Differences in sex-typed behaviour, including physical activity, are already apparent among presc... more Differences in sex-typed behaviour, including physical activity, are already apparent among preschool children. To examine the associations between early sex-typed behaviour and later physical activity. Children from the Avon Longitudinal Study of Parents and Children were asked to wear an accelerometer for 7 days at age 12. Physical activity outcomes were counts per minute (counts/min) and minutes of moderate to vigorous physical activity (MVPA). Sex-typed behaviour was assessed using the Pre-School Activities Inventory (PSAI) at age 3(1/2). Multivariable regression was used to examine the association between PSAI and physical activity, separately for boys and girls. Accelerometer data were collected from 2593 boys and 2858 girls, mean (SD) age 11.8 (0.23) years. A one point higher PSAI score (mean (SD) 61.7 (8.7) and 37.0 (9.1) for boys and girls, respectively) was associated with a higher level of physical activity (counts/min) of 2.3 (95% CI 0.9 to 3.7) in boys and 0.7 (95% CI -0.1 to 1.4) in girls. This is equivalent to a higher counts/min of 56.7 (95% CI 23.1 to 90.3) and 16.6 (95% CI -2.4 to 35.5) for boys and girls, respectively, for a higher PSAI score equivalent to the difference between boys and girls (24.7). Results for MVPA were similar. Higher male-typical behaviour in early childhood is associated with higher physical activity in early adolescence, particularly in boys.
Objective To examine factors in early life (up to age 5 years) that are associated with objective... more Objective To examine factors in early life (up to age 5 years) that are associated with objectively measured physical activity in 11-12 year olds. Design Prospective cohort study. Setting Avon longitudinal study of parents and children, United Kingdom. Participants Children aged 11-12 years from the Avon longitudinal study of parents and children. Main outcome measure Physical activity levels in counts per minute (cpm) and minutes of moderate to vigorous physical activity for seven days measured with a uniaxial actigraph accelerometer. Results Valid actigraph data, defined as at least three days of physical activity for at least 10 hours a day, were collected from 5451 children. Several factors were associated with physical activity at ages 11-12 years. Regression coefficients are compared with the baseline of "none" for categorical variables: maternal brisk walking during pregnancy (regression coefficient 5.0, 95% confidence interval −8.5 to 18.5; cpm for <1 h/wk and ≥2 h/wk of physical activity 17.7, 5.3 to 30.1), maternal swimming during pregnancy (21.5, 10.9 to 32.1 and cpm for <1 h/wk and ≥2 h/wk of physical activity 24.2, 7.8 to 40.7), parents' physical activity when the child was aged 21 months (28.5, 15.2 to 41.8 and cpm of physical activity for either parent active and both parents active 33.5, 17.8 to 49.3), and parity assessed during pregnancy (2.9, −7.6 to 13.4 and cpm of physical activity for 1 and ≥2 parity 21.2, 7.1 to 35.3). Conclusions Few factors in early life predicted later physical activity in 11-12 year olds. Parents' physical activity during pregnancy and early in the child's life showed a modest association with physical activity of the child at age 11-12 years, suggesting that active parents tend to raise active children. Helping parents to increase their physical activity therefore may promote children's activity.
