Moderate-to-vigorous Physical Activity Bouts Research Articles

Analysing physical activity measures and clustering in patients with type 2 diabetes in secondary care: insights from the DIAbetes and LifEstyle Cohort Twente (DIALECT)—an observational cohort study

ObjectivesTo analyse variance in accelerometer-based physical activity (PA) measures in patients with type 2 diabetes, identify the most distinctive PA measures and classify patients into different PA clusters based on...

Do personality profiles contribute to patterns of physical activity and sedentary behavior in adulthood? A prospective cohort study

BackgroundDespite the observed associations of personality traits with levels of moderate-to-vigorous physical activity (MVPA) and sedentary behavior (SB), studies exploring whether the personality profiles differ in terms of the pattern of accumulation of physical behavior are lacking. The aim of this study was to identify adults’ personality profiles and to characterize and investigate how these profiles differ in physical behavior.MethodsThe study utilized the longitudinal data of the participants of the Jyväskylä Longitudinal Study of Personality and Social Development (n = 141–307). Information on the five-factor model of personality, including the traits of neuroticism, extraversion, conscientiousness, openness, and agreeableness, was collected at ages 33, 42, 50, and 61 years, and used to create latent personality profiles. Physical behavior, operationalized as the amount and accumulation of MVPA and SB bouts, was captured using a triaxial accelerometer worn during waking hours at age 61 years. The differences in the behavior between the personality profiles were analyzed using the Kruskal-Wallis test.ResultsFive personality profiles were identified: resilient (20.2%), brittle (14.0%), overcontrolled (9.8%), undercontrolled (15.3%), and ordinary (40.7%). Although there were no statistically significant differences between the personality profiles in the time spent in MVPA relative to SB (MVPA per hour of daily SB), individuals with resilient (low in neuroticism and high in other traits) and ordinary (average in each trait) profiles had MVPA-to-SB ratios of 0.12 (7 min) and those with a brittle (high in neuroticism and low in extraversion) profile had a ratio of 0.09 (5.5 min). The individuals in the resilient group exhibited a longer usual MVPA bout duration than those in the overcontrolled (low in extraversion, openness, and agreeableness) (8 min vs. 2 min) and undercontrolled (high in openness and low in conscientiousness) groups (8 min vs. 3 min). They also exhibited a longer usual SB bout duration than those in the ordinary group (29 min vs. 23 min).ConclusionsThe resilient group displayed the most prolonged MVPA and SB bout patterns. The results suggest that personality characteristics may contribute to how MVPA and SB are accumulated.

Timing of Moderate to Vigorous Physical Activity, Mortality, Cardiovascular Disease, and Microvascular Disease in Adults With Obesity.

To assess the association between timing of aerobic moderate to vigorous physical activity (MVPA) and risk of cardiovascular disease (CVD), microvascular disease (MVD), and all-cause mortality in adults with obesity and a subset with obesity and type 2 diabetes (T2D). Participants included adults with obesity (BMI ≥30 kg/m2) and a subset of those with T2D from the UK Biobank accelerometry substudy. Aerobic MVPA was defined as bouts of MVPA lasting ≥3 continuous minutes. Participants were categorized into morning, afternoon, or evening MVPA based on when they undertook the majority of their aerobic MVPA. The reference group included participants with an average of less than one aerobic MVPA bout per day. Analyses were adjusted for established and potential confounders. The core sample included 29,836 adults with obesity, with a mean age of 62.2 (SD 7.7) years. Over a mean follow-up period of 7.9 (SD 0.8) years, 1,425 deaths, 3,980 CVD events, and 2,162 MVD events occurred. Compared with activity in the reference group, evening MVPA was associated with the lowest risk of mortality (hazard ratio [HR] 0.39; 95% CI 0.27, 0.55), whereas afternoon (HR 0.60; 95% CI 0.51, 0.71) and morning MVPA (HR 0.67; 95% CI 0.56, 0.79) demonstrated significant but weaker associations. Similar patterns were observed for CVD and MVD incidence, with evening MVPA associated with the lowest risk of CVD (HR 0.64; 95% CI 0.54, 0.75) and MVD (HR 0.76; 95% CI 0.63, 0.92). Findings were similar in the T2D subset (n = 2,995). Aerobic MVPA bouts undertaken in the evening were associated with the lowest risk of mortality, CVD, and MVD. Timing of physical activity may play a role in the future of obesity and T2D management.

