Contribution of the After-School Period to Children’s Daily Participation in Physical Activity and Sedentary Behaviours

ObjectivesChildren’s after-school physical activity (PA) and sedentary behaviours (SB) are not well understood, despite the potential this period holds for intervention. This study aimed to describe children’s after-school physical activity and sedentary behaviours; establish the contribution this makes to daily participation and to achieving physical activity and sedentary behaviours guidelines; and to determine the association between after-school moderate- to vigorous-intensity physical activity (MVPA), screen-based sedentary behaviours and achieving the physical activity and sedentary behaviour guidelines.MethodsChildren (n = 406, mean age 8.1 years, 58% girls) wore an ActiGraph GT3X accelerometer. The percentage of time and minutes spent sedentary (SED), in light- physical activity (LPA) and MVPA between the end-of-school and 6pm (weekdays) was calculated. Parents (n = 318, 40 years, 89% female) proxy-reported their child’s after-school participation in screen-based sedentary behaviours. The contribution that after-school SED, LPA, MVPA, and screen-based sedentary behaviours made to daily levels, and that after-school MVPA and screen-based sedentary behaviours made to achieving the physical activity/sedentary behaviour guidelines was calculated. Regression analysis determined the association between after-school MVPA and screen-based sedentary behaviours and achieving the physical activity/sedentary behaviours guidelines.ResultsChildren spent 54% of the after-school period SED, and this accounted for 21% of children’s daily SED levels. Boys spent a greater percentage of time in MVPA than girls (14.9% vs. 13.6%; p<0.05), but this made a smaller contribution to their daily levels (27.6% vs 29.8%; p<0.05). After school, boys and girls respectively performed 18.8 minutes and 16.7 minutes of MVPA, which is 31.4% and 27.8% of the MVPA (p<0.05) required to achieve the physical activity guidelines. Children spent 96 minutes in screen-based sedentary behaviours, contributing to 84% of their daily screen-based sedentary behaviours and 80% of the sedentary behaviour guidelines. After-school MVPA was positively associated with achieving the physical activity guidelines (OR: 1.31, 95%CI 1.18, 1.44, p<0.05), and after-school screen-based sedentary behaviours were negatively associated with achieving the sedentary behaviours guidelines (OR: 0.97, 95%CI: 0.96, 0.97, p<0.05).ConclusionsThe after-school period plays a critical role in the accumulation of children’s physical activity and sedentary behaviours. Small changes to after-school behaviours can have large impacts on children’s daily behaviours levels and likelihood of meeting the recommended levels of physical activity and sedentary behaviour. Therefore interventions should target reducing after-school sedentary behaviours and increasing physical activity.     

Association of physical activity intensity and bout length with mortality: An observational study of 79,503 UK Biobank participants

BackgroundSpending more time active (and less sedentary) is associated with health benefits such as improved cardiovascular health and lower risk of all-cause mortality. It is unclear whether these associations differ depending on whether time spent sedentary or in moderate-vigorous physical activity (MVPA) is accumulated in long or short bouts. In this study, we used a novel method that accounts for substitution (i.e., more time in MVPA means less time sleeping, in light activity or sedentary) to examine whether length of sedentary and MVPA bouts associates with all-cause mortality.Methods and findingsWe used data on 79,503 adult participants from the population-based UK Biobank cohort, which recruited participants between 2006 and 2010 (mean age at accelerometer wear 62.1 years [SD = 7.9], 54.5% women; mean length of follow-up 5.1 years [SD = 0.73]). We derived (1) the total time participants spent in activity categories—sleep, sedentary, light activity, and MVPA—on average per day; (2) time spent in sedentary bouts of short (1 to 15 minutes), medium (16 to 40 minutes), and long (41+ minutes) duration; and (3) MVPA bouts of very short (1 to 9 minutes), short (10 to 15 minutes), medium (16 to 40 minutes), and long (41+ minutes) duration. We used Cox proportion hazards regression to estimate the association of spending 10 minutes more average daily time in one activity or bout length category, coupled with 10 minutes less time in another, with all-cause mortality. Those spending more time in MVPA had lower mortality risk, irrespective of whether this replaced time spent sleeping, sedentary, or in light activity, and these associations were of similar magnitude (e.g., hazard ratio [HR] 0.96 [95% CI: 0.94, 0.97; P < 0.001] per 10 minutes more MVPA, coupled with 10 minutes less light activity per day). Those spending more time sedentary had higher mortality risk if this replaced light activity (HR 1.02 [95% CI: 1.01, 1.02; P < 0.001] per 10 minutes more sedentary time, with 10 minutes less light activity per day) and an even higher risk if this replaced MVPA (HR 1.06 [95% CI: 1.05, 1.08; P < 0.001] per 10 minutes more sedentary time, with 10 minutes less MVPA per day). We found little evidence that mortality risk differed depending on the length of sedentary or MVPA bouts. Key limitations of our study are potential residual confounding, the limited length of follow-up, and use of a select sample of the United Kingdom population.ConclusionsWe have shown that time spent in MVPA was associated with lower mortality, irrespective of whether it replaced time spent sleeping, sedentary, or in light activity. Time spent sedentary was associated with higher mortality risk, particularly if it replaced MVPA. This emphasises the specific importance of MVPA. Our findings suggest that the impact of MVPA does not differ depending on whether it is obtained from several short bouts or fewer longer bouts, supporting the recent removal of the requirement that MVPA should be accumulated in bouts of 10 minutes or more from the UK and the United States policy. Further studies are needed to investigate causality and explore health outcomes beyond mortality.

