Worldwide surveillance of self-reported sitting time: a scoping review.

BACKGROUND: Prolonged sitting time is a risk factor for chronic disease, yet recent global surveillance is not well described. The aims were to clarify: (i) the countries that have collected country-level data on self-reported sitting time; (ii) the single-item tools used to collect these data; and (iii) the duration of sitting time reported across low- to high-income countries. METHODS: Country-level data collected within the last 10 years using single-item self-report were included. The six-stage methodology: (1) reviewing Global Observatory for Physical Activity! Country Cards; (2-4) country-specific searches of PubMed, the Demographic and Health Survey website and Google; (5) analysing the Eurobarometer 88.4; and (6) country-specific searches for World Health Organization STEPwise reports. RESULTS: A total of 7641 records were identified and screened for eligibility. Sixty-two countries (29%) reported sitting time representing 47% of the global adult population. The majority of data were from high-income (61%) and middle income (29%) countries. The tools used were the International Physical Activity Questionnaire (IPAQ; n = 34), a modified IPAQ (n = 1) or the Global Physical Activity Questionnaire (GPAQ; n = 27). The median of mean daily sitting times was 4.7 (IQR: 3.5-5.1) hours across all countries. Higher-income countries recorded a longer duration of sitting time than lower-income countries (4.9 vs 2.7 h). CONCLUSIONS: This study provides an updated collation of countries collecting self-reported sitting time data. The daily sitting time findings should be interpreted cautiously. Current surveillance of sitting time is limited by a lack of coverage. Measures of population sitting time that are valid, feasible and sensitive to change should be embedded within global surveillance systems, to help guide future policy, research and practice. TRIAL REGISTRATION: Not applicable.

Associations between maternal physical activity in early and late pregnancy and offspring birth size: remote federated individual level meta-analysis from eight cohort studies.

OBJECTIVE: Evidence on the impact of leisure time physical activity (LTPA) in pregnancy on birth size is inconsistent. We aimed to examine the association between LTPA during early and late pregnancy and newborn anthropometric outcomes. DESIGN: Individual level meta-analysis, which reduces heterogeneity across studies. SETTING: A consortium of eight population-based studies (seven European and one US) comprising 72 694 participants. METHODS: Generalised linear models with consistent inclusion of confounders (gestational age, sex, parity, maternal age, education, ethnicity, BMI, smoking, and alcohol intake) were used to test associations between self-reported LTPA at either early (8-18 weeks gestation) or late pregnancy (30+ weeks) and the outcomes. Results were pooled using random effects meta-analyses. MAIN OUTCOME MEASURES: Birth weight, large-for-gestational age (LGA), macrosomia, small-for-gestational age (SGA), % body fat, and ponderal index at birth. RESULTS: Late, but not early, gestation maternal moderate to vigorous physical activity (MVPA), vigorous activity, and LTPA energy expenditure were modestly inversely associated with BW, LGA, macrosomia, and ponderal index, without heterogeneity (all: I2  = 0%). For each extra hour/week of MVPA, RR for LGA and macrosomia were 0.97 (95% CI: 0.96, 0.98) and 0.96 (95% CI: 0.94, 0.98), respectively. Associations were only modestly reduced after additional adjustments for maternal BMI and gestational diabetes. No measure of LTPA was associated with risk for SGA. CONCLUSIONS: Physical activity in late, but not early, pregnancy is consistently associated with modestly lower risk of LGA and macrosomia, but not SGA. TWEETABLE ABSTRACT: In an individual participant meta-analysis, late pregnancy moderate to vigorous physical activity modestly reduced birth size outcomes.

The descriptive epidemiology of the diurnal profile of bouts and breaks in sedentary time in older English adults.

