Free-living Physical Activity Research Articles

Effects of Breaking up Sitting on Gut Hormone Responses and Subsequent Compensatory Behaviours in Physically Inactive Adults.

The effects of breaking up sitting on gut hormone responses and free-living energy compensatory behaviours are still unclear in people of Asian ethnicity. 26 Asians including 13 lean individuals (Lean) and 13 individuals with centrally overweight/obesity (OW), aged between 20 to 45 years, completed a randomized crossover study with either 5.5-h uninterrupted sitting (SIT) or 5.5-h sitting with 2 min walking at 6.4 km/h every 20 min (ACTIVE) in the laboratory. Blood samples were collected at regular time-points to examine postprandial glucagon-like peptide 1 (GLP-1), peptide YY (PYY) and glucose-dependent insulinotropic polypeptide (GIP) concentrations. Free-living physical activity and energy intake were recorded using wearable devices and weighed food diaries outside the laboratory until midnight. Paired t-tests were conducted to compare responses between trials. Postprandial GLP-1 and PYY incremental area under curve values were higher in the ACTIVE trial versus SIT in both Lean and OW groups (all, p < 0.05), but there was no difference in GIP in either group (both, p > 0.05). There were no differences in free-living physical activity (volume and intensity) or energy intake (total and macronutrients) between trials in either group (all, p > 0.05), resulting in greater total physical activity over the 24-h monitoring period in ACTIVE trial versus SIT trial (both, p < 0.05). Breaking up sitting increases postprandial GLP-1 and PYY concentrations in Asians, but does not induce subsequent behavioural compensation, resulting in greater 24-h physical activity levels and lower relative energy intake, in inactive individuals irrespective of bodyweight status.

Validation of physical activity levels from shank-placed Axivity AX6 accelerometers in older adults.

This cross-sectional study aimed to identify and validate cut-points for measuring physical activity using Axivity AX6 accelerometers positioned at the shank in older adults. Free-living physical activity was assessed in 35 adults aged 55 and older, where each participant wore a shank-mounted Axivity and a waist-mounted ActiGraph simultaneously for 72 hours. Optimized cut-points for each participant's Axivity data were determined using an optimization algorithm to align with ActiGraph results. To assess the validity between the physical activity assessments from the optimized Axivity cut-points, a leave-one-out cross-validation was conducted. Bland-Altman plots with 95% limits of agreement, intraclass correlation coefficients (ICC), and mean differences were used for comparing the systems. The results indicated good agreement between the two accelerometers when classifying sedentary behaviour (ICC = 0.85) and light physical activity (ICC = 0.80), and moderate agreement when classifying moderate physical activity (ICC = 0.67) and vigorous physical activity (ICC = 0.70). Upon removal of a significant outlier, the agreement was slightly improved for sedentary behaviour (ICC = 0.86) and light physical activity (ICC = 0.82), but substantially improved for moderate physical activity (ICC = 0.81) and vigorous physical activity (ICC = 0.96). Overall, the study successfully demonstrated the capability of the resultant cut-point model to accurately classify physical activity using Axivity AX6 sensors placed at the shank.

Associations between monitor-independent movement summary (MIMS) and fall risk appraisal combining fear of falling and physiological fall risk in community-dwelling older adults.