Pre-exercise protein intake is associated with reduced time in hypoglycaemia among adolescents with type 1 diabetes.

Secondary analyses were conducted from a randomized trial of an adaptive behavioural intervention to assess the relationship between protein intake (g and g/kg) consumed within 4 h before moderate-to-vigorous physical activity (MVPA) bouts and glycaemia during and following MVPA bouts among adolescents with type 1 diabetes (T1D). Adolescents (n = 112) with T1D, 14.5 (13.8, 15.7) years of age and 36.6% overweight/obese, provided measures of glycaemia using continuous glucose monitoring [percentage of time above range (>180 mg/dl), time in range (70-180 mg/dl), time below range (TBR; <70 mg/dl)], self-reported physical activity (previous day physical activity recalls), and 24 h dietary recall data at baseline and 6 months post-intervention. Mixed effects regression models adjusted for design (randomization assignment, study site), demographic, clinical, anthropometric, dietary, physical activity and timing covariates estimated the association between pre-exercise protein intake on percentage of time above range, time in range and TBR during and following MVPA. Pre-exercise protein intakes of 10-19.9 g and >20 g were associated with an absolute reduction of -4.41% (p = .04) and -4.83% (p = .02) TBR during physical activity compared with those who did not consume protein before MVPA. Similarly, relative protein intakes of 0.125-0.249 g/kg and ≥0.25 g/kg were associated with -5.38% (p = .01) and -4.32% (p = .03) absolute reductions in TBR during physical activity. We did not observe a significant association between protein intake and measures of glycaemia following bouts of MVPA. Among adolescents with T1D, a dose of ≥10 g or ≥0.125 g/kg of protein within 4 h before MVPA may promote reduced time in hypoglycaemia during, but not following, physical activity.

Research-Grade Accelerometers to Assess Intervention Effectiveness and Commercial Wearables as a Self-Monitoring Tool: Are the Two Aligned on Moderate to Vigorous Physical Activity?

There is limited evidence about how comparable commercial monitors and moderate to vigorous physical activity (MVPA) cut-points frequently used with research-grade accelerometers are in estimating time spent in MVPA when both are worn on the wrist. We used data from 14 adults (57.3 years) who concurrently wore Fitbit (Versa 2) and Axivity (AX3) monitors to assess comparability between the Fitbit and Axivity data, aggregated to 5-s and 60-s epochs, for time spent in daily MVPA and MVPA in bouts of ≥1 – &lt;2 min, ≥2 – &lt;5 min, and ≥5 min. The Fitbit provided higher estimates of total daily MVPA (93.8 ± 66.3 min/day) compared with Axivity-assessed MVPA derived from either 5-s (59.2 ± 37.3 min/day) or 60-s (47.4 ± 36.2 min/day) epochs. The number and duration of MVPA bouts were also higher from Fitbit compared with Axivity (5-s and 60-s epochs). Intraclass correlation coefficients showed moderate to good reliability between MVPA assessed by the Fitbit and Axivity devices (5 s and 60 s). Bland–Altman analysis suggested proportional bias between the Fitbit and Axivity outcomes with wide limits of agreement. No MVPA outcomes were within the 10% equivalency zone. Researchers utilizing the Fitbit as a self-monitoring tool within an intervention should be aware of the potential misalignment with the research-grade accelerometer used to evaluate intervention effectiveness. Feedback from a Fitbit may inform participants they have achieved the required MVPA, while outcomes from the research-grade device may classify them as not meeting their target.

Effects of mindful physical activity on perceived exercise exertion and other physiological and psychological responses: results from a within-subjects, counter-balanced study.

