Objectively measured sedentary time and associations with insulin sensitivity: Importance of reallocating sedentary time to physical activity

ObjectiveThe aim of this study is to quantify associations between objectively measured sedentary time and markers of insulin sensitivity by considering allocation into light-intensity physical activity or moderate- to vigorous-intensity physical activity (MVPA).MethodsParticipants with an increased risk of impaired glucose regulation (IGR) were recruited (Leicestershire, United Kingdom, 2010–2011). Sedentary, light-intensity physical activity and MVPA time were measured using accelerometers. Fasting and 2-hour post-challenge insulin and glucose were assessed; insulin sensitivity was calculated by HOMA-IS and Matsuda-ISI. Isotemporal substitution regression models were used. Data were analysed in 2014.Results508 participants were included (average age = 65 years, female = 34%). Reallocating 30 min of sedentary time into light-intensity physical activity was associated a 5% (95% CI 1, 9%; p = 0.024) difference in Matsuda-ISI after adjustment for measured confounding variables. Reallocation into MVPA was associated with a 15% (7, 25%; p < 0.001) difference in HOMA-IS and 18% (8, 28%; p < 0.001) difference in Matsuda-ISI. Results for light-intensity physical activity were modified by IGR status with stronger associations seen in those with IGR.ConclusionsReallocating sedentary time into light-intensity physical activity or MVPA was associated with differences in insulin sensitivity, with stronger and more consistent associations seen for MVPA.     

Implementing classroom physical activity breaks: Associations with student physical activity and classroom behavior

ObjectiveTo investigate the relation of classroom physical activity breaks to students' physical activity and classroom behavior.MethodsSix elementary-school districts in California implemented classroom physical activity interventions in 2013–2014. Students' (N = 1322) accelerometer-measured moderate-to-vigorous physical activity (MVPA) during school and teachers' (N = 397) reports of implementation and classroom behavior were assessed in 24 schools at two time points (both post-intervention). Mixed-effects models accounted for nested data.ResultsMinutes/day of activity breaks was positively associated with students' MVPA (βs = .07–.14; ps = .012–.016). Students in classrooms with activity breaks were more likely to obtain 30 min/day of MVPA during school (OR = 1.75; p = .002). Implementation was negatively associated with students having a lack of effort in class (β = − .17; p = .042), and student MVPA was negatively associated with students being off task or inattentive in the classroom (β = − .17; p = .042). Students provided with 3–4 physical activity opportunities (classroom breaks, recess, PE, dedicated PE teacher) had ≈ 5 more min/day of school MVPA than students with no opportunities (B = 1.53 min/opportunity; p = .002).ConclusionsImplementing classroom physical activity breaks can improve student physical activity during school and behavior in the classroom. Comprehensive school physical activity programs that include classroom-based activity are likely needed to meet the 30 min/day school physical activity guideline.     

Empowering adolescents to be physically active: Three-year results of the Sigue la Huella intervention

ObjectiveTo examine the effects of a school-based intervention called Sigue la Huella (Follow the Footstep) on adolescents' daily moderate-to-vigorous physical activity (MVPA).MethodThis quasi-experimental, cohort study took place in four secondary schools in Huesca (Spain) during the 2009–2010, 2010–2011, and 2011–2012 academic years (students aged 12–15 years). Two schools were assigned to the experimental condition (n = 368) and two schools to the control condition (n = 314). Sigue la Huella was based on the social ecological model and self-determination theory. MVPA was measured for 7 days on 4 occasions using accelerometers. Data were analyzed with individual growth curve models.ResultsThere was a significant difference in linear growth rate of daily MVPA between the experimental and the control group, independent of study wave, type of school (public vs. private), grade level and gender (p < 0.001). Specifically, MVPA increased in the experimental group (β = 7.02, 95% confidence interval (CI) = 1.27 to 12.78, p = 0.017) and tended to decrease in the control group (β = − 5.26, 95% CI = − 11.17 to 0.65, p < 0.081). The observed increase was larger in boys than in girls (p = 0.003).ConclusionsSigue la Huella had a positive effect on adolescents' daily MVPA over three school years. Both genders benefited from the intervention, although boys to a greater extent.     

