Moderate- And Vigorous-intensity Physical Activity Research Articles

The Joint Associations of Physical Activity and Sedentary Behaviors on Adiposity during Adolescence: The 1993 Pelotas (Brazil) Cohort Study.

A prior study conducted in high-income countries demonstrated that specific sedentary behavior, such as TV viewing, is prospectively associated with adiposity in both active and inactive adolescents. The aim of this study was to examine the joint associations of sedentary behaviors and moderate- and vigorous-intensity physical activity (MVPA) with adiposity among Brazilian adolescents. This prospective cohort study included 377 participants of the 1993 Pelotas (Brazil) Study who completed an accelerometry assessment at age 13 years and a dual-energy X-ray absorptiometry (DXA) assessment at age 18 years. Accelerometer-measured MVPA was dichotomized into high (≥60 min/day) and low (<60 min/day). Accelerometer-measured sedentary time (SED) was dichotomized into low (<49 min/h) and high (≥49 min/h) based on the median. Self-reported TV viewing time was also dichotomized into low (<3 h/day) and high (≥3 h/day) based on the median. We combined the two MVPA groups (high and low) and two SED groups (low and high) to form the four MVPA&SED groups: high&low, high&high, low&low, and low&high. We also created four MVPA&TV groups in the same manner. Fat mass index (FMI; kg/m2) was calculated using DXA-derived fat mass. Multivariable linear regression analyses compared FMI at 18 years among the four MVPA&SED groups and among the four MVPA&TV groups, adjusting for socioeconomic status, energy intake, and baseline adiposity. The analysis results showed that SED or TV viewing time was not prospectively associated with adiposity in both active and inactive Brazilian adolescents. This study suggests that the association between specific sedentary behaviors, such as TV viewing, and adiposity may differ across societal settings-in this case, high-income vs. middle-income countries.

Risk Factor Assessment in Virtual Cardiac Rehabilitation Amid the Covid-19 Pandemic.

Risk Factor Assessment in Virtual Cardiac Rehabilitation Amid the Covid-19 Pandemic.

Longitudinal Change In Physical Activity And Adiposity In Transition From Adolescence To Adulthood

The current recommendations for moderate- and vigorous-intensity physical activity (MVPA) have a poorly-justified, abrupt transition that recommends youth achieve ≥60 minutes/day (min/d) and adults achieve ≥150 minutes/week (≥22 min/d on average). PURPOSE: To examine how body fat mass changes according to changes in MVPA from late adolescence (age 18 years) to early adulthood (age 22 years). METHODS: The study sample included 2,099 participants (1,113 females) from the 1993 Pelotas (Brazil) Study. At ages 18 and 22 years, MVPA was measured using wrist-worn accelerometry and fat mass was measured using dual-energy X-ray absorptiometry. MVPA at age 18 was categorized into two groups: 0-59 and ≥ 60 min/d (no [N] and yes [Y] for meeting the youth recommendation). MVPA at age 22 was categorized into three groups: 0-21, 22-59, and ≥ 60 min/d (N, Y22, and Y60 for meeting the adult or youth recommendation). The combination of these groups created six MVPA groups (N&N, N&Y22, N&Y60, Y&N, Y&Y22, and Y&Y60). Sex-specific multivariable linear regression analyses were conducted to estimate changes in fat mass index (FMI, kg/m2) from age 18 to 22 years according to the six MVPA groups. RESULTS: Among males, compared to Y&Y60 (FMI increase = 1.2 [95% CI = 1.0, 1.4]), Y&Y22 and Y&N had larger FMI increases (1.9 [1.6, 2.1] and 1.9 [1.2, 2.5], respectively). Among females, Y&Y60 and Y&Y22 had an equal FMI increase (1.6 [1.4, 1.9] for both groups), while Y&N had a larger FMI increase (2.4 [1.8, 3.0]). For males and females who were inactive at age 18 years, the FMI increase was the smallest among those with ≥60 min/d of MVPA at age 22 years (0.6 [0.1, 1.1] for males and 1.0 [0.5, 1.5] for females), followed by 22-59 min/d (1.0 [0.6, 1.3] for males and 1.4 [1.1, 1.6] for females), and 0-21 min/d (1.7 [1.1, 2.3] for males and 1.7 [1.4, 2.1] for females). CONCLUSION: These findings suggest that among those who were active in late adolescence, engaging in ≥22 min/d of MVPA in adulthood (adult recommendation) is sufficient to lower fat accumulation for females, but insufficient for males. With respect to healthy adiposity levels, these findings call into question the abrupt change in MVPA recommendations for young adult males.