Louise Millard and co-workers study associations between bouts of moderate-to-vigorous physical activity and mortality.     

Association between Dietary Fiber Intake and Physical Performance in Older Adults: A Nationwide Study in Taiwan

Background

Physical performance is a major determinant of health in older adults, and is related to lifestyle factors. Dietary fiber has multiple health benefits. It remains unclear whether fiber intake is independently linked to superior physical performance. We aimed to assess the association between dietary fiber and physical performance in older adults.

Methods

This was a cross-sectional study conducted with community-dwelling adults aged 55 years and older (n=2680) from the ongoing Healthy Aging Longitudinal Study (HALST) in Taiwan 2008-2010. Daily dietary fiber intake was assessed using a validated food frequency questionnaire. Physical performance was determined objectively by measuring gait speed, 6-minute walk distance, timed “up and go” (TUG), summary performance score, hand grip strength.

Results

Adjusting for all potential confounders, participants with higher fiber intake had significantly faster gait speed, longer 6-minute walk distance, faster TUG, higher summary performance score, and higher hand grip strength (all P <.05). Comparing with the highest quartile of fiber intake, the lowest quartile of fiber intake was significantly associated with the lowest sex-specific quartile of gait speed (adjusted OR, 2.18 in men [95% CI, 1.33-3.55] and 3.65 in women [95% CI, 2.20-6.05]), 6-minute walk distance (OR, 2.40 in men [95% CI, 1.38-4.17] and 4.32 in women [95% CI, 2.37-7.89]), TUG (OR, 2.42 in men [95% CI, 1.43-4.12] and 3.27 in women [95% CI, 1.94-5.52]), summary performance score (OR, 2.12 in men [95% CI, 1.19-3.78] and 5.47 in women [95% CI, 3.20-9.35]), and hand grip strength (OR, 2.64 in men [95% CI, 1.61-4.32] and 4.43 in women [95% CI, 2.62-7.50]).

Conclusions

Dietary fiber intake was independently associated with better physical performance.     

Physical activity, sedentary time, and pericardial fat in healthy older adults

Pericardial fat is emerging as a unique risk factor for coronary disease. We examined the relationship between objectively measured physical activity during free-living and pericardial fat. Participants were 446 healthy men and women (mean age = 66 ± 6 years), without history or objective signs of cardiovascular disease (CVD), drawn from the Whitehall II epidemiological cohort. Physical activity was objectively measured using accelerometers (Actigraph GT3X) worn around the hip during waking hours for 7 consecutive days (average daily wear time = 889 ± 68 min/day), and was classified as sedentary (<200 counts/min (cpm)), light (200-1,998 cpm), or moderate-vigorous physical activity (MVPA; ≥1,999 cpm). Pericardial fat volume was measured in each participant using electron beam computed tomography. Average daily cpm in men was 338.0 ± 145.0 and in women 303.8 ± 130.2. There was an inverse association between average cpm and pericardial fat (B = -0.070, 95% confidence interval (CI), -0.101, -0.040, P < 0.001), and this remained significant after adjusting for age, sex, registered wear time, BMI, lipids, glycemic control, blood pressure, smoking, statins, and social status. Both sedentary time (B = 0.081, 95% CI, 0.022, 0.14) and MVPA (B = -0.362, 95% CI, -0.527, -0.197) were also associated with pericardial fat, although associations for sedentary time did not remain significant after adjustment for MVPA. The inverse association between physical activity and pericardial fat was stronger among overweight and obese adults than in normal weight. Objectively assessed daily activity levels are related to pericardial fat in healthy participants, independently of BMI. This might be an important mechanism in explaining the association between physical activity and CVD prevention.     

