Light-intensity Activity Research Articles

Prediction of Physical Activity Intensity with Accelerometry in Young Children.

Background: An algorithm for the classification of ambulatory and non-ambulatory activities using the ratio of unfiltered to filtered synthetic acceleration measured with a triaxial accelerometer and predictive models for physical activity intensity (METs) in adults and in elementary school children has been developed. The purpose of the present study was to derive predictive equations for METs with a similar algorithm in young children. Methods: Thirty-seven healthy Japanese children (four- to six-years old) participated in this study. The five non-ambulatory activities including low-intensity activities, and five ambulatory activities were selected. The raw accelerations using a triaxial accelerometer and energy expenditure by indirect calorimetry using the Douglas bag method during each activity were collected. Results: For non-ambulatory activities, especially light-intensity non-ambulatory activities, linear regression equations with a predetermined intercept (0.9) or quadratic equations were a better fit than the linear regression. The equations were different from those for adults and elementary school children. On the other hand, the ratios of unfiltered to filtered synthetic acceleration in non-ambulatory activities were different from those in ambulatory activities, as in adults and elementary school children. Conclusions: Our calibration model for young children could accurately predict intensity of physical activity including low-intensity non-ambulatory activities.

Identifying Free-Living Physical Activities Using Lab-Based Models with Wearable Accelerometers

The purpose of this study was to classify, and model various physical activities performed by a diverse group of participants in a supervised lab-based protocol and utilize the model to identify physical activity in a free-living setting. Wrist-worn accelerometer data were collected from () adult participants; age 18–64 years, and processed the data to identify and model unique physical activities performed by the participants in controlled settings. The Gaussian mixture model (GMM) and the hidden Markov model (HMM) algorithms were used to model the physical activities with time and frequency-based accelerometer features. An overall model accuracy of 92.7% and 94.7% were achieved to classify 24 physical activities using GMM and HMM, respectively. The most accurate model was then used to identify physical activities performed by 20 participants, each recorded for two free-living sessions of approximately six hours each. The free-living activity intensities were estimated with 80% accuracy and showed the dominance of stationary and light intensity activities in 36 out of 40 recorded sessions. This work proposes a novel activity recognition process to identify unsupervised free-living activities using lab-based classification models. In summary, this study contributes to the use of wearable sensors to identify physical activities and estimate energy expenditure in free-living settings.

Low Levels of Physical Activity Among Older Persons Living with HIV/AIDS Are Associated with Poor Physical Function.

Antiretroviral therapy (ART) has prolonged lives of persons living with HIV/AIDS (PLWHA), resulting in greater incidence of aging-related diseases and disability. Physical activity (PA) is recommended for healthy aging, but little is known about PA in older PLWHA. The purpose of this study was to objectively assess PA levels in older PLWHA and the associations with physical function. Twenty-one PLWHA, ≥50 years old, on ART with undetectable HIV-1 viral loads, wore an accelerometer to assess PA, including number of steps, activity intensity, and energy expenditure over 7 days. A physical function performance battery assessing aerobic capacity, strength, and gait speed was also completed. Average age was 66, and 67% were male. An average of 3,442 (interquartile range: 4,613) steps were walked daily, with 254.9 kcals expended. Participants spent most waking hours (75%) sedentary, with minimal hours (24%) in light-intensity activity. Only 5 min per day (35 min per week), on average, were spent in moderate-to-vigorous physical activity (MVPA). Maximal gait speed and 6-min walk test significantly correlated (p < .05) with all PA outcomes. Usual gait speed significantly correlated with all PA outcomes, except for daily kcals and light-intensity activity. Greater PA was associated with better physical performance, while high sedentary time was associated with poorer performance. To our knowledge, this is the first study to objectively measure PA in older PLWHA. Our findings indicate that older PLWHA accumulate substantial sedentary time. Most (86%) do not achieve recommended MVPA levels. This activity profile was associated with poor physical function. Providers should promote PA among PLWHA.

