The health effects of daily activity behaviours (physical activity, sedentary time and sleep) are widely studied. While previous research has largely examined activity behaviours in isolation, recent ...studies have adjusted for multiple behaviours. However, the inclusion of all activity behaviours in traditional multivariate analyses has not been possible due to the perfect multicollinearity of 24-h time budget data. The ensuing lack of adjustment for known effects on the outcome undermines the validity of study findings. We describe a statistical approach that enables the inclusion of all daily activity behaviours, based on the principles of compositional data analysis. Using data from the International Study of Childhood Obesity, Lifestyle and the Environment, we demonstrate the application of compositional multiple linear regression to estimate adiposity from children’s daily activity behaviours expressed as isometric log-ratio coordinates. We present a novel method for predicting change in a continuous outcome based on relative changes within a composition, and for calculating associated confidence intervals to allow for statistical inference. The compositional data analysis presented overcomes the lack of adjustment that has plagued traditional statistical methods in the field, and provides robust and reliable insights into the health effects of daily activity behaviours.
This study aimed to compare estimations of sedentary time (SED) and time spent in physical activity (PA) intensities in children with overweight/obesity across different age‐appropriate cut‐points ...based on different body‐worn attachment sites and acceleration metrics. A total of 104 overweight/obese children (10.1 ± 1.1 years old, 43 girls) concurrently wore ActiGraph GT3X+ accelerometers on their right hip and non‐dominant wrist for 7 days (24 hours). Euclidean norm −1 g (ENMO) and activity counts from both vertical axis (VACounts) and vector magnitude (VMCounts) were derived. We calculated estimates of SED and light, moderate, vigorous, and moderate‐to‐vigorous (MVPA) intensity PA using different published cut‐points for children. The prevalence of children meeting the recommended 60 min/d of MVPA was calculated. The time spent in SED and the different PA intensities largely differed across cut‐points based on different attachment sites and acceleration metrics (ie, SED = 11‐252 min/d; light PA = 10‐217 min/d; moderate PA = 1‐48 min/d; vigorous PA = 1‐35 min/d; MVPA = 4‐66 min/d). Consequently, the prevalence of children meeting the recommended 60 min/d of MVPA varied from 8% to 96% of the study sample. The present study provides a comprehensive comparison between available cut‐points for different attachment and acceleration metrics in children. Furthermore, our data clearly show that it is not possible (and probably will never be) to know the prevalence of meeting the PA guidelines based on accelerometer data since apparent differences range from almost zero to nearly everyone meeting the guidelines.
Objective
To compare objectively measured physical activity in older adults with symptomatic knee osteoarthritis (OA) with similarly aged adults without osteoarthritis (OA) or knee symptoms from the ...general population.
Methods
We included people ages 50–85 years with symptomatic knee OA from the Osteoarthritis Initiative (OAI, n = 491), and ages 50–85 years from the general population using National Health and Nutrition Examination Survey (NHANES, n = 449) data. A uniaxial accelerometer was worn for ≥10 hours/day for ≥4 days in the NHANES group in 2003–2004 and in the OAI group in 2008–2010. We calculated time spent in moderate‐to‐vigorous physical activity (MVPA in minutes/day) and described differences in MVPA and demographic variables between the samples. We conducted matched‐pairs sensitivity analyses to further evaluate the role of potential confounders.
Results
Both cohorts had similarly low levels of physical activity in age‐ and sex‐specific strata. Time in MVPA ranged from a median of 1–22 minutes/day in people with symptomatic knee OA, and from 1–24 minutes/day in the general population without OA or knee pain. These results were similar in sensitivity analyses.
Conclusion
Time spent in MVPA was similarly low in those with symptomatic knee OA as in older adults without knee pain or OA.