Screen-Based Sedentary Behavior,Physical Activity,and Muscle Strength in the English Longitudinal Study of Ageing

Background

Sarcopenia is associated with loss of independence and ill-health in the elderly although the causes remain poorly understood. We examined the association between two screen-based leisure time sedentary activities (daily TV viewing time and internet use) and muscle strength.

Methods and Results

We studied 6228 men and women (aged 64.9±9.1 yrs) from wave 4 (2008-09) of the English Longitudinal Study of Ageing, a prospective study of community dwelling older adults. Muscle strength was assessed by a hand grip test and the time required to complete five chair rises. TV viewing and internet usage were inversely associated with one another. Participants viewing TV ≥6hrs/d had lower grip strength (Men, B = −1.20 kg, 95% CI, −2.26, −0.14; Women, −0.75 kg, 95% CI, −1.48, −0.03) in comparison to <2hrs/d TV, after adjustment for age, physical activity, smoking, alcohol, chronic disease, disability, depressive symptoms, social status, and body mass index. In contrast, internet use was associated with higher grip strength (Men, B = 2.43 kg, 95% CI, 1.74, 3.12; Women, 0.76 kg, 95% CI, 0.32, 1.20). These associations persisted after mutual adjustment for both types of sedentary behaviour.

Conclusions

In older adults, the association between sedentary activities and physical function is context specific (TV viewing vs. computer use). Adverse effects of TV viewing might reflect the prolonged sedentary nature of this behavior.     

Feasibility and Inter-Rater Reliability of Physical Performance Measures in Acutely Admitted Older Medical Patients

ObjectivePhysical performance measures can be used to predict functional decline and increased dependency in older persons. However, few studies have assessed the feasibility or reliability of such measures in hospitalized older patients. Here we assessed the feasibility and inter-rater reliability of four simple measures of physical performance in acutely admitted older medical patients.DesignDuring the first 24 hours of hospitalization, the following were assessed twice by different raters in 52 (≥ 65 years) patients admitted for acute medical illness: isometric hand grip strength, 4-meter gait speed, 30-s chair stand and Cumulated Ambulation Score. Relative reliability was expressed as weighted kappa for the Cumulated Ambulation Score or as intra-class correlation coefficient (ICC_1,1) and lower limit of the 95%-confidence interval (LL_95%) for grip strength, gait speed, and 30-s chair stand. Absolute reliability was expressed as the standard error of measurement and the smallest real difference as a percentage of their respective means (SEM% and SRD%).ResultsThe primary reasons for admission of the 52 included patients were infectious disease and cardiovascular illness. The mean± SD age was 78±8.3 years, and 73.1% were women. All patients performed grip strength and Cumulated Ambulation Score testing, 81% performed the gait speed test, and 54% completed the 30-s chair stand test (46% were unable to rise without using the armrests). No systematic bias was found between first and second tests or between raters. The weighted kappa for the Cumulated Ambulation Score was 0.76 (0.60–0.92). The ICC1,1 values were as follows: grip strength, 0.95 (LL_95% 0.92); gait speed, 0.92 (LL_95% 0.73), and 30-s chair stand, 0.82 (LL_95% 0.67). The SEM% values for grip strength, gait speed, and 30-s chair stand were 8%, 7%, and 18%, and the SRD_95% values were 22%, 17%, and 49%.ConclusionIn acutely admitted older medical patients, grip strength, gait speed, and the Cumulated Ambulation Score measurements were feasible and showed high inter-rater reliability when administered by different raters. The feasibility and inter-rater reliability of the 30-s chair stand were moderate, complicating the use of the 30-s chair stand in acutely admitted older medical patients. However, the predefined modified version of the chair stand test was both feasible and with high inter-rater reliability in this population.     

Light Intensity Physical Activity and Sedentary Behavior in Relation to Body Mass Index and Grip Strength in Older Adults: Cross-Sectional Findings from the Lifestyle Interventions and Independence for Elders (LIFE) Study