Daily movement patterns and predicted 10-yr risk for a first atherosclerotic cardiovascular disease (ASCVD) event using the pooled cohort risk equations among US adults

ObjectiveExamine the association between movement patterns and predicted risk of a first atherosclerotic cardiovascular disease (ASCVD) event.MethodsData from the 2003–2006 National Health and Nutrition Examination Survey (NHANES) were used (40–79 yrs; N = 2421). Participants wore an ActiGraph 7164 accelerometer to create four movement pattern groups; Group 1: ≥ 150 min/wk of moderate-to-vigorous physical activity (MVPA) and light-intensity physical activity (LIPA) ≥ sedentary behavior (SB); Group 2: ≥ 150 min/wk of MVPA and LIPA < SB; Group 3: < 150 min/wk of MVPA and LIPA ≥ SED; and Group 4: < 150 min/wk of MVPA and LIPA < SB. 10-yr risk for a first ASCVD event was estimated using the pooled cohort equations.ResultsAfter adjusting for age, gender, race–ethnicity and obesity, Group 2 (β = − 0.28; p = 0.44) was not significantly different than Group 1, but Groups 3 (β = 1.09; p = 0.01) and 4 (β = 1.44; p < 0.001) had a higher pooled risk score.ConclusionsThose in the least desirable movement pattern (Group 4) had the highest pooled risk score. Given the similar risk scores for Groups 1 and 2, future research is needed to determine if sufficient MVPA can counteract the potential consequences associated with an imbalanced LIPA:SB ratio (i.e., LIPA < SB).     

Objectively assessed physical activity,fitness and subjective wellbeing

BackgroundThe existing evidence for a cross-sectional association between physical activity and subjective wellbeing is inconsistent, mainly because of the reliance on self reported physical activity, which might have conceptual overlap with subjective health.PurposeTo examine associations of objectively assessed physical activity and cardiorespiratory fitness with subjective wellbeing.MethodsA sub-sample of participants (921 men and women, mean age 44.6 ± 15.0 yrs, 46.4% men) from the 2008 Health Survey for England completed objective measures of physical activity (Actigraph) and an 8 min sub-maximal step test to estimate levels of cardiorespiratory fitness. The General Health Questionnaire and self-rated health was used as indicators of subjective wellbeing.ResultsThe recorded levels of moderate to vigorous physical activity (MVPA) were higher in participants reporting very good health (adjusted mean difference = 6.7, 95% CI, 1.1–12.4 min/d, p = 0.019) compared with participants reporting fair–poor health after adjustment for various confounders and fitness level. Neither physical fitness, objectively assessed sedentary time or light activity was related to self-rated health. There was also no association between objectively measured physical activity and fitness with psychological health, despite a robust association with self reported MVPA in the overall sample.ConclusionsObjectively assessed MVPA is independently associated with self-rated health. Self reported, but not objectively assessed MVPA, was associated with psychological health. The null findings with regards to psychological health might partly reflect selection biases associated with the healthy nature of this sub-sample of participants.     

Investigating links between moderate-to-vigorous physical activity and cognitive performance in elementary school students

BackgroundResearch has noted both physical and psychological benefits when children participate in physical activity. Recent studies indicate there may also be academic benefits and students may be more efficient learners after physical activity. This study investigated the influence of moderate-to-vigorous physical activity (MVPA) on four cognitive processes: planning, attention, simultaneous processing, and successive processing.MethodsParticipants were two classes of fourth-grade students in Ontario (n = 40). Using a counterbalanced design, students in the two classes completed standardized tests for each cognitive process both after no physical activity and following it (20 min MVPA within a 45 min lesson).ResultsThe results indicate that performance on the planning test significantly improved after physical activity (p < 0.001), controlling for sequence and habituation/retesting effects. No improvement was observed for attention, simultaneous processing, or successive processing.ConclusionPlanning is associated with problem solving skills and behaviour self-regulation. These skills may be improved in elementary school students immediately following physical activity.     

Does social support mediate the relationship among neighborhood disadvantage,incivilities, crime and physical activity?

