Exploring boundary conditions of physical activity maintenance: A secondary analysis of time-series data from a weight-loss intervention

Objective: A key concept in health psychology is behavioral maintenance. However, previous research has struggled to establish shared conceptualizations and operational definitions. This study aimed to contribute to this debate by examining whether a simple conceptual proposition of physical activity maintenance as ‘the performance of physical activity according to an intended target threshold over a specific period of observation’ can be empirically supported, and under which boundary conditions. Specifically, we explored different formulations of two boundary conditions: activity threshold and timescale of change. Methods: We analyzed 352 time series (length=182 days) of moderate-to-vigorous physical activity (MVPA) collected daily with Fitbit from participants in a weight loss intervention. Activity thresholds were defined based on each participant’s baseline MVPA and their intention to maintain or increase activity over six months. Generalized Additive Models were used to model individual trajectories across varying timescales (7, 14, 28, and 56 days). Results: At short timescales (7–14 days) trajectories crossed the threshold frequently, indicating high variability. At longer timescales (28–56 days) trajectories were more stable, with participants tending to stay either above or below their threshold, aligning with our target conceptualization of maintenance. Relaxing the threshold by 10-20% relatively increased the proportion of participants classified as maintainers, though maintenance remained uncommon for participants with higher thresholds. Conclusions: Our findings provide initial evidence on which boundary conditions support detecting physical activity maintenance as conceptually defined. These results underscore the importance of systematically testing boundary conditions to advance understanding of behavioral maintenance.

Adolescents and young adults with intellectual and developmental disabilities (IDD) have high rates of obesity and low levels of physical activity. This analysis examined changes in light, moderate-to-vigorous physical activity (MVPA) and sedentary time, and the association between changes in MVPA and weight loss in adolescents and young adults with IDD and overweight and obesity participating in a 6-month multi-component weight loss intervention. Adolescents and young adults with IDD and overweight or obesity (body mass index≥85 percentile, n=110, age ~16years, 52.7% female) and a parent were randomised to one of three intervention groups: face-to-face delivery/conventional reduced energy diet (n=36), remote delivery (RD)/conventional reduced energy diet (n=39), or RD/reduced energy enhanced stop light diet (eSLD) (n=35.) Participants were asked to engage in 60min/day of MVPA on 5 or more days/wk. Participants and a parent attended twice monthly education/behavioural counselling sessions with a health educator to assist participants in complying with dietary and MVPA recommendations. Education/counselling in the RD arms was delivered remotely using video conferencing, and self-monitoring of MVPA and daily steps was completed using a wireless activity tracker. Education/counselling in the face-to-face arm was delivered during home-visits and self-monitoring of MVPA and daily steps was completed by self-report using paper tracking forms designed for individuals with IDD. MVPA, light activity, and sedentary time were assessed over 7days at baseline and 6months using a portable accelerometer (ActiGraph wGT3x-BT). Mixed modelling analysis completed using participants with valid accelerometer data (i.e. ≥4-10h days) at baseline (n=68) and 6months (n=30) revealed no significant changes in light, moderate- MVPA, or sedentary time across the 6-month intervention (all P>0.05). Participants obtained 15.2±21.5min/day of MVPA at baseline and 19.7±19.7min/day at 6months (P=0.119). Mixed modelling indicated no significant effects of group (P=0.79), time (P=0.10), or group-by-time interaction (P=0.21) on changes in MVPA from baseline to 6months. Correlational analysis conducted on participants with valid accelerometer data at both baseline and 6months (n=24) revealed no significant associations between baseline sedentary time (r=0.10, P=0.40) and baseline MVPA (r=-0.22, P=0.30) and change in MVPA across the 6-month intervention. Additionally, attendance at education/counselling sessions (r=0.26, P=0.22) and frequency of self-monitoring of MVPA were not significantly associated with change in MVPA from baseline to 6months (r=0.26, P=0.44). Baseline MVPA (r=0.02, P=0.92) and change in MVPA from baseline to 6months (r=0.13, P=0.30) were not associated with changes in body weight across the 6-month intervention. We observed a non-significant increase in MVPA (30%), which was not associated with the magnitude of weight loss in a sample of adolescents and young adults with IDD who participated in a 6-month multi-component weight loss intervention. Additional strategies to increase MVPA in adolescents and young adults with IDD participating in weight loss interventions need to be developed and evaluated.