We examined the influence of habitual levels of physical activity on bone mass in childhood by st... more We examined the influence of habitual levels of physical activity on bone mass in childhood by studying the relationship between accelerometer recordings and DXA parameters in 4457 11-yearold children. Physical activity was positively related to both BMD and bone size in fully adjusted models. However, further exploration revealed that this effect on bone size was modified by fat mass. Introduction-Exercise interventions have been reported to increase bone mass in children, but it is unclear whether levels of habitual physical activity also influence skeletal development. Materials and Methods-We used multivariable linear regression to analyze associations between amount of moderate and vigorous physical activity (MVPA), derived from accelerometer recordings for a minimum of 3 days, and parameters obtained from total body DXA scans in 4457 11-year-old boys and girls from the Avon Longitudinal Study of Parents and Children. The influence of different activity intensities was also studied by stratification based on lower and higher accelerometer cut-points for moderate (3600 counts/minute) and vigorous (6200 counts/ minute) activity, respectively. Results-MVPA was positively associated with lower limb BMD and BMC adjusted for bone area (aBMC; p < 0.001, adjusted for age, sex, socioeconomic factors, and height, with or without additional adjustment for lean and fat mass). MVPA was inversely related to lower limb bone area after adjusting for height and lean mass (p = 0.01), whereas a positive association was observed when fat mass was also adjusted for (p < 0.001). Lower limb BMC was positively related to MVPA after adjusting for height and lean and fat mass (p < 0.001), whereas little relationship was observed after adjusting for height and lean mass alone (p = 0.1). On multivariable regression analysis using the fully adjusted model, moderate activity exerted a stronger influence on lower limb BMC compared with light activity (light activity: 2.9 [1.2-4.7, p = 0.001]; moderate activity: 13.1 [10.6-15.5, p < 0.001]; regression coefficients with 95% confidence intervals and p values). Conclusions-Habitual levels of physical activity in 11-year-old children are related to bone size and BMD, with moderate activity exerting the strongest influence. The effect on bone size (as reflected by DXA-based measures of bone area) was modified by adjustment for fat mass, such
Clinical Medicine Insights Pediatrics, Nov 5, 2008
Advances in technology have improved our ability to measure physical activity in free-living huma... more Advances in technology have improved our ability to measure physical activity in free-living humans. In the last few years, several large epidemiological studies in Europe and the United States have used accelerometers to assess physical activity in children and adolescents. The use of accelerometers to study physical activity has presented some challenges on how to summarise and interpret the data that they generate, however these studies are providing important information on the levels and patterns of physical activity among children and adolescents. Some studies have reported that few children and adolescents appear to meet the recommended minimum of 60 minutes of moderate to vigorous activity per day. Accelerometers have also allowed examination of the relationships between physical activity and health outcomes like obesity and other chronic disease risk factors such as insulin resistance, aerobic fi tness, blood lipids and blood pressure. Use of accelerometers allows such relationships to be estimated with a precision that was previously impossible with self-report measures of physical activity. Such information is already advancing our understanding of the role that physical activity plays in preventing childhood obesity and cardiovascular disease risk.
Physical inactivity during childhood and adolescence is a serious health concern. There are few s... more Physical inactivity during childhood and adolescence is a serious health concern. There are few studies of the activity undertaken by adolescents when walking with the family dog, and the effect of this on objectively measured physical activity levels. Objective measures of physical activity using accelerometers were recorded at age 11-12, 13-14, and 15-16 years in the Avon Longitudinal Study of Parents and Children (ALSPAC) (ALSPAC, UK) birth cohort during the 2000s. Family pet ownership was collected retrospectively using a questionnaire at age 18 years, for the ages 7, 11, 13, and 15 years. In addition, approximate frequency per week of walks undertaken with dogs were also reported. Multilevel, multivariable modeling was used to investigate the relationship between dog ownership and dog walking status, and physical activity outcomes. There were a total of 4,373 complete data observations for use in 2,055 children. Reported participation in dog walking tended to increase during ad...
Statistical methods in medical research, Jan 17, 2015
Accelerometers are widely used in health sciences, ecology and other application areas. They quan... more Accelerometers are widely used in health sciences, ecology and other application areas. They quantify the intensity of physical activity as counts per epoch over a given period of time. Currently, health scientists use very lossy summaries of the accelerometer time series, some of which are based on coarse discretisation of activity levels, and make certain implicit assumptions, including linear or constant effects of physical activity. We propose the histogram as a functional summary for achieving a near lossless dimension reduction, comparability between individual time series and easy interpretability. Using the histogram as a functional summary avoids registration of accelerometer counts in time. In our novel method, a scalar response is regressed on additive multi-dimensional functional predictors, including the histogram of the high-frequency counts, and additive non-linear predictors for other continuous covariates. The method improves on the current state-of-the art, as it c...