ObjectiveNeighborhood disadvantage (ND), incivilities, and crime disproportionately impact minority women, discouraging physical activity (PA). Social support (SS) is a cultural tool promoting PA in minority women. Socially supportive environments may promote PA in disadvantaged neighborhoods, yet few studies have investigated the mediating role of social support among minority women. This study examined SS as a mediator among ND, incivilities, crime, and PA.MethodsThe Health Is Power study aimed to increase PA in African American and Hispanic Latina women (N = 410) in Houston and Austin, TX. ND and crime data were taken from the National Neighborhood Crime Study. Incivilities were measured using the Pedestrian Environment Data Scan (PEDS). SS was measured using the Family and Friend Support for Exercise Habits scale and physical activity was measured using the International Physical Activity Questionnaire. Linear regression analysis was used to examine SS as a mediator following the Baron and Kenny method.ResultsND was negatively associated with PA and SS. SS was not a mediator as it was not significantly associated with ND, crime, and incivilities (F_(3,264) = 2.02, p > .05) or PA (F_(1,266) = 3.8 p = .052).ConclusionND significantly discourages PA and limits SS. Future research should focus on developing strategies to overcoming these negative environmental factors.     

Joint effects of objectively-measured sedentary time and physical activity on all-cause mortality

ObjectiveExamine the joint effects of objectively-measured sedentary time and moderate-to-vigorous physical activity (MVPA) on all-cause mortality.MethodsThe present study included data from the 2003–2006 National Health & Nutrition Examination Survey, with mortality follow-up data (via National Death Index) through 2011 (N = 5575 U.S. adults). Sedentary time (activity counts/min between 0 and 99) and MVPA (activity counts/min ≥ 2020) were objectively measured using the ActiGraph 7164 accelerometer.ResultsThe median age of the participants was 50 yrs; proportion of men was 50.2%; proportion of whites was 53.8%, 18.7% for blacks; median follow-up was 81 months; and 511 deaths occurred over the follow-up period. After adjusting for age, gender, race-ethnicity, cotinine, weight status, poverty level, C-reactive protein and comorbid illness (summed score of 0–8 chronic diseases), and for a 1 min increase in MVPA and sedentary time, both MVPA (HR_adjusted = 0.98; 95% CI: 0.96–0.99; P = 0.04) and sedentary time (HR_adjusted = 1.001; 95% CI: 1.0003–1.002; P = 0.008) were independently associated with all-cause mortality. Further, MVPA was associated with all-cause mortality among those with greater (above median) sedentary time (HR_adjusted = 0.95; 95% CI: 0.93–0.97; P < .001). Sedentary time was not associated with all-cause mortality among those engaging in above median levels of MVPA (HR_adjusted = 0.998; 95% CI: 0.996–1.001; P = .32), but sedentary time was associated with increased mortality risk among those below median levels of MVPA (HR = 1.002; 95% CI: 1.001–1.003; P < 0.001).ConclusionsSedentary time and MVPA are independently associated with all-cause mortality. Above median sedentary time levels did not negate the beneficial effects of MVPA on all-cause mortality risk.     

Physically active vs. sedentary academic lessons: A dose response study for elementary student time on task

BackgroundPhysically active academic lessons are an effective intervention to reduce sedentary time and increase student physical activity. They have also been shown to enhance task engagement, as indicated by observations of attention and behavior control, time on task (TOT). However, it is not clear if the improved TOT stems from the physical activity or if it is the result of an enjoyable break from traditional instruction. If it is due to physical activity, what dose of intensity is required for the effect? This study was designed to test these questions.MethodsParticipants were 320 children (7–9 years) recruited from school districts in Central Texas in 2012. They were assigned by classroom (n = 20) to one of four conditions: 1) sedentary, standard lesson (n = 72); 2) sedentary academic game (n = 87); 3) low to moderate intensity PA (LMPA), academic game (n = 81); and 4) moderate to vigorous intensity PA (MVPA), academic game (n = 76). Measures included PA via accelerometer and TOT.ResultsMixed-method RMANOVA indicated TOT decreased following the standard lesson (p < 0.001), showed no change following the sedentary academic game (p = 0.68), and increased following the LMPA (p < 0.01) and MVPA (p < 0.001) academic games.ConclusionsWhile the sedentary, academic game prevented the reduction in TOT observed in the standard lesson, PA resulted in increased TOT. Future research should be designed to examine the potential academic benefits of the change in TOT.     