Background: High sedentary time is associated with adverse metabolic health outcomes and mortality in older adults. It has been suggested that breaking up sedentary time may be beneficial for metabolic health; however, population prevalence data are lacking on the patterns of sedentary behaviour which would identify opportunities for intervention. Methods: We used data of adults aged ≥ 60 years (n = 3705) from the population-based EPIC-Norfolk cohort, to characterize the patterns of total sedentary time, breaks in sedentary time and sedentary bouts across the day and assess their associations with participant characteristics, using multi-level regression. Sedentary time was measured objectively by a hip-mounted accelerometer (ActigraphTM GT1M) worn for 7 days during waking time. Results: More than 50% of every waking hour was spent sedentary, increasing to a peak of 83% in the evening. On average fewer breaks were accrued in the evenings compared with earlier in the day. Marginally more sedentary time was accrued on weekend days compared with weekdays (difference 7.4 min, 95% confidence interval 5.0-9.7). Large proportions of this sedentary time appear to be accrued in short bouts (bouts of < 10 min for 32% of the time). Older age, being male, being retired, not being in paid employment and having a higher body mass index were associated with greater sedentary time and fewer breaks. Conclusion: Sedentary time is common throughout the day but peaks in the evenings with fewer breaks and longer bouts. We identified a number of characteristics associated with sedentary time and additionally inversely associated with sedentary breaks, which should inform the development and targeting of strategies to reduce sedentary time among older adults.

Adiposity and grip strength as long-term predictors of objectively measured physical activity in 93 015 adults: the UK Biobank study.

BACKGROUND/OBJECTIVES: Fatness and fitness are associated with physical activity (PA) but less is known about the prospective associations of adiposity and muscle strength with PA. This study aimed to determine longitudinal associations of body mass index (BMI), waist circumference (WC) and grip strength (GS) with objectively measured PA. SUBJECTS/METHODS: Data are from the UK Biobank study. At baseline (2006-2010), BMI, WC and GS were objectively measured. At follow-up (2013-2015), a sub-sample of 93 015 participants (52 161 women) wore a tri-axial accelerometer on the dominant wrist for 7 days. Linear regression was performed to investigate longitudinal associations of standardised BMI, WC and GS at baseline with moderate-to-vigorous PA (MVPA) and acceleration after a median 5.7-years follow-up (interquartile range: 4.9-6.5 years). RESULTS: Linear regression revealed strong inverse associations for BMI and WC, and positive associations for GS with follow-up PA; in women, MVPA ranges from lowest to highest quintiles of GS were 42-48 min day-1 in severely obese (BMI⩾35 kg m-2), 52-57 min day-1 in obese (30⩽BMI<35 kg m-2), 61-65 min day-1 in overweight (25⩽BMI<30 kg m-2) and 69-75 min day-1 in normal weight (18.5⩽BMI<25 kg m-2). Follow-up MVPA was also lower in the lowest GS quintile (42-69 min day-1) compared with the highest GS quintile (48-75 min day-1) across BMI categories in women. The pattern of these associations was generally consistent for men, and in analyses using WC and mean acceleration as exposure and outcome, respectively. CONCLUSIONS: More pronounced obesity and poor strength at baseline independently predict lower activity levels at follow-up. Interventions and policies should aim to improve body composition and muscle strength to promote active living.

The descriptive epidemiology of accelerometer-measured physical activity in older adults.

BACKGROUND: Objectively measured physical activity between older individuals and between populations has been poorly described. We aimed to describe and compare the variation in accelerometry data in older UK (EPIC-Norfolk) and American (NHANES) adults. METHODS: Physical activity was measured by uniaxial accelerometry in 4,052 UK (49-91 years) and 3459 US older adults (49-85 years). We summarized physical activity as volume (average counts/minute), its underlying intensity distribution, and as time spent <100counts/minute, ≥809counts/minute and ≥2020counts/minute both for total activity and that undertaken in ≥10-min bouts. RESULTS: In EPIC-Norfolk 65% of wear-time was spent at <100 counts/minute and 20% spent in the range 100-500 counts/minute. Only 4.1% of this cohort accumulated more than 30 min/day of activity above 2020 counts/minute in 10-min bouts. If a cut-point of >809 counts/minute is used 18.7% of people reached the 30 min/day threshold. By comparison, 2.5% and 9.5% of American older adults accumulated activity at these levels, respectively. CONCLUSION: As assessed by objectively measured physical activity, the majority of older adults in this UK study did not meet current activity guidelines. Older adults in the UK were more active overall, but also spent more time being sedentary than US adults.

Objectively measured physical activity and longitudinal changes in adolescent body fatness: an observational cohort study.