To determine the predictors of magnitude of change in response to a participation-focused leisure-time physical activity intervention in children with cerebral palsy (CP) using the ParticiPAte CP protocol. We included 33 children (16 males, 17 females) aged 8 to 12years (mean age=10y, SD=1y 6mo) with CP with pre/postintervention data from a wait-list randomized trial. The hypothesized linear predictors of change in primary outcomes (Canadian Occupational Performance Measure [COPM]-performance and COPM-satisfaction, Belief in Goal Self-Competence Scale (BiGSS), and minutes per day moderate-to-vigorous physical activity [MVPA]) were: age; Gross Motor Function Classification System level; comorbid autism spectrum disorder (ASD); Goal Attainment Scaling T score; Problems in Schools Questionnaire; Physical Activity Climate Questionnaire; Motives for Physical Activities Measure-Revised; and stage of behaviour change. Multivariable models were selected using the Bayesian information criterion. Overcoming barriers to participation, age, and comorbid ASD explained 49% of the variance in change in COPM-performance. Being motivated by interest and/or enjoyment and age explained 32% of the variance in change in COPM-satisfaction. Being motivated by physical activity competence or appearance (extrinsic motivation) explained 24% of the variance in change in BiGSS. Parental autonomy supportiveness, overcoming barriers to participation, appearance motivation, and baseline MVPA explained 59% of the variance in change in MVPA. These findings support a behaviour paradigm for conceptualizing physical activity in children with CP. Children who met their treatment goals showed a greater increase in physical activity participation. Children who were more intrinsically motivated by physical activity at baseline improved more. Being older and having a comorbid diagnosis of autism spectrum disorder were associated with an attenuated effect of the therapy.

There is a paucity of prospective evidence examining the links between sedentary time (ST) and cardiometabolic outcomes in youth. We examined the associations between objectively assessed ST and moderate to vigorous physical activity (MVPA) in childhood with cardiometabolic risk in adolescence. The study included 4639 children (47% male) aged 11 to 12 years at baseline whose mothers were enrolled in ALSPAC (Avon Longitudinal Study of Parents and Children) during their pregnancy in the early 1990s. A total of 2963 children had valid blood samples at age 15 to 16 years. Associations with baseline ST and MVPA were examined for BMI, waist circumference, body fat mass, lean body mass, systolic and diastolic blood pressure, fasting triglycerides, total cholesterol, low-density lipoprotein and high-density lipoprotein (HDL) cholesterol, glucose, insulin, C-reactive protein, and a clustered standardized cardiometabolic risk score (CMscore). Baseline ST was not associated deleteriously with any cardiometabolic markers. MVPA was beneficially associated with the 3 adiposity indicators, lean body mass, systolic blood pressure, triglycerides, C-reactive protein, insulin, HDL cholesterol, and CMscore; once the models were adjusted for baseline levels of these markers, these associations remained for body fat mass (mean difference per 10 minutes of MVPA: -0.320 [95% confidence interval (CI): -0.438 to -0.203]; P < .001), HDL cholesterol (0.006 logged mmol/L [95% CI: 0.001 to 0.011]; P = .028), insulin (-0.024 logged IU/L [95% CI: -0.036 to -0.013]; P < .001), and CMscore (-0.014 [95% CI: -0.025 to -0.004]; P = .009). We found no evidence linking ST in late childhood with adverse cardiometabolic outcomes in adolescence. Baseline MVPA was beneficially linked to broad cardiometabolic health in adolescence.