Physical activity mediates the relationship between perceived crime safety and obesity

ObjectiveThe current cross-sectional study tests whether low perceived crime safety is associated with body mass index (BMI) and obesity risk and whether less moderate-to-vigorous physical activity (MVPA) accounts for part of this relationship.MethodAdults (n = 864) from a relatively low-income and ethnically mixed neighborhood in Salt Lake City UT (2012) were assessed for perceived crime safety, objective physical activity, and BMI measures.ResultsThis neighborhood had lower perceived safety than for other published studies utilizing this safety measure. In a mediation test, lower perceived crime safety was significantly associated with higher BMI and greater risk of obesity, net of control variables. Residents with lower perceived safety had less MVPA. Lower MVPA partially explained the relationship between less safety and both elevated BMI and higher obesity risk, suggesting that perceiving less crime safety limits MVPA which, in turn, increases weight.ConclusionIn this neighborhood, with relatively low perceived safety from crime, residents' low perceived safety is related to more obesity and higher BMI; lower MVPA among residents explained part of this relationship. If residents are to become more active in their neighborhood it may be important to address perceived crime safety as part of broader efforts to enhance active living.     

The association of C-reactive protein and physical activity among a church-based population of African Americans

ObjectiveRegular physical activity can reduce systemic inflammation and, thereby, the burden of chronic inflammatory-related conditions. This study examined whether regular physical activity, measured subjectively (Rapid Assessment of Physical Activity [RAPA]) and objectively (Bodymedia's SenseWear® activity monitor [SWA]), is associated with inflammatory or glycemic control markers.MethodsSubjects were 345 participants of the Healthy Eating and Active Living in the Spirit (HEALS) lifestyle intervention among African American (AA) churches in South Carolina from 2009 to 2012. Linear regression analyses were performed to assess the relationship between both subjectively and objectively measured physical activity and inflammatory markers including high sensitivity C-reactive protein (CRP), interleukin-6 (IL-6), and glycosylated hemoglobin (HbA1c).ResultsThose who participated in regular physical activity (from RAPA) had lower CRP values compared to those who were sedentary (2.3 vs. 3.8 mg/L, p < 0.01). Lower levels of CRP or IL-6 were observed among those in the highest quartile of active energy expenditure (CRP: 2.0 vs. 3.6 mg/L, p = 0.01) or moderate–vigorous physical activity minutes (CRP = 1.7 vs. 4.5 mg/L, p < 0.01; IL-6 = 1.5 vs. 2.1 pg/mL, p = 0.01) compared to their lowest respective quartiles as measured by the SWA.ConclusionPhysical activity may improve chronic inflammation, which is a primary pathophysiological mechanism for numerous chronic disorders, especially among minority populations.     

Dose–response association of physical activity with HbA1c: Intensity and bout length

ObjectiveThe aims of this study were to characterize the dose–response relationship between moderate-to-vigorous intensity physical activity (MVPA), and light-intensity activity with HbA1c in adults at low, moderate, and high risks of type 2 diabetes, and to compare the relationship of short (1 to 9 min) versus long (10 + min) bouts of MVPA with HbA1c.MethodsData from 2707 participants from the 2003–2006 National Health And Nutrition Examination Survey were analyzed in 2014–2015. Type 2 diabetes risk was classified into three groups based upon age (< 40 years; ≥ 40 years) and BMI (< 30; ≥ 30). The relationship between HbA1c and accelerometer-based physical activity variables was assessed using multiple regression models.ResultsThere was a curvilinear dose–response relationship between HbA1c with total activity and MVPA in adults at moderate or high risk for type 2 diabetes: higher amounts of physical activity were associated with lower HbA1c. The association of physical activity on HbA1c was stronger at lower levels of physical activity. There was no dose–response relationship in adults at low risk for type 2 diabetes. The relationship between short bouts with HbA1c was stronger than for bouts ≥ 10 min.ConclusionsIn adults at risk for type 2 diabetes, there is a dose–response relationship between physical activity and HbA1c levels such that the relationship: (1) is curvilinear; (2) is stronger when a higher percent of total activity comes from MVPA; and (3) is more potent with short bouts of MVPA. Fractionalized physical activity of at least moderate-intensity may contribute to long-term glucose control.     

