Objectively measured physical activity,body composition and physical fitness: Cross-sectional associations in 9- to 15-year-old children

The aim of this study was to examine and quantify the cross-sectional associations of body composition (BC), physical activity (PA) and sedentary time (ST) with physical fitness (PF) in children and adolescents. A sample of 594 Finnish students (56% girls), aged 9–15 (12.4?±?1.3 years) were selected for a study performed in 2013. The measurements of the Move! monitoring system for physical functional capacity were used to measure cardiorespiratory and musculoskeletal fitness and fundamental movement skills. Moderate-to-vigorous PA (MVPA) and ST were measured objectively with an accelerometer and BC by a bioelectrical impedance analysis. Fat mass index (FMI) and fat-free mass index (FFMI) were calculated to represent height-adjusted BC. Associations were explored with a linear regression model. In general, FMI had statistically significant negative associations, while FFMI and MVPA had positive associations with PF. No statistically significant associations were observed between ST and PF. In general, FMI had the strongest association with PF, although some variation occurred with sex and PF component. However, associations were practically relevant only in 20-m shuttle run, push-up, curl-up and 5-leaps test. For example, approximately 5?kg increase in fat mass in 155?cm tall children was estimated to correspond to 8 laps in 20-m shuttle run. Similar increase in fat-free mass corresponded to +4 and +6 laps, and 10?min increase in daily MVPA +3 and +2 laps in 20-m shuttle run, in boys and girls, respectively. Understanding these associations is necessary when interpreting children’s PF and designing interventions.     

Evaluation of Actical equations and thresholds to predict physical activity intensity in young children

This study examined the validity of current Actical activity energy expenditure (AEE) equations and intensity cut-points in preschoolers using AEE and direct observation as criterion measures. Forty 4–6-year-olds (5.3 ± 1.0 years) completed a ~150-min room calorimeter protocol involving age-appropriate sedentary behaviours (SBs), light intensity physical activities (LPAs) and moderate-to-vigorous intensity physical activities (MVPAs). AEE and/or physical activity intensity were calculated using Actical equations and cut-points by Adolph, Evenson, Pfeiffer and Puyau. Predictive validity was examined using paired sample t-tests. Classification accuracy was evaluated using weighted kappas, sensitivity, specificity and area under the receiver operating characteristic curve. The Pfeiffer equation significantly overestimated AEE during SB and underestimated AEE during LPA (P < 0.0125 for both). There was no significant difference between measured and predicted AEEs during MVPA. The Adolph cut-point showed significantly higher accuracy for classifying SB, LPA and MVPA than all others. The available Actical equation does not provide accurate estimates of AEE across all intensities in preschoolers. However, the Pfeiffer equation performed reasonably well for MVPA. Using cut-points of ≤6 counts · 15 s^?1, 7–286 counts · 15 s^?1 and ≥ 287 counts · 15 s^?1 when classifying SB, LPA and MVPA, respectively, is recommended.     

Impact of the choice of threshold on physical activity patterns in free living conditions among adolescents measured using a uniaxial accelerometer: The HELENA study

Abstract

The aim of this study was to assess the impact of the choice of threshold on physical activity patterns measured in adolescents under free living conditions (FLC) using a uniaxial accelerometer. The study comprised 2043 adolescents (12.5–17.5 years) participating in the HELENA Study. Participants wore a uniaxial accelerometer for 7 days. The PA patterns were assessed using thresholds determined from six different studies. For each of the thresholds used, the number of adolescents fulfilling the recommendation of 60 min of moderate to vigorous PA (MVPA) per day was also calculated. A significant difference was found between thresholds regardless of the activity level: differences of 38%, 207%, 136%, and 2780% for sedentary, light, moderate, and vigorous intensity PA, respectively (P < 0.001). Time of MVPA varied between methods from 25.3 to 55.2 min · day^–1. The number of adolescents fulfilling the recommendation varied from 5.9% to 37% according to the thresholds used. The kappa coefficient for concordance in the assessment of the number of adolescents achieving the PA recommendations was generally low. The definition of the threshold for PA intensity may considerably affect the PA patterns in FLC when assessed using a uniaxial accelerometer and the number of participants fulfilling the recommendations.     