The Association Between Park Facilities and Duration of Physical Activity During Active Park Visits

Public parks provide places for urban residents to obtain physical activity (PA), which is associated with numerous health benefits. Adding facilities to existing parks could be a cost-effective approach to increase the duration of PA that occurs during park visits. Using objectively measured PA and comprehensively measured park visit data among an urban community-dwelling sample of adults, we tested the association between the variety of park facilities that directly support PA and the duration of PA during park visits where any PA occurred. Cross-classified multilevel models were used to account for the clustering of park visits (n = 1553) within individuals (n = 372) and parks (n = 233). Each additional different PA facility at a park was independently associated with a 6.8% longer duration of PA bouts that included light-intensity activity, and an 8.7% longer duration of moderate to vigorous PA time. Findings from this study are consistent with the hypothesis that more PA facilities increase the amount of PA that visitors obtain while already active at a park.

A Review of Accelerometer-based Activity Monitoring in Cancer Survivorship Research.

In the cancer survivorship context, physical activity and sedentary behavior have been measured using different methods. To conduct a narrative review of published research in cancer survivor populations to summarize the quality and identify gaps in reporting on accelerometer data collection, data processing, and outcome measures in cancer survivors. An initial PubMed® search of articles published in English was conducted in January 2017, and a final search was conducted in May 2017. Variables extracted included study characteristics, methods for accelerometry data collection (e.g., device used), data processing (e.g., cut points used), and data reporting (e.g., time spent in different activity intensities). A total of 46 articles were eligible for inclusion in the review. The majority of studies (34 of 46) targeted a single cancer group and 18 of these 34 studies were in survivors of breast cancer. Half (54%) of the studies used an ActiGraph® accelerometer. Methods of accelerometer data processing varied across studies. Definitions of non-wear time, vectors used during processing, and filters applied during processing were reported by 51%, 60%, and 8% of studies, respectively. Most studies reported moderate and vigorous physical activity (78%), 50% reported sedentary time, and 43% reported light-intensity activity. Cut points to categorize these activities varied between studies. This narrative review highlights inconsistency in the methods used to collect, process, and report accelerometry data across cancer survivor studies. Accelerometry has potential to add detailed knowledge of the levels and patterns of physical activities and sedentary behaviors across the cancer spectrum. Recommendations are made to improve data processing and reporting methods to maximize the scientific validity of future accelerometer research in this field.

Quantifying postoperative mobilisation following oesophagectomy

ObjectiveEarly mobilisation is in integral component of postoperative recovery following complex surgical procedures such as oesophageal cancer resections, however evidence to guide early mobilisation protocols in critical care settings is limited. Furthermore, little is known about actual mobilisation levels postoperatively. This study quantified postoperative mobilisation post- oesophagectomy and investigated barriers to mobility. DesignProspective observational study. SettingPostoperative critical care setting in a tertiary care referral centre for oesophagectomy. ParticipantsThirty participants (mean age 65 (SD 7) years, n=19 males) scheduled for oesophagectomy. Main Outcome MeasuresThe primary outcome, postoperative physical activity, was measured objectively using the Actigraph GT3X+. Medical records were examined for a range of outcomes including medical status, pain scores and physiotherapy comments to identify factors which may have influenced mobility. ResultsDuring postoperative day (POD) 1–5, participants spent the majority of time (>96%) sedentary. Participation in light intensity activity was low but did increase daily from a median of 12 (IQR 19) minutes/day on POD1 to a median of 53 (IQR 73.25) minutes/day on POD5 p<0.001), with a corresponding increase in daily step count. Haemodynamic instability was the most common reason reported by physiotherapists for either not attempting mobility or limiting postoperative mobilisation levels. ConclusionsThese data demonstrate that despite daily physiotherapy, there are multiple challenges to postoperative mobilisation. Haemodynamic instability, likely related to thoracic epidurals, was the key limitation to early mobilisation. Goal-directed mobilisation in collaboration with the multidisciplinary team may play a considerable role in overcoming modifiable barriers to postoperative mobilisation.