BackgroundIdentifying modifiable determinants of fat mass and muscle strength in older adults is important given their impact on physical functioning and health. Light intensity physical activity and sedentary behavior are potential determinants, but their relations to these outcomes are poorly understood. We evaluated associations of light intensity physical activity and sedentary time—assessed both objectively and by self-report—with body mass index (BMI) and grip strength in a large sample of older adults.MethodsWe used cross-sectional baseline data from 1130 participants of the Lifestyle Interventions and Independence for Elders (LIFE) study, a community-dwelling sample of relatively sedentary older adults (70-89 years) at heightened risk of mobility disability. Time spent sedentary and in light intensity activity were assessed using an accelerometer worn for 3–7 days (Actigraph GT3X) and by self-report. Associations between these exposures and measured BMI and grip strength were evaluated using linear regression.ResultsGreater time spent in light intensity activity and lower sedentary times were both associated with lower BMI. This was evident using objective measures of lower-light intensity, and both objective and self-reported measures of higher-light intensity activity. Time spent watching television was positively associated with BMI, while reading and computer use were not. Greater time spent in higher but not lower intensities of light activity (assessed objectively) was associated with greater grip strength in men but not women, while neither objectively assessed nor self-reported sedentary time was associated with grip strength.ConclusionsIn this cross-sectional study, greater time spent in light intensity activity and lower sedentary times were associated with lower BMI. These results are consistent with the hypothesis that replacing sedentary activities with light intensity activities could lead to lower BMI levels and obesity prevalence among the population of older adults. However, longitudinal and experimental studies are needed to strengthen causal inferences.     

Associations of Objectively Assessed Physical Activity and Sedentary Time with All-Cause Mortality in US Adults: The NHANES Study

Background

Sedentary behavior is related to increased mortality risk. Whether such elevated risk can be offset by enhanced physical activity has not been examined using accelerometry data.

Materials and Methods

We examined the relations of sedentary time and physical activity to mortality from any cause using accelerometry data among 1,677 women and men aged 50 years or older from the National Health and Nutrition Examination Survey (NHANES) 2003–2004 cycle with follow-up through December 31, 2006.

Results

During an average follow-up of 34.67 months and 4,845.42 person-years, 112 deaths occurred. In multivariate Cox proportional hazard models, greater sedentary time (≥ median of 8.60 hours/day) was associated with increased risk of mortality from any cause (relative risk (RR) = 2.03; 95% confidence interval (CI) = 1.09-3.81). Low level of moderate to vigorous physical activity (< median of 6.60 minutes/day) was also related to enhanced all-cause mortality risk (RR = 3.30; 95% CI = 1.33-8.17). In combined analyses, greater time spent sedentary and low levels of moderate to vigorous physical activity predicted a substantially elevated all-cause mortality risk. As compared with the combination of a low sedentary level and a high level of moderate to vigorous physical activity, the risks of mortality from all causes were 4.38 (95% CI = 1.26-15.16) for low levels of both sedentary time and physical activity, 2.79 (95% CI = 0.77-10.12) for greater time spent sedentary and high physical activity level, and 7.79 (95% CI = 2.26-26.82) for greater time spent sedentary and low physical activity level. The interaction term between sedentary time and moderate to vigorous physical activity was not statistically significant (p = 0.508).

Conclusions

Both high levels of sedentary time and low levels of moderate to vigorous physical activity are strong and independent predictors of early death from any cause. Whether a high physical activity level removes the increased risk of all-cause mortality related to sedentariness requires further investigation.     

Moderate‐To‐vigorous physical activity is associated with decreases in body mass index from ages 9 to 15 years

Objective:

The purpose of this study is to determine whether time spent in objectively measured physical activity is associated with change in body mass index (BMI) from ages 9 to 15.

Design and Methods:

The participants were enrolled in the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development (n = 938). At ages 9, 11, 12, and 15 the time spent in moderate‐to‐vigorous physical activity (MVPA) was objectively measured, and BMI was calculated (kg/m²). Longitudinal quantile regression was used to analyze the data. The 10th, 25th, 50th, 75th, and 90th BMI percentiles were modeled as the dependent variables with age and MVPA (h/day) modeled as predictors. Adjustment was also made for gender, race, sleep, healthy eating score, maternal education, and sedentary behavior.

Results:

A negative association between MVPA and change in BMI was observed at the 90th BMI percentile (?3.57, 95% CI ?5.15 to ?1.99 kg/m² per hour of MVPA). The negative association between time spent in MVPA and change in BMI was progressively weaker toward the 10th BMI percentile (?0.27, 95% CI ?0.62 to 0.07 kg/m² per hour of MVPA). The associations remained similar after adjusting for the covariates, and when the analyses were stratified by gender.

Conclusion:

Time spent in MVPA was negatively associated with change in BMI from age 9 to 15. The association was strongest at the upper tail of the BMI distribution, and increasing time spent in MVPA could help reduce the prevalence of childhood obesity.

