Free-living Physical Activity Research Articles

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

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.

Accelerometer measured physical activity and sedentary time in individuals with multiple sclerosis versus age matched controls: A systematic review and meta-analysis.

People with Multiple Sclerosis (PwMS) find it more difficult to engage in physical activity (PA) than healthy controls. Accelerometers can be used to measure sedentary time and free-living physical activity, understanding the differences between PwMS and controls can help inform changes such as interventions to promote a more active lifestyle. This in turn will help prevent secondary conditions and reduce symptom progression. To conduct a systematic review and meta-analysis on accelerometer measured sedentary behavior and physical activity between PwMS and healthy controls. A systematic search of five databases (PubMed, Web of Science, Ovid, Science Direct and CINAHIL) from inception until 22nd November 2019. Inclusion criteria was (1) included a group of participants with a definite diagnosis of multiple sclerosis of any type; (2) have 3 or more days of PA monitoring using accelerometers during free living conditions; (3) include age matched healthy controls; (4) assess adults over the age of 18; (5) reported data had to have been reported in a manner suitable for quantitative pooling including: percent of time spent sedentary, minutes per day of sedentary, light, moderate, vigorous activity (moderate and vigorous totaled together), steps per day or counts per day. Initial search produced 9021 papers, after applying inclusion criteria 21 eligible papers were included in the study. One paper was a longitudinal study from which only baseline data was included. One paper was a reliability and validity study, with data for PwMS versus controls in the validity section. All other papers are cross sectional, with one being a pilot study and another a random control study. One paper used two devices in unison, only one set of data is included in the statistics. Outcome data was available for 1098 participants, 579 PwMS and 519 healthy controls. Significant differences were seen in all categories tested: (1) sedentary time (min/day), standard mean difference -0.286, P=0.044, n=4 studies; (2) relative sedentary time (%/day), standard mean difference -0.646, P=0.000, n=5 studies; (3) LPA (min/day), standard mean difference 0.337, P=0.039, n=5 studies; (4) relative LPA (%/day), standard mean difference 0.211, P=0.152, n=studies; (5) MVPA (min/day), standard mean difference 0.801, P=0.000, n=8 studies; (6) relative MVPA (%/day), mean difference 0.914, P=0.000, n=5 studies; (7) step count, standard mean difference 0.894, P=0.000, n=8 studies; (8) activity count, standard mean difference 0.693, P=0.000, n=13 studies. PwMS are more sedentary and engage in less LPA, MVPA, steps per day and accelerometer counts per day than healthy controls when measured using accelerometers during free-living conditions.

Objectively measured physical activity, sedentary time, extracurricular habits, and IQ in 7 to 8 years old children

The effects of an active lifestyle including extracurricular habits on children’s cognitive function are topics of health and human development, besides that the maintenance of sedentary behavior seems to be related to cognitive function. Considering an active lifestyle, studies present mixed results in terms of cognitive factors, physical activity exposures and tests applied. Existent studies identified that objectively measured physical activity should be more explored to further help elucidate these results since this type of measure assessed by accelerometer provides accurate time spent in free-living daily physical activity. Moreover, children who spend time in specific sedentary activities and have active extracurricular habits present higher academic achievement. Therefore, it was conducted a cross-sectional study in 609 children at 7 and 8 years old from Pelotas, Brazil. WASI scale was applied to evaluate intelligence; total IQ, verbal IQ and execution IQ were considered. Reading practice was associated with verbal IQ and execution IQ and extracurricular physical activities were associated with execution IQ. Accelerometer analyses indicate an association for sedentary time and total IQ and execution IQ. Light PA was inversely associated with execution IQ. Moderate PA was inversely associated with execution IQ and vigorous PA was not associated with IQ. Significant associations were found in the analyses between sedentary time, physical activity, and cognitive function.

Enhancing cardiometabolic health through physical activity and breakfast manipulations in children and adolescents: good for humans, good for the planet.