The Effect of Match Schedule on Accelerometry-Derived Exercise Dose during Training Sessions throughout a Competitive Basketball Season.

Accelerometry-derived exercise dose (intensity × duration) was assessed throughout a competitive basketball season. Nine elite basketballers wore accelerometers during a Yo-Yo intermittent recovery test (Yo-Yo-IR1) and during three two-week blocks of training that represented phases of the season defined as easy, medium, and hard based on difficulty of match schedule. Exercise dose was determined using accumulated impulse (accelerometry-derived average net force × duration). Relative exercise intensity was quantified using linear relationships between average net force and oxygen consumption during the Yo-Yo-IR1. Time spent in different intensity zones was computed. Influences of match schedule difficulty and playing position were evaluated. Exercise dose reduced for recovery and pre-match tapering sessions during the medium match schedule. Exercise dose did not vary during the hard match schedule. Exercise dose was not different between playing positions. The majority of activity during training was spent performing sedentary behaviour or very light intensity activity (64.3 ± 6.1%). Front-court players performed a greater proportion of very light intensity activity (mean difference: 6.8 ± 2.8%), whereas back-court players performed more supramaximal intensity activity (mean difference: 4.5 ± 1.0%). No positional differences existed in the proportion of time in all other intensity zones. Objective evaluation of exercise dose might allow coaches to better prescribe and monitor the demands of basketball training.

Use of Time and Energy on Exercise, Prolonged TV Viewing, and Work Days

The goal of this study was to describe differences in time use and energy expenditure associated with exercise, prolonged TV viewing, and work days in a longitudinal study of older adults. Participants were 1,020 adults who completed previous-day recalls that provided a profile of the use of time in sedentary and physical activity. Time use and physical activity energy expenditure were predicted for each type of day (exercise, prolonged TV, work) using linear mixed models, adjusting for age, sex, season of the year, and day of the week. Data were collected in 2012-2013; analysis was completed in 2017. Exercise days had less sedentary time (-0.37 hours/day) and light activity (-0.29 hours/day), and less household, work, and shopping activities, such that the increase in total physical activity energy expenditure on exercise days (2.83 MET-hours/day) was only about half that expended during exercise (5.98 MET-hours/day). Prolonged TV viewing days had more total sedentary time (0.86 hours/days) and less light (-0.45 hours/day) and moderate-vigorous intensity activity (-0.41 hours/day), and thus lower total physical activity energy expenditure (-2.43 MET-hours/day). Work days had less sleep (-0.91 hours/day) and more total sedentary time (1.32 hours/day). Exercise days had more physical activity energy expenditure, but because of reductions in other activities, only about half of the energy expended during exercise was added to total daily physical activity energy expenditure. Prolonged TV viewing days had less physical activity energy expenditure and less moderate-vigorous activity. These findings provide new insights into possible compensation associated with exercise, and suggest a strong link between TV viewing and physical inactivity.