There is a paucity of prospective evidence examining the links between sedentary time (ST) and ca... more There is a paucity of prospective evidence examining the links between sedentary time (ST) and cardiometabolic outcomes in youth. We examined the associations between objectively assessed ST and moderate to vigorous physical activity (MVPA) in childhood with cardiometabolic risk in adolescence. The study included 4639 children (47% male) aged 11 to 12 years at baseline whose mothers were enrolled in ALSPAC (Avon Longitudinal Study of Parents and Children) during their pregnancy in the early 1990s. A total of 2963 children had valid blood samples at age 15 to 16 years. Associations with baseline ST and MVPA were examined for BMI, waist circumference, body fat mass, lean body mass, systolic and diastolic blood pressure, fasting triglycerides, total cholesterol, low-density lipoprotein and high-density lipoprotein (HDL) cholesterol, glucose, insulin, C-reactive protein, and a clustered standardized cardiometabolic risk score (CMscore). Baseline ST was not associated deleteriously with ...
The aim of the current study was to test the hypothesis that children with probable Developmental... more The aim of the current study was to test the hypothesis that children with probable Developmental Coordination Disorder have an increased risk of reduced moderate to vigorous physical activity (MVPA), using data from a large population based study. Prospectively collected data from 4331 children (boys=2065, girls=2266) who had completed motor coordination testing at 7 years and accelerometry at 12 years were analysed from the Avon Longitudinal Study of Parents and Children (ALSPAC). Probable DCD (p-DCD) was defined, using criteria based on the DSM IV classification, as those children below the 15th centile of the ALSPAC Coordination Test at seven years who had a functional impairment in activities of daily living or handwriting, excluding children with a known neurological diagnosis or IQ<70. Secondary exposure variables consisted of subtests from the ALSPAC Coordination test (manual dexterity, ball skills and balance). Objective measurement of the average daily minutes of MVPA w...
Physical activity during the first three decades of life may increase peak bone mass and reduce f... more Physical activity during the first three decades of life may increase peak bone mass and reduce future osteoporosis risk. The aim of this study was to determine the extent to which different components of physical activity may influence bone mineral status within a representative population sample of young men and women. Bone mineral density (BMD) and content (BMC) were determined at the lumbar spine and femoral neck in 242 men and 212 women, aged 20-25 years, by dual-energy X-ray absorptiometry. Physical activity was assessed by a self-report questionnaire designed to measure the frequency and duration of physical activity and its components (i.e., work, non-sports leisure, sports-related activities, and peak strain sports activities). Potential confounding factors such as height, weight, diet, and smoking habits were also assessed. In multivariate linear regression models, sports activity and peak strain sports activity undertaken by men were strongly associated with both lumbar spine BMD (beta = 0.35 [0.21, 0.49] and beta = 0.31 [0.17, 0.44], respectively) and BMC (beta = 0.33 [0.21, 0.45] and beta = 0.26 [0.14, 0.38], respectively) and femoral neck BMD (beta = 0.35 [0.21, 0.48] and beta = 0.27 [0.14, 0.40], respectively) and BMC (beta = 0.32 [0.19, 0.44] and beta = 0.29 [0.17, 0.41], respectively) (all p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01), but work and non-sports leisure activities were not. In women, there were no associations between bone measurements and any component of physical activity. In models involving all subjects the gender/sports activity, but not the gender/peak strain, interaction term was statistically significant. Sports activity explained 10.4% of the observed variance in lumbar spine BMD in men, but &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;1% in women. These results demonstrate the importance of sports activities, especially those involving high peak strain, in determining peak bone status in young men. Failure to observe this association in women reflects their lower participation in such activities, but they may have the same capacity to benefit from these activities as men. Intervention studies are warranted to determine whether peak bone density in women can be improved by participating, during childhood and adolescence, in sports activities involving high peak strain.