     

Does Birth Weight Influence Physical Activity in Youth? A Combined Analysis of Four Studies Using Objectively Measured Physical Activity

Animal models suggest growth restriction in utero leads to lower levels of motor activity. Furthermore, individuals with very low birth weight report lower levels of physical activity as adults. The aim of this study was to examine whether birth weight acts as a biological determinant of physical activity and sedentary time. This study uses combined analysis of three European cohorts and one from South America (n = 4,170). Birth weight was measured or parentally reported. Height and weight were measured and used to calculate Body Mass Index (BMI). PA was objectively measured using accelerometry for ≥3 days, ≥10 hours day. Data was standardized to allow comparisons between different monitors. Total physical activity was assessed as counts per minute (cpm), with time spent above moderate activity (MVPA) >2,000 counts and time spent sedentary (<100 counts). There was no evidence for an association between birth weight and total physical activity (p = 0.9) or MVPA (p = 0.7). Overall there was no evidence for an association between birth weight and sedentary time (p = 0.8). However in the Pelotas study we did find an association between higher birth weight (kg) and lower overall physical activity (cpm) (β = −31, 95%CI: −58, −46, p = 0.03) and higher birth weight and greater sedentary time (mins/day) (β = 16.4, 95%CI: 5.3, 27.5, p = 0.004), although this was attenuated and no longer significant with further adjustment for gestational age. Overall this combined analysis suggests that birth weight may not be an important biological determinant of habitual physical activity or sedentary behaviour in children and adolescents.     

Objectively measured sedentary behavior,physical activity,and plasma lipids in overweight and obese children

Objective:

This study examines the associations between objectively measured sedentary behavior, light physical activity (LPA), and moderate‐to‐vigorous physical activity (MVPA), and plasma lipids in overweight and obese children.

Design and Methods:

Cross‐sectional analyses were conducted among 126 children aged 5.5‐9.9 years. Sedentary behavior, LPA, and MVPA were assessed using accelerometry. Fasting blood samples were analyzed for plasma lipids (high‐density lipoprotein cholesterol [HDL‐C], low‐density lipoprotein cholesterol [LDL‐C], total cholesterol [TC], and triglycerides [TG]).

Results:

MVPA was not related to plasma lipids (P > 0.05). Independent of age, sex, energy intake, and waist circumference z‐score, sedentary behavior and LPA were associated with HDL‐C (β = ?0.23, 95% CI ?0.42 to ?0.04, P = 0.020; β = 0.20, 95% CI 0.14 to 0.39, P = 0.036, respectively). The strength of the associations remained after additionally adjusting for MVPA (sedentary behavior: β = ?0.22, 95% CI ?0.44 to 0.006, P = 0.056; LPA: β = 0.19, 95% CI ?0.005 to 0.38, P = 0.056, respectively).

Conclusion:

Substituting at least LPA for sedentary time may contribute to the development of healthy HDL‐C levels among overweight and obese children, independent of their adiposity. Comprehensive prevention and treatment strategies to improve plasma HDL‐C among overweight and obese children should target reductions in total sedentary time and promote the benefits of LPA, in addition to promoting healthy levels of adiposity, healthy dietary behaviors, and MVPA.

     

Effect of the PPARG2 Pro12Ala Polymorphism on Associations of Physical Activity and Sedentary Time with Markers of Insulin Sensitivity in Those with an Elevated Risk of Type 2 Diabetes

BackgroundPeroxisome proliferator-activated receptor gamma (PPARγ) is an important regulator of metabolic health and a common polymorphism in the PPAR-γ2 gene (PPARG2) may modify associations between lifestyle behaviour and health.ObjectiveTo investigate whether the PPARG2 Pro12Ala genotype modifies the associations of sedentary behaviour and moderate-to-vigorous intensity physical activity (MVPA) with common measures of insulin sensitivity.MethodsParticipants with a high risk of impaired glucose regulation were recruited, United Kingdom, 2010-2011. Sedentary and MVPA time were objectively measured using accelerometers. Fasting and 2-hour post-challenge insulin and glucose were assessed; insulin sensitivity was calculated using Matsuda-ISI and HOMA-IS. DNA was extracted from whole blood. Linear regression examined associations of sedentary time and MVPA with insulin sensitivity and examined interactions by PPARG2 Pro12Ala genotype.Results541 subjects were included (average age = 65 years, female = 33%); 18% carried the Ala12 allele. Both sedentary time and MVPA were strongly associated with HOMA-IS and Matsuda-ISI after adjustment for age, sex, ethnicity, medication, smoking status and accelerometer wear time. After further adjustment for each other and BMI, only associations with Matsuda-ISI were maintained. Every 30 minute difference in sedentary time was inversely associated with a 4% (0, 8%; p = 0.043) difference in Matsuda-ISI, whereas every 30 minutes in MVPA was positively associated with a 13% (0, 26%; p = 0.048) difference. The association of MVPA with Matsuda-ISI was modified by genotype (p = 0.005) and only maintained in Ala12 allele carriers. Conversely, sedentary time was not modified by genotype and remained inversely associated with insulin sensitivity in Pro12 allele homozygotes.ConclusionThe association of MVPA with Matsuda-ISI was modified by PPARG2 Pro12Ala genotype with significant associations only observed in the 18% of the population who carried the Ala12 allele, whereas associations with sedentary time were unaffected.     