The human health benefits of cardiometabolic disease prevention can be accompanied by planetary co-benefits. Focusing efforts towards young people, including children and adolescents, is conducive to disease prevention. In the context of cardiometabolic disease prevention, this review paper critically summarises the available literature on the acute cardiometabolic responses to physical activity and breakfast manipulations among young people. Given the seriousness of global climate change, which will disproportionally affect our younger generations, this review paper offers new insights into the inherent interactions between child-adolescent behaviour and cardiometabolic health from an environmental sustainability perspective to aid climate change mitigation efforts, including exploring future research avenues. A growing evidence base suggests acute moderate- to high-intensity exercise bouts can attenuate postprandial plasma glucose, insulin and triacylglycerol concentrations for up to 24-48 h in young people. Whether accumulating physical activity throughout the day with short, frequent bouts promotes cardiometabolic risk marker attenuations is unclear. Breakfast consumption may enhance free-living physical activity and reduce glycaemic responses to subsequent meals for a possible additive impact. If repeated habitually, attenuations in these cardiometabolic risk factors would be conducive to disease prevention, reducing the greenhouse gas emissions associated with disease diagnosis and treatment. To progress current understanding with high public health and planetary relevance, research among samples of 'at risk' young people that span cellular-level responses to ecologically valid settings and address human and planetary health co-benefits is needed. Indeed, certain physical activity opportunities, such as active travel to school, offer important direct co-benefits to humans and planetary health.

Abstract 14318: The Effect of Time-Restricted Eating on Physical Activity: Results From the Time-Restricted Intake of Meals (Trim) Randomized Trial

Introduction: Time-restricted eating (TRE) is a dietary pattern that may promote weight loss by limiting caloric intake, but evidence for its effects on physical activity are limited. Objective: To determine the effect of a TRE pattern compared to a usual eating pattern (UEP) on physical activity. Methods: We examined physical activity data from 41 adults with prediabetes or untreated diabetes (HbA1c 5.7-6.9%) and obesity (BMI 30-50 kg/m 2 ) randomized to consume 80% of their total calories before 1 pm (TRE) or ≥50% of their calories after 5 pm (UEP) with identical macronutrient content. Participants were fitted with a wrist-worn GT9X accelerometer (Actigraph; Pensacola FL) to measure free-living physical activity behaviors for one week at baseline and 12 weeks. Outcomes were mean total activity counts (measure of activity volume and intensity) and time spent active (measure of activity volume) per day. We used linear mixed effects regression models with participant-specific random intercepts to examine the difference in outcomes between the two groups from baseline to 12 weeks; the intervention-by-time interaction was the term of interest (β int ). Results: Thirty-nine adults (mean age 59.5 years; 92% female; 92% African American) completed actigraphy assessments. We observed a significant decrease in all physical activity measures from baseline to 12 weeks in TRE, but not in UEP ( Table ). Total activity counts (p for β int =0.005), but not time spent active (p for β int =0.094) declined significantly in TRE compared to UEP. Conclusion: In this randomized feeding study, TRE was associated with reduced physical activity intensity while overall physical activity volume was unaffected, compared to a UEP. This unexpected compensatory decrease in physical activity intensity may limit the efficacy of TRE for achieving weight loss. Future studies are needed to understand the mechanisms behind this effect, and to optimize TRE interventions to maintain physical activity levels.

Brief report: Free-living physical activity levels and cognitive control in multi-problem young adults