Physical activity has been identified as a key behavior contributing to weight loss and long-term weight maintenance. Current ACSM recommendations include engagement in 200-300 min/wk of moderate-to-vigorous physical activity (MVPA) for long-term weight maintenance. Strategies for achieving this high volume of activity warrant further investigation. PURPOSE: To examine the association between early MVPA adoption and 6-month MVPA engagement within a lifestyle intervention for weight loss. METHODS: 65 adults with Class I obesity (age: 46.2±7.6 years, BMI: 31.7±4.1 kg/m2) participated in a lifestyle intervention for weight loss. Groups were based on moderate (150 min/wk, N=29) and high (250 min/wk, N=36) MVPA prescriptions achieved by week 25. Diet was prescribed at 1200-1800 kcal/day in both groups. Physical activity was objectively measured at baseline and 6 months using a wearable activity monitor. The average minutes of MVPA were computed from self-reported diaries (weeks 2-5) to demonstrate adoption of activity within the first month of the intervention. Partial correlations controlling for baseline MVPA were used to determine the relationship between activity adoption (month 1) and MVPA engagement (month 6). RESULTS: There was a significant increase in MVPA in both the moderate (86.6±214.7 min/wk, p=.038) and high (226.7±208.7 min/wk, p<.001) prescription groups across the first 6-months of the intervention. Month 1 self-reported adoption of MVPA was associated with objectively measured MVPA engagement at month 6 in the high group (r=.44, p=.015), but not the moderate group. Likewise, month 1 self-reported adoption of MVPA was associated with 6-month change in body weight in the high group (r=.41, p=.016), but not the moderate group. CONCLUSIONS: When prescribing high-doses of MVPA within the context of a lifestyle intervention for weight loss, adopting activity in the first month appears to be important in achieving high activity thresholds at 6 months. However, this relationship was not apparent in lower doses of physical activity. Given the significance of relatively high doses of MVPA to improve weight loss success, it appears that it is important to target strategies for promoting early activity adoption. This may facilitate achievement of the ACSM recommended high-dose of physical activity. Supported by NIH (HL103646)

Introduction: Reviewing gaps in self-monitoring during weight loss interventions may help identify individuals demonstrating signs of disengagement in behaviors, including moderate to vigorous physical activity (MVPA), associated with weight loss maintenance. This study examined the associations of different aspects of self-monitoring during a weight loss intervention with 24-month MVPA and weight. Methods: Secondary data analysis from the Tracking Study, a trial comparing weight-tracking frequency during a lifestyle weight loss program, was conducted. Self-monitoring logs from n =339 participants were used to define 4 characteristics and 4 specific gap lengths: short (1-4 weeks), medium (5-8 weeks), long (9-12 weeks), and extra long (>12 weeks). Self-reported MVPA and staff-measured weight were measured at baseline, 6, 12, 18, and 24 months. Generalized estimating equation modeling examined the association between self-monitoring characteristics and reported MVPA and weight. Results: Participants with gaps in self-monitoring as early as the second week of the intervention reported less MVPA and weighed more at 24 months. Furthermore, consistent tracking of MVPA was associated with higher reported MVPA and lower weight. Conclusions: Behavior tracking provides important information about behavioral disengagement early in the intervention process. Future work should test intervention augmentations to improve behavior change when disengagement is detected.