Introduction: Fall Risk Appraisal (FRA), a process that integrates perceived and objective fall risk measures, serves as a crucial component for understanding the incongruence between fear of falling (FOF) and physiological fall risk in older adults. Despite its importance, scant research has been undertaken to investigate how habitual physical activity (PA) levels, quantified in Monitor-Independent Movement Summary (MIMS), vary across FRA categories. MIMS is a device-independent acceleration summary metric that helps standardize data analysis across studies by accounting for discrepancies in raw data among research-grade and consumer devices. Objective: This cross-sectional study explores the associations between MIMS (volume and intensity) and FRA in a sample of older adults in the United States. Methods: We assessed FOF (Short Falls Efficacy Scale-International), physiological fall risk (balance: BTrackS Balance, leg strength: 30-s sit-to-stand test) and 7-day free-living PA (ActiGraph GT9X) in 178 community-dwelling older adults. PA volume was summarized as average daily MIMS (MIMS/day). PA intensity was calculated as peak 30-min MIMS (average of highest 30 non-consecutive MIMS minutes/day), representing a PA index of higher-intensity epochs. FRA categorized participants into following four groups: Rational (low FOF-low physiological fall risk), Irrational (high FOF-low physiological fall risk), Incongruent (low FOF-high physiological fall risk) and Congruent (high FOF-high physiological fall risk). Results: Compared to rational group, average MIMS/day and peak 30-min MIMS were, respectively, 15.8% (p = .025) and 14.0% (p = .004) lower in irrational group, and 16.6% (p = .013) and 17.5% (p < .001) lower in congruent group. No significant differences were detected between incongruent and rational groups. Multiple regression analyses showed that, after adjusting for age, gender, and BMI (reference: rational), only irrational FRA was significantly associated with lower PA volume (β = -1,452.8 MIMS/day, p = .034); whereas irrational and congruent FRAs were significantly associated with lower "peak PA intensity" (irrational: β = -5.40 MIMS/day, p = .007; congruent: β = -5.43 MIMS/day, p = .004). Conclusion: These findings highlight that FOF is a significant barrier for older adults to participate in high-intensity PA, regardless of their balance and strength. Therefore, PA programs for older adults should develop tailored intervention strategies (cognitive reframing, balance and strength exercises, or both) based on an individual's FOF and physiological fall risk.

Abstract P274: Beyond MVPA: Machine Learning Insights Into Activity Patterns and Cardiometabolic Health in the National Health and Nutrition Examination Survey (NHANES) 2003-2004

Physical activity (PA) and sedentary behavior (SB) volumes and patterns may be useful in identifying individuals who are at elevated cardiometabolic risk. Identifying individuals at risk will facilitate early interventions for prevention of cardiovascular diseases. The objective of this project is to identify important free-living physical activity patterns to classify cardiometabolic markers including insulin, plasma glucose, and triglyceride. Methods: We used cross-sectional NHANES 2003-2004 accelerometer, blood exam and demographic data. We included adults age ≥18 years who wore a hip-worn ActiGraph 7164 during waking hours for at least 4 days of 10 hours/day of wear time. We included PA and SB predictors including minutes per day (min/d) in sedentary time (0-99 counts per minute, cpm), light intensity PA (100-759 cpm), Lifestyle PA (760-2019 cpm), moderate to vigorous PA (MVPA, ≥2019 cpm), number of breaks in SB, and number of 30-min and 60-min SB, 10-min MVPA bouts etc. The cut points for cardiovascular disease risk were defined based on literature as: fasting serum insulin ≤ 5 μU/mL, plasma glucose ≤ 100 mg/dL and triglyceride &lt; 150 mg/dL. Three random forest (RF) classification models were developed for each cardiometabolic marker using age, body-mass-index, general health, and PA variables as predictors. Models were trained and tested using a 60% training - 40% testing split. We tuned the hyperparameters (final selection: number of trees = 500 and variables = 3) to find the model with the highest testing accuracy based on the out-of-bag error. The importance of each predictor was measured and ranked by the mean decrease in GINI index. Results: The three datasets include insulin (n = 2810, age=34 ±23, 50% females), glucose (n = 1852, age = 49±20, 51% females) and triglyceride (n = 3180, age=36 ±24, 50% females). For insulin model, the PA variables with largest mean decrease in GINI index were SB time, light intensity PA, MVPA, and SB bouts of 30-min. Similarly, time spent in Lifestyle PA, light intensity PA, number of SB breaks and SB bouts of 30-min were the most important variables for abnormal fasting glucose prediction. The number of sedentary breaks, light intensity PA, SB time and SB bouts of 30-min were the most important PA predictors for risk of high triglyceride. Both BMI and age were important demographic variables for prediction of increased risk in each model. The prediction accuracy and precision are as following: Insulin(73%; 76%), Plasma Glucose(68%; 58%), and Triglyceride(64%; 46%). Conclusion: Cardiometabolic markers using free-living PA has the potential to provide insights for classifying the risk for cardiovascular disease based on given physiological marker cut-off points. The time spent lower intensity PA patterns and the number of sedentary breaks, and 30-minutes bouts are important predictors for identifying individuals who may have increased cardiometabolic risk.