Combined Effects of Time Spent in Physical Activity,Sedentary Behaviors and Sleep on Obesity and Cardio-Metabolic Health Markers: A Novel Compositional Data Analysis Approach

The associations between time spent in sleep, sedentary behaviors (SB) and physical activity with health are usually studied without taking into account that time is finite during the day, so time spent in each of these behaviors are codependent. Therefore, little is known about the combined effect of time spent in sleep, SB and physical activity, that together constitute a composite whole, on obesity and cardio-metabolic health markers. Cross-sectional analysis of NHANES 2005–6 cycle on N = 1937 adults, was undertaken using a compositional analysis paradigm, which accounts for this intrinsic codependence. Time spent in SB, light intensity (LIPA) and moderate to vigorous activity (MVPA) was determined from accelerometry and combined with self-reported sleep time to obtain the 24 hour time budget composition. The distribution of time spent in sleep, SB, LIPA and MVPA is significantly associated with BMI, waist circumference, triglycerides, plasma glucose, plasma insulin (all p<0.001), and systolic (p<0.001) and diastolic blood pressure (p<0.003), but not HDL or LDL. Within the composition, the strongest positive effect is found for the proportion of time spent in MVPA. Strikingly, the effects of MVPA replacing another behavior and of MVPA being displaced by another behavior are asymmetric. For example, re-allocating 10 minutes of SB to MVPA was associated with a lower waist circumference by 0.001% but if 10 minutes of MVPA is displaced by SB this was associated with a 0.84% higher waist circumference. The proportion of time spent in LIPA and SB were detrimentally associated with obesity and cardiovascular disease markers, but the association with SB was stronger. For diabetes risk markers, replacing SB with LIPA was associated with more favorable outcomes. Time spent in MVPA is an important target for intervention and preventing transfer of time from LIPA to SB might lessen the negative effects of physical inactivity.     

Correlates of reported and recorded time spent in physical activity in working adults: results from the commuting and health in cambridge study

Background

The correlates of physical activity in adults are relatively well studied. However, many studies use self-reported (‘reported’) measures of activity and we know little about the possible differences between the correlates of reported and objective (‘recorded’) measures of physical activity. We compared the correlates of reported and recorded time spent in moderate-to-vigorous physical activity (MVPA) in a sample of working adults.

Methods

In 2009, participants in the Commuting and Health in Cambridge study completed questionnaires assessing individual, socio-demographic, health and contextual characteristics. Recorded time spent in MVPA over seven days was ascertained using accelerometers and reported time spent in MVPA was assessed using the Recent Physical Activity Questionnaire (RPAQ). Correlates of MVPA were investigated using sex-specific linear regression models.

Results

486 participants (70% women) provided both reported and recorded physical activity data. 89% recorded at least 30 minutes of MVPA per day. In men, none of the potential explanatory variables were associated with both reported and recorded time spent in MVPA. In women, of all the potential explanatory variables only that of having a standing or manual occupation was associated with both reported (+42 min/day; 95% CI 16.4 to 68.4, p = 0.001) and recorded (+9 min/day; 95% CI: 3.5 to 15.7, p = 0.002) time spent in MVPA.

Discussion

The use of an objective measure of physical activity may influence the correlates which are observed. Researchers may wish to consider using and analysing recorded and reported measures in combination to gain a more complete view of the correlates of physical activity.     

Different Methods Yielded Two-Fold Difference in Compliance with Physical Activity Guidelines on School Days

Introduction

The aim was to compare the average and the days method in exploring the compliance of children with physical activity guidelines and describe their physical activity patterns in different school day segments.

Methods

Physical activity was objectively measured in 472 children aged 6–13 for one school week. Children were compliant when fulfilling PA recommendations 1) on average over all measured days (average method) or 2) on at least four measured days (days method). To explore the difference in moderate to vigorous physical activity (MVPA) minutes between compliant and non-complaint children (using both the average and days method) in various day segments, linear mixed models was used.

