Sedentary behaviour and bone health in older adults: a systematic review.

Older adults spend more than 8 h/day in sedentary behaviours. Detrimental effects of sedentary behaviour (SB) on health are established, yet little is known about SB and bone health (bone mineral density; BMD) in older adults. The purpose of this review is to examine associations of SB with BMD in older adults. Five electronic databases were searched: Web of Science (Core Collection); PubMed; EMBASE; Sports Medicine and Education and PsycInfo. Inclusion criteria were healthy older adults mean age ≥ 65 years; measured SB and measured BMD using dual-energy X-ray absorptiometry. Quality was assessed using National Institute of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. After excluding duplicates 17813 papers were assessed; 17757 were excluded on title/abstract, 49 at full text, resulting in two prospective and five cross-sectional observational studies reviewed. Four were rated 'good' and three were rated 'fair' using the quality assessment criteria. Findings varied across the studies and differed by gender. In women, four studies reported significant positive associations of SB with BMD at different sites, and two found significant negative associations. Five studies which examined both men and women, men reported negative or no associations of SB with femoral neck, pelvic, whole body, spine or leg BMD. Whilst these findings suggest differences between men and women in the associations of SB with BMD, they may be due to the varying anatomical sections examined for BMD, the different methods used to measure SB, the varied quality of the studies included and the limited number of published findings.

Mobility in Community Dwelling Older Adults: Predicting Successful Mobility Using an Instrumented Battery of Novel Measures.

Mobility in older adults is associated with better quality of life. However, evidence suggests that older people spend less time out-of-home than younger adults. Traditional methods for assessing mobility have serious limitations. Wearable technologies provide the possibility of objectively assessing mobility over extended periods enabling better estimates of levels of mobility to be made and possible predictors to be explored. Eighty-six community dwelling older adults (mean age 79.8 years) had their mobility assessed for one week using GPS, accelerometry and self-report. Outcomes were: number of steps, time spent in dynamic outdoor activity, total distance travelled and total number of journeys made over the week. Assessments were also made of personal, cognitive, psychological, physical and social variables. Four regression models were calculated (one for each outcome). The models predicted 32 to 43% of the variance in levels of mobility. The ability to balance on one leg significantly predicted all four outcomes. In addition, cognitive ability predicted number of journeys made per week and time spent engaged in dynamic outdoor activity, and age significantly predicted total distance travelled. Overall estimates of mobility indicated step counts that were similar to those shown by previous research but distances travelled, measured by GPS, were lower. These findings suggest that mobility in this sample of older adults is predicted by the ability to balance on one leg. Possible interventions to improve out-of-home mobility could target balance. The fact that participants travelled shorter distances than those reported in previous studies is interesting since this high-functioning subgroup would be expected to demonstrate the highest levels.

Dose-response between frequency of interruption of sedentary time and fasting glucose, the dawn phenomenon and night-time glucose in Type 2 diabetes.

AIM: To explore the dose-response between frequency of interruption of sedentary time