Abstract P217: Directionality of Associations Between Daily Physical Activity and Cognition Among Older Adults in the Baltimore Longitudinal Study of Aging

Physical activity is a modifiable risk factor for dementia. Associations between physical activity and cognition are likely bidirectional, as cognitive functions are required to initiate and perform activities. Understanding the directionality of these associations has potential implications for both dementia prevention and physical activity engagement. Yet, the directionality between cognitive function and free-living physical activity patterns is unclear. This study included 237 cognitively unimpaired older adults in the BLSA with cognitive test performance and ≥ 3 valid days of wrist accelerometry measured at 2 visits over an average of 1.8 (0.9-4.0) years. Cognitive domain factor scores were derived using confirmatory factor analysis. Accelerometry data were used to calculate daily physical activity patterns: 1) total activity counts (TAC), 2) time spent active, 3) time spent non-active, 4) active-to-sedentary-transition probability (ASTP), 5) mean active bout length, 6) sedentary-to-active transition probability (SATP), 7) mean non-active bout length. Bivariate latent change score models estimated directionality of associations between changes in cognitive factor scores and changes in daily physical activity patterns. Models were adjusted for age, sex, race, education, and number of comorbidities. Participants were on average 77 (60-96) years, 48% women, and 22% Black. After covariate adjustment, one SD higher in baseline TAC was associated with less memory decline (estimate = 0.089, SE = 0.045). One SD higher in baseline time spent non-active was associated with greater declines in language (estimate = -0.068, SE = 0.035), visuospatial processing (estimate = -0.079 SE = 0.034), and global cognition (estimate = -0.058, SE = 0.024). One SD higher in baseline ASTP was associated with greater declines in memory (estimate = -0.114, SE = 0.047) and visuospatial processing (estimate = -0.074, SE = 0.034), whereas mean active bout length was associated with less decline in these domains (memory: estimate = 0.121, SE = 0.046; visuospatial processing: estimate = 0.081, SE = 0.033). There were no associations with time spent active, SATP, or mean non-active bout length and changes in any cognitive factor score. Cognitive factor scores were not associated with changes in any activity pattern. Patterns relating to amount of daily activity, time spent sedentary, and probability of transitioning from active-to-sedentary states were primarily associated with changes in memory and visuospatial processing. This suggests increasing free-living movement or decreasing sedentary behavior might be related to short-term changes in cognition among older adults. Future studies are needed to determine causality of these associations and to evaluate directionality over longer periods of time.

Psychosocial correlates of physical activity in cancer survivors: a systematic review and meta-analysis.

Physical activity (PA) is a non-pharmacological approach to optimize health benefits in cancer survivors and is recommended as part of care. However, most cancer survivors fail to meet PA recommendations. The current systematic review and meta-analysis aimed to identify psychosocial correlates of free-living PA in cancer survivors. Three electronic databases were searched (PubMed, PsycINFO, and SportDiscus). Meta-analyses were conducted for psychosocial correlates tested ≥ 3 times. Sixty-four articles were included. Eighty-eight different free-living PA correlates were identified. Meta-analyses (n = 32 studies) tested 23 PA correlates, of which 16 were significant (p < 0.05). Larger effect sizes (0.30 < ES > 0.45) were found for exercise self-efficacy, perceived behavioral control, intention, lower perceived barriers for exercise, enjoyment, perceived PA benefits, and attitudes. Small-to-moderate effects (0.18 < ES < 0.22) were found for subjective norms, physical functioning, quality of life, depression, and mental health. These findings were generally in line with narrative results. This systematic review highlights important psychosocial correlates of free-living PA that can be targeted in future PA promotion interventions for cancer survivors. Constructs mainly from SCT and TPB were the most studied and appear to be associated with free-living PA in this population. However, we cannot currently assert which frameworks might be more effective. Further studies of better methodological quality, per correlate and theory, exploring longer-term associations and across different types of cancer, are needed. Having higher exercise self-efficacy, perceived behavioral control, intention, enjoyment and perceived PA benefits, more positive attitudes towards PA, and lower perceived barriers for exercise, can help increase PA in cancer survivors.