Physical Activity in a Randomized Culturally Adapted Lifestyle Intervention

Middle Eastern immigrants exhibit high levels of physical inactivity and are at an increased risk for Type 2 diabetes. The primary aim of this study was to examine the changes in objectively assessed physical activity levels following a culturally adapted lifestyle intervention program. The secondary aim was to examine the association between objectively assessed physical activity and insulin sensitivity. RCT conducted over 4 months in 2015. Iraqi immigrants residing in Malmö, Sweden, exhibiting one or more risk factors for Type 2 diabetes. The intervention group (n=50) was offered a culturally adapted lifestyle intervention comprising seven group sessions including a cooking class. The control group (n=46) received usual care. Raw accelerometry data were processed by validated procedures and daily mean physical activity intensity, vector magnitude high-pass filtered (VM-HPF), was inferred. Further inferences into the number of hours/day spent in sedentary (VM-HPF <48 milli-Gs [mGs] where G=9.8 m/sec2) and light- (48- <163 mGs); moderate- (163- <420 mGs); and vigorous-intensity (≥420 mGs) activities were also calculated (year of analysis was 2016-2017). No difference was observed between the two groups in terms of change over time in VM-HPF. There was a significant increase in the number of hours/day spent in light intensity physical activity in the intervention group compared with the control group (β=0.023, 95% CI=0.001, 0.045, p=0.037). The intervention group also increased the time spent in sedentary activities, with the highest VM-HPF (36- <48 mGs) within the sedentary behavior (B=0.022, 95% CI=0.002, 0.042, p=0.03). Higher VM-HPF was significantly associated with a higher insulin sensitivity index (β=0.014, 95% CI=0.0004, 0.025, p=0.007). The findings favor the culturally adapted intervention approach for addressing low physical activity levels among Middle Eastern immigrants. Replacing sedentary time with light-intensity activities could be an achievable goal and will have potential beneficial effects for diabetes prevention among this sedentary group of immigrants. This study was registered at www.clinicaltrials.gov NCT01420198.

Replacing sedentary time with physical activity or sleep: effects on cancer-related cognitive impairment in breast cancer survivors

BackgroundEvidence suggests reallocating daily sedentary time to physical activity or sleep confers important health benefits in cancer survivors. Despite emerging research suggesting physical activity as a treatment for cancer-related cognitive impairment (CRCI), little is known about the interactive effects of behaviors across the 24-h period. The present purpose was to examine the cognitive effects of reallocating sedentary time to light-intensity physical activity, moderate-to-vigorous physical activity (MVPA), or sleep in breast cancer survivors.MethodsBreast cancer survivors (N = 271, Mage = 57.81 ± 9.50 years) completed iPad-based questionnaires and cognitive tasks assessing demographics, health history, executive function, and processing speed (Task-Switch, Trail Making). Participants wore an accelerometer for seven consecutive days to measure their sedentary, physical activity, and sleep behaviors. Single effects (each behavior individually) and partition (controlling for other behaviors) models were used to examine associations among behaviors and cognitive performance. Isotemporal substitution models were used to test the cognitive effects of substituting 30 min of sedentary time with 30 min of light-intensity activity, MVPA, and sleep.ResultsMVPA was associated with faster Task-switch reaction time in the partition models (stay: B = − 35.31, p = 0.02; switch: B = − 48.24, p = 0.004). Replacing 30 min of sedentary time with 30 min of MVPA yielded faster reaction times on Task-Switch stay (B = − 29.37, p = 0.04) and switch (B = − 39.49, p = 0.02) trials. In Trails A single effects models, sedentary behavior was associated with faster completion (B = − 0.97, p = 0.03) and light-intensity activity with slower completion (B = 1.25, p = 0.006). No single effects were observed relative to Trails B completion (all p > 0.05). Only the effect of MVPA was significant in the partition models (Trails A: B = − 3.55, p = 0.03; Trails B: B = − 4.46, p = 0.049). Replacing sedentary time with light-intensity activity was associated with slower Trails A (B = 1.55 p = 0.002) and Trails B (B = 1.69, p = 0.02) completion. Replacing light activity with MVPA yielded faster Trails A (B = − 4.35, p = 0.02) and Trails B (B = − 5.23, p = 0.03) completion.ConclusionsFindings support previous research suggesting MVPA may be needed to improve cognitive function in breast cancer survivors. Trails findings underscore the need to dissect sedentary contexts to better understand the impact of daily behavioral patterns on CRCI. Additional research investigating the cognitive impacts of behaviors across the 24-h period is warranted.Trial registrationThis study is registered with United States ClinicalTrials.gov (NCT02523677; 8/14/2015).

Physical activity during pregnancy is associated with a lower prevalence of gestational diabetes mellitus in Vietnam.