Previous studies indicate a positive association between physical activity and cognitive control in sedentary but healthy adults, yet not much is known about physical activity levels in multi-problem young adults. We examined the level of self-reported free-living physical activity (i.e., MET minutes per week) in an ecologically valid sample of young adults facing multiple problems, including unemployment, lack of education, frequent substance use, and history of delinquency. We compared cognitive control with an age- and sex-matched control sample. Additionally, the association between physical activity and cognitive control (i.e., response inhibition, error processing, interference effect) in the multi-problem group was examined. Physical activity and cognitive control were measured with the International Physical Activity Questionnaire-Long Form and three cognitive control experiments (i.e., Flanker, Go/NoGo, Stroop), respectively. With M = 4428 Metabolic Equivalents (METs), our multi-problem sample (n = 63) showed physical activity levels similar to the age- and sex-matched control sample from the general population (n = 62). The multi-problem young adults also showed impaired cognitive control indexed as decreased response inhibition and decreased Flanker correctness effect compared to their peers. We could not find an association between self-reported physical activity and cognitive control in the multi-problem sample. Due to the small sample size, results should be interpreted with caution. However, future dose-response studies could still use these results to further examine if within-individual increased physical activity may possibly lead to improved cognitive control in (already relatively active) multi-problem young adults.

Impact of ActiGraph sampling rate on free-living physical activity measurement in youth

ActiGraph sampling frequencies of more than 30 Hz may result in overestimation of activity counts in both children and adults, but research on free-living individuals has not included the range of sampling frequencies used by researchers. Objective. We compared count- and raw-acceleration-based metrics from free-living children and adolescents across a range of sampling frequencies. Approach. Participants (n = 445; 10–15 years of age) wore an ActiGraph accelerometer for at least one 10 h day. Vector magnitude counts, mean amplitude deviation, monitor-independent movement summary units, and activity intensity classified using six methods (four cut-points, two-regression model, and artificial neural network) were compared between 30 Hz and 60, 80, 90, and 100 Hz sampling frequencies using mean absolute differences, correlations, and equivalence testing. Main results. All outcomes were statistically equivalent, and correlation coefficients were ≥0.970. Absolute differences were largest for the 30 versus 80 and 30 versus 100 Hz count comparisons. For comparisons of 30 with 60, 80, 90, or 100 Hz, mean (and maximum) absolute differences in minutes of moderate-to-vigorous physical activity per day ranged from 0.1 to 0.3 (0.4 to 1.5), 0.3 to 1.3 (1.6 to 8.6), 0.1 to 0.3 (1.1 to 2.5), and 0.3 to 2.5 (1.6 to 14.3) across the six classification methods. Significance. Acceleration-based outcomes are comparable across the full range of sampling rates and therefore recommended for future research. If using counts, we recommend a multiple of 30 Hz because using a 100 Hz sampling rate resulted in large maximum individual differences and epoch-level differences, and increasing differences with activity level.

Feasibility, acceptability, and fidelity of Physical Activity Routines After Stroke (PARAS): a multifaceted behaviour change intervention targeting free-living physical activity and sedentary behaviour in community-dwelling adult stroke survivors

BackgroundLow levels of habitual physical activity and high levels of sedentary behaviour are commonly observed post-stroke. We aimed to assess the feasibility, acceptability and fidelity of a multifaceted, theory- and evidence-informed supported self-management intervention targeting physical activity and sedentary behaviour after stroke: Physical Activity Routines After Stroke (PARAS).MethodsAdult stroke survivors and healthcare professionals were recruited from North East England stroke services. Stroke survivor physical activity and sedentary behaviour were targeted by a self-management behavioural intervention supported by healthcare professionals trained in intervention delivery. The main outcomes were protocol and intervention acceptability and feasibility and fidelity of intervention delivery.ResultsEleven healthcare professionals (9 physiotherapists; 2 occupational therapists) participated in the study. Stroke survivor recruitment was lower than anticipated (19 versus target of up to 35). The healthcare professional training programme was feasible, with fidelity assessment of delivery supporting this finding. Data completeness was acceptable according to a priori criteria (>60%), except for stroke survivor questionnaire return rate (59%) and interview uptake (52%). No serious adverse events occurred. Healthcare professionals and stroke survivors perceived intervention delivery to be feasible and acceptable with minor modifications highlighted including the potential for earlier delivery in the stroke pathway.ConclusionsThe study protocol and intervention delivery were feasible and acceptable to stroke survivors and healthcare professionals with modifications required before large-scale evaluation.Trial registrationISRCTN35516780. Registered on October 24, 2018