Most adults are insufficiently active. Mindfulness training may increase moderate to vigorous physical activity (MVPA) adoption and adherence. However, physiological and psychological factors underlying these effects are not well understood. This study examined the effects of an acute bout of MVPA, mindfulness training, and combined MVPA and mindfulness training on physiological and psychological outcomes. Healthy adults (N = 29, Mage = 28.6) completed 20-min counterbalanced conditions: (a) mindfulness training (MIND); (b) moderate intensity walking (PA), and (c) moderate intensity walking while listening to MVPA-specific guided mindfulness training (PAMIND). Heart rate (HR), Rating of Perceived Exertion (RPE), Feeling Scale (FS) and Blood Pressure (BP) were measured at rest, at regular intervals during each condition, and post-condition. Mindfulness, state anxiety, and self-efficacy were assessed pre- and post-condition. Average and peak HR, systolic BP (SBP), and RPE were significantly higher, and average and peak FS were significantly lower during the PA and PAMIND conditions compared to MIND (p < 0.001). Average RPE was significantly higher for PA compared to PAMIND (p < 0.001). Heart rate, feeling scale, body and mental events mindfulness, and self-efficacy for walking increased from pre to post (all p's < 0.001) for all conditions. Time by condition interactions were significant for change in heart rate, mental events mindfulness, and state anxiety from pre- to post-condition. The physiological response to MVPA and PAMIND were similar. However, RPE was rated lower in the PAMIND condition, which could have implications for MVPA adoption and maintenance. Future work should further explore RPE combining MVPA and mindfulness training.

Participation in youth sports influences sarcopenia parameters in older adults.

The degree of deterioration in sarcopenia parameters may be affected by a person's level of physical activity (PA) and sedentary behavior (SB). Our study focused on examining the PA and SB of active older adults including those with and without history of sports in youth. Forty-four participants (20 men and 24 women, mean age of total sample 76.1 ± 5.2 years) were included in analysis of PA, SB habits and sarcopenia parameters, determined by skeletal muscle index, hand-grip strength, gait speed, Timed Up and Go tests (TUG). PA and SB were recorded with accelerometers. Our primary aim was to compare participants with (AH) or without a sport history in youth (NAH), in their sarcopenia parameters and PA and SB habits. When divided participants in two groups (AH and NAH) and adjusting for age, we have detected the differences for skeletal muscle index (p = 0.007) and hand-grip strength (p = 0.004) in favor of participants who were engaged in sports in youth. We did not find any differences in PA and SB habits between the AH and NAH groups. After adjusting for age, participants with a higher number of daily steps, longer moderate to vigorous physical activity (MVPA) bouts, a higher number of MVPA bouts in a day and higher overall MVPA engagement achieved better results in hand-grip strength and TUG. Participants with lower SB had better TUG and gait speed results. Our findings suggest that engaging in sports activities in youth can make a difference with sarcopenia parameters. Although we found no differences in PA and SB habits between participants with AH and NAH, participants with an athlete history performed better results in sarcopenia parameters.

A High Protein Diet Is Associated with Improved Glycemic Control Following Exercise among Adolescents with Type 1 Diabetes.

Nutritional strategies are needed to aid people with type 1 diabetes (T1D) in managing glycemia following exercise. Secondary analyses were conducted from a randomized trial of an adaptive behavioral intervention to assess the relationship between post-exercise and daily protein (g/kg) intake on glycemia following moderate-to-vigorous physical activity (MVPA) among adolescents with T1D. Adolescents (n = 112) with T1D, 14.5 (13.8, 15.7) years of age, and 36.6% overweight or obese, provided measures of glycemia using continuous glucose monitoring (percent time above range [TAR, >180 mg/dL], time-in-range [TIR, 70-180 mg/dL], time-below-range [TBR, <70 mg/dL]), self-reported physical activity (previous day physical activity recalls), and 24 h dietary recall data at baseline and 6 months post-intervention. Mixed effects regression models adjusted for design (randomization assignment, study site), demographic, clinical, anthropometric, dietary, physical activity, and timing covariates estimated the association between post-exercise and daily protein intake on TAR, TIR, and TBR from the cessation of MVPA bouts until the following morning. Daily protein intakes of ≥1.2 g/kg/day were associated with 6.9% (p = 0.03) greater TIR and -8.0% (p = 0.02) less TAR following exercise, however, no association was observed between post-exercise protein intake and post-exercise glycemia. Following current sports nutrition guidelines for daily protein intake may promote improved glycemia following exercise among adolescents with T1D.