Accelerometer-measured daily physical activity related to aerobic fitness in children and adolescents

Abstract

Maximum oxygen uptake ([Vdot]O_2PEAK) is generally considered to be the best single marker for aerobic fitness. While a positive relationship between daily physical activity and aerobic fitness has been established in adults, the relationship appears less clear in children and adolescents. The purpose of this paper is to summarise recently published data on the relationship between daily physical activity, as measured by accelerometers, and [Vdot]O_2PEAK in children and adolescents. A PubMed search was performed on 29 October 2010 to identify relevant articles. Studies were considered relevant if they included measurement of daily physical activity by accelerometry and related to a [Vdot]O_2PEAK either measured directly at a maximal exercise test or estimated from maximal power output. A total of nine studies were identified, with a total number of 6116 children and adolescents investigated. Most studies reported a low-to-moderate relationship (r = 0.10–0.45) between objectively measured daily physical activity and [Vdot]O_2PEAK. No conclusive evidence exists that physical activity of higher intensities are more closely related to [Vdot]O_2PEAK, than lower intensities.     

Unprompted vigorous physical activity is associated with higher levels of subsequent sedentary behaviour in participants with low cardiorespiratory fitness: a cross-sectional study

Abstract

Performing physical activity is considered health promoting but may induce a need for subsequent rest periods. This study aimed to determine the within-day interactions between vigorous physical activity (VPA) and sedentary behaviour (SB) in participants with low cardiorespiratory fitness. We tested the hypothesis that VPA is associated with a temporary subsequent increase in SB. One week of accelerometer data containing a minimum of one 10-min bout of VPA from 62 participants with low cardiorespiratory fitness (31–50 years old) were obtained from the MILE study. A comparison of SB was made between days with a bout of VPA and days without (control). Due to a positive association between VPA and number and duration of sedentary bouts, the time accumulated in both uninterrupted and total sedentary bouts were 27 (95% CI, 10–45)?min and 29 (95% CI, 9–50)?min higher on VPA days compared to control days (P?<?0.05). Our results indicate that in participants with low cardiovascular fitness, unprompted VPA is positively associated with an increase in subsequent sedentary time. We propose that such VPA-associated sedentary time may be viewed as part of a healthy activity pattern.     

Comparison of physical activity estimates using International Physical Activity Questionnaire (IPAQ) and accelerometry in fibromyalgia patients: The Al-Andalus study

Abstract

The International Physical Activity Questionnaire (IPAQ) has been widely used to assess physical activity in healthy populations. The present study compared physical activity assessed by the long, self-administrated version of the International Physical Activity Questionnaire with physical activity assessed by accelerometry in patients with fibromyalgia. A total of 99 (five men) participants with fibromyalgia completed the International Physical Activity Questionnaire and wore an accelerometer for nine consecutive days. We analysed the correlations of physical activity expressed as min · day^?1 of light, moderate, vigorous, and moderate to vigorous (MVPA) intensity, as well as time spent sitting, by the International Physical Activity Questionnaire and accelerometry by Spearman correlations. Bland and Altman plots were performed to verify the agreements between both instruments. The results showed weak yet significant correlations (Rs = 0.15–0.39, all P < 0.05) in all physical activity intensities between the two instruments, except for sedentary time. The highest correlations were observed for physical activity at home or in garden (Rs = 0.297, P < 0.01). The results suggest that the long self-administrated International Physical Activity Questionnaire is a questionable instrument to assess physical activity in patients with fibromyalgia. Therefore, physical activity measurement in fibromyalgia patients should not be limited solely to self-reported measures.     

Perceived environment in relation to objective and self-reported physical activity in Spanish youth. The UP&DOWN study

The aims of the present study were to assess the association of environmental perception with objective and self-reported physical activity (PA) and the relation between environmental perception and meeting PA recommendations on children and adolescents. A sample of 1520 youth (770 boys) aged 8–18 years (12.1 ± 2.5 years) from the UP&;DOWN study were included in the data analyses. Environmental perception was assessed with the short adapted version of the ALPHA environmental questionnaire. PA was objectively (accelerometers) and self-reported measured (PA Questionnaire for Children, Patient-centered Assessment and Counseling for Exercise Questionnaire and Finnish PA Index). Linear regression models were used to assess the association of environmental perception with PA. Bivariate logistic regression models were used to assess differences between environmental perception and meeting PA recommendations. Environmental perception was positively associated with both objective and self-reported PA. Some differences were found in the association of environmental perception and PA between sex- and age-specific groups. Youth who perceived a more favourable environment were more likely to meet PA recommendations (at least 60 min · day^?1 of moderate to vigorous PA (MVPA)). Results suggest that environmental perceptions of children and adolescents may play an important role in achieving higher levels of PA.     