Self-determined motivation and physical activity in children and adolescents: A systematic review and meta-analysis

ObjectiveSelf-determination theory is used as a framework for examining the relation between motivation and physical activity. The purpose of this review was to systematically review studies that assessed the association between self-determined motivation and physical activity levels in children and adolescents.MethodWe searched electronic databases in April 2013. Included studies assessed the relation between motivation (as outlined in self-determination theory) and physical activity in children and adolescents.ResultsForty-six studies (n = 15,984 participants) met the inclusion criteria. Meta-analysis indicated that overall levels of self-determined motivation had a weak to moderate, positive associations with physical activity (ρ = .21 to .31). Autonomous forms of motivation (i.e., intrinsic motivation and identified regulation) had moderate, positive associations with physical activity (ρ = .27 to .38), whereas controlled forms of motivation (i.e., introjection and external regulation) had weak, negative associations with physical activity (ρ = − .03 to −.17). Amotivation had a weak, negative association with physical activity (ρ = − .11 to − .21).ConclusionsEvidence provides some support for self-determination theory tenets. However, there was substantial heterogeneity in most associations and many studies had methodological shortcomings.     

Symptoms of specific anxiety disorders may relate differentially to different physical activity modalities in young adults

BackgroundAnxiety symptoms may be a barrier to physical activity (PA) such that persons who experience anxiety engage in less PA. The purpose of this study was to assess if symptoms of panic disorder, social phobia, generalized anxiety disorder (GAD) or agoraphobia are associated with frequency, intensity or type of PA in young adults.MethodsData on lifetime anxiety symptoms and current PA levels were collected in self-report questionnaires in 2007–2008 from 880 persons aged 18–24 years participating in the Nicotine Dependence in Teens (NDIT) study. The associations between anxiety symptom subtypes and different PA modalities were investigated in five multivariable logistic regression models, one for each of five PA indicators (i.e., meeting moderate-to vigorous PA (MVPA) guidelines, meeting strength training guidelines, meeting both MVPA and strength training guidelines, participating in team sports, frequent walking) as outcomes.Results37%, 47%, 40% and 21% of participants reported lifetime symptoms of panic disorder, social phobia, GAD, and agoraphobia, respectively. In multivariable logistic regression, participants who endorsed lifetime GAD symptoms were statistically significantly less likely to meet MVPA guidelines (OR 0.5, 95% CI 0.4–0.8, p < 0.05), and MVPA and strength training guidelines (OR 0.7, 95% CI 0.5–1.0, p < 0.05). Those with agoraphobia symptoms were more likely to walk frequently [OR (95% CI) = 1.6 (1.1, 2.3)].ConclusionPA interventions may need to be tailored to people who have experienced specific anxiety symptoms to maximize adherence to PA recommendations, and increase the potential for health benefits from PA participation.     

Daily movement patterns and biological markers among adults in the United States

ObjectiveTo examine the combined effects of sedentary (SED), light (LPA) and moderate-to-vigorous physical activity (MVPA) on biological markers among a nationally representative sample of U.S. adults.MethodsData from the 2003–2006 NHANES study was used, with 5580 adults (≥ 20 years) included in the study. Participants wore an ActiGraph 7164 accelerometer with accelerometry data used to create four movement pattern groups: ≥ 150 min/week of MVPA and LPA ≥ SED; ≥ 150 min/week of MVPA and LPA < SED; < 150 min/week of MVPA but LPA ≥ SED; and < 150 min/week of MVPA and LPA < SED. Blood samples were taken to assess various biological parameters (e.g., cholesterol).Results47.2% (SE: 1.2) of Americans engaged in < 150 min/week of MVPA and had a negative LPA–SED balance. In general, participants who engaged in ≥ 150 min/week of MVPA, regardless of LPA–SED balance, had more favorable biological levels; however, there was evidence showing that even if individuals engaged in < 150 min/week of MVPA, but if their LPA exceeded SED, they had more favorable levels of triglycerides and insulin.ConclusionsPrograms are needed to increase American's engagement in MVPA, and also ensure that LPA exceeds SED behavior.     