Associations Of Physical Activity And Bone Health Outcomes Among Underweight Adolescents

PURPOSE. To examine the relationship between physical activity (PA) and bone mineral density (BMD) at 5 sites: total body minus head, left leg/arm, lumbar spine, and pelvis among underweight adolescents (BMI < 5th percentile). METHODS. Data from the 2011-2012 National Health and Nutrition Examination Survey (NHANES) were used. Free-living PA was assessed over 7 days using ActiGraph accelerometers, and bone health metrics were measured through dual-energy X-ray absorptiometry (DXA). After selecting the underweight adolescents with both PA and DXA, there remained 47 participants (Age: 15.53 ± 2.71 yr., Male%: 63.83%, Height: 163.64 ± 13.13 cm, Weight: 43.63 ± 9.40 kg, BMI: 16.05 ± 1.35 kg/m2). The PA metric was assessed by Monitor-Independent Movement Summary (MIMS) units per day. Maximal PA MIMS (PA.max), mean PA MIMS (PA.mean), and summed PA MIMS (PA.sum) over 7 days were computed to represent PA dose. The bone health outcomes were the BMD of the total body minus head, left leg/arm, lumbar spine, and pelvis. The partial correlations between PA and bone health metrics controlled by height and weight were computed. RESULTS. Means ± standard deviations of PA.max: 16,735.79 ± 5,333.40, PA.mean: 12,398.54 ± 4,423.51, and PA.sum: 85,131.52 ± 32,148.25. Correlations between different PA metrics and BMDs are summarized below:CONCLUSION. For males, there were low positive correlations between PA.mean/PA.sum and BMDs, but moderate correlations with pelvis BMD; there were low positive correlations between PA.max and left arm/lumbar spine BMD, but moderate correlations with BMDs at the total body minus head, left leg, and pelvis. Some sex differences were noticed, with in general higher correlation in males and some negative correlations in females’ up-body sites. The results indicated the importance of PA on bone development in underweight adolescents, especially for boys, and more studies with large samples on sex differences in certain location are urgently needed.

Associations of Self-Control with Physical Activity, Physical Fitness, and Adiposity in Adolescents

The associations between self-control and objective measures of physical activity, physical fitness, and adiposity are yet to be explored in young people; this is a gap in the literature that the present study aimed to address. The study employed a cross-sectional design. A total of 101 young people participated in the study. Participants completed the Brief Self-Control Scale as a measure of trait self-control. Free-living physical activity was assessed using an ActiGraph GT3X + triaxial accelerometer, which was worn for 7 days. Participants also completed the 15-meter version of the multistage fitness test as a measure of physical fitness. For the assessment of adiposity, three criterion measures were used: body mass index (BMI), sum of skinfolds, and waist circumference. Data were analyzed using the glm function in the open access software R. Higher levels of trait self-control were associated with higher levels of physical fitness (measured by distance run on the multistage fitness test) and lower adiposity (BMI, waist circumference, and sum of skinfolds) in adolescents. There was a tendency for a positive association between self-control and time spent in vigorous physical activity, although this did not reach statistical significance. In a combined model, self-control was also associated with both physical fitness and waist circumference, with these effects independent of each other. These findings suggest that self-control is associated with healthy behaviors and characteristics in adolescents and is thus potentially an attractive target for future interventions aimed at increasing physical activity and physical fitness and reducing adiposity in this population.