To assess the association between physical activity (PA) during pregnancy and the prevalence of gestational diabetes mellitus (GDM) accounting for sitting time. The study used data from a cohort study of 2030 pregnant women in Vietnam. Women were recruited from six hospitals in Ha Noi, Hai Phong, and Ho Chi Minh City. Baseline measurements including PA and GDM were taken at 24-28weeks of gestation. PA was assessed during the past 3months before the interview using the interviewer-administered Pregnancy Physical Activity Questionnaire. GDM was diagnosed at 24-28weeks of gestation using the 2013 World Health Organization criteria. 1987 out of 2030 pregnant women were included in the final analysis, of which 432 had GDM (21.7%). Women undertaking the highest level (upper tertile) of PA during pregnancy appeared to have a lower risk of GDM [odds ratio (OR) 0.70, 95% confidence interval (CI) 0.53-0.94, Ptrend 0.017] when compared to those at the lowest tertile of PA. Similarly, women with increased levels of moderate-intensive activity and household/caregiving activity during pregnancy were associated with reduced risks of GDM (OR 0.66, 95% CI 0.50-0.86, Ptrend 0.002 and OR 0.72, 95% CI 0.55-0.95, Ptrend 0.020, respectively). These apparent inverse associations were not attenuated by their sitting time. There were no significant associations between sitting time, light-intensity activity, vigorous-intensity activity, occupation, sports/exercise, commuting, or meeting exercise guidelines and GDM risk. High levels of PA, particularly moderate-intensity and household/caregiving activities during pregnancy were associated with a lower prevalence of GDM independent of sitting time.

Energy Cost of Stone Knapping

Stone tool manufacture and use are considered key adaptations in human evolution. The understanding of the biomechanical features and anatomical constraints of hominins during stone tool production have received increased attention in recent years. Similarly, research on the cognitive capabilities and manipulative complexity involved in toolmaking is in progress. However, data on the palaeophysiological constraints of stone knapping are scarce. The balance between energy acquisition and energy expenditure is a key factor to determine the fitness of any individual, and stone knapping is essential for resource procurement in any Palaeolithic society. Thus, the combination of energetic analyses and experimental archaeology provides an excellent tool to improve our understanding of prehistoric behaviours. Here, we present experimental research on the energetics of stone tool production that involves nine experienced subjects. Each subject produced three handaxes through direct hard- and soft-hammer percussion in a total of 27 experiments of toolmaking. All knappers were described by their anthropometric data, and their energetic expenditure was monitored in a breath-by-breath indirect calorimetry procedure. Because knapping is considered a light-intensity level activity, based on its MET (Metabolic Equivalent Task of Intensity) value, our results show some differences in net energy expenditure between direct hard percussion and soft percussion knapping during the configuration of a handaxe. Furthermore, our results suggest that the brachial index of the subjects represents an anatomical constraint for stone knapping because the lever of a shorter forearm reduces energy expenditure during striking and represents an advantage during handaxe production. Differences in the energetic efficiency of knapping, even if they are low, may increase the general fitness of the individual and, indeed, its survival.

A User-Adaptive Algorithm for Activity Recognition Based on K-Means Clustering, Local Outlier Factor, and Multivariate Gaussian Distribution.

Mobile activity recognition is significant to the development of human-centric pervasive applications including elderly care, personalized recommendations, etc. Nevertheless, the distribution of inertial sensor data can be influenced to a great extent by varying users. This means that the performance of an activity recognition classifier trained by one user’s dataset will degenerate when transferred to others. In this study, we focus on building a personalized classifier to detect four categories of human activities: light intensity activity, moderate intensity activity, vigorous intensity activity, and fall. In order to solve the problem caused by different distributions of inertial sensor signals, a user-adaptive algorithm based on K-Means clustering, local outlier factor (LOF), and multivariate Gaussian distribution (MGD) is proposed. To automatically cluster and annotate a specific user’s activity data, an improved K-Means algorithm with a novel initialization method is designed. By quantifying the samples’ informative degree in a labeled individual dataset, the most profitable samples can be selected for activity recognition model adaption. Through experiments, we conclude that our proposed models can adapt to new users with good recognition performance.