South Asians Active Together (SAATH): Protocol for a multilevel physical activity intervention trial for South Asian American mother and daughter dyads

South Asian (SA), including Asian Indian and Pakistani Americans, have a high burden of cardiometabolic risk factors and low levels of physical activity (PA). Increasing PA in the U.S. population is a national priority; however, SA American women and girls experience unique barriers to PA that are not addressed by current promotion efforts. To address this gap, our community-based participatory research partnership developed the South Asians Active Together (SAATH) intervention. This study is a two-arm randomized clinical trial to evaluate the effects, mediators, and implementation of the 18-week SAATH intervention. A total of 160 mother-daughter dyads will be randomized in a 1:1 ratio to the SAATH intervention and control groups. The intervention was designed for mother-daughter dyads and targets individual, interpersonal, and family levels through (1) group exercise classes, (2) mother-daughter discussions, and (3) peer group discussions. The intervention targets the environment level through community partner meetings aimed at creating environment changes to enhance PA opportunities for SA women and girls. The control group will receive PA education materials. We hypothesize that dyads who receive the intervention will have significantly greater increases in moderate- and vigorous-intensity PA (MVPA) from baseline to 4 months, compared to the control group. MVPA will be measured at 12 months in intervention participants to examine if changes are sustained. A process evaluation will use the reach, effectiveness, adoption, implementation, and maintenance (RE-AIM) framework. This study will fill knowledge gaps about the effectiveness and implementation of culturally adapted, community-based PA interventions for SA women and girls.

Physical activity, sedentary behaviors and all-cause mortality in patients with heart failure: Findings from the NHANES 2007-2014.

BackgroundLimited data are available examining the effects of both moderate- and vigorous-intensity physical activity (MVPA) and sedentary behavior (SB) on longevity among patients with heart failure (HF). This study examined the associations of MVPA and SB with all-cause mortality in HF patients using a nationally representative survey data.MethodsNational Health and Nutrition Examination Survey data (2007–2014) were used. 711 adults with self-reported congestive HF, linked to 2015 mortality data were analyzed. Self-reported MVPA and SB minutes were used to create the three MVPA [No-MVPA, insufficient (I-MVPA; <150 min/wk), and sufficient (S-MVPA; ≥150 min/wk)] and two SB (<8 and ≥8 hrs/d) groups. Cox proportional hazard models were constructed to test the associations of MVPA and SB with all-cause mortality.Results119 deaths occurred over an average of 4.9 years of follow-up. Lower MVPA and higher SB were independently associated with poor survival (P < .001). Joint and stratified analyses showed that the protective effect of MVPA was most pronounced among patients with SB<8 hrs/d. There was no difference in the mortality risk by SB levels within I-MVPA and S-MVPA groups; however, in the No-MVPA group, those with SB≥8 hrs/d had a greater risk of mortality compared to those with <8 hrs/d (Hazard ratio = 1.60).ConclusionIn this HF cohort, MVPA and SB were independently and jointly associated with all-cause mortality. The beneficial effect of MVPA is attenuated by excessive SB; however, engaging in some amount of MVPA may provide a protective effect and attenuates the detrimental effects associated with excessive SB.