Results

Compliance with physical activity guidelines was significantly higher with the average compared to the days method (51.7% and 23.7%, respectively). In segmented-day analysis, compliant children accrued more MVPA minutes in all day segments, especially during after-school. Gender differences appeared only during the in-school segments, where girls spent less time in MVPA (average method: -4.39 min, 95% CI = -5.36,-3.42, days method: -4.45 min, 95%CI = -5.46,-3.44). Older children accrued more MVPA minutes during physical education classes, but less during breaks, compared to younger children.

Conclusions

The used methods yielded remarkably different prevalence estimates for compliance to physical activity recommendations. To ensure comparability between studies, interventions and reports, there is a need for internationally agreed operationalization and assessment methods of physical activity guidelines. As non-compliant children had lower MVPA during all day segments, greater efforts should be made to provide physical activity opportunities both during and after school.     

Childhood socioeconomic position and objectively measured physical capability levels in adulthood: a systematic review and meta-analysis

Background

Grip strength, walking speed, chair rising and standing balance time are objective measures of physical capability that characterise current health and predict survival in older populations. Socioeconomic position (SEP) in childhood may influence the peak level of physical capability achieved in early adulthood, thereby affecting levels in later adulthood. We have undertaken a systematic review with meta-analyses to test the hypothesis that adverse childhood SEP is associated with lower levels of objectively measured physical capability in adulthood.

Methods and Findings

Relevant studies published by May 2010 were identified through literature searches using EMBASE and MEDLINE. Unpublished results were obtained from study investigators. Results were provided by all study investigators in a standard format and pooled using random-effects meta-analyses. 19 studies were included in the review. Total sample sizes in meta-analyses ranged from N = 17,215 for chair rise time to N = 1,061,855 for grip strength. Although heterogeneity was detected, there was consistent evidence in age adjusted models that lower childhood SEP was associated with modest reductions in physical capability levels in adulthood: comparing the lowest with the highest childhood SEP there was a reduction in grip strength of 0.13 standard deviations (95% CI: 0.06, 0.21), a reduction in mean walking speed of 0.07 m/s (0.05, 0.10), an increase in mean chair rise time of 6% (4%, 8%) and an odds ratio of an inability to balance for 5s of 1.26 (1.02, 1.55). Adjustment for the potential mediating factors, adult SEP and body size attenuated associations greatly. However, despite this attenuation, for walking speed and chair rise time, there was still evidence of moderate associations.

Conclusions

Policies targeting socioeconomic inequalities in childhood may have additional benefits in promoting the maintenance of independence in later life.     

Identification and validity of accelerometer cut-points for toddlers

The purpose of this study was to derive ActiGraph cut-points for sedentary (SED), light-intensity physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) in toddlers and evaluate their validity in an independent sample. The predictive validity of established preschool cut-points were also evaluated and compared. Twenty-two toddlers (mean age = 2.1 years ± 0.4 years) wore an ActiGraph accelerometer during a videotaped 20-min play period. Videos were subsequently coded for physical activity (PA) intensity using the modified Children's Activity Rating Scale (CARS). Receiver operating characteristic (ROC) curve analyses were conducted to determine cut-points. Predictive validity was assessed in an independent sample of 18 toddlers (mean age = 2.3 ± 0.4 years). From the ROC curve analyses, the 15-s count ranges corresponding to SED, LPA, and MVPA were 0-48, 49-418, and >418 counts/15 s, respectively. Classification accuracy was fair for the SED threshold (ROC-AUC = 0.74, 95% confidence interval = 0.71-0.76) and excellent for MVPA threshold (ROC-AUC = 0.90, 95% confidence interval = 0.88-0.92). In the cross-validation sample, the toddler cut-point and established preschool cut-points significantly overestimated time spent in SED and underestimated time in spent in LPA. For MVPA, mean differences between observed and predicted values for the toddler and Pate cut-points were not significantly different from zero. In summary, the ActiGraph accelerometer can provide useful group-level estimates of MVPA in toddlers. The results support the use of the Pate cut-point of 420 counts/15 s for MVPA.     