Physical activity self-efficacy online intervention for adults with obesity: protocol for a feasibility study

BackgroundEven without weight loss, adults with obesity can greatly benefit from regular physical activity. The Physical Activity Self-efficacy (PAS) intervention is an online behavioral intervention newly developed to promote physical activity in adults with obesity by providing capability-enhancing learning opportunities. The objective of this manuscript is to describe the protocol for a feasibility study designed to investigate the feasibility and acceptability of implementing the PAS online intervention for adults with obesity recruited from a local weight management center in the United States of America (USA).MethodsThe study design is a prospective, double-blind, parallel-group individual randomized pilot trial. Thirty participants will be randomly assigned to the PAS group or usual care group to achieve a 1:1 group assignment. Recruitment of participants is scheduled to begin on 1 March 2024 at a local weight management center within a private healthcare system in the USA. There are six eligibility criteria for participation in this study (e.g., a body mass index ≥ 25.00 kg/m2). Eligibility verification and data collection will be conducted online. Three waves of data collection will take up to 14 weeks depending on participants’ progress in the study. The primary feasibility outcomes in the study will be: (a) participation rate, (b) engagement behavior, and (c) a preliminary effect size estimate for the effect of the PAS intervention on physical activity. Instruments designed to measure demographic information, anthropometric characteristics, self-efficacy, and acceptability will be included in the survey battery. A research-grade accelerometer will be used to measure free-living physical activity objectively. Data will be analyzed using descriptive statistics and inferential statistical models under an intention-to-treat approach.DiscussionResults are intended to inform the preparation of a future definitive randomized controlled trial.Trial registrationClinicalTrials.gov, NCT05935111, registered 7 July 2023.

Are associations between physical activity and bone mineral density in adults sex- and age-dependent? An analysis of the UK Biobank study.

Although physical activity (PA) is recognized as a key bone mass determinant across life, athlete studies suggest that it may be less effective in women and older individuals. This has not been explored within the general population. We aimed to address this knowledge gap using data from the UK Biobank Study, a large population-based study of middle-aged and older adults. Free-living PA data collected at 100Hz for 7 d using wrist-worn accelerometers were classified as sedentary behavior (0-29 milligravities [mg]), light (30-124mg), or moderate-to-vigorous PA (125 + mg). LS and FN-BMD were assessed using DXA. The associations between PA and BMD were assessed using linear regression models, with formal assessments of sex and age interactions undertaken and adjustments made for accelerometer wear time, height, body mass index, education, ethnicity, disability, and (in women only) menopausal status. In total, 15 133 UK Biobank participants (52% women) had complete PA, bone, and covariate data. In this sample, greater overall and moderate-to-vigorous PA was associated with higher LS BMD. In women, these associations were typically weaker in older individuals, for example, regression coefficients in women aged 70 yr or older were ~50% lower than at 45-54 yr (age-by-PA interactions P< .01 in all models). Similar associations were observed in basic but not full models for FN BMD. Greater sedentary time was associated with lower LS BMD in men only, and greater light PA and sedentary time were associated with higher and lower FN BMD, respectively, in both sexes. These results suggest that associations between PA and bone health at clinically-relevant sites are weaker in older than younger women. That positive associations are evident between overall and moderate-vigorous PA and FN BMD even in women ≥70 yr suggests that PA for bone health should still be promoted in older women.

Free-living ambulatory physical activity and cognitive function in multiple sclerosis: the significance of step rate vs. step volume.

Physical activity (PA) represents a promising behavioral approach for managing cognitive dysfunction in multiple sclerosis (MS). However, there is a lack of information on the pattern of free-living PA intensity (e.g., step rate) and its unique association with cognition. Such information is essential for informing clinical trials in MS. We examined associations among PA volume and intensity with cognitive function in persons with MS, and intensity was derived from steps-based metrics (peak 30-min cadence [Peak-30CAD], and time spent in incremental cadence bands). We included data from 147 persons with MS who underwent assessments of cognitive function (via Brief International Cognitive Assessment in MS) and wore an ActiGraph GT3X + accelerometer for 7days. We performed bivariate and partial correlations and regression analyses examining associations among PA metrics and cognitive outcomes. Higher Peak-30CAD was significantly associated with better performance in cognitive processing speed and verbal learning and memory (rs = 0.19-0.38), and the associations remained significant when controlling for daily steps, age, sex, and years of education (p < 0.05). By comparison, daily steps was only correlated with cognitive processing speed (rs = 0.26), and the association was non-significant when controlling for Peak-30CAD and covariates. There were stronger correlations among time spent in higher intensity cadence bands with cognitive performance (rs = 0.18-0.38). Our results highlight the important role of PA intensity for cognition in MS, and may inform future development of focal PA interventions that focusing on step rate patterns for improving cognition in persons with MS.