Longitudinal change in physical activity and adiposity in the transition from adolescence to early adulthood: the 1993 Pelotas cohort study

BackgroundIn the current Physical Activity Guidelines (PAG) for moderate- and vigorous-intensity physical activity (MVPA), abrupt transition from ≥ 60 min/day [youth PAG] to ≥ 150 min/week (≥ 22 min/day on average) [adult PAG] during emerging adulthood is poorly justified. The aim of this study was to examine body fat mass changes according to whether meeting the youth and adult PAGs in late adolescence (age 18 years) to early adulthood (age 22 years).MethodsThe study sample included 2,099 participants (1,113 females) from the 1993 Pelotas (Brazil) Study. At ages 18 and 22 years, MVPA was measured using wrist-worn accelerometry and fat mass was measured using dual-energy X-ray absorptiometry. MVPA at age 18 was categorized into two groups: 0–59 or ≥ 60 min/day (no [N] or yes [Y] for meeting the youth recommendation, respectively). MVPA at age 22 was categorized into three groups: 0–21, 22–59, or ≥ 60 min/day (N, Y22, or Y60 for not meeting the adult recommendation, meeting the adult recommendation, or meeting the youth recommendation, respectively). The combination of these groups created six MVPA groups (N&N, N&Y22, N&Y60, Y&N, Y&Y22, and Y&Y60). Sex-specific multivariable linear regression analyses were conducted to estimate change in fat mass index (FMI) from age 18 to 22 years in the six MVPA groups.ResultsAmong males, compared to Y&Y60 (FMI increase = 1.2 kg/m2 [95% CI = 1.0, 1.4]), Y&Y22 and Y&N had larger FMI increases (1.9 [1.6, 2.1] and 1.9 [1.2, 2.5], respectively). Among females, Y&Y60 and Y&Y22 had an equal FMI increase (1.6 [1.4, 1.9] for both groups), while Y&N had a larger FMI increase (2.4 [1.8, 3.0]).ConclusionsThese findings suggest that among those who were active in late adolescence, engaging in ≥ 22 min/day of MVPA in adulthood is associated with lower body fat gain for females, but not for males.

Effects of Replacing Sedentary Time With Physical Activity on Mortality Among Patients With Heart Failure: National Health and Nutrition Examination Survey Follow-Up Study

A sedentary lifestyle is prevalent among patients with heart failure (HF) and is associated with poor prognosis and survival, possibly owing to the displacement of health-enhancing behaviors, such as physical activity (PA). However, there is limited evidence examining the displacement effects of reducing duration of sedentary time (ST) on clinical outcomes in patients with HF. The current study examined the theoretical effects of relocating ST with PA on all-cause and cardiovascular disease (CVD)-specific mortality risks in patients with HF. We analyzed 265 patients with HF who participated in the National Health and Nutrition Examination Survey from 2003 to 2006. Cox proportional hazards regression model was fitted to estimate mortality risks based on objectively measured ST well as time spent in light-intensity PA (LPA) and moderate- and vigorous-intensity PA (MVPA). The theoretical changes in the hazard ratio (HR) by replacing ST with LPA or MVPA were examined using isotemporal substitutional modeling. On average, patients with HF spent 70% of waking hours per day in ST (9.01 hours), followed by LPA (29%; 3.75 hours) and MVPA (1%; 0.13 hours). Ten-minute substitution of ST with LPA was associated with significantly lower all-cause and CVD-specific mortality risks (hazard ratio [HR]=0.93 for both). The mortality risks progressively decreased as more ST was relocated to LPA. The relocation effects of ST with MVPA were not statistically significant, possibly because of limited MVPA accrued in this clinical population. The current study provides empirical evidence about the potential health benefits of replacing a modest amount of ST with LPA among patients with HF.

Joint associations of physical activity and sedentary time with adiposity during adolescence: ALSPAC.

BackgroundIn developing evidence-based physical activity (PA) guidelines for youth, a knowledge gap exists regarding the health effects of sedentary time (SED). The aim of this study was to determine the joint associations of moderate- and vigorous-intensity PA (MVPA) and SED with adiposity during adolescence.MethodsThe study sample was 2619 non-obese participants (56.7% female) from the UK Avon Longitudinal Study of Parents and Children. Accelerometer-measured MVPA and SED at age 11, 13, 15 years and self-reported TV viewing at age 13 and 16 years were used to create two exposure variables: six MVPA&SED combinations based on two MVPA patterns [≥60 (active) and <60 min/day (inactive)] and three SED patterns [≈25 (low), ≈30 (middle) and ≈35 min/h (high)] and six MVPA&TV combinations based on two MVPA patterns and three TV viewing patterns [<1–2 (low), 1–2 (middle) and >1–2 h/day (high)]. Adiposity was evaluated using fat mass index (FMI) at age 17 years.ResultsSED was not significantly associated with FMI in either active or inactive adolescents. However, higher TV viewing was associated with higher FMI in both active [adjusted FMI = 4.53 vs. 5.09 (95% CI = 4.87, 5.33) for low TV vs. high TV] and inactive adolescents [adjusted FMI = 4.91 vs. 5.21 (95% CI = 5.02, 5.39) for low TV vs. high TV].ConclusionsHigher TV viewing time, but not total SED, was prospectively associated with higher adiposity among both active and inactive adolescents, suggesting a specific sedentary behavior target for public health.