Influence of Volume and Bouts of Sedentary Time and Physical Activity on School-Aged Youth’s Physical Fitness: The UP &amp; DOWN Longitudinal Study

The aim of this study was to examine associations of total volume and bouts of sedentary time (ST) and moderate to vigorous physical activity (MVPA) with physical fitness (PF) in youth. This was a 2-year follow-up study with 1418 children and adolescents (51.7% boys). Accelerometers were used to assess ST and MVPA. Cardiorespiratory and muscular fitness values were objectively measured and combined in a global PF variable. Weight status was objectively obtained. Linear regression analyses were used to examine the cross-sectional (using scores at baseline) and longitudinal associations (using the change in the variables) of total volume and bouts of ST and MVPA with PF. Total ST was negatively associated with global PF (β = -0.488, P < .001 in cross-sectional analysis; β = -0.234, P = .003 in longitudinal analysis). However, this association was not independent of MVPA. Total volume of MVPA showed a positive association with global PF independently of ST and weight status (β = 0.285, P < .001 in cross-sectional analysis; β = 0.119, P = .001 in longitudinal analysis). Longitudinal associations found between ST and MVPA accumulated in bouts of various lengths and global PF became nonsignificant when their respective total volumes are included in the model. These results underline the need to accumulate minutes of MVPA, regardless of the bout duration, to increase PF levels in youth.

Associations Between Wearable-Specific Indicators of Physical Activity Behaviour and Insulin Sensitivity and Glycated Haemoglobin in the General Population: Results from the ORISCAV-LUX 2 Study

BackgroundParameters derived from an acceleration signal, such as the time accumulated in sedentary behaviour or moderate to vigorous physical activity (MVPA), may not be sufficient to describe physical activity (PA) which is a complex behaviour. Incorporating more advanced wearable-specific indicators of PA behaviour (WIPAB) may be useful when characterising PA profiles and investigating associations with health. We investigated the associations of novel objective measures of PA behaviour with glycated haemoglobin (HbA1c) and insulin sensitivity (Quicki index).MethodsThis observational study included 1026 adults (55% women) aged 18-79y who were recruited from the general population in Luxembourg. Participants provided ≥ 4 valid days of triaxial accelerometry data which was used to derive WIPAB variables related to the activity intensity, accumulation pattern and the temporal correlation and regularity of the acceleration time series.ResultsAdjusted general linear models showed that more time spent in MVPA and a higher average acceleration were both associated with a higher insulin sensitivity. More time accumulated in sedentary behaviour was associated with lower insulin sensitivity. With regard to WIPAB variables, parameters that were indicative of higher PA intensity, including a shallower intensity gradient and higher average accelerations registered during the most active 8 h and 15 min of the day, were associated with higher insulin sensitivity. Results for the power law exponent alpha, and the proportion of daily time accumulated in sedentary bouts > 60 min, indicated that activity which was characterised by long sedentary bouts was associated with lower insulin sensitivity. A greater proportion of time spent in MVPA bouts > 10 min was associated with higher insulin sensitivity. A higher scaling exponent alpha at small time scales (< 90 min), which shows greater correlation in the acceleration time series over short durations, was associated with higher insulin sensitivity. When measured over the entirety of the time series, metrics that reflected a more complex, irregular and unpredictable activity profile, such as the sample entropy, were associated with lower HbA1c levels and higher insulin sensitivity.ConclusionOur investigation of novel WIPAB variables shows that parameters related to activity intensity, accumulation pattern, temporal correlation and regularity are associated with insulin sensitivity in an adult general population.

Bidirectional associations of accelerometer-assessed physical activity and sedentary time with physical function among older English adults: the EPIC-Norfolk cohort study

To develop healthy ageing interventions, longitudinal associations between objectively assessed physical behaviours and physical function need to be better understood. We assessed associations between accelerometer-assessed total physical activity (PA), moderate-to-vigorous physical activity (MVPA), light physical activity (LPA), sedentary time and prolonged sedentary bout time, and clinically assessed physical function (grip strength, usual walking speed (UWS), chair stand speed) at two time-points in 3188 participants (≥ 60 years) of the EPIC-Norfolk study. Bidirectional associations were assessed using multivariable linear regression. Over an average of 6.1 years, baseline physical behaviours (greater total PA, MVPA and LPA, and less sedentary time) were associated with better subsequent walking and chair stand speed. Better baseline physical function was associated with better follow-up physical behaviours. There were no bidirectional associations between changes in physical behaviours and grip strength. Improvements in UWS were associated with improvements in all physical behaviours. Improvements in chair stand speed were associated with improvements in total PA, MVPA, and sedentary bout time. Improvements in physical behaviours were associated with improvements in UWS (3.1 cm/s/yr per 100 cpm/yr total PA, 3.6 cm/s/yr per hr/day/yr MVPA, 2.5 cm/s/yr per hr/day/yr LPA, − 2.9 cm/s/yr per hour/day/yr sedentary time, and − 1.6 cm/s/yr per hr/day/yr prolonged sedentary bout time). Only improvements in total PA, MVPA and sedentary bout time were associated with improvements in chair stand speed. In conclusion, we found bidirectional associations between changes in some physical behaviours and physical function and between baseline physical behaviours and subsequent physical function, highlighting the importance of considering the full range of physical behaviours to promote healthy ageing.