We reported that a social cognitive theory-based (SCT), Internet-delivered behavioral intervention increased device-measured minutes/day of moderate-to-vigorous physical activity (MVPA) over a 6-month period among persons with multiple sclerosis (MS). This paper examined the pattern and predictors of heterogeneity in change for MVPA. Based on previous research, we hypothesized that mild MS disability, fewer MS symptoms, lower baseline MVPA, and positive SCT characteristics (e.g., high exercise self-efficacy) would be associated with greater change in MVPA. Persons with MS (N = 318) were randomized into behavioral intervention (n = 159) or attention/social contact control (n = 159) conditions that were administered via Internet websites and supported with behavioral coaching. Demographic, clinical, symptom, behavioral, and SCT data were from before the 6-month period of delivering the conditions, and MVPA data were from before and after the 6-month period. We examined heterogeneity based on waterfall plots, box plots, and the Levene statistic. We identified predictors of MVPA change using bivariate correlation and multiple, linear regression analyses per condition. The Levene statistic indicated statistically significant heterogeneity of variances for MVPA change between conditions (p = .003), and the waterfall plots and box plots indicated greater heterogeneity in MVPA change for the behavioral intervention. MVPA change score was correlated with baseline MVPA (r = - .33 and r = - .34, p = .0004 and p = .0001) in both conditions and walking impairment (r = - .188, p = .047) and race (r = .233, p = .014) in the behavioral intervention condition. The regression analysis indicated that baseline MVPA (Standardized B = - .449, p = .000002), self-reported walking impairment (Standardized B = - .310, p = .0008), and race (Standardized B = .215, p = .012) explained 25.6% of variance in MVPA change for the behavioral intervention condition. We provide evidence for walking impairment, baseline MVPA, and race as predictors of the heterogeneity in the pattern of MVPA change with a behavioral intervention.

Physical activity and albuminuria in individuals recently diagnosed with type 2 diabetes.

We examined the longitudinal associations of accelerometer-measured physical activity and sedentary time with leg muscle strength (LMS), balance, and falls in middle-aged women. This was a 5-year cohort study among 308 women aged 36–56 years. We used linear mixed-effects models to examine associations of baseline and change in accelerometer-measured sedentary time, light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA) with baseline and 5-year change in LMS and balance (timed up and go test [TUG], functional reach test [FRT], lateral reach test [LRT], and step test [ST]), and negative binomial/Poisson and log-binomial regression as appropriate to assess associations with falls after 5-year follow-up. Greater baseline MVPA was associated with better baseline LMS (β = 4.65 kg/SD, 95% CI: 1.37, 7.93) and TUG (β = −0.09 s/SD, 95% CI: –0.18, –0.01) but not with change in them over 5 years. Baseline MVPA was not associated with FRT at baseline but associated with a greater decrease in FRT (β = −0.87 cm/SD, 95% CI: –1.57, –0.17). Increased MVPA over 5 years was associated with less deterioration in FRT (β = 0.88 cm/SD, 95% CI: 0.14, 1.61). Increased sedentary time over 5 years was associated with a larger decrease in FRT (β = −0.82 cm/SD, 95% CI: –1.58, –0.07). Higher baseline LPA was associated with higher falls risk (IRR = 1.27, 95% CI: 1.02, 1.57). Higher baseline MVPA may benefit LMS and balance, while increasing MVPA in the medium term has little effect on change in these outcomes in mid-life. Detrimental association of LPA with falls may be due to greater exposures to environmental hazards. Highlights Our study for the first time examined the longitudinal associations of objectively measured physical activity and sedentary time with leg muscle strength, balance and falls in middle-aged women. Higher baseline moderate-to-vigorous physical activity (MVPA) may be beneficial for muscle strength and balance at baseline but increasing MVPA in the medium term has little effect on change in LMS or balance outcomes in middle-aged women. Higher baseline light physical activity (LPA) was associated with an increased risk of falls. The detrimental association of LPA with falls may be due to a greater exposure to environmental hazards in midlife, which needs to be clarified in future research.