Mortality risk and physical activity across the lifespan in endometrial cancer survivors.

Physical activity (pre- and post-diagnosis) has been studied in prevention and survivorship contexts for endometrial cancer. However, the association of physical activity (PA) across the lifespan on mortality risk among endometrial cancer survivors is understudied. The study's objective was to identify the association of lifetime PA on mortality risk in endometrial cancer survivors. Seven hundred forty-five endometrial cancer survivors drawn from a population-based cancer registry (diagnosed between 1991 and 1994) reported the frequency (sessions/week) of moderate- and vigorous intensity physical activity (MVPA) at age 12, age 20, and 5years pre-interview (post-diagnosis). Cox proportional hazards were used to estimate hazard ratios (HR) and 95% confidence intervals for the association between PA, all-cause, and cardiovascular disease mortality as assessed in 2016. MVPA was modeled using natural cubic splines. Diagnosis age, body mass index, and smoking (pack-years) were each positively associated with increased all-cause mortality risk. Those who did one session of MVPA 5years pre-interview had a lower mortality risk (HR 0.61; 95% CI 0.41-0.92) compared to those with no MVPA. Those reporting one session of MVPA was similarly observed at age 12 (HR 0.95; 95% CI 0.86-1.06) and at age 20 (HR 0.87; 95% CI 0.65-1.16). Those who participated in PA, compared to those who did not, in the 5years before diagnosis had a lower mortality risk. While PA was not independently protective against mortality risk at ages 12 or 20, PA is still important for endometrial cancer survivors for other non-mortality outcomes.

Examining the day-to-day bidirectional associations between physical activity, sedentary behavior, screen time, and sleep health during school days in adolescents.

BackgroundAdolescence is a vulnerable period for experiencing poor sleep health. Growing studies have demonstrated lifestyle behaviors including physical activity (PA), screen time (SCT), and sedentary behaviors (SED) as the potential factors associated with sleep health in adolescents; yet, the evidence is inconclusive and the directionality of temporal associations across school days are not well understood. This study examined the day-to-day bidirectional associations of lifestyle behaviors with sleep health parameters in adolescents.MethodsA total of 263 adolescents (58% boys) in 6th - 8th grades wore an accelerometer for 24-hour across the three consecutive school days and completed recording SCT in time-diary and answering sleep quality (SQ) questions for each day. Sleep-wake patterns as well as time spent in moderate- and vigorous-intensity PA (MVPA) and SED were objectively quantified from the wrist-worn accelerometry data across the two segments of the day (during and after school hours). Mixed model analyses were conducted to test bidirectional associations between lifestyle factors and sleep health parameters in each temporal direction across the days. Additionally, indirect associations across the days were tested using an autoregressive cross-lagged model analysis in the framework of path analysis.ResultsMVPA minutes in a day did not predict sleep health parameters that night. The bidirectional associations were partially observed between SED and sleep health, but the significance and direction of the associations largely varied by the time segment of a day as well as types of sleep health parameters. Additionally, greater SCT during the day was associated with lower SQ that night (b = -0.010; P = .018), and greater SQ was associated with greater MVPA during school hours (b = 6.45; P = .028) and lower SED after school hours (b = -39.85; P = .029) the next day. Lastly, there were significant indirect associations of SCT with sleep health parameters across the days indicating multi-day lagged effects of SCT on sleep health the later nights.ConclusionThis study highlights the importance of lowering SCT for better sleep health in adolescents during school days. Additionally, perceived SQ is shown to be a potential significant predictor promoting healthy behaviors the next day independent of sleep-wake patterns. Further studies are warranted to confirm the observed temporal associations between SCT, SQ, and behavioral outcomes in this vulnerable population.