A Self-Paced Walk Test for Individual Calibration of Heart Rate to Energy Expenditure

Introduction: Estimating free-living physical activity (PA) with continuous heart rate (HR) monitoring is challenging due to individual variation in the relationship between HR and energy expenditure. This variation can be captured through individual calibration with graded exercise tests, but structured tests with prescribed load require medical screening and are not always feasible in population settings. We present and evaluate an individual calibration method using HR response to a less demanding self-paced walk test. Methods: Six hundred and forty-three participants from the Fenland Study (Cambridgeshire, the United Kingdom) completed a 200-m self-paced walk test, a treadmill test, and 1 week of continuous HR and accelerometry monitoring. Mixed-effects regression was used to derive a walk test calibration model from HR response to the walk using treadmill-based parameters as criterion. Free-living PA estimates from the calibration model were compared with treadmill-calibrated and non-exercise-calibrated estimates. Results: Walk calibration captured 57% of the variance in the HR–energy expenditure relationship determined by the treadmill test. Applying walk calibration to data from free-living yielded similar PA estimates to those using treadmill calibration (52.7 vs. 52.0 kJ·kg−1·day−1; mean difference: 0.7 kJ·kg−1·day−1, 95% confidence interval [−0.0, 1.5]) and high correlation (r = .89). Individual differences were observed (root mean square error: 10.0 kJ·kg−1·day−1; 95% limits of agreement: −20.6, 19.1 kJ·kg−1·day−1). Walk calibration improved precision by 29% compared with nonexercise group calibration (root mean square error: 14.0 kJ·kg−1·day−1; 95% limits of agreement: −30.4, 24.5 kJ·kg−1·day−1). Conclusions: A 200-m self-paced walk test captures between-individual variation in the HR–energy expenditure relationship and facilitates estimation of free-living PA in population settings.

FREE-LIVING HEART RATE VARIABILITY/PHYSICAL ACTIVITY AND COGNITIVE FUNCTION AND DEMENTIA IN ARIC

Abstract Low heart rate variability (HRV) and physical activity (PA) are associated with cognitive dysfunction in clinical settings. Yet, associations with these measures among older adults in the free-living environment remain unexplored. We hypothesize higher free-living HRV and PA are associated with higher cognitive test scores and less likelihood of mild cognitive impairment (MCI)/dementia. This study includes 1,590 ARIC participants aged 72-94 years who wore the Zio XT Patch for 14-days to simultaneously capture ECG and accelerometry, from which we derived HRV as the standard deviation (SDNN) or root mean squared successive difference (rMSSD) of normal RR intervals and PA as total mean amplitude deviation (TMAD; higher values represent more movement). Linear or ordinal regression models were fitted to estimate cross-sectional associations between log transformed HRV or PA with latent-variable derived global and domain-specific cognitive factor scores or adjudicated MCI/dementia, respectively. Participants were on average 79 years, 57% female, and 32% Black. There were no significant associations between either HRV measure and cognition. After adjusting for demographic and medical covariates, 1-unit higher in log TMAD was associated with a 0.30-point higher global factor score (95% CI: 0.16-0.44), 0.38-point higher executive function factor score (95% CI: 0.22-0.53), 62% lower odds of MCI (95% CI: 0.22-0.67) and 75% lower odds of dementia compared to normal cognition (95% CI: 0.08-0.74). In summary, free-living PA, but not HRV of RR intervals, is associated with cognitive and dementia status. Further investigation of other objective HRV measures and directionality of associations between PA and cognition is needed.