Validation of Accelerometer-Based Estimations of Energy Expenditure During High-Intensity Interval Training

Accelerometers are used to assess free-living physical activity (PA) and energy expenditure (EE). Energy expenditure estimation algorithms have been calibrated using steady-state exercise. However, most free-living PA is not steady-state. Objective: The purpose of this study was to discern the differences between criterion-measured and accelerometer-estimated EE (kCals) during a non-steady-state High-Intensity Interval Training (HIIT) session. Methods: Recreationally active adults (N=29, 18-30 years) completed one of two HIIT protocols. Each participant wore ActiGraph GT3X+ accelerometers on the right hip and non-dominant wrist while EE was measured using portable indirect calorimetry. Data analysis was conducted using custom R scripts and bias [95% CIs] to determine significant differences between indirect calorimetry and EE estimates using previously developed algorithms. Results: All accelerometer algorithms underestimated EE during recovery intervals (range; -4.31 to -6.55 kCals) and overestimated EE during work intervals (0.57 to 5.70 kcals). Over the whole HIIT session, only the Hildebrand wrist method was not significantly different from the criterion measured EE. Conclusion: Current ActiGraph EE estimations based on steady-state activities underestimate EE during recovery periods of treadmill HIIT sessions. Future studies should investigate accelerometer signals immediately after high-intensity bouts to more accurately predict EE of the subsequent recovery period. KEYWORDS: ActiGraph; Accelerometer; HIIT; Indirect calorimetry; EPOC; Energy expenditure; Non-steady state; Calories

Lack of validity of free-living physical activity energy expenditure estimated from ActiGraph equations in severely obese women: A doubly labelled water study

ABSTRACT The current study aimed to investigate the validity of three ActiGraph predictive equations that are available to estimate free-living physical activity energy expenditure (PAEE) in women with severe obesity. The study included 20 women with class III obesity (age: 22–38 years). During 14 days of free-living conditions, total energy expenditure was measured using the doubly labelled water method; in addition, participants wore a triaxial accelerometer (model GT3X+) on the hip. The resting metabolic rate was measured by indirect calorimetry. At group level, the Freedson VM3 Combination was found to be more precise (bias = −61 kcal/day) than the Williams Work-Energy (bias = −283 kcal/day) and the Freedson Combination equations (bias = −186 kcal/day) for estimating PAEE. However, the three predictive equations had a wider limit of agreement (Williams Work-Energy [258, −824 kcal/day], Freedson Combination equations [324, −697 kcal/day] and Freedson VM3 Combination [424, −546 kcal/day]), indicating great uncertainty of the estimate. In conclusion, a wide variation was observed in the performance of different ActiGraph equations in estimating free-living PAEE among women with class III obesity. Therefore, our data do not support the use of these equations, and more studies are needed to improve predictive performance in free-living conditions.

Comparison of Child and Adolescent Physical Activity Levels From Open-Source Versus ActiGraph Counts

ActiGraph counts are commonly used for characterizing physical activity intensity and energy expenditure and are among the most well-studied accelerometer metrics. Researchers have recently replicated the counts processing method using a mechanical setup, now allowing users to generate counts from raw acceleration data. Purpose: The purpose of this study was to compare ActiGraph-generated counts to open-source counts and assess the impact on free-living physical activity levels derived from cut points, machine learning, and two-regression models. Methods: Children (n = 488, 13.0 ± 1.1 years of age) wore an ActiGraph wGT3X-BT on their right hip for 7 days during waking hours. ActiGraph counts and counts generated from raw acceleration data were compared at the epoch-level and as overall means. Seven methods were used to classify overall and epoch-level activity intensity. Outcomes were compared using weighted kappa, correlations, mean absolute deviation, and two one-sided equivalence testing. Results: All outcomes were statistically equivalent between ActiGraph and open-source counts; weighted kappa was ≥.971 and epoch-level correlations were ≥.992, indicating very high agreement. Bland–Altman plots indicated differences increased with activity intensity, but overall differences between ActiGraph and open-source counts were minimal (e.g., epoch-level mean absolute difference of 23.9 vector magnitude counts per minute). Regardless of classification model, average differences translated to 1.4–2.6 min/day for moderate- to vigorous-intensity physical activity. Conclusion: Open-source counts may be used to enhance comparability of future studies, streamline data analysis, and enable researchers to use existing developed models with alternative accelerometer brands. Future studies should verify the performance of open-source counts for other outcomes, like sleep.