Examining mediators of intervention efficacy in a randomised controlled m-health trial to improve physical activity and sleep health in adults

Objectives: Examining mediators of intervention efficacy in an m-health intervention targeting physical activity and sleep in 160 Australian adults.Design: Nationwide randomised controlled trial.Main outcome measures: Moderate- and vigorous-intensity physical activity (MVPA), assessed using the Active Australia Questionnaire; sleep quality (Pittsburgh Sleep Quality Index); and sleep hygiene practices (Sleep Hygiene Index). Hypothesised psychosocial (e.g. self-efficacy) and behavioural (i.e. MVPA, sleep quality, sleep hygiene) mediators were tested on primary endpoint data at 3 months using bias-corrected bootstrapping (PROCESS 2 for SPSS). All outcomes and mediators were assessed using self-report.Results: At three months, the intervention had significantly improved sleep quality (d = 0.48, 95% CI: −2.26, −0.33, p = 0.009) and sleep hygiene (d = 0.40, 95% CI: −3.10, −0.19, p = 0.027). Differences in MVPA were not significant (d = 0.24, 95% CI: −35.53, 254.67, p = 0.139). Changes in MVPA were mediated by self-efficacy, perceived capability, environment, social support, intentions and planning, some of which showed inconsistent mediation (suppression). None of the hypothesised psychosocial factors mediated sleep outcomes. Changes in sleep hygiene mediated changes in sleep quality.Conclusions: Several psychosocial factors mediated changes in physical activity but not in sleep outcomes. Mediation effects of sleep hygiene on sleep quality highlight the importance of providing evidence-based strategies to improve sleep quality.

Physical education environment and student physical activity levels in low-income communities

BackgroundThe purpose of this study was to examine the association of physical education (PE) class characteristics, such as lesson context, teacher’s physical activity (PA) promotion behavior, and lesson location, with student engagement in moderate- and vigorous-intensity physical activity (MVPA) during PE lessons in elementary school (ES), middle school (MS), and high school (HS).MethodsThe study sample included 2106 PE classes from 40 schools located in low-income communities. The System for Observing Fitness Instruction Time (SOFIT) was used to assess lesson context, teacher’s behavior, and student PA during PE lessons. Mixed models were used to examine the association between PE class characteristics and the probability of meeting the recommended level of MVPA during PE lessons (MVPA ≥50%), accounting for within-school random effects and school characteristics.ResultsAlmost all PE classes (90%) with ≥60–70% of lesson time spent in motor content and ≥ 10–20% in teacher’s in-class PA promotion met the recommended level of MVPA across the school levels. More specifically, among the sub-categories of motor content, more lesson time spent in fitness was significantly associated with MVPA ≥50% in all school levels. However, more lesson time spent in game play was a significant factor only in ES (OR = 2.1; 95% CI = 1.4–3.0). Outdoor lessons were a significant factor in ES (OR = 5.3; 95% CI = 3.1–9.0) and MS (OR = 21.0; 95% CI = 6.3–69.4), but not HS (OR = 1.4; 95% CI = 0.6, 3.2).ConclusionsPE lessons with higher motor content and higher teacher’s in-class PA promotion are more likely to meet the recommended level of MVPA in all school levels. However, the sub-categories of motor content and lesson location could impact student MVPA differently by school levels.

The association between physical activity and a composite measure of sleep health.