Regular brief interruptions to sitting after a high-energy evening meal attenuate glycemic excursions in overweight/obese adults

Background and aimsModern Western lifestyles are characterized by consumption of approximately 45% of total daily energy intake at the evening meal, followed by prolonged sitting while watching television (TV), which may deleteriously impact glycemic control. After a high-energy evening meal (dinner), we examined whether regular, brief activity bouts during TV commercial breaks could acutely lower postprandial glucose and insulin responses in overweight/obese adults, compared to prolonged uninterrupted sitting. Methods and resultsNine overweight/obese adults (29.7 ± 4.06 kg m−2; aged 32 ± 3 years; 5 male) completed two laboratory-based conditions of three and a half hours: prolonged sitting during TV viewing (SIT); and, prolonged sitting interrupted every 20 min with 3 min of light-intensity body-weight resistance activities (active commercial breaks; ACBs). Venous postprandial glucose and insulin responses to dinner were calculated as positive incremental area under the curve (iAUC) from baseline. Interstitial glucose was measured using a continuous glucose monitor and quantified as total AUC (tAUC).Compared to SIT, plasma glucose iAUC was reduced by 33% [3.4 ± 1.0 vs 5.1 ± 1.0 (mean ± SEM) mmol h·L−1, p = 0.019] and plasma insulin iAUC by 41% (813 ± 224 vs 1373 ± 224, p = 0.033 pmol h·L−1) for the ACB condition. During the ACB condition there was a significant reduction in interstitial glucose tAUC (24.4 ± 5.2 vs 26.9 ± 5.2 mmol h·L−1, p < 0.001), but this did not persist beyond the laboratory observation period. ConclusionsRegular brief light-intensity activity bouts can attenuate glycemic responses during television viewing time following a high-energy evening meal in overweight/obese adults.

Objectively Quantified Doses of Activity and Inactivity and Subjective Well-Being in Breast Cancer Survivors

INTRODUCTION: Physically active breast cancer (BC) survivors have higher quality of life (QOL) compared to those who are sedentary. However, exercise programs may introduce compensatory responses to total daily physical activity (PA) and sedentary time (ST) that could undermine the expected benefits of exercise training. The primary aim of this study was to evaluate changes in daily PA and ST following the implementation of an exercise training program in BC survivors. A secondary aim was to examine the relationship between PA/ST and fatigue/QOL. Methods: 12 postmenopausal BC survivors wore an ActiGraph GT3X monitor on the right hip for 7 consecutive days and completed the EORTC QOL questionnaire and Piper Fatigue Scale prior to and during the final week of a supervised 12-wk exercise training program (45-60 min/day, 2-4 days/wk). The activity data were categorized using the Freedson 1998 cut-points and are presented as a percentage of wear-time spent in each intensity category. RESULTS: The table presents PA, ST, perceived fatigue and QOL scores.Table: No title available.Note: Data are presented as mean (SD); * indicates significant change from baseline (p<0.05) By post-intervention these women replaced ST with light intensity activity. The EORTC score was significantly correlated with ST at baseline (R2=0.33, p=0.05), but this relationship was not significant at post-intervention. There were no significant relationships found between the Piper Fatigue Score and ST. DISCUSSION: These findings suggest participants did not reduce PA or increase ST during the exercise program. It has been reported that exercise training may lead to compensatory declines in habitual PA and/or increases in ST but our results do not support this. It is possible that as BC survivors increase purposeful exercise, they are able to substitute low levels of PA for ST. The relationship found between QOL and ST suggests that reductions in ST could be a potential target for interventions that aim to improve QOL in BC survivors.