Sedentary time is associated with depressive symptoms and state anxiety in women with fibromyalgia. Could physical activity and fitness modify this association? The al-Ándalus project

Purpose To analyze the associations of total and prolonged sedentary time (ST) with depressive symptoms and state anxiety in women with fibromyalgia and whether these associations are modified by moderate-to-vigorous physical activity (MVPA) and physical fitness. Methods This cross-sectional exploratory study included 386 women with fibromyalgia aged 51.2 ± 7.6 years. Total ST, time in prolonged bouts of ST (≥30- and ≥60-min) and MVPA were measured with triaxial accelerometry. Depressive symptoms were assessed with the “Beck Depression Inventory-second edition,” state anxiety with the “State-Trait Anxiety Inventory,” and physical fitness with the “Senior Fitness Test Battery.” Results Total and prolonged ST were directly associated with depressive symptoms (total: β = 0.19, ≥30-min bout: β = 0.15, and ≥60-min bout: β = 0.12) and odds of severe depressive symptoms (all, p < 0.001). These associations generally remained significant after adjustments for MVPA and physical fitness (all, p < 0.05). Total and prolonged ST were directly associated with state anxiety (total: β = 0.11, ≥30-min bout: β = 0.12, and ≥60-min bout: β = 0.07; all, p < 0.001). These associations were generally independent of MVPA (p < 0.05) but vanished when considering physical fitness (p > 0.05). Conclusions Higher levels of total and prolonged ST are associated with greater depressive symptoms and state anxiety in women with fibromyalgia. MVPA did not modify these associations, although physical fitness could play a protective role specially for state anxiety. IMPLICATIONS FOR REHABILITATION Reducing sedentary time and avoiding its accumulation in prolonged periods could potentially reduce depressive symptoms and state anxiety in fibromyalgia. Higher sedentary time is associated with more severe depressive symptoms even in patients who engage in moderate-to-vigorous physical activity. Higher levels of physical fitness could attenuate the negative associations of sedentary time with depressive symptoms and, specially, state anxiety. “Sit less, move more and exercise to increase your fitness” could be a positive message for people with fibromyalgia in clinical settings.

Impact Of Moderate-to-vigorous Physical Activity And Visceral Adiposity On Postprandial Triglycerides In Metabolically At-risk Adults

Postprandial lipemia occurs early in chronic disease progression. The degree of postprandial triglyceride (ppTG) is influenced by physiological and lifestyle factors such as diet, central obesity, and physical activity (PA). However, it is unclear how habitual dietary factors and PA impact ppTG in healthy adults with high central adiposity. PURPOSE: To examine the impact of habitual moderate-to-vigorous PA (MVPA), saturated fat (SF) in the habitual diet, and central adiposity on ppTG in metabolically at-risk adults. METHODS: Non-diabetic adults (n = 21) with a high waist circumference (> 35” women, >40” men) completed a high-fat meal challenge (50 g FAT, 54 g CHO, 12 g PRO), with blood collected at fasting and hourly after meal ingestion for 5 h. TG (mmol/L) was determined by lipid panels and summarized as iAUC and the change from fasting (TGmax). Habitual dietary data was collected through the online DHQ-III, with SF percentage (SF / total fat) used for analysis. Visceral adipose tissue (VAT) was determined through bioelectrical impedance analysis. Participants wore an accelerometer for 7 days (>10 h/day) and average number of MVPA bouts/day (≥ 2690 counts/min) was derived. Separate linear models for TG iAUC and TG magnitude were used to test the impact of an interaction between average MVPA bouts and VAT, accounting for habitual dietary SF. RESULTS: MVPA, VAT, and habitual dietary SF explain ~36% of variation in TG iAUC and TGmax. Average MVPA bouts and VAT jointly impacted TG iAUC (p < 0.01), with a ppTG-lowering effect observed with lower VAT and more frequent MVPA bouts and a pronounced ppTG-raising effect observed with greater VAT with frequent MVPA bouts (β = 1.1). Habitual SF did not predict TG iAUC (p = 0.68). Likewise, average MVPA bouts and VAT impacted TGmax (p = 0.03), with a TG-raising effect observed with greater VAT despite more MVPA bouts (β = 0.31). Interestingly, an inverse relationship was observed between habitual SF intake and TGmax (β = - 0.04, p = 0.02). CONCLUSION: Frequent MVPA promotes lower ppTG, a benefit that is reversed with increased VAT. These findings suggest that increased VAT promotes ppTG even with regular MVPA, stressing the importance of strategies to decrease VAT in improving regulation of postprandial lipemia in at-risk adults. Supported by USDA-ARS Pulse Crop Health Initiative 58-3060-9-040.