Physical activity has been associated with several individual dimensions of sleep. However, the association between physical activity and sleep health, a construct that emphasizes the multidimensional nature of sleep, has not been explored. This analysis examined the relationship between physical activity and a composite measure of sleep health. A total of 114 adults (66% female, 60.3 ± 9.2years) were included in the analyses. Participants reported daily light-intensity physical activity (LPA) and moderate- and vigorous-intensity physical activity (MVPA) via diary, while wearing a pedometer (Omron HJ-720ITC) to measure daily steps. Sleep health was measured using the RU_SATED questionnaire, which addresses regularity of sleep patterns, satisfaction with sleep, daytime alertness, and sleep timing, efficiency, and duration. Multiple linear regression, binary logistic regression, and analysis of covariance (ANCOVA) were utilized for analyses. Mean sleep health score was 9.6 ± 2.4 (0 [poor]-12 [good]). Participants reported 62.9 ± 66.0 and 51.2 ± 51.2min/day of LPA and MVPA, respectively, and took 5585.5 ± 2806.7 steps/day. Greater MVPA was associated with better sleep health (β = 0.27, P = 0.005) and sleep health scores differed between those reporting < 30min/day and ≥ 60min/day of MVPA (P = 0.004). Greater MVPA was associated with higher odds of having good sleep satisfaction (OR = 1.58 [1.14-2.20], P < 0.01), timing (OR = 2.07 [1.24-3.46], P < 0.01), and duration (OR = 1.48 [1.02-2.18], P = 0.04). Pedometer-based physical activity and LPA were not related to sleep health or its individual dimensions. In middle- to older-aged adults, higher-intensity activity, but not lower-intensity or volume of activity, was associated with greater sleep health. These data suggest that physical activity intensity may be important for sleep health.

Daily Physical Activity Among Toddlers: Hip and Wrist Accelerometer Assessments.

Physical activity (PA) habits seem to track over time from as young as early childhood. For children under age 3 years, wearable sensor-measured PA levels have begun to be investigated. The aims of this study were to evaluate the feasibility of using hip- vs. wrist-worn accelerometers, and to report accelerometer-derived PA metrics among toddlers. A convenience sample of 22 toddlers aged 13 to 35 months and their mothers were recruited for this study. ActiGraph wGT3X-BT accelerometers were attached to wrist bands and waist belts. The mothers were asked to affix a wrist band and a waist belt to their participating children during waking hours for four days. They also completed an acceptability survey. Of the 22 toddlers, 19 (86%) had ≥ 3 valid days of hip data, while only 14 (64%) did so for wrist data (p = 0.16). In terms of acceptability, 18 mothers (82%) responded that the 4-day hip wear was easy, while only 13 (59%) responded that the 4-day wrist wear was easy (p = 0.19). Daily light-intensity PA (LPA) was on average 161 min, and daily moderate- and vigorous-intensity PA (MVPA) was on average 47 min, as determined using published hip accelerometer cut-points. There were no significant differences in LPA or MVPA by age or by sex. In conclusion, this study suggests that hip placement of an ActiGraph accelerometer is more feasible than wrist placement among toddlers.

A closer look at the relationship among accelerometer-based physical activity metrics: ICAD pooled data

BackgroundAccelerometers are widely used to assess child physical activity (PA) levels. Using the accelerometer data, several PA metrics can be estimated. Knowledge about the relationships between these different metrics can improve our understanding of children’s PA behavioral patterns. It also has significant implications for comparing PA metrics across studies and fitting a statistical model to examine their health effects. The aim of this study was to examine the relationships among the metrics derived from accelerometers in children.MethodsAccelerometer data from 24,316 children aged 5 to 18 years were extracted from the International Children’s Accelerometer Database (ICAD) 2.0. Correlation coefficients between wear time, sedentary behavior (SB), light-intensity PA (LPA), moderate-intensity PA (MPA), vigorous-intensity PA (VPA), moderate- and vigorous-intensity PA (MVPA), and total activity counts (TAC) were calculated.ResultsTAC was approximately 22X103 counts higher (p < 0.01) with longer wear time (13 to 18 h/day) as compared to shorter wear time (8 to < 13 h/day), while MVPA was similar across the wear time categories. MVPA was very highly correlated with TAC (r = .91; 99% CI = .91 to .91). Wear time-adjusted correlation between SB and LPA was also very high (r = −.96; 99% CI = -.96, − 95). VPA was moderately correlated with MPA (r = .58; 99% CI = .57, .59).ConclusionsTAC is mostly explained by MVPA, while it could be more dependent on wear time, compared to MVPA. MVPA appears to be comparable across different wear durations and studies when wear time is ≥8 h/day. Due to the moderate to high correlation between some PA metrics, potential collinearity should be addressed when including multiple PA metrics together in statistical modeling.