Free-living physical activity and executive function: A multi-study analysis of age groups and times of day

BackgroundExecutive Function (EF) is a potential mechanism linking physical activity (PA) and mental health. However, evidence regarding the association between free-living PA and EF is limited with mixed results. Across two studies, we examined associations between accelerometer-assessed moderate-to-vigorous PA (MVPA) and facets of EF in different age groups (Study 1) and at different times of day (Study 2). MethodIn Study 1, we tested the association between MVPA and verbal fluency across seven days in 285 participants (children, adults, older adults). In Study 2, we tested between- and within-person associations between MVPA and working memory (afternoon, evening, next morning) across three 18-day bursts in 64 preadolescents. ResultsStudy 1 showed no association between MVPA and verbal fluency overall, but there was an interaction by age group: a positive association was evident in older adults only. In Study 2, we observed a positive between-person association between MVPA and subsequent afternoon and next morning working memory, but not within-person. In the evening, MVPA was not related to working memory. ConclusionsThe association between free-living PA and EF differs between age groups and times of day. Future research should consider these factors when examining the association and its role for mental health.

Effects of dietary nitrate and vitamin C co-ingestion on blood pressure and hand-grip strength in young adults

Abstract: Background: Co-administration of vitamin C and inorganic nitrate ([Formula: see text]) may reduce oxidative stress, boost the conversion of nitrite ([Formula: see text]) into NO and elicit positive vascular effects. Aims: We aimed to test the effects of oral inorganic [Formula: see text] and vitamin C co-supplementation on vascular function, muscular strength, and on concentrations of urinary [Formula: see text], vitamin C, 8-isoprostanes and salivary [Formula: see text] in healthy young adults. Methods: Ten young healthy participants were enrolled in a randomised, double-blind (only for the [Formula: see text] intervention) crossover clinical trial. Participants consumed in random order: 1) nitrate-rich beetroot juice and vitamin C (N+VC), 2) nitrate-rich beetroot juice alone (N) or 3) nitrate-depleted beetroot juice alone (ND). Resting blood pressure (BP) was measured at the research centre and at home. Non-invasive, continuous measurements of BP and cardiac function parameters were performed using a Finometer device. Free-living physical activity and hand-grip strength were assessed. Salivary [Formula: see text] and [Formula: see text] and urinary [Formula: see text], 8-isoprostanes and vitamin C concentrations were measured. Results: There were no significant differences for any of the vascular outcomes between the three interventions groups. However, analyses of within-intervention changes showed a significant lower daily systolic BP in the [Formula: see text]+vitamin C (N+VC) group only (P=0.04). Urinary [Formula: see text] (P=0.002) and salivary [Formula: see text] (P=0.001) were significantly higher in the N+VC group compared to the N and ND groups. Conclusion: These preliminary findings suggest that combining dietary [Formula: see text] with vitamin C could have protective effects on vascular function in young adults and could represent an effective strategy for the maintenance of healthy cardiovascular trajectories.

Weekly minutes of moderate to vigorous physical activity is associated with movement quality in overweight and obese older adults, independent of age.

Physical activity can improve function and decrease healthcare spending among overweight and obese older adults. Although unstructured physical activity has been related to cardiometabolic improvements, the relationship between unstructured activity and movement quality is unclear. This study aimed to evaluate the association of amount of unstructured free-living moderate-vigorous physical activity (MVPA) with measures of movement quality in overweight and obese older adults. The association of MVPA with movement quality was assessed in 165 overweight and obese older adults (Age: 77.0(8.0) years; Body mass index (BMI): 29.2(5.3) kg/m2). Participants performed overground walking, the Figure of 8 Walk test, and the Five-Times Sit to Stand. Weekly physical activity was measured using a waist-worn Actigraph activity monitor. Movement quality during straight path [gait speed (ρ = 0.30, p < 0.01), stride length (ρ = 0.33, p < 0.01), double-limb support time (ρ = -0.26, p < 0.01), and gait symmetry (ρ = 0.17, p = 0.02)] and curved path [F8W time (ρ = -0.22, p < 0.01) and steps (ρ = -0.22, p < 0.01)] walking were associated with weekly minutes of MVPA after controlling for age. Five-Times Sit to Stand performance was not significantly associated with weekly minutes of MVPA (ρ = -0.10, p = 0.13). Older adults with high BMIs who are less active also demonstrate poorer movement quality, independent of age. Physical activity engagement and task-specific training should be targeted in interventions to promote healthy aging, decrease falls, and delay disability development. Future work should consider the interconnected nature of movement quality with physical activity engagement and investigate if targeting one influences the other.