Adolescent confidence in immunisation: Assessing and comparing attitudes of adolescents and adults

IntroductionThere is limited knowledge of adolescent views and attitudes towards immunisation. Our study investigated adolescent attitudes to immunisation and compared differences in vaccination attitudes between adolescents and adults.MethodsThis study was a cross-sectional, national online survey. Recruitment was stratified by state and gender to ensure findings were nationally representative. Regression analyses were performed to assess and compare adolescent and adult views on vaccine benefits, community protection, risks, side effects, sources of information, and decision-making preference.ResultsIn 2013, 502 adolescents and 2003 adults completed the online survey. Lower levels of vaccine confidence were observed in adolescents with adolescents less likely to believe vaccines are beneficial and/or safe compared to adults (p = 0.043). Compared to females, males were less confident of vaccine benefits (p < 0.05) but less concern about vaccine side effects (p < 0.05). Adolescents were more concerned about vaccine side effects than adults for pain (p < 0.001), redness or swelling (p < 0.001), and fever (p = 0.006). Adolescents were less likely than adults to consider health professionals (p < 0.001) and the media (e.g. internet) (p = 0.010) as important sources of information, and were more likely to seek information from social networks (p < 0.001) including families and schools. Although 62.0% of adolescents agreed that parents should make the decision about vaccination for them, adolescents were more likely to prefer a joint decision with parents (p < 0.001) or by themselves (p = 0.007) compared with adults.ConclusionAdolescents have a lesser understanding of vaccine safety and benefits than adults and have higher concerns about potential vaccine reactions. Improving adolescent awareness and knowledge of the benefits and risks of vaccination through school-based educational programs may improve confidence in and uptake of vaccines for adolescents and increase vaccine confidence in the next generation of parents.     

The association between physical activity and liver fat after five years of follow-up in a primary prevention multi-ethnic cohort

Objective: Excess liver fat (LF) is associated with dyslipidemia, insulin resistance and cardiovascular disease. Evidence suggests that there is an independent relationship between physical activity (PA) and LF although little is known of the role of PA intensity in reducing LF. The purpose was to evaluate whether meeting PA guidelines, the amount of PA and the intensity of PA at baseline were associated with LF after five-years.Methods: Men and women (n = 478) living in Vancouver, Canada of Aboriginal, Chinese, European or South Asian background completed baseline measurements in 2004–2005. Liver fat was assessed using CT scans at 5-year follow-up, and PA using a PA questionnaire at baseline as well as demographics and anthropometry.Results: In separate unadjusted models, meeting moderate–vigorous PA (MVPA) guidelines (p = 0.009), vigorous PA (p = 0.002) and MVPA (p = 0.017) but not moderate PA (p = 0.068) was predictive of LF at five years (p = 0.009). In multiple linear regression models, when adjusted for covariates, meeting MVPA guidelines and MVPA with LF at five years was no longer significant (p > 0.05) while vigorous PA remained significant (p = 0.021).Conclusion: Meeting PA guidelines through MVPA may not be adequate to prevent the accumulation of LF and PA guidelines may require revision. Vigorous PA should be encouraged to prevent LF accumulation.     

Establishing school day pedometer step count cut-points using ROC curves in low-income children

Previous research has not established pedometer step count cut-points that discriminate children that meet school day physical activity recommendations using a tri-axial ActiGraph accelerometer criterion. The purpose of this study was to determine step count cut-points that associate with 30 min of school day moderate-to-vigorous physical activity (MVPA) in school-aged children. Participants included 1053 school-aged children (mean age = 8.4 ± 1.8 years) recruited from three low-income schools from the state of Utah in the U.S. Physical activity was assessed using Yamax DigiWalker CW600 pedometers and ActiGraph wGT3X-BT triaxial accelerometers that were concurrently worn during school hours. Data were collected at each school during the 2014–2015 school year. Receiver operating characteristic (ROC) curves were used to determine pedometer step count cut-points that associated with at least 30 min of MVPA during school hours. Cut-points were determined using the maximum Youden's J statistic (J max). For the total sample, the area-under-the-curve (AUC) was 0.77 (p < 0.001) with a pedometer cut-point of 5505 steps (J max = 0.46, Sensitivity = 63%, Specificity = 84%; Accuracy = 76%). Step counts showed greater diagnostic ability in girls (AUC = 0.81, p < 0.001; Cut-point = 5306 steps; Accuracy = 78.8%) compared to boys (AUC = 0.72, p < 0.01; Cut-point = 5786 steps; Accuracy = 71.4%). Pedometer step counts showed good diagnostic ability in girls and fair diagnostic ability in boys for discriminating children that met at least 30 min of MVPA during school hours.     