BACKGROUND: The data regarding prospective associations between physical activity (PA) and adiposity in youth are inconsistent. OBJECTIVE: The objective of this study was to investigate associations between baseline levels of objectively measured PA and changes in adiposity over 2.5 years from mid-to-late adolescence. METHODS: This was an observational cohort study in 728 school students (43% boys) from Cambridgeshire, United Kingdom. Fat mass index (FMI, kg m(-2) ) was estimated at baseline (mean ± standard deviation age: 15 ± 0.3 years) and follow-up (17.5 ± 0.3 years) by anthropometry and bioelectrical impedance. Habitual PA was assessed at baseline by ≥3 d combined heart rate and movement sensing. Average daily PA energy expenditure (PAEE) and the time (min d(-1) ) spent in light, moderate and vigorous intensity PA (LPA, MPA and VPA, respectively) was estimated. Multilevel models were used to investigate associations between baseline PA and change in FMI (ΔFMI). Adjustment for baseline age, sex, follow-up duration, area-level socioeconomic status, season of PA assessment, sedentary time, energy intake and sleep duration was made; baseline FMI was also added in a second model. RESULTS: FMI increased significantly over follow-up (0.6 ± 1.2 kg m(-2) , P < 0.001). Baseline PAEE and LPA positively predicted ΔFMI in overfat participants (P ≤ 0.030), as did VPA in initially normal fat participants (P ≤ 0.044). There were further positive associations between PAEE and ΔFMI in normal fat participants, and between MPA and ΔFMI in both fat groups, when adjusted for baseline FMI (P ≤ 0.024). CONCLUSIONS: Baseline PAEE and its subcomponents were positively associated with small and unlikely clinically relevant increases in ΔFMI. These counter-intuitive findings may be explained by behavioural changes during the course of study follow-up.

Physical activity, sedentary time and gain in overall and central body fat: 7-year follow-up of the ProActive trial cohort.

OBJECTIVE: The objective of this study is to examine the independent associations of time spent in moderate-to-vigorous physical activity (MVPA) and sedentary (SED-time), with total and abdominal body fat (BF), and the bidirectionality of these associations in adults at high risk of type 2 diabetes. DESIGN AND SUBJECTS: We measured MVPA (min per day) and SED-time (h per day) by accelerometry, and indices of total (body weight, fat mass (FM), BF% and FM index) and abdominal BF (waist circumference (WC)) using standard procedures in 231 adults (41.3 ± 6.4 years) with parental history of type 2 diabetes (ProActive UK) at baseline, 1-year and 7-year follow-up. Mixed effects models were used to quantify the independent associations (expressed as standardised ß-coefficients (95% confidence interval (CI))) of MVPA and SED-time with fat indices, using data from all three time points. All models were adjusted for age, sex, intervention arm, monitor wear time, follow-up time, smoking status, socioeconomic status and MVPA/SED-time. RESULTS: MVPA was inversely and independently associated with all indices of total BF (for example, 1 s.d. higher MVPA was associated with a reduction in FM, ß = -0.09 (95% CI: -0.14, -0.04) s.d.) and abdominal BF (for example, WC: ß = -0.07 (-0.12, -0.02)). Similarly, higher fat indices were independently associated with a reduction in MVPA (for example, WC: ß = -0.25 (-0.36, -0.15); FM: ß = -0.27 (-0.36, -0.18)). SED-time was positively and independently associated with most fat indices (for example, WC: ß = 0.03 (-0.04, 0.09); FM: ß = 0.10 (0.03, 0.17)). Higher values of all fat indices independently predicted longer SED-time (for example, WC: ß = 0.10 (0.02, 0.18), FM: ß = 0.15 (0.07, 0.22)). CONCLUSIONS: The associations of MVPA and SED-time with total and abdominal BF are bidirectional and independent among individuals at high risk for type 2 diabetes. The association between BF and MVPA is stronger than the reciprocal association, highlighting the importance of considering BF as a determinant of decreasing activity and a potential consequence. Promoting more MVPA and less SED-time may reduce total and abdominal BF.

Rate of weight gain predicts change in physical activity levels: a longitudinal analysis of the EPIC-Norfolk cohort.