Background: Daily step count is the simplest measure of physical activity. However, little is known about how daily step count related to time spent in different intensities of physical activity (PA) ...and sedentary behavior (SB). Methods: These cross-sectional data were derived from 450 older Japanese adults (56.7% men; mean age, 74.3 years) who were randomly selected from three communities and responded a survey. Daily step count and time spent in moderate-to-vigorous PA (MVPA), light-intensity PA (LPA), and SB were measured using a validated wearable technology (HJA-350IT). Associations of daily step count with time spent in measured behaviors were examined using linear regression models with isometric log-ratio transformations of time-use composition, adjusting for gender, age, and residential area. Results: Participants averaged 5,412 (standard deviation, 2,878) steps/d and accumulated MVPA, LPA, and SB corresponding to 4.0%, 34.8%, and 61.2% of daily waking time, respectively. Daily step count significantly increased with increase in time spent in MVPA relative to other behaviors (ie, LPA and SB) and in the ratio of LPA to SB after allowing for MVPA. After stratification, daily step count was significantly related to the ratio of LPA to SB in those taking <5,000 steps/d, but not in those taking 5,000–7,499 and ≥7,500 steps/d. Conclusions: Higher daily step count can be an indicator of not only larger relative contribution of time spent in MVPA, but also higher ratio between LPA and SB, particularly among those who are the least physically active.
Older adults and special populations (living with disability and/or chronic illness that may limit mobility and/or physical endurance) can benefit from practicing a more physically active lifestyle, ...typically by increasing ambulatory activity. Step counting devices (accelerometers and pedometers) offer an opportunity to monitor daily ambulatory activity; however, an appropriate translation of public health guidelines in terms of steps/day is unknown. Therefore this review was conducted to translate public health recommendations in terms of steps/day. Normative data indicates that 1) healthy older adults average 2,000-9,000 steps/day, and 2) special populations average 1,200-8,800 steps/day. Pedometer-based interventions in older adults and special populations elicit a weighted increase of approximately 775 steps/day (or an effect size of 0.26) and 2,215 steps/day (or an effect size of 0.67), respectively. There is no evidence to inform a moderate intensity cadence (i.e., steps/minute) in older adults at this time. However, using the adult cadence of 100 steps/minute to demark the lower end of an absolutely-defined moderate intensity (i.e., 3 METs), and multiplying this by 30 minutes produces a reasonable heuristic (i.e., guiding) value of 3,000 steps. However, this cadence may be unattainable in some frail/diseased populations. Regardless, to truly translate public health guidelines, these steps should be taken over and above activities performed in the course of daily living, be of at least moderate intensity accumulated in minimally 10 minute bouts, and add up to at least 150 minutes over the week. Considering a daily background of 5,000 steps/day (which may actually be too high for some older adults and/or special populations), a computed translation approximates 8,000 steps on days that include a target of achieving 30 minutes of moderate-to-vigorous physical activity (MVPA), and approximately 7,100 steps/day if averaged over a week. Measured directly and including these background activities, the evidence suggests that 30 minutes of daily MVPA accumulated in addition to habitual daily activities in healthy older adults is equivalent to taking approximately 7,000-10,000 steps/day. Those living with disability and/or chronic illness (that limits mobility and or/physical endurance) display lower levels of background daily activity, and this will affect whole-day estimates of recommended physical activity.
Objective
Physical activity is recommended to mitigate functional limitations associated with knee osteoarthritis (OA). However, it is unclear whether walking on its own protects against the ...development of functional limitation.
Methods
Walking over 7 days was objectively measured as steps/day within a cohort of people with or at risk of knee OA from the Multicenter Osteoarthritis Study. Incident functional limitation over 2 years was defined by performance‐based (gait speed <1.0 meter/second) and self‐report (Western Ontario and McMaster Universities Osteoarthritis Index physical function score >28 of 68) measures. We evaluated the association of steps/day at baseline with developing functional limitation 2 years later by calculating risk ratios adjusted for potential confounders. The number of steps/day that best distinguished risk for developing functional limitation was estimated from the maximum distance from chance on receiver operating characteristic curves.
Results
Among 1,788 participants (mean age 67 years, mean body mass index 31 kg/m2, 60% women), each additional 1,000 steps/day was associated with a 16% and 18% reduction in incident functional limitation by performance‐based and self‐report measures, respectively. Walking <6,000 and <5,900 steps/day were the best thresholds to distinguish incident functional limitation by performance‐based (sensitivity 67.3%, specificity 71.8%) and self‐report (sensitivity 58.7%, specificity 68.9%) measures, respectively.