Differences in sex-typed behaviour, including physical activity, are already apparent among presc... more Differences in sex-typed behaviour, including physical activity, are already apparent among preschool children. To examine the associations between early sex-typed behaviour and later physical activity. Children from the Avon Longitudinal Study of Parents and Children were asked to wear an accelerometer for 7 days at age 12. Physical activity outcomes were counts per minute (counts/min) and minutes of moderate to vigorous physical activity (MVPA). Sex-typed behaviour was assessed using the Pre-School Activities Inventory (PSAI) at age 3(1/2). Multivariable regression was used to examine the association between PSAI and physical activity, separately for boys and girls. Accelerometer data were collected from 2593 boys and 2858 girls, mean (SD) age 11.8 (0.23) years. A one point higher PSAI score (mean (SD) 61.7 (8.7) and 37.0 (9.1) for boys and girls, respectively) was associated with a higher level of physical activity (counts/min) of 2.3 (95% CI 0.9 to 3.7) in boys and 0.7 (95% CI -0.1 to 1.4) in girls. This is equivalent to a higher counts/min of 56.7 (95% CI 23.1 to 90.3) and 16.6 (95% CI -2.4 to 35.5) for boys and girls, respectively, for a higher PSAI score equivalent to the difference between boys and girls (24.7). Results for MVPA were similar. Higher male-typical behaviour in early childhood is associated with higher physical activity in early adolescence, particularly in boys.
Objective To examine factors in early life (up to age 5 years) that are associated with objective... more Objective To examine factors in early life (up to age 5 years) that are associated with objectively measured physical activity in 11-12 year olds. Design Prospective cohort study. Setting Avon longitudinal study of parents and children, United Kingdom. Participants Children aged 11-12 years from the Avon longitudinal study of parents and children. Main outcome measure Physical activity levels in counts per minute (cpm) and minutes of moderate to vigorous physical activity for seven days measured with a uniaxial actigraph accelerometer. Results Valid actigraph data, defined as at least three days of physical activity for at least 10 hours a day, were collected from 5451 children. Several factors were associated with physical activity at ages 11-12 years. Regression coefficients are compared with the baseline of "none" for categorical variables: maternal brisk walking during pregnancy (regression coefficient 5.0, 95% confidence interval −8.5 to 18.5; cpm for <1 h/wk and ≥2 h/wk of physical activity 17.7, 5.3 to 30.1), maternal swimming during pregnancy (21.5, 10.9 to 32.1 and cpm for <1 h/wk and ≥2 h/wk of physical activity 24.2, 7.8 to 40.7), parents' physical activity when the child was aged 21 months (28.5, 15.2 to 41.8 and cpm of physical activity for either parent active and both parents active 33.5, 17.8 to 49.3), and parity assessed during pregnancy (2.9, −7.6 to 13.4 and cpm of physical activity for 1 and ≥2 parity 21.2, 7.1 to 35.3). Conclusions Few factors in early life predicted later physical activity in 11-12 year olds. Parents' physical activity during pregnancy and early in the child's life showed a modest association with physical activity of the child at age 11-12 years, suggesting that active parents tend to raise active children. Helping parents to increase their physical activity therefore may promote children's activity.