24 h Accelerometry: impact of sleep-screening methods on estimates of sedentary behaviour and physical activity while awake

Although accelerometers can assess sleep and activity over 24 h, sleep data must be removed before physical activity and sedentary time can be examined appropriately. We compared the effect of 6 different sleep-scoring rules on physical activity and sedentary time. Activity and sleep were obtained by accelerometry (ActiGraph GT3X) over 7 days in 291 children (51.3% overweight or obese) aged 4–8.9 years. Three methods removed sleep using individualised time filters and two methods applied standard time filters to remove sleep each day (9 pm–6 am, 12 am–6 am). The final method did not remove sleep but simply defined non-wear as at least 60 min of consecutive zeros over the 24-h period. Different methods of removing sleep from 24-h data markedly affect estimates of sedentary time, yielding values ranging from 556 to 1145 min/day. Estimates of non-wear time (33–193 min), wear time (736–1337 min) and counts per minute (384–658) also showed considerable variation. By contrast, estimates of moderate-to-vigorous activity (MVPA) were similar, varying by less than 1 min/day. Different scoring methods to remove sleep from 24-h accelerometry data do not affect measures of MVPA, whereas estimates of counts per minute and sedentary time depend considerably on which technique is used.     

Self-reported and activPALTM-monitored physical activity and sedentary behaviour in college students: Not all sitting behaviours are linked to perceived stress and anxiety

ABSTRACT

This study examined relationships between physical activity (PA) and sedentary behaviour (SB) with state-trait anxiety and stress. State-Trait anxiety (State-Trait Anxiety Inventory), psychological stress (Perceived Stress Scale), SB across domains during weekdays and weekends (Last 7-day Sedentary Behaviour Questionnaire) and PA intensities (International Physical Activity Questionnaire) were assessed by self-report in 360 undergraduates (44% females, mean age 20.9 ± 2.93 years). A subsample (n = 121; 53.7% females; mean age 20.8 ± 2.6 years) wore an activPAL^TM to determine total SB, light, and moderate-to-vigorous intensity PA (MVPA). Self-reported MVPA was significantly associated with lower trait anxiety and perceived stress, whereas light PA was only associated with lower perceived stress. Weekend total self-reported SB was related to higher trait anxiety and perceived stress levels, while total SB during the week was not. Of all SB domains, only leisure SB (screen and non-screen based) was associated with higher trait anxiety and perceived stress. PA attenuated the negative relationships between excessive sitting time and trait anxiety but not perceived stress. No associations were found for monitor-based measures of PA and SB. No associations were found between PA or SB variables with state anxiety. Further research is needed to assess causal and reciprocal relationships between PA, SB and mental health in college students.     

Health-enhancing physical activity and sedentary behaviour in children and adolescents

We provide a wide-ranging review of health-related physical activity in children and adolescents using a behavioural epidemiology framework. In contrast to many other reviews, we highlight issues associated with true sedentary behaviours alongside physically active behaviours. Specifically, we review the evidence concerning the links between physical activity and cardiovascular disease, overweight and obesity, psychosocial measures, type II diabetes, and skeletal health. Although the evidence is unconvincing at times, several factors lead to the conclusion that promoting physical activity in youth is desirable. A review of the prevalence of physical activity and sedentary behaviours shows that many young people are active, but this declines with age. A substantial number are not adequately active for health benefits and current trends in juvenile obesity are a cause for concern. Prevalence data on sedentary behaviours are less extensive but suggest that total media use by young people has not changed greatly in recent years. Most children and adolescents do not exceed recommended daily hours of TV viewing. Physical activity is unrelated to TV viewing. We also identified the key determinants of physical activity in this age group, highlighting demographic, biological, psychological, behavioural, social and environmental determinants. Interventions were considered for school, family and community environments. Finally, policy recommendations are offered for the education, governmental, sport and recreation, health, and mass media sectors.     