Mediating Effect of Muscle on the Relationship of Physical Activity and Bone.

This study analyzed prospective associations between distinct trajectories of objectively measured physical activity (PA) and late adolescent bone parameters and explored the mediating effects of lean soft tissue, a surrogate of muscle mass to associations. Physical activity was measured by accelerometry starting at age 5 yr and continuing at 8, 11, 13, 15, and 17 yr in approximately 524 participants from the Iowa Bone Development Study. Sex-specific group-based trajectory modeling was used to construct developmental trajectories of moderate- and vigorous-intensity PA (MVPA) from childhood to late adolescence. At age 17 yr, proximal femur bone mineral density (aBMD) was assessed by dual X-ray energy absorptiometry, and its distribution was calculated by aBMD ratios. Specific geometric measures of the proximal femur were assessed using hip structural analysis. A significant portion of the total effect of MVPA from age 5 to 17 yr on bone parameters at age 17 yr was explained by an increase in leg lean soft tissue in both sexes. For males and females, indirect effects were observed on the total and all regional proximal femur aBMD, and on the ratio between the inferomedial and superolateral neck aBMD. The effect on the ratio between the trochanter and the total proximal femur was specific to females, whereas the effect on the hip axis length was specific to males. Direct effects of MVPA on aBMD were identified only in males. Using robust mediation analysis, this is the first study addressing the indirect effect (through muscle) of PA across childhood and adolescence on proximal femur bone parameters. To improve bone health at the proximal femur, the results suggest PA interventions during growth that increase muscle mass, particularly in females.

Objectively measured sedentary time and physical activity and associations with body weight gain: does body weight determine a decline in moderate and vigorous intensity physical activity?

High levels of physical activity (PA) may prevent the development of obesity. However, the magnitude and direction of the association between PA of various intensities, sedentary time and weight status remain unclear. Thus, we examined whether objectively measured sedentary time and PA independently predict gain in body weight, change in body weight and to examine the possibility of reverse causation. We examined the prospective associations between sedentary time, PA and body weight (BW). Baseline measurements were conducted in 2008/2009 and follow-up measurements in 2014/2015 in a random sample of the adult Norwegian population (N=1710, 45.1% men). Moderate and vigorous intensity PA (MVPA) and sedentary time were measured by accelerometry and BW and height self-reported. We first modelled the associations between baseline sedentary time and PA with BW at follow-up. We then modelled the reverse associations (BW as the exposure) and sedentary time and PA (as outcomes) in separate models. All models were adjusted for age, sex, baseline value of the outcome, socio-economic status, alcohol consumption, smoking, monitor wear time and follow-up time. Body mass index (BMI) increased by 0.2 units (P=0.003) between baseline and follow-up, and 46.5% of participants were either overweight (36.4%) or obese (10.1%) at baseline increasing to 49.6% (11.7% obese) at follow-up. Baseline sedentary time, MVPA and vigorous PA were not associated with BW at follow-up after adjustment for covariates. In contrast, baseline BW was inversely associated with MVPA (β=-0.11; 95% confidence interval (CI); -0.21, -0.009) and VPA (β=-0.035; 95% CI; -0.059, -0.011) in adjusted models. These associations were unchanged when BW was substituted by BMI. Baseline BW seems to determine a decrease in MVPA in healthy adult Norwegian men and women, more so than the reverse.

Assessing pre- and postoperative activity levels with an accelerometer: a proof of concept study