We examined the influence of habitual levels of physical activity on bone mass in childhood by st... more We examined the influence of habitual levels of physical activity on bone mass in childhood by studying the relationship between accelerometer recordings and DXA parameters in 4457 11-yearold children. Physical activity was positively related to both BMD and bone size in fully adjusted models. However, further exploration revealed that this effect on bone size was modified by fat mass. Introduction-Exercise interventions have been reported to increase bone mass in children, but it is unclear whether levels of habitual physical activity also influence skeletal development. Materials and Methods-We used multivariable linear regression to analyze associations between amount of moderate and vigorous physical activity (MVPA), derived from accelerometer recordings for a minimum of 3 days, and parameters obtained from total body DXA scans in 4457 11-year-old boys and girls from the Avon Longitudinal Study of Parents and Children. The influence of different activity intensities was also studied by stratification based on lower and higher accelerometer cut-points for moderate (3600 counts/minute) and vigorous (6200 counts/ minute) activity, respectively. Results-MVPA was positively associated with lower limb BMD and BMC adjusted for bone area (aBMC; p < 0.001, adjusted for age, sex, socioeconomic factors, and height, with or without additional adjustment for lean and fat mass). MVPA was inversely related to lower limb bone area after adjusting for height and lean mass (p = 0.01), whereas a positive association was observed when fat mass was also adjusted for (p < 0.001). Lower limb BMC was positively related to MVPA after adjusting for height and lean and fat mass (p < 0.001), whereas little relationship was observed after adjusting for height and lean mass alone (p = 0.1). On multivariable regression analysis using the fully adjusted model, moderate activity exerted a stronger influence on lower limb BMC compared with light activity (light activity: 2.9 [1.2-4.7, p = 0.001]; moderate activity: 13.1 [10.6-15.5, p < 0.001]; regression coefficients with 95% confidence intervals and p values). Conclusions-Habitual levels of physical activity in 11-year-old children are related to bone size and BMD, with moderate activity exerting the strongest influence. The effect on bone size (as reflected by DXA-based measures of bone area) was modified by adjustment for fat mass, such
Clinical Medicine Insights Pediatrics, Nov 5, 2008
Advances in technology have improved our ability to measure physical activity in free-living huma... more Advances in technology have improved our ability to measure physical activity in free-living humans. In the last few years, several large epidemiological studies in Europe and the United States have used accelerometers to assess physical activity in children and adolescents. The use of accelerometers to study physical activity has presented some challenges on how to summarise and interpret the data that they generate, however these studies are providing important information on the levels and patterns of physical activity among children and adolescents. Some studies have reported that few children and adolescents appear to meet the recommended minimum of 60 minutes of moderate to vigorous activity per day. Accelerometers have also allowed examination of the relationships between physical activity and health outcomes like obesity and other chronic disease risk factors such as insulin resistance, aerobic fi tness, blood lipids and blood pressure. Use of accelerometers allows such relationships to be estimated with a precision that was previously impossible with self-report measures of physical activity. Such information is already advancing our understanding of the role that physical activity plays in preventing childhood obesity and cardiovascular disease risk.
Physical inactivity during childhood and adolescence is a serious health concern. There are few s... more Physical inactivity during childhood and adolescence is a serious health concern. There are few studies of the activity undertaken by adolescents when walking with the family dog, and the effect of this on objectively measured physical activity levels. Objective measures of physical activity using accelerometers were recorded at age 11-12, 13-14, and 15-16 years in the Avon Longitudinal Study of Parents and Children (ALSPAC) (ALSPAC, UK) birth cohort during the 2000s. Family pet ownership was collected retrospectively using a questionnaire at age 18 years, for the ages 7, 11, 13, and 15 years. In addition, approximate frequency per week of walks undertaken with dogs were also reported. Multilevel, multivariable modeling was used to investigate the relationship between dog ownership and dog walking status, and physical activity outcomes. There were a total of 4,373 complete data observations for use in 2,055 children. Reported participation in dog walking tended to increase during ad...
Statistical methods in medical research, Jan 17, 2015
Accelerometers are widely used in health sciences, ecology and other application areas. They quan... more Accelerometers are widely used in health sciences, ecology and other application areas. They quantify the intensity of physical activity as counts per epoch over a given period of time. Currently, health scientists use very lossy summaries of the accelerometer time series, some of which are based on coarse discretisation of activity levels, and make certain implicit assumptions, including linear or constant effects of physical activity. We propose the histogram as a functional summary for achieving a near lossless dimension reduction, comparability between individual time series and easy interpretability. Using the histogram as a functional summary avoids registration of accelerometer counts in time. In our novel method, a scalar response is regressed on additive multi-dimensional functional predictors, including the histogram of the high-frequency counts, and additive non-linear predictors for other continuous covariates. The method improves on the current state-of-the art, as it c...