The association between discrepant weight perceptions and objectively measured physical activity

BackgroundSome individuals perceive themselves as being normal weight, despite having an excess body fat percentage (e.g., underestimate weight). Conversely, other individuals perceive themselves as being overweight, despite having a normal body fat percentage (e.g., overestimate weight). When perceived and actual weight statuses are incongruent, individuals possess a discrepant weight perception. The association between discrepant weight perceptions and engagement in moderate-to-vigorous physical activity (MVPA) has not been thoroughly investigated, which was this study's purpose.MethodsFor this cross-sectional study, data from the 2003–2006 National Health and Nutrition Examination Survey were utilized (N = 5462 adults). MVPA was assessed via accelerometry. Based on measured body mass index and whether participants considered themselves as overweight, underweight, or about the right weight, we classified individuals as accurate perception, overestimate weight (discrepant), or underestimate weight (discrepant). A negative binomial logistical regression was used to assess the association between discrepant weight perception (independent variable) and engagement in MVPA (outcome variable).ResultsFemales who said that they are normal weight, but were in fact overweight based on body mass index, engaged in 13% less MVPA (rate ratio = .87, 95% confidence interval: .769–.999, P = .05). Also, older adults (> 60 yrs) who said that they are normal weight, but were overweight based on body mass index, engaged in 23% less MVPA (rate ratio = .77, 95% confidence interval: .616–.965, P = .025).ConclusionDiscrepant weight perceptions were associated with less objectively measured MVPA. Interventions should take weight perceptions into consideration when designing and evaluating intervention impact.     

Association between characteristics of physical activity in leisure time and obesity in Brazilians adults and elderly

ObjectiveTo verify the association of obesity with volume, intensity and types of physical activity in leisure time among Brazilian adults and elderly.Study designCross-sectional study, with a secondary analysis of data from "Surveillance of Risk Factors and Protection for Chronic Diseases by Telephone Survey".MethodsThe target population comprised adults aged ≥18 years. The outcome was obesity (BMI ≥ 30.0 ??kg/m²) and the exposures were the volume, intensity, and main type of physical activity in leisure time. Binary logistic regression was used and the results were expressed as odds ratio (OR) and 95% confidence intervals (CI95%), with a significance level of 5%.ResultsCompared to inactive, the highest volume of leisure time physical activity (≥300 min/week) had a lower occurrence of obesity in adults (OR = 0.76; CI95%: 0.63, 0.92; p = 0.001) and elderly (OR = 0.62; CI95%: 0.46, 0.82; p = 0.001). In adults, vigorous activities (OR = 0.65; CI95%: 0.55, 0.78; p < 0.001) and, in the elderly, light/moderate activities (OR = 0.75; CI95%: 0.62, 0.89; p < 0.001) and vigorous (OR = 0.54; CI95%: 0.37, 0.78; p < 0.001) presented protective effect for obesity. Among the types of physical activity, running was the most strongly associated with a lower occurrence of obesity in adults (OR = 0.54; CI95%: 0.32, 0.92; p = 0.024) and elderly (OR = 0.27; CI95%: 0.10, 0.69; p = 0.006). In adults, strength training (p < 0.001), gymnastics (p = 0.032) and sports (p = 0.013) and in elderly, walking (p = 0.001) and sports (p = 0.003) also had protective effect.ConclusionA greater volume, vigorous intensity and physical activities of a structuring character and intensity progression, such as running, were associated with the lower occurrence of obesity.