Associations of accelerometer-measured sedentary time,sedentary bouts,and physical activity with adiposity and fitness in children

ABSTRACT

Sedentary time (ST) has been inconsistently associated with adiposity and cardiorespiratory fitness in children in previous studies. We studied cross-sectional associations of ST, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) with fat mass index (FMI) and cardiorespiratory fitness (estimated VO₂max). Associations were evaluated with and without considering pattern of ST by bout length. We measured ST and activity by a wrist-worn accelerometer, FMI by bioelectrical impedance, and VO₂max by Pacer test in 443 children (51.2% girls, 10.2 ± 0.6 years). Isotemporal substitution regression models estimated the effects of substituting ST, LPA, and MVPA on FMI and VO₂max. Further models repeated analyses separating ST into short (<10 min) and long (≥10 min) bouts. Only replacing ST or LPA with MVPA was consistently associated with lower FMI and greater VO₂max. When separated by bout length, only one unique association was found where replacing long ST bouts with short ST bouts was associated with lower FMI in girls only. In conclusion, activity pattern is associated with adiposity in girls and fitness in boys and girls. Separating ST into long and short ST bouts may be of minimal importance when assessing associations with adiposity and fitness using wrist-worn accelerometry in children.     

The association between environmental and psychosocial factors towards physical activity and screen time of children: an application of the Integrative Behavioural Model

Physical activity is beneficial at all stages of life, and has been linked as a protective factor from obesity, and other chronic health conditions. Despite the benefits of physical activity, less than half of US children meet the current recommendations, and activity levels decline with age. When planning physical activity interventions, behavioural theories should be utilised, given the inherent benefits theory-based approaches possess. The purpose of this study was to investigate how constructs of the Integrative Theoretical Model (IM) are associated with physical activity and screen time among children (9 years ±1.2; n = 264). Using structural equation modeling, a final model proved to have a good fit (CFI = 0.989; TLI = 0.975; RMSEA = 0.043), and results indicated intentions and perceived behavioural control (PBC) explained 19.4% of the variance for physical activity, and attitudes, perceived norms, and PBC accounted for 62% of the variance of intentions. Furthermore, attitudes and perceived norms were negatively associated with total screen time, and accounted for 10% of the variance. Results suggest that IM is a useful framework for explaining physical activity and screen time among children.     

Number of days required for reliably estimating physical activity and sedentary behaviour from accelerometer data in older adults

The purpose of the study was to examine the minimum number of monitoring days for reliably estimating physical activity (PA) and sedentary behaviour (SB) from accelerometer data in older adults. Forty-two older adults from a local senior centre participated in this study. Participants wore an ActiGraph wGT3X-BT on the right hip for 7 consecutive days. Accelerometer data were downloaded to a computer and converted to activity count data in 60s epochs. Time spent in SB and different PA intensity categories were estimated with commonly used activity count cut-points. Participants with at least 7 valid days of monitoring (≥10 h^.day^?1) were included in the analysis. Intraclass correlation coefficients (ICC) were calculated for determining single-day monitoring reliability. The Spearman-Brown prophecy formula was used to estimate the minimum number of monitoring days required for achieving an ICC of 0.80. Single-day ICC values for time spent in SB and PA intensity categories ranged from 0.45 to 0.61. Minimum number of monitoring days required for achieving an ICC of 0.80 ranged from 2.5 to 4.9 days. In this study, a minimum of 5 consecutive days of monitoring was required for reliably estimating SB and PA from accelerometer data in older adults.     

Recurrent pain and discomfort in relation to fitness and physical activity among young school children

Abstract

As an increase in pain symptoms among children has been shown in the last decades, the aim of this study was to describe perceptions of recurrent pain, measured physical fitness and levels of reported physical activity (PA) in children, and to investigate if any associations between PA, fitness and recurrent pain could be identified. A school-based study comprised 206 Swedish children 8–12 years old, 114 boys, 92 girls. A questionnaire with questions about perceived pain, self-reported PA and lifestyle factors was used. Health-related fitness was assessed by 11 physical tests. A physical index was calculated from these tests as a z score. High physical index indicated high fitness and low physical index indicated low fitness. ANOVA test, chi-square test and logistic regression analysis were used to compare active and inactive children. The prevalence of one pain location (head, abdomen or back) was 26%, two 11% and three 4% (n=206). Female gender, living in single-parent families, low PA and low subjective health were associated with reported recurrent pain. Children reporting high levels of PA had high physical index and reported low prevalence of pain symptoms. The physical index and level of self-reported PA decreased gradually the more pain locations. Physically active children had higher fitness levels and reported less pain symptoms than inactive peers. Coping with pain is an integral part of PA, and active children learn to cope with unpleasant body sensations which together with high fitness may reduce the perception of pain.     