Conclusion
More walking was associated with less risk of functional limitation over 2 years. Walking >6,000 steps/day provides a preliminary estimate of the level of walking activity to protect against developing functional limitation in people with or at risk of knee OA.
The 2005-2006 National Health and Nutrition Examination Survey (NHANES) is used to describe an accelerometer-derived physical activity/inactivity profile in normal weight (BMI < 25 kg/m2), overweight ...(25 </= BMI < 30 kg/m2), and obese (BMI >/= 30 kg/m2) U.S. adults.
We computed physical activity volume indicators (activity counts/day, uncensored and censored steps/day), rate indicators (e.g., steps/minute), time indicators (employing NHANES activity counts/minute cut points to infer time in non-wear, sedentary, low, light, moderate, and vigorous intensities), the number of breaks in sedentary time (occasions when activity counts rose from < 100 activity/counts in one minute to >/= 100 activity counts in the subsequent minute), achievement of public health guidelines, and classification by step-defined physical activity levels. Data were examined for evidence of consistent and significant gradients across BMI-defined categories.
In 2005-2006, U.S adults averaged 6,564 +/- SE 107 censored steps/day, and after considering non-wear time, they spent approximately 56.8% of the rest of the waking day in sedentary time, 23.7% in low intensity, 16.7% in light intensity, 2.6% in moderate intensity, and 0.2% in vigorous intensity. Overall, approximately 3.2% of U.S. adults achieved public health guidelines. The normal weight category took 7,190 +/- SE 157 steps/day, and spent 25.7 +/- 0.9 minutes/day in moderate intensity and 7.3 +/- 0.4 minutes/day in vigorous intensity physical activity. The corresponding numbers for the overweight category were 6,879 +/- 140 steps/day, 25.3 +/- 0.9 minutes/day, and 5.3 +/- 0.5 minutes/day and for the obese category 5,784 +/- 124 steps/day, 17.3 +/- 0.7 minutes/day and 3.2 +/- 0.4 minutes/day. Across BMI categories, increasing gradients and significant trends were apparent in males for sedentary time and decreasing gradients and significant trends were evident in time spent in light intensity, moderate intensity, and vigorous intensity. For females, there were only consistent gradients and significant trends apparent for decreasing amounts of time spent in moderate and vigorous intensity.
Simple indicators of physical activity volume (i.e., steps/day) and time in light, moderate or vigorous intensity physical activity differ across BMI categories for both sexes, suggesting that these should continue to be targets for surveillance.
How many steps/day are enough? for children and adolescents Tudor-Locke, Catrine; Craig, Cora L; Beets, Michael W ...
The international journal of behavioral nutrition and physical activity,
07/2011, Letnik:
8, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Worldwide, public health physical activity guidelines include special emphasis on populations of children (typically 6-11 years) and adolescents (typically 12-19 years). Existing guidelines are ...commonly expressed in terms of frequency, time, and intensity of behaviour. However, the simple step output from both accelerometers and pedometers is gaining increased credibility in research and practice as a reasonable approximation of daily ambulatory physical activity volume. Therefore, the purpose of this article is to review existing child and adolescent objectively monitored step-defined physical activity literature to provide researchers, practitioners, and lay people who use accelerometers and pedometers with evidence-based translations of these public health guidelines in terms of steps/day. In terms of normative data (i.e., expected values), the updated international literature indicates that we can expect 1) among children, boys to average 12,000 to 16,000 steps/day and girls to average 10,000 to 13,000 steps/day; and, 2) adolescents to steadily decrease steps/day until approximately 8,000-9,000 steps/day are observed in 18-year olds. Controlled studies of cadence show that continuous MVPA walking produces 3,300-3,500 steps in 30 minutes or 6,600-7,000 steps in 60 minutes in 10-15 year olds. Limited evidence suggests that a total daily physical activity volume of 10,000-14,000 steps/day is associated with 60-100 minutes of MVPA in preschool children (approximately 4-6 years of age). Across studies, 60 minutes of MVPA in primary/elementary school children appears to be achieved, on average, within a total volume of 13,000 to 15,000 steps/day in boys and 11,000 to 12,000 steps/day in girls. For adolescents (both boys and girls), 10,000 to 11,700 may be associated with 60 minutes of MVPA. Translations of time- and intensity-based guidelines may be higher than existing normative data (e.g., in adolescents) and therefore will be more difficult to achieve (but not impossible nor contraindicated). Recommendations are preliminary and further research is needed to confirm and extend values for measured cadences, associated speeds, and MET values in young people; continue to accumulate normative data (expected values) for both steps/day and MVPA across ages and populations; and, conduct longitudinal and intervention studies in children and adolescents required to inform the shape of step-defined physical activity dose-response curves associated with various health parameters.