The effect of metformin treatment on volumes of free-living physical activity and sedentary behaviour: A post-hoc analysis of the PRE-D trial

ABSTRACT Perceived physical exertion is increased when exercise is performed on metformin treatment, but the clinical relevance of this is unknown. In this post hoc analysis of a randomized, controlled trial, we investigated whether metformin treatment was associated with lower levels of free-living physical activity. Ninety individuals with overweight/obesity (BMI>25 m2/kg) and HbA1c-defined prediabetes (39-47 mmol/mol) were randomized to treatment with dapagliflozin (SGLT2-inhibitor; 10 mg once daily, n=30), metformin (850 mg twice daily, n=30) or no treatment (control, n=30) for 13 weeks in a parallel-group, open-label trial. Before (baseline), during (6 weeks) and immediately after (13 weeks) cessation of treatment, a 6-day assessment of physical activity and sedentary behaviour was performed using accelerometer-based physical activity monitors. Intention-to-treat analyses revealed no within-group changes or differences in change between the groups for any measures of physical activity or sedentary behaviour at neither 6 nor 13 weeks. Short-term metformin treatment does not reduce free-living physical activity level in individuals with overweight/obesity and HbA1c-defined prediabetes.

O.1.2-9 Sex-related differences in free-living estimates of physical activity energy expenditure between older men and women

Abstract Purpose Physical activity is often quantified as physical activity energy expenditure (PAEE), which may be affected by individual ability to sustain physical activity intensity. We examined if there is a true difference in physical activity between older women and men when their physical capacity is considered. Methods Out of the population-based sample of 1021 (75-85-year-old) adults (62 % women), 410 wore an accelerometer (100 Hz) and a single-channel ECG monitor (250 Hz) for at least 3 days in free-living. A treadmill walk calibration and previously validated equations were used to estimate PAEE from combined acceleration and heart rate sensing using branched equation modelling. Preferred walking speed in a six-minute walking test, fat free mass (FFM) using bioimpedance and isometric maximal leg extension strength scaled to FFM were measured. Independent t-test, Pearson correlation and hierarchical multiple regression were used for statistical analyses. Results PAEE was 41.4 (14.2) kJ/kg/day for men, which was significantly higher (p &amp;lt; 0.001) than the PAEE 34.8 (10.9) for women. Walking speed (1.2 (0.2) vs. 1.1 (0.2) m/s), FFM (56.9 (6.5) vs. 42.1 (4.8) kg) and maximal strength (7.4 (1.8) vs. 6.7 (1.8) N/kg) were higher in men than in women (all p &amp;lt; 0.001). PAEE was significantly associated with walking speed (r = 0.44, p &amp;lt; 0.001), FFM (r = 0.26, p &amp;lt; 0.001), and maximal strength (r = 0.26, p &amp;lt; 0.001). In the regression analysis, 22 % of the variation in PAEE was explained by walking speed, FFM and maximal strength combined (F = 37.8, p &amp;lt; 0.001), whereas adding sex did not improve the model (F = 28.9, p &amp;lt; 0.001). The strongest predictor of PAEE was preferred walking speed (standardized beta=0.35, p &amp;lt; 0.001). Conclusions The results indicate that the observed difference in physical activity volume between sexes was largely explained by physical characteristics, especially the faster preferred walking speed of men compared to women. Free-living physical activity is largely comprised of habitual walking especially in older people which makes walking speed a significant contributor of daily PAEE. Walking speed could be measured more widely in physical activity counselling and health care settings as a potential underlying factor of low physical activity in older people. Support/Funding Sources European Research Council, Academy of Finland and Yrjö Jahnsson Foundation.

Physical Activity among Colorectal Cancer Patients and Survivors in Egypt.