Device-assessed sleep and physical activity in individuals recovering from a hospital admission for COVID-19: a multicentre study

BackgroundThe number of individuals recovering from severe COVID-19 is increasing rapidly. However, little is known about physical behaviours that make up the 24-h cycle within these individuals. This study aimed to describe physical behaviours following hospital admission for COVID-19 at eight months post-discharge including associations with acute illness severity and ongoing symptoms.MethodsOne thousand seventy-seven patients with COVID-19 discharged from hospital between March and November 2020 were recruited. Using a 14-day wear protocol, wrist-worn accelerometers were sent to participants after a five-month follow-up assessment. Acute illness severity was assessed by the WHO clinical progression scale, and the severity of ongoing symptoms was assessed using four previously reported data-driven clinical recovery clusters. Two existing control populations of office workers and individuals with type 2 diabetes were comparators.ResultsValid accelerometer data from 253 women and 462 men were included. Women engaged in a mean ± SD of 14.9 ± 14.7 min/day of moderate-to-vigorous physical activity (MVPA), with 12.1 ± 1.7 h/day spent inactive and 7.2 ± 1.1 h/day asleep. The values for men were 21.0 ± 22.3 and 12.6 ± 1.7 h /day and 6.9 ± 1.1 h/day, respectively. Over 60% of women and men did not have any days containing a 30-min bout of MVPA. Variability in sleep timing was approximately 2 h in men and women. More severe acute illness was associated with lower total activity and MVPA in recovery. The very severe recovery cluster was associated with fewer days/week containing continuous bouts of MVPA, longer total sleep time, and higher variability in sleep timing. Patients post-hospitalisation with COVID-19 had lower levels of physical activity, greater sleep variability, and lower sleep efficiency than a similarly aged cohort of office workers or those with type 2 diabetes.ConclusionsThose recovering from a hospital admission for COVID-19 have low levels of physical activity and disrupted patterns of sleep several months after discharge. Our comparative cohorts indicate that the long-term impact of COVID-19 on physical behaviours is significant.

Momentary affective response to bouts of moderate-to-vigorous physical activity predicts changes in physical activity and sedentary behavior during behavioral weight loss

BackgroundAffective responses are posited to be key predictors of the uptake and maintenance of health behaviors. However, few studies have examined how individuals’ affective response to physical activity, as well as the degree to which their affect response changes, may predict changes in physical activity and sedentary time during behavioral weight loss treatment. PurposeThe current study examined how baseline momentary affective response (i.e., stress and anxiety) to moderate-to-vigorous physical activity (MVPA) and the degree of pre--post intervention change in this response predicted change in daily sedentary, light, and MVPA time during a three-month internet-based weight loss program. MethodsWomen with overweight/obesity (final N = 37) completed 14-day ecological momentary assessment (EMA) protocols with objective measurement of physical activity (i.e., bout-related MVPA time) before and after the intervention. ResultsWomen who had more reinforcing responses to MVPA (i.e., greater reductions in anxiety and stress response following MVPA bouts) at baseline had greater increases in overall MVPA at the end of the intervention. Those who had greater anxiety reductions after MVPA bouts at baseline also evidenced less sedentary time at the end of the intervention. Changes in affective responses across the intervention were not related to changes in physical activity levels. ConclusionsFindings suggest initial levels of affective reinforcement from MVPA bouts predict future change in MVPA and sedentary time during behavioral weight loss. Future work is needed to examine the utility of more precisely targeting affective responses to physical activity to optimize intervention approaches.

