in sedentary activities than in summer (difference 35 min/d; P = .007) and less time in light activities (difference −29 min/d, P = .018) and moderate or vigorous activities (difference −6 min/d, P = .051).

Conclusions:

Women living in the southeastern United States had lower PA levels in winter compared with summer and spring/fall, and the magnitude of this effect was greater on weekends than weekdays.

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Stacy A. Clemes and Stuart J.H. Biddle

Background:

Pedometers are increasingly being used to measure physical activity in children and adolescents. This review provides an overview of common measurement issues relating to their use.

Methods:

Studies addressing the following measurement issues in children/adolescents (aged 3−18 years) were included: pedometer validity and reliability, monitoring period, wear time, reactivity, and data treatment and reporting. Pedometer surveillance studies in children/adolescents (aged: 4−18 years) were also included to enable common measurement protocols to be highlighted.

Results:

In children > 5 years, pedometers provide a valid and reliable, objective measure of ambulatory activity. Further evidence is required on pedometer validity in preschool children. Across all ages, optimal monitoring frames to detect habitual activity have yet to be determined; most surveillance studies use 7 days. It is recommended that standardized wear time criteria are established for different age groups, and that wear times are reported. As activity varies between weekdays and weekend days, researchers interested in habitual activity should include both types of day in surveillance studies. There is conflicting evidence on the presence of reactivity to pedometers.

Conclusions:

Pedometers are a suitable tool to objectively assess ambulatory activity in children (> 5 years) and adolescents. This review provides recommendations to enhance the standardization of measurement protocols.