Habitual physical activity levels and sedentary time of children in different childcare arrangements from a nationally representative sample of Canadian preschoolers

BackgroundChildren spend substantial time in childcare, and the reasons parents choose a particular childcare type may differ by family. However, little is known about how childcare type influences habitual (full day) activity levels among children. Therefore, exploring patterns between childcare type and habitual physical activity (PA) (i.e., light, moderate-to-vigorous PA (MVPA), and total PA) and sedentary time (ST) in young Canadian children is needed.MethodsA nationally representative sample of preschoolers from Cycles 3 and 4 of the Canadian Health Measures Survey was used in this cross-sectional study. Childcare type (e.g., center-based childcare, home-based childcare, home with parent, kindergarten) was reported by parents. Preschoolers wore an Actical accelerometer for 7 days. Device and population-spcific cut-points were applied to delineate PA intensities and ST. Population means and sample totals were calculated to examine average daily and hourly rates of activity.ResultsPreschoolers’ rates of MVPA and total PA from the 4 childcare arrangements ranged from 65.99 min/day to 74.62 min/day (5.48–6.18 min/h) and 274.20 min/day to 281.66 min/day 22.69–23.21 min/h), respectively, while ST ranged from 443.13 min/day to 460.57 min/day (36.80–37.31 min/h). No significant differences were observed in daily or hourly rates of activity.ConclusionThis study provides a snapshot of the levels of PA and ST among preschoolers in various childcare settings at a national level, with no differences observed in habitual activity levels based on childcare enrollment. Additional research is needed to clarify the relationship between young children's PA and childcare type, with consideration given to the quality of the childcare settings.     

Association between physical activity and health in German adolescents

Abstract

The aim of the study was to examine the relationships between physical activity and several health parameters in German adolescents. We predicted that the association between physical activity and physical and psychosocial health resources (physical and psychosocial characteristics that tend to enhance coping and well-being) would be stronger than the association between physical activity and health deficits. This research is based on a large representative, cross-sectional study (the German Health Interview and Examination Survey [KiGGS] and the Motoric-Module [MoMo]). Health was assessed using medical parameters, motor fitness data, and questionnaire data for various health-related parameters. To assess physical activity, the participants answered questions regarding the duration and intensity of weekly physical activity in leisure and organized sports. We tested our assumptions using a representative sample (N=2291; 50.5% boys) of German adolescents aged 11–17 years. Participants were classified as physically inactive (16.7%), somewhat active (24.7%), medium active (19.8%), active (14.4%) or highly active (24.4%), based on the duration and intensity of their weekly physical activity. In support of our hypothesis, the data revealed that the amount of physical activity explains up to 12.6% in the variance of physical and psychosocial health resources, but only 2.5% of the variance in physical and psychosocial health deficits. We conclude that the relationship between physical activity and health among adolescents should not only be viewed as a way of reducing health deficits, but should also focus on the enhancement of physical and psychosocial resources.     

A critical review of national physical activity policies relating to children and young people in England

BackgroundThere has been an increasing focus on the importance of national policy to address population levels of physical inactivity. It has been suggested that the 4 cornerstones of policy comprise (1) national guidelines on physical activity (PA), (2) setting population goals and targets, (3) surveillance or health-monitoring systems, and (4) public education. The current study aimed to review the policy actions that have addressed each of these elements for children and youth in England and to identify areas of progress and remaining challenges.MethodsA literature search was undertaken to identify past and present documents relevant to PA policy for children and youth in England. Each document was analyzed to identify content relevant to the 4 cornerstones of policy.ResultsPhysical activity guidelines (Cornerstone 1) for children and youth have been in place since 1998 and reviewed periodically. Physical activity targets (Cornerstone 2) have focussed on the provision of opportunities for PA, mainly through physical education in schools rather than in relation to the proportion of children meeting recommended PA levels. There has been much surveillance (Cornerstone 3) of children''s PA, but this has been undertaken infrequently over time and with varying inclusions of differing domains of activity. There has been only 1 campaign (Cornerstone 4) that targeted children and their intermediaries, Change4Life, which was an obesity campaign focussing on dietary behavior in combination with PA. Most recently, a government infographic supporting the PA guidelines for children and young people was developed, but details of its dissemination and usage are unknown.ConclusionThere have been many developments in national PA policy in England targeted to children and young people. The area of most significant progress is national PA guidelines. Establishing prevalence targets, streamlining surveillance systems, and investing in public education with supportive policies, environments, and opportunities would strengthen national policy efforts to increase PA and reduce sedentary behavior.     