PURPOSEThe objective of this study is to compare step outputs obtained from waist and wrist accelerometer attachment sites under laboratory and free-living conditions.
METHODSUnder the laboratory ...condition, participants concurrently wore ActiGraph accelerometers at their waist and nondominant wrist while walking/running at treadmill speeds between 14 and 188 m·min. Visually counted steps served as a criterion standard. Participants then wore both accelerometers for 7 d. All accelerometer step data were processed applying both the manufacturer’s default and low-frequency extension filters. Paired sample t-tests were used to evaluate mean differences in criterion steps per minute and the four (attachment site × filter) estimates produced from the waist- and wrist-worn accelerometers in the laboratory study. Free-living differences in mean steps per day detected between the waist and wrist (considering both filters) were computed.
RESULTSRelative to visually counted steps, the waist attachment site generally outperformed the wrist attachment site at most speeds, regardless of the applied filtering process. Under free-living conditions, the waist-worn accelerometer detected 6743 ± 2398 (default filter) and 13,029 ± 3734 (low-frequency extension) steps per day. The concurrently worn wrist accelerometer detected 9301 ± 2887 (default filter) and 15,493 ± 3958 (low-frequency extension) steps per day.
CONCLUSIONThe wrist attachment site detected consistently fewer visually counted steps than the waist attachment site at most treadmill speeds during laboratory testing. In contrast, the wrist attachment site produced a higher average step count (ranging from approximately 2500 to 8700 more steps per day under free-living conditions, dependent on the filtering process applied) than the waist attachment site under free-living conditions. In conclusion, step outputs obtained from waist- and wrist-worn accelerometer attachment sites are generally not comparable under either laboratory or free-living conditions.
BackgroundCadence (steps/min) may be a reasonable proxy-indicator of ambulatory intensity. A summary of current evidence is needed for cadence-based metrics supporting benchmark (standard or point of ...reference) and threshold (minimums associated with desired outcomes) values that are informed by a systematic process.ObjectiveTo review how fast, in terms of cadence, is enough, with reference to crafting public health recommendations in adults.MethodsA comprehensive search strategy was conducted to identify relevant studies focused on walking cadence and intensity for adults. Identified studies (n=38) included controlled (n=11), free-living observational (n=18) and intervention (n=9) designs.ResultsThere was a strong relationship between cadence (as measured by direct observation and objective assessments) and intensity (indirect calorimetry). Despite acknowledged interindividual variability, ≥100 steps/min is a consistent heuristic (e.g, evidence-based, rounded) value associated with absolutely defined moderate intensity (3 metabolic equivalents (METs)). Epidemiological studies report notably low mean daily cadences (ie, 7.7 steps/min), shaped primarily by the very large proportion of time (13.5 hours/day) spent between zero and purposeful cadences (<60 steps/min) at the population level. Published values for peak 1-min and 30-min cadences in healthy free-living adults are >100 and >70 steps/min, respectively. Peak cadence indicators are negatively associated with increased age and body mass index. Identified intervention studies used cadence to either prescribe and/or quantify ambulatory intensity but the evidence is best described as preliminary.ConclusionsA cadence value of ≥100 steps/min in adults appears to be a consistent and reasonable heuristic answer to ’How fast is fast enough?' during sustained and rhythmic ambulatory behaviour.Trial registration numberNCT02650258
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