PURPOSE: Early-stage chronic kidney disease (CKD) is prevalent in pre-diabetes. A healthy lifestyle is promoted in those at high risk of developing type 2 diabetes (T2DM) yet any relationships between physical activity and nutritional intake on kidney function in these individuals is unknown. This study aimed to quantify the independent associations that may exist between changes in physical activity, dietary fats and fibre, and estimated kidney function in individuals with pre-diabetic stage-2 CKD. METHODS: The study analysed data from a subset of adults at high risk of T2DM recruited to a lifestyle education programme (Yates et al. Diabet Med. 34:698-707, 2017). At baseline and 24 months, 126 (84 male) pre-diabetic CKD stage 2 (mean(SD) baseline estimated glomerular filtration rate (eGFR) 76.7(8.0) ml/min/1.73 m2, age 66(6) years, BMI 31.6(5.1) kg/m2) provided dietary data via the Dietary Instrument for Nutrition Education food frequency questionnaire and physical activity and steps by 7-day accelerometry. Linear regression examined the independent associations of baseline and change at 24 month in eGFR and average number of steps, moderate to vigorous physical activity (MVPA), total fat and unsaturated fat, and dietary fibre against 95% level of significance (p≤0.05). RESULTS: Between baseline and 24 months eGFR decreased by -3.04(9.4) ml/min/1.73 m2. There were no changes in MVPA, steps, fat and fibre intake but responses were highly variable between individuals. Baseline and change in eGFR at 24 months were positively associated with baseline MVPA (Pearson correlation, r=0.182, p=0.02 and r=0.160, p=0.04 for baseline eGFR and change in eGFR respectively), but not change in MVPA. There was a positive association between change in eGFR and average number of steps at baseline (r=0.140, p=0.059). However, after adjustment for known confounders (including age, sex, BMI, smoking status, ethnicity), these associations disappeared. There were no associations between eGFR and dietary fats (total and unsaturated), and fibre. CONCLUSIONS: Higher MVPA and average number of steps were associated with (but not predictive of) higher eGFR in a group of adults with pre-diabetic stage-2 CKD. Therefore, a healthy active lifestyle should be encouraged in pre-diabetes to prevent decline in kidney function.

BackgroundIncreasing the frequency of periods of outdoor free-play in childcare may represent an opportunity to increase child physical activity. This study aimed to assess the efficacy of scheduling multiple periods of outdoor free-play in increasing the time children spend in moderate-to-vigorous physical activity (MVPA) while attending childcare.MethodsThe study employed a cluster randomised controlled trial design involving children aged 3 to 6 years, attending ten childcare services in the Hunter New England region of New South Wales, Australia. Five services were randomised to receive the intervention and five to a control condition. The intervention involved services scheduling three separate periods of outdoor free-play from 9 am to 3 pm per day, each at least 15 min in duration, with the total equivalent to their usual daily duration of outdoor play period. Control services implemented the usual single continuous period of outdoor free-play over this time. The primary outcome, children’s moderate-to-vigorous physical activity (MVPA) while in care per day, was measured over 5 days via accelerometers at baseline and at 3 months post baseline. Secondary outcomes included percentage of time spent in MVPA while in care per day, total physical activity while in care per day and documented child injury, a hypothesised potential unintended adverse event. Childcare services and data collectors were not blind to the experimental group allocation.ResultsParents of 439 (71.6%) children attending participating childcare services consented for their child to participate in the trial. Of these, 316 (72.0%) children provided valid accelerometer data at both time points. Relative to children in control services, mean daily minutes of MVPA in care was significantly greater at follow-up among children attending intervention services (adjusted difference between groups 5.21 min, 95% CI 0.59–9.83 p = 0.03). Percentage of time spent in MVPA in care per day was also greater at follow-up among children in intervention services relative to control services (adjusted difference between groups 1.57, 95% CI 0.64–2.49 p < 0.001). Total physical activity while in care per day, assessed via counts per minute approached but did not reach significance (adjusted difference between groups 14.25, 95% CI 2.26–30.76 p = 0.09). There were no differences between groups in child injury nor subgroup interactions for the primary trial outcome by child age, sex, or baseline MVPA levels.ConclusionScheduling multiple periods of outdoor free-play significantly increased the time children spent in MVPA while in attendance at childcare. This simple ecological intervention could be considered for broader dissemination as a strategy to increase child physical activity at a population level.Trial registrationThis trial was prospectively registered with the Australian New Zealand Clinical Trials Registry (ANZCTR) (ACTRN1261000347460). Prospectively registered 17th March 2016.

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Are early increases in physical activity a behavioral marker for successful antidepressant treatment?