There is a paucity of prospective evidence examining the links between sedentary time (ST) and ca... more There is a paucity of prospective evidence examining the links between sedentary time (ST) and cardiometabolic outcomes in youth. We examined the associations between objectively assessed ST and moderate to vigorous physical activity (MVPA) in childhood with cardiometabolic risk in adolescence. The study included 4639 children (47% male) aged 11 to 12 years at baseline whose mothers were enrolled in ALSPAC (Avon Longitudinal Study of Parents and Children) during their pregnancy in the early 1990s. A total of 2963 children had valid blood samples at age 15 to 16 years. Associations with baseline ST and MVPA were examined for BMI, waist circumference, body fat mass, lean body mass, systolic and diastolic blood pressure, fasting triglycerides, total cholesterol, low-density lipoprotein and high-density lipoprotein (HDL) cholesterol, glucose, insulin, C-reactive protein, and a clustered standardized cardiometabolic risk score (CMscore). Baseline ST was not associated deleteriously with ...
The aim of the current study was to test the hypothesis that children with probable Developmental... more The aim of the current study was to test the hypothesis that children with probable Developmental Coordination Disorder have an increased risk of reduced moderate to vigorous physical activity (MVPA), using data from a large population based study. Prospectively collected data from 4331 children (boys=2065, girls=2266) who had completed motor coordination testing at 7 years and accelerometry at 12 years were analysed from the Avon Longitudinal Study of Parents and Children (ALSPAC). Probable DCD (p-DCD) was defined, using criteria based on the DSM IV classification, as those children below the 15th centile of the ALSPAC Coordination Test at seven years who had a functional impairment in activities of daily living or handwriting, excluding children with a known neurological diagnosis or IQ<70. Secondary exposure variables consisted of subtests from the ALSPAC Coordination test (manual dexterity, ball skills and balance). Objective measurement of the average daily minutes of MVPA w...
Physical activity during the first three decades of life may increase peak bone mass and reduce f... more Physical activity during the first three decades of life may increase peak bone mass and reduce future osteoporosis risk. The aim of this study was to determine the extent to which different components of physical activity may influence bone mineral status within a representative population sample of young men and women. Bone mineral density (BMD) and content (BMC) were determined at the lumbar spine and femoral neck in 242 men and 212 women, aged 20-25 years, by dual-energy X-ray absorptiometry. Physical activity was assessed by a self-report questionnaire designed to measure the frequency and duration of physical activity and its components (i.e., work, non-sports leisure, sports-related activities, and peak strain sports activities). Potential confounding factors such as height, weight, diet, and smoking habits were also assessed. In multivariate linear regression models, sports activity and peak strain sports activity undertaken by men were strongly associated with both lumbar spine BMD (beta = 0.35 [0.21, 0.49] and beta = 0.31 [0.17, 0.44], respectively) and BMC (beta = 0.33 [0.21, 0.45] and beta = 0.26 [0.14, 0.38], respectively) and femoral neck BMD (beta = 0.35 [0.21, 0.48] and beta = 0.27 [0.14, 0.40], respectively) and BMC (beta = 0.32 [0.19, 0.44] and beta = 0.29 [0.17, 0.41], respectively) (all p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01), but work and non-sports leisure activities were not. In women, there were no associations between bone measurements and any component of physical activity. In models involving all subjects the gender/sports activity, but not the gender/peak strain, interaction term was statistically significant. Sports activity explained 10.4% of the observed variance in lumbar spine BMD in men, but &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;1% in women. These results demonstrate the importance of sports activities, especially those involving high peak strain, in determining peak bone status in young men. Failure to observe this association in women reflects their lower participation in such activities, but they may have the same capacity to benefit from these activities as men. Intervention studies are warranted to determine whether peak bone density in women can be improved by participating, during childhood and adolescence, in sports activities involving high peak strain.
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