Understanding physical activity (PA) levels is important when developing tertiary cancer prevention interventions, especially in Egypt where colorectal cancer (CRC) is more often diagnosed at later stages and at a younger age of onset (≤40 years). We assessed PA levels among CRC patients and survivors in Alexandria, Egypt. All participants completed two self-reported PA assessments: Global Physical Activity Questionnaire (GPAQ) and Godin Leisure-Time Exercise Questionnaire (GLTEQ). Participants could opt to wear an accelerometer for seven days. Results were compared against WHO recommendations of ≥150 minutes or ≥600 metabolic equivalents of tasks (METs) of moderate-to-vigorous PA weekly. Of 86 participants enrolled, all completed the surveys and 29 agreed to accelerometer use. Prevalence of meeting PA recommendations was 62.8% based on the GPAQ, 14.0% based on GLTEQ, and 41% based on accelerometer. Based on the GPAQ, very few respondents reported vigorous occupational, vigorous recreational, or moderate recreational activity (median = 0 with interquartile range [IQR] of 0 - 0 weekly minutes for all three) while most activity resulted from moderate occupational and transportation (median [IQR] of 60 [0-840] and 60 [0-187.5] weekly minutes, respectively). Participants meeting PA recommendations were less likely to be married (p = 0.043) according to GPAQ and more likely to be female (p=0.047) and early cancer stage (p=0.007) by GLTEQ. Non-leisure free-living PA is a major contributor to meeting PA recommendations while leisure-time PA is a potential target for future interventions that increase PA in this population.

Can quantifying the relative intensity of a person’s free-living physical activity predict how they respond to a physical activity intervention? Findings from the PACES RCT

ObjectivesTo determine whether quantifying both the absolute and relative intensity of accelerometer-assessed physical activity (PA) can inform PA interventions. We hypothesised that individuals whose free-living PA is at a low...

A Case for Unifying Accelerometry-Derived Movement Behaviors and Tests of Exercise Capacity for the Assessment of Relative Physical Activity Intensity.

Albert Einstein taught us that "everything is relative." People's experience of physical activity (PA) is no different, with "relativism" particularly pertinent to the perception of intensity. Markers of absolute and relative intensities of PA have different but complimentary utilities, with absolute intensity considered best for PA guideline adherence and relative intensity for personalized exercise prescription. Under the paradigm of exercise and PA as medicine, our Technical Note proposes a method of synchronizing accelerometry with the incremental shuttle walking test to facilitate description of the intensity of the free-living PA profile in absolute and relative terms. Our approach is able to generate and distinguish "can do" or "cannot do" (based on exercise capacity) and "does do" or "does not do" (based on relative intensity PA) classifications in a chronic respiratory disease population, facilitating the selection of potential appropriate individually tailored interventions. By synchronizing direct assessments of exercise capacity and PA, clearer insights into the intensity of PA performed during everyday life can be gleaned. We believe the next steps are as follows: (1)to determine the feasibility and effectiveness of using relative and absolute intensities in combination to personalize the approach, (2)to determine its sensitivity to change following interventions (eg,exercise-based rehabilitation), and (3)to explore the use of this approach in healthier populations and in other long-term conditions.

An Evaluation of Participant Perspectives and Wear-Time Compliance for a Wrist-Worn Versus Thigh-Worn Accelerometer in Cancer Survivors.

Accelerometers are frequently used to measure free-living physical activity and sleep in cancer survivors. To obtain valid data, participants must adhere to wear-time guidelines; therefore, understanding survivor's preference may be critical when selecting an accelerometer. This study compared cancer survivors' reported discomfort and interference, and wear-time compliance between a wrist-worn accelerometer and a thigh-worn accelerometer. This was a secondary data analysis. Cancer survivors (N = 52, mean age = 51.8 [13.0], 82.3% female) wore the Actiwatch-2 (wrist) and the activPAL (thigh) for 7 days, 24hours per day. On day 7, participants completed a questionnaire to evaluate each accelerometer using a 1 to 5 Likert scale and open-ended questions. The Kolmogorov-Smirnov test evaluated differences in discomfort and interference. Paired samples t test evaluated differences in wear-time compliance. Open-ended responses were analyzed using thematic analysis methods. No differences were observed in discomfort, interference, or wear-time compliance (P = .08). Qualitative analysis resulted in 2 themes: discomfort and ease of use and interference and adverse reaction. Interferences were primarily reported with the Actiwatch-2, whereas discomfort and ease were primarily reported with the activPAL. No significant differences were observed regarding discomfort, interference, and compliance. Results of this study can prepare researchers for common issues regarding accelerometer compliance, allowing researchers to offer resources to alleviate discomforts or interferences that may affect wear-time compliance.