OBJECTIVE: To investigate the relationship of body weight and its changes over time with physical activity (PA). DESIGN: Population-based prospective cohort study (Norfolk cohort of the European Prospective Investigation into Cancer and Nutrition, EPIC-Norfolk, United Kingdom). SUBJECTS: A total of 25 639 men and women aged 39-79 years at baseline. PA was self-reported. Weight and height were measured by standard clinical procedures at baseline and self-reported at 18-month and 10-year follow-ups (calibrated against clinical measures). Main outcome measure was PA at the 10-year follow-up. RESULTS: Body weight and PA were inversely associated in cross-sectional analyses. In longitudinal analyses, an increase in weight was associated with higher risk of being inactive 10 years later, after adjusting for baseline activity, 18-month activity, sex, baseline age, prevalent diseases, socioeconomic status, education, smoking, total daily energy intake and alcohol intake. Compared with stable weight, a gain in weight of >2 kg per year in the short-, medium- and long-term was consistently and significantly associated with greater likelihood of physical inactivity after 10 years, with the most pronounced effect for long-term weight gain, OR=1.89 (95% CI: 1.30-2.70) in fully adjusted analysis. Weight gain of 0.5-2 kg per year over long-term was substantially associated with physical inactivity after full adjustment, OR=1.26 (95% CI: 1.11-1.41). CONCLUSION: Weight gain (during short-, medium- and long-term) is a significant determinant of future physical inactivity independent of baseline weight and activity. Compared with maintaining weight, moderate (0.5-2 kg per year) and large weight gain (>2 kg per year) significantly predict future inactivity; a potentially vicious cycle including further weight gain, obesity and complications associated with a sedentary lifestyle. On the basis of current predictions of obesity trends, we estimate that the prevalence of inactivity in England would exceed 60% in the year 2020.

Adverse associations of increases in television viewing time with 5-year changes in glucose homoeostasis markers: the AusDiab study.

BACKGROUND: Television viewing time is associated cross-sectionally with abnormal glucose tolerance and diabetes risk; however, the impact of changes in television viewing time on glycaemic measures is less understood. We examined relationships of 5-year change in television viewing time with 5-year change in glucose homeostasis markers. METHODS: Participants in the Australian Diabetes, Obesity and Lifestyle study with data available at the 1999-2000 baseline and the 2004-2005 follow-up were included (4870; 45% men). Television viewing time (h/week) was assessed by questionnaire. Fasting plasma glucose, serum insulin and 2-h plasma glucose were obtained from an oral glucose tolerance test. Beta-cell function and insulin resistance were ascertained using the homeostasis model assessment 2-calculator. Associations of change in television viewing time with changes in glucose homeostasis markers were examined using linear regression models [ß-coefficients (95% CI)]. Adjustments included baseline measures of age, television viewing time and glycaemic marker, and baseline and 5-year change in diet quality, energy intake, physical activity and waist circumference. RESULTS: For every 5-h per week increase in television viewing time from baseline to 5-year follow-up, changes in glucose homeostasis markers were observed: among women there was a significant increase in fasting plasma glucose [0.01 (0.00-0.02) mmol/l] insulin resistance [0.03 (0.01-0.05)] and insulin secretion [1.07 (0.02-2.12) %]; insulin levels increased [men: 1.20 (0.30-2.09); women: 1.06 (0.32-1.80) pmol/l]; in men, 2-h plasma glucose levels increased [0.06 (0.01-0.1) mmol/l]. CONCLUSION: Five-year increases in television viewing time were associated adversely with changes in glucose homeostasis markers. These findings add to earlier cross-sectional evidence that television viewing time can be associated with biomarkers of diabetes risk.

Influencing factors of screen time in preschool children: an exploration of parents' perceptions through focus groups in six European countries.

Preschoolers already spend significant proportions of their waking hours being sedentary. Screen time (i.e. television/DVD viewing and computer use) has been negatively associated with several health outcomes but interventions aiming to reduce preschoolers' sedentary behaviour are scarce. This study aimed to explore parents' perceptions of their preschool children's screen time. One hundred twenty-two parents of low and medium-high socioeconomic status from six European countries with children between 4 and 6 years old were involved in 24 focus groups. Following a qualitative content analysis, the available information and key findings were centrally analysed. Results showed that children tend to like watching television (TV) and most parents do not express worries about their children's TV viewing time. Education is considered to be the main benefit of watching TV and in general, parents only have informal rules about TV viewing. Computer and active games use are less frequent compared with TV viewing. No univocal results are found about the influence of siblings or friends on children's screen time. Weather conditions and parental habits at home are the most important factors influencing children's screen time. Alternatives for screen activities and information on how to set rules for screen time should be provided to parents to assist them in decreasing their preschool children's screen time.