BackgroundPostoperative recovery after abdominal surgery is measured mostly based on subjective or self-reported data. In this article we aim to evaluate whether recovery of daily physical activity levels can be measured postoperatively with the use of an accelerometer.MethodsIn this multicenter, observational pilot study, 30 patients undergoing laparoscopic abdominal surgery (hysterectomy, adnexal surgery, cholecystectomy and hernia inguinal surgery) were included. Patients were instructed to wear an Actigraph wGT3X-BT accelerometer during one week before surgery (baseline) and during the first, third and fifth week after surgery. Wear time, steps taken and physical activity intensity levels (sedentary, light, moderate and vigorous) were measured. Patients were blinded for the accelerometer outcomes. Additionally, an activity diary comprising patients’ self-reported time of being recovered and a list of 18 activities, in which the dates of resumption of these 18 activities were recorded after surgery, was completed by the patient.ResultsFive patients were excluded from analyses because of technical problems with the accelerometer (n = 1) and protocol non-adherence (n = 4). Light, moderate, vigorous, combined moderate and vigorous intensity physical activity (MVPA), and step counts showed a clear recovery curve after surgery. Patients who underwent minor surgery reached their baseline step count and MVPA three weeks after surgery. Patients who underwent intermediate surgery had not yet reached their baseline step count during the last measuring week (five weeks after surgery). The results of the activity diaries showed a fair agreement with the accelerometer results (Cohens Kappa range: 0.273-0.391). Wearing the accelerometer was well tolerated and not regarded as being burdensome by the patients.ConclusionsThe accelerometer appeared to be a feasible way to measure recovery of postoperative physical activity levels in this study and was well tolerated by the patients. The agreement with self-reported physical recovery times was fair.

The effect of family and friend support on physical activity through adolescence: a longitudinal study.

BackgroundThis study examined if family and friend support predicted adolescent physical activity (PA) across a five-year time span.MethodsThe Iowa Bone Development Study collected objective measures of physical activity and self-report of physical activity psychosocial factors at ages 13 (n = 306), 15 (n = 356), and 17 yr (n = 317). Total moderate and vigorous-intensity PA (MVPA) and MVPA after 3 pm on weekdays (MVPA-PM Weekday) were measured using ActiGraph accelerometers. Family Support for PA and Friend Support for PA scales were measured using the Choices questionnaire. Models were adjusted for SES (mother’s education) and somatic maturity (Mirwald predictive equations for maturity offset). Spearman correlation coefficients examined tracking of scales at ages 13, 15 and 17. Logistic regression estimated the odds ratio for being in the lowest tertile of each scale at age 17 if in the lowest tertile at age 13. Linear mixed regression models investigated associations between these scales and MVPA outcomes over time.ResultsTwo- and five-year intra-variable tracking associations for Family Support and Friend Support scales were moderate (r = 0.32–0.58), except for the comparison between age 13 and age 17 Friend Support for girls, which resulted in a low association (r = 0.26). Boys and girls in the lowest tertile for support at age 13 were more likely to remain in the lowest tertile at age 17 compared to those in the middle and upper tertiles. The regression models indicated that when all other factors were held constant, an increase in family and/or friend support resulted in an increase in both MVPA outcomesConclusionsFrom early to late adolescence, support for PA from the family and/or support from friends results in higher levels of total and discretionary MVPA. However, the importance of support in predicting MVPA decreased with age.

Physical activity during work, transport and leisure in Germany--prevalence and socio-demographic correlates.

BackgroundThis study aimed 1) to provide data estimates concerning overall moderate- and vigorous-intensity physical activity (MVPA) as well as MVPA during work, transport and leisure in Germany and 2) to investigate MVPA and possible associations with socio-demographic correlates.MethodsA cross-sectional telephone survey interviewed 2248 representative participants in the age of 18–65 years (1077 men; 42.4±13.4 years; body mass index: 25.3±4.5kg•m−2) regarding their self-reported physical activity across Germany. The Global Physical Activity Questionnaire was applied to investigate MVPA during work, transport and leisure and questions were answered concerning their demographics. MVPA was stratified by gender, age, body mass index, residential setting, educational and income level. To identify socio-demographic correlates of overall MVPA as well as in the domains, we used a series of linear regressions.Results52.8% of the sample achieved physical activity recommendations (53.7% men/52.1% women). Overall MVPA was highest in the age group 18–29 years (p<.05), in participants with 10 years of education (p<.05) and in participants with lowest income levels <1.500€ (p<.05). Regression analyses revealed that age, education and income were negatively associated with overall and work MVPA. Residential setting and education was positively correlated with transport MVPA, whereas income level was negatively associated with transport MVPA. Education was the only correlate for leisure MVPA with a positive association.ConclusionsThe present data underlines the importance of a comprehensive view on physical activity engagement according to the different physical activity domains and discloses a need for future physical activity interventions that consider socio-demographic variables, residential setting as well as the physical activity domain in Germany.