Age-Related Macular Degeneration Is Associated with Less Physical Activity among US Adults: Cross-Sectional Study

BackgroundWe have a limited understanding of the effects of age-related macular degeneration (AMD) on physical activity (PA), and we have no prevalence estimates of the daily movement patterns among Americans with AMD. Therefore, we examined the association between AMD and PA and provided estimates of the daily movement patterns of Americans with AMD.MethodsData from the 2005-2006 National Health and Nutrition Examination Survey were used, including 1,656 adults (40-85 yrs). Retinal imaging was performed to classify individuals as no AMD, early AMD, or late AMD. Participants wore an ActiGraph 7164 accelerometer for 7 days to measure PA behavior.Results93.2% of participants with late AMD were in the least desirable group (not sufficiently active and having a negative light intensity-sedentary behavior balance). After adjustments (including age), participants with late AMD, as compared to those with no AMD, engaged in 50% less moderate-to-vigorous physical activity (MVPA) (RR = 0.50; 95% CI: 0.28-0.90). When visual acuity was entered into the model along with the other covariates, the association between late AMD and MVPA was no longer significant (RR = 0.54; 95% CI: 0.29-1.01), suggesting that visual acuity may partially mediate this relationship.ConclusionsIndividuals with late AMD engage in very little moderate-to-vigorous physical activity. Visually acuity, in part, explains the relationship between late AMD and PA.     

Physical Activity Levels and Domains Assessed by Accelerometry in German Adolescents from GINIplus and LISAplus

Background

Physical activity (PA) is a well-known and underused protective factor for numerous health outcomes, and interventions are hampered by lack of objective data. We combined accelerometers with diaries to estimate the contributions to total activity from different domains throughout the day and week in adolescents.

Methods

Accelerometric and diary data from 1403 adolescents (45% male, mean age 15.6 ± 0.5 years) were combined to evaluate daily levels and domains of sedentary, light, and moderate-to-vigorous activity (MVPA) during a typical week. Freedson’s cutoff points were applied to determine levels of activity. Total activity was broken down into school physical education (PE), school outside PE, transportation to school, sport, and other time.

Results

About 2/3 of adolescents’ time was spent sedentary, 1/3 in light activity, and about 5% in MVPA. Boys and girls averaged 46 (SD 22) and 38 (23) minutes MVPA per day. Adolescents were most active during leisure sport, spending about 30% of it in MVPA, followed by PE (about 20%) transport to school (14%) and either school class time or other time (3%). PE provided 5% of total MVPA, while leisure sport provided 16% and transportation to school 8%. School was the most sedentary part of the day with over 75% of time outside PE spent sedentary.

Conclusions

These German adolescents were typical of Europeans in showing low levels of physical activity, with significant contributions from leisure sport, transportation and school PE. Leisure sport was the most active part of the day, and participation did not vary significantly by sex, study center (region of Germany) or BMI. Transportation to school was frequent and thus accounted for a significant fraction of total MVPA. This indicates that even in a population with good access to dedicated sporting activities, frequent active transportation can add significantly to total MVPA.     

Caffeine Intake,Short Bouts of Physical Activity,and Energy Expenditure: A Double-Blind Randomized Crossover Trial

PA energy expenditure (PAEE) is the most variable component of Total Energy Expenditure (TEE) and largely due to the balance of sedentary time (SedT) and low intensity physical activity (LIPA). There has been an emergence for seeking an understanding of factors which determine variations in SedT, LIPA, and PAEE. Sedentary behavior and physical activity are relatively resistant to change by experimental dietary treatments and significant body weight changes. Although caffeine (Caf) is by far the most heavily used nutritional agent ingested to promote a sense of vigor/alertness, it is still unknown if Caf is effective in increasing PAEE and physical activity. The aim of the study was to test the hypothesis that 2 daily doses of Caf (as a capsule to blind the treatment and divided equally during breakfast and lunch) increase PAEE and TEE, and it would do so through increasing the frequent and brief bouts of physical activity (~1-5 min long) through the day as measured by accelerometry. In 21 low Caf users (<100 mg day^-1), we used a double-blind crossover trial (ClinicalTrials.govID;{"type":"clinical-trial","attrs":{"text":"NCT01477294","term_id":"NCT01477294"}}NCT01477294) with two conditions (4-day each with a 3-day washout period) randomly ordered as 5 mg kg^-1 day^-1 of Caf and maltodextrin as placebo (Plc). Resting energy expenditure (REE) by indirect calorimetry, total energy expenditure (TEE) from doubly labeled water, PAEE calculated as TEE-(REE+0.1TEE), and accelerometry measurements of both LIPA and MVPA were not different between conditions. However, regardless of caffeine or placebo, there were several significant relationships between brief bouts of LIPA and MVPA with PAEE. In conclusion, this double-blind study found that low and moderate-vigorous activity as well as the total volume of PAEE in free-living conditions is resistant to dietary caffeine intake that was equivalent to 5 cups of espresso or 7 cups of tea.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01477294","term_id":"NCT01477294"}}NCT01477294