The Acute Effects of Exercising in Air Pollution: A Systematic Review of Randomized Controlled Trials.

The acute effects of air pollution (AP) exposure during physical activity have been studied. However, comprehensive systematic reviews are lacking, particularly regarding moderate-to-vigorous physical activity (MVPA). Our objective was to determine the acute health- and exercise-related effects of AP exposure during a bout of MVPA in healthy individuals. We searched for randomized controlled trials in MEDLINE, Embase, Cochrane CENTRAL, SPORTDiscus, Agricultural and Environmental Science Database, ClinicalTrials.gov, International Standard Randomised Controlled Trial Number Registry, and the World Health Organization (WHO) International Clinical Trials Registry Platform up to July 2020 without language or date restrictions. Studies including healthy subjects engaging in a bout of MVPA while exposed to one or more of the following air pollutants were eligible: particulate matter, black carbon, carbon monoxide, nitrogen dioxide, ozone, diesel exhaust, and traffic-related air pollution (TRAP). Main outcome measures were markers of pulmonary function, symptoms, cardiovascular function, cognitive function, systemic inflammation, and exercise response. The evidence was synthesized by vote counting based on direction of effect. In total, 53 studies were included in the systematic review. Studies employed a heterogeneous mix of exercise protocols, AP interventions, and measured outcomes. Pooled results suggest ozone exposure during MVPA has an adverse effect on pulmonary function (100% [95% confidence interval (CI) 88-100], p < 0.001; high-certainty evidence) and reported symptoms (88% [95% CI 69-96], p < 0.001; low-certainty evidence). The effect of exposure to carbon monoxide, nitrogen dioxide, small engine exhaust, or diesel exhaust during MVPA on health- and exercise-related outcomes is uncertain because of insufficient evidence and the low to very low certainty of available evidence. The evidence is strongest for ozone, exposure to which generally induced a reduction in pulmonary function and increased symptoms during MVPA. The research related to otheroutcomedomains remains inconclusive. Although long-term exposure to AP is proven to be hazardous, the evidence for healthy individuals to forgo MVPA during periods of high (non-ozone) pollution remains weak. Retrospectively registered in PROSPERO (CRD42020188280) on 10 July 2020.

The consequences of using different epoch lengths on the classification of accelerometer based sedentary behaviour and physical activity.

We examined the influence of using different epoch lengths on the classification accuracy of laboratory-controlled sedentary behaviour (SB), and free-living total time and time spent in bouts of SB and moderate-to-vigorous physical activity (MVPA), in children and adolescents. We used two studies including accelerometer-derived data of: 1) controlled activities, i.e. seven sedentary, one standing and one dancing (n = 90); 2) free-living activities (n = 902). For the controlled-activity data, we calculated percentages of time classified as SB and MVPA. For the free-living data, we calculated medians (25th-75th percentiles) of total time and time spent in bouts of SB and MVPA. Applying 8counts/5seconds, 25counts/15seconds and 100counts/60seconds for SB on controlled-activity data revealed respectively (1) 92-96%, 89-99% and 98-100% of sedentary time accurately classified as SB (activity- and age-dependent); (2) 91-98%, 88-99% and 97-100% of standing time classified as SB (age-dependent); (3) 25-37%, 20-25% and 25-38% of dancing time classified as SB (age-dependent). Using longer epochs, children's total time in SB and MVPA decreased while time accumulated in bouts of SB and MVPA accumulated in bouts increased. We conclude that a 60-second epoch seems preferable when the aim is to classify sedentary behaviour, while a shorter epoch length is needed to capture children's short bursts of MPVA. Furthermore, we should be aware that a longer epoch results in averaging of intensities to the middle category.