Sedentary behaviour, physical activity and a continuous metabolic syndrome risk score in adults.

OBJECTIVE: The association of sedentary behaviour and leisure time physical activity with a validated continuous metabolic syndrome risk score was investigated in adults. SUBJECTS/METHODS: A number of 992 adults (559 men) without cardiovascular disease or diabetes. Subjects reported time spent in leisure time physical activity and television watching/computer activities. A validated metabolic syndrome risk score, based on waist circumference, triglycerides, blood pressure, fasting plasma glucose and high-density lipoprotein cholesterol, was used. The metabolic syndrome risk score and time spent in sedentary behaviour and physical activity were analysed as continuous variables using multiple linear regression. RESULTS: Metabolic syndrome risk was positively associated with time spent watching television/computer activities, irrespective of physical activity level, and after adjustment for age, education level, smoking status and dietary intake in women aged > or =45 years (beta=0.184, P<0.05). Independent of the time being sedentary, moderate to vigorous leisure time physical activity was inversely associated with metabolic syndrome risk in men (<45 years: beta=-0.183, P<0.01; > or =45 years: beta=-0.192, P<0.01) and women aged > or =45 years (beta=-0.203, P<0.01). CONCLUSIONS: Although cross-sectional, the present results support inclusion of efforts to decrease sedentary behaviour in metabolic syndrome prevention strategies for women aged > or =45 years, besides promotion of moderate to vigorous physical activity, since both behavioural changes might show additional effects.

Relationship of obesity with physical activity, aerobic fitness and muscle strength in Flemish adults.

AIM: The aim of this study was to analyse differences in physical activity, cardiorespiratory fitness (CRF) and muscle strength between normal weight, overweight and obese adults and to investigate the role of physical activity variables in the analyses of differences in CRF and muscle strength between these groups. METHODS: A total of 807 men and 633 women (age: 18-75 years) were included in this cross-sectional study. Weight, height, waist circumference (WC) and bioelectrical impedance were measured. Different dimensions of physical activity were assessed using a validated questionnaire. CRF (VO(2peak)) was evaluated by a maximal test on a cycle ergometer. Knee strength was measured with a calibrated Biodex System Pro 3 dynamometer. Three methods were used for classification in obesity groups: body mass index (BMI), WC and combined BMI-WC classification. RESULTS: Health-related sports and physical activity level are negatively associated with obesity in men, but not in women. Television viewing is positively associated with obesity, while VO(2peak)/fat free mass (FFM) and knee strength/FFM show a negative association with obesity in both genders. Overall, subjects with normal WC seem to be more physically active and to have somewhat better values for CRF compared to those with high WC within the same BMI category. Lower values for relative CRF and knee strength in obese subjects compared to their lean counterparts remain after adjustment for physical activity. CONCLUSION: This study confirms the lower level of physical activity and the impaired CRF and knee strength in obese adults compared to their lean counterparts. This study also sustains the importance of measuring WC and CRF during clinical examinations.

Validity of a physical activity computer questionnaire in 12- to 18-year-old boys and girls.

The reliability and validity of a physical activity computer questionnaire of a usual week were studied in 33 adolescents between 12 and 18 years of age. Intraclass correlation coefficients and Kappa values were calculated to verify test-retest reliability. Validity was investigated by calculating Pearson correlation coefficients between the questionnaire and the Computer Science and Applications uniaxial accelerometer (CSA). Accelerometer data were obtained during seven successive days (sum and mean counts, estimated MET). Intraclass coefficients generally exceeded 0.70 and all Kappa values but one varied between 0.44 and 1.00. Transport variables (active transport from and to school, and during leisure time) showed no relationship with CSA. Sport participation during leisure time, sport participation summed with total transport, and the frequencies of moderate and hard activity were significantly correlated with CSA (r between 0.48 and 0.78). These data indicate that the physical activity computer variables provide reliable information. Moreover, sport participation (and summed with total transport) and the frequencies of moderate and hard activity provide valid data about adolescents' usual week physical activity, based on CSA comparison.