In-school and out-of-school physical activity in primary and secondary school children

Abstract

The aim of this study was to compare in-school and out-of-school physical activity within a representative sample. Socio-demographic, physical activity, and anthropometric data were collected from a random sample of children (250 boys, 253 girls) aged 3–16 years attending nine primary and two secondary schools. Actigraph GT1M accelerometers, worn for seven days, were used to estimate physical activity levels for in-school (typically 09.00–15.00 h), out-of-school (weekday), and weekend periods. Physical activity as accelerometer counts per minute were lower in school versus out of school overall (in school: 437.2 ± 172.9; out of school: 575.5 ± 202.8; P < 0.001), especially in secondary school pupils (secondary: 321.6 ± 127.5; primary: 579.2 ± 216.3; P < 0.001). Minutes of moderate-to-vigorous physical activity accumulated in school accounted for 29.4 ± 9.8% of total weekly moderate-to-vigorous physical activity overall but varied by sector (preschool: 37.4 ± 6.2%; primary: 33.6 ± 8.1%; secondary: 23.0 ± 9.3%; F = 114.3, P < 0.001). Approximately half of the children with the lowest in-school activity compensated out of school during the week (47.4%) and about one-third at the weekend (30.0%). Overall, physical activity during the school day appears to be lower than that out of school, especially in secondary school children, who accumulate a lower proportion of their total weekly moderate-to-vigorous physical activity at school than younger children. As low in-school activity was compensated for beyond the school setting by less than half of children, promoting physical activity within the school day is important, especially in secondary schools.     

Daily physical activity and sports participation among children from ethnic minorities in Denmark

Abstract

The purpose of this study was to investigate whether Danish children from immigrant backgrounds are less physically active than children from the ethnic majority, and to investigate the possible reasons for any differences found. Accelerometer measures of physical activity as well as questionnaire data about organised sports, family demography, resources and values were collected from 594 children of whom 67 had other ethnic background than Danish. Data were collected when the children were 6–7 years old and again later when the children were 9–10 years old. It was found that children from immigrant backgrounds were not less physically active than other children when their amounts of daily physical activity were measured by direct objective measures, despite their participation rate in organised sports being much lower. Using multiple logistic regression modelling, this study showed that lack of parental experience with organised sports and lack of economic/material resources explained much of the difference in sports participation. Children of immigrant background had significant lower participation in club sports but this did not affect their overall physical activity level.     

Relationship between school rhythm and physical activity in adolescents: the HELENA study

The aim was to assess the relationship between school rhythm and physical activity (PA) in adolescents. The study included 2024 adolescents (12.5–17.4 years). Participants wore an accelerometer for 7 days. A short school rhythm was defined as a short time at school with short recesses and less time in teaching per day (Group 1). A long school rhythm was defined as a longer time at school with more time in teaching and recess (Group 2). Adolescents in Group 1 performed less moderate to vigorous PA (MVPA) than those in Group 2 per week (P < .0001), especially during school days (recess: 3.9 ± 4.0 vs. 9.8 ± 7.9 min · day^?1; P < .0001; teaching hours: 14.5 ± 9.8 vs. 19.1 ± 12.0 min · day^?1; P < .0001). Adolescents in Group 1 were less likely to meet the PA recommendations than were adolescents in Group 2: 30.7% vs. 34.1% (P < .0001). During school days, the percentage of adolescents who spent more than 2 h · day^?1 in sedentary activities was greater in the Group 1 (P < .001). Our results suggest that leisure-time out-of-school hours is used mainly for sedentary activities, and that school time provides a good opportunity for promoting PA.