Association Between Exercise And Prolonged Television Viewing Days On Time-use And Physical Activity Energy Expenditure In Older Us Adults

PURPOSE. Our goal was to estimate the time-use exchanges associated with exercise, prolonged television viewing, and work days on the amount and type of sedentary and physically active behaviors and physical activity energy expenditure. METHODS. Participants were 1,020 older adults who completed up to 6 detailed previous-day recalls over 12-months that provided a profile of the use of time in sedentary and physically active pursuits. We predicted time-use and physical activity energy expenditure (PAEE) outcomes for 1) days with and without exercise, 2) days with or without prolonged television (2+h/day), and 3) work vs non-work days. To estimate time-use exchanges we used repeated measures and linear mixed models, adjusting for age, sex, season of the year, and day of the week. RESULTS. Exercise days were associated with less sedentary time (-0.37 hrs/d) and light activity (-0.29 hrs/d), and less household, work, and shopping activities. Compared to non-exercise days, the increase in total PAEE on exercise days (2.83 MET-hrs/d) was only about half that expended during exercise (5.98 MET-hrs/d). Prolonged television viewing was associated with an increase in total sedentary time (0.86 hrs/d) and less light (-0.45 hrs/d) and moderate-vigorous intensity activity (-0.41 hrs/d), and thus lower total PAEE (-2.43 MET-hrs/d). Work days were associated with less sleep (-0.91 hrs/d) and an increase in total sedentary time (1.32 hrs/d). DISCUSSION. Exercise was associated with an increase in PAEE, but due to reductions in other activities, only about half of the energy expended during exercise trickled-up to total daily PAEE. Prolonged television viewing was associated less PAEE and less moderate- vigorous activity. These findings provide new insights into possible compensation associated with exercise training, and suggest a strong link between television viewing and physical inactivity.

Myopia Prevention and Outdoor Light Intensity in a School-Based Cluster Randomized Trial

To investigate the effectiveness of a school-based program promoting outdoor activities in Taiwan for myopia prevention and to identify protective light intensities. Multi-area, cluster-randomized intervention controlled trial. A total 693 grade 1 schoolchildren in 16 schools participated. Two hundred sixty-seven schoolchildren were in the intervention group and 426 were in the control group. Initially, 24 schools were randomized into the intervention and control groups, but 5 and 3 schools in the intervention and control groups, respectively, withdrew before enrollment. A school-based Recess Outside Classroom Trial was implemented in the intervention group, in which schoolchildren were encouraged to go outdoors for up to 11 hours weekly. Data collection included eye examinations, cycloplegic refraction, noncontact axial length measurements, light meter recorders, diary logs, and questionnaires. Change in spherical equivalent and axial length after 1 year and the intensity and duration of outdoor light exposures. The intervention group showed significantly less myopic shift and axial elongation compared with the control group (0.35 diopter [D] vs. 0.47 D; 0.28 vs. 0.33 mm; P= 0.002 and P= 0.003) and a 54% lower risk of rapid myopia progression (odds ratio, 0.46; 95% confidence interval [CI], 0.28-0.77; P= 0.003). The myopic protective effects were significant in both nonmyopic and myopic children compared with controls. Regarding spending outdoor time of at least 11 hours weekly with exposure to 1000 lux or more of light, the intervention group had significantly more participants compared with the control group (49.79% vs. 22.73%; P < 0.001). Schoolchildren with longer outdoor time in school (≥200 minutes) showed significantly less myopic shift (measured by light meters; ≥1000 lux: 0.14 D; 95% CI, 0.02-0.27; P= 0.02; ≥3000 lux: 0.16 D; 95% CI,0.002-0.32; P= 0.048). The school-based outdoor promotion program effectively reduced the myopia change in both nonmyopic and myopic children. Outdoor activities with strong sunlight exposure may not be necessary for myopia prevention. Relatively lower outdoor light intensity activity with longer time outdoors, such as in hallways or under trees, also can be considered.