Are all MVPA minutes equal? Associations between MVPA characteristics, independent of duration, and childhood adiposity

BackgroundThe inverse relationship between moderate-to-vigorous physical activity (MVPA) duration and childhood adiposity is well established. Less is known about how characteristics of MVPA accumulation may be associated with adiposity, independent of MVPA duration. This study aimed to investigate how the MVPA characteristics of children, other than duration (bout length, time of day, day-to-day consistency, intensity), were associated with adiposity.MethodsCross-sectional study of the Australian arm of the International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE) (participants: n = 424, age range 9–11, 44% male). Adiposity was determined by percent body fat via bioelectrical impedance. MVPA duration and characteristics (bout length, time of day, consistency, intensity) were derived from 7-day, 24-h accelerometry. Generalised estimating equations were used to examine the individual and multivariate associations between MVPA characteristics and adiposity.ResultsUnivariate analyses showed that higher MVPA duration (β range = − 0.26,-0.15), longer bouts of MVPA (β range = 0.15,0.22) and higher MVPA intensity (β range = − 0.20,-0.13) were all inversely associated with adiposity (all p < 0.05). When models were adjusted for MVPA duration, only MVPA intensity (β range = − 0.16,-0.04) showed consistent significant associations with adiposity.ConclusionsCharacteristics of MVPA other than duration and intensity appear to be unrelated to adiposity.

Associations among masticatory muscle activity, physical activity and self-reported oral behaviours in adult women.

To examine the relationship between masticatory muscle activity (MMA), self-reported oral behaviours (OBs) and overall physical activity (PA) in adult women. MMA and PA were assessed by a wearable electromyography (EMG) device and accelerometer respectively, worn over 2 non-consecutive days by 53 women (mean age 27.5 ± 6.4 years). Following the second recording day, self-reported OBs were assessed. MMA was assessed by the number, amplitude and duration of masseter contraction episodes. Masseter muscle EMG outcome measures were number of contraction episodes per hour (CEs/h) and the relative contraction time (RCT%). PA was assessed by time accumulated in moderate to vigorous physical activity (MVPA) and 10-min bouts of MVPA per hour. Data were analysed using mixed model analysis. MMA in free-living conditions consisted mostly of low-amplitude (<10% maximum voluntary clenching) and short-duration (<10 s) contraction episodes. Masseter CEs/h were not associated with self-reported levels of OB. Masseter CEs/h were positively associated with time accumulated in MVPA (F = 9.9; p = 0.002) and negatively associated with 10-min bouts of MVPA/h (F = 15.8; p <0.001). RCT% was not significantly associated with either. Objectively assessed MMA is not associated with self-reported OB in free-moving adult females. Moderate to vigorous exercise and physical inactivity are accompanied with an increase in the number of masseter muscle contractions and thus possibly tooth clenching activity. OB can be influenced by the type and extent of PA. Subjective assessment of MMA by questionnaire and/or interviews may be invalid.

A 2-Year Longitudinal Study of Physical Activity and Cardiovascular Risk in Survivors of Stroke.

The purpose of this study was to explore associations between physical activity, cardiovascular risk factors, mobility, mood, fatigue, and cognition over 2years following stroke rehabilitation discharge. In this longitudinal observational study, survivors of first-ever stroke were evaluated at rehabilitation discharge and 6, 12, and 24months later. Moderate to vigorous physical activity (MVPA) duration (minutes/day) assessed with an electronic monitor was the primary outcome. Further outcomes included step count, the number and duration of MVPA and sedentary bouts, cardiovascular risk factors (eg, blood pressure, fasting lipid profile, body mass index [BMI]), gait speed and endurance, mood, fatigue, and cognition. Associations between physical activity and cardiovascular risk factors over time were assessed with random-effects regression modeling. Associations between baseline characteristics and physical activity at 2years were explored using regression modeling. Seventy-nine participants (68.4% men) with a mean age of 65years (SD=14) and a median gait speed of 1.2m/s (interquartile range=0.8 to 1.4) were included at baseline. Associations were found between higher physical activity (MVPA duration, number and duration of MVPA bouts) and lower BMI. Better gait speed, endurance, and cognition at baseline were associated with higher MVPA and step count at 2years. Duration and bouts of MVPA are associated with BMI. Increasing MVPA and bouts of MVPA may be a valuable treatment goal to reduce cardiovascular risk in survivors of stroke. This 2-year study found that MVPA is associated with important cardiovascular risk factors in people who have survived stroke. Understanding these associations could be useful for developing effective treatments to prevent recurrent stroke. Performing MVPA and accumulating in bouts of at least 10minutes might be challenging, but it could be an important component of treatments to reduce cardiovascular risk after stroke.