Effect of sleep curtailment on dietary behavior and physical activity: A randomized crossover trial

Our objective was to clarify the effect of sleep curtailment on energy intake (EI) and physical activity under free-living conditions. Participants were 16 healthy women aged 21–22years. A randomized crossover trial design was used to compare a short sleep condition (SS): 4h/night (2:00–6:00) and a control sleep condition (CS): 7h/night (23:00–6:00). Each condition comprised 3 consecutive nights. Sleep duration was assessed using a wristwatch-type accelerometer at home. All living activities except sleeping were free-living. Physical activity was assessed using a tri-axial accelerometer, and was categorized by intensity level (sedentary; sedentary to light; moderate to vigorous). Participants were asked to purchase and consume meals with visible nutrient information. EI was evaluated by adding values from these food labels. Mean sleep duration in the two conditions was significantly different (4.3±0.3 vs. 7.1±0.4h, p<0.01). For the shared wakefulness period in the two conditions (6:00–23:00), step counts and physical activity were not significantly different. Sedentary time (878±61 vs. 727±40min, p<0.01), and sedentary to light-intensity activity time (1122±18 vs. 932±63min, p<0.01) were significantly increased in SS (waking time, 06:00–02:00) compared with CS (waking time, 06:00–23:00). However, these significant effects were clearly attenuated after adjustment for awake time (p>0.05). Total EI was not significantly different between conditions (8.64±0.82 vs. 8.46±1.28MJ, p>0.05), nor were leptin levels (p>0.05), but insulin and cortisol levels after SS were significantly higher than after CS (p<0.05). In this study, physical activity was increased in the SS condition and attributed to differences in awake time between conditions. However, there were no differences in EI. Further studies to investigate the effect of sleep curtailment on weight gain through stress and insulin resistance are necessary.

Validity of the Fitbit One for Measuring Activity in Community-Dwelling Stroke Survivors.

Purpose: We determined the correlation between the Fitbit One and Actical accelerometer for quantifying the 3-day step count and activity levels in community-dwelling individuals with stroke. Method: Twelve participants with a mean age of 62.6 (SD 9.3) years wore both the Fitbit One and the Actical on the non-paretic ankle for 3 days. Regression analyses were performed to examine concurrent validity between the devices for step counts and sedentary, light, moderate, and vigorous activity. The relative error of the Fitbit One compared with the Actical in measuring step count was calculated. Results: Participants spent about 80% of their days being sedentary. The associations between the Fitbit One and the Actical were r>0.80 for step count and light-intensity activity across the 3 days of free-living activity. The overall relative error in measuring step count was 3.8%, with differences between those with walking speeds of less than 0.58 metres per second and 0.58 metres per second or more (27.4% [SD 34.2] vs. -8.0% [SD 10.7], p<0.001). Conclusions: The Fitbit One was associated with the Actical accelerometer in measuring step count and light-intensity activity during free-living activity after stroke, but had lower error in capturing step count for those with faster walking speeds. The Fitbit One may not be valid for capturing higher intensity activity after stroke.

Relationship of knee pain to time in moderate and light physical activities: Data from Osteoarthritis Initiative.

While OA literature indicates greater pain is related to less time being physically active, it is not known if time curtailment occurs primarily for moderate intensity activities or for light activities or in both. We examine the cross-sectional association of knee pain with physical activity using data from 1874 Osteoarthritis Initiative participants. Knee pain characteristics of constant and intermittent pain were each scored by the Intermittent and Constant Osteoarthritis Pain instrument and categorized into four pain levels (no pain, intermittent pain below and above median level, and constant pain). The relationships between knee pain levels and objectively measured physical activity (average weekly moderate or light intensity minutes) were assessed by quantile regression adjusted for socio-demographics and health factors. Knee pain levels had a strong negative relationship with moderate intensity physical activities (p-value for trend =0.029). Compared to the no pain group, persons with more severe knee pain, particularly those reporting higher intermittent or constant pain spent less time in moderate activity. In contrast, there was no notable trend related to pain with time spent in light intensity activity. These patterns remained when restricted to persons with clinical evidence (symptoms and/or radiographic) of knee OA and among persons not using medications for knee symptoms. Greater knee pain levels were strongly related to less moderate intensity activity time, but not time spent in light intensity physical activity. This relationship suggests that light activity may be a more acceptable way to increase physical activity than moderate activity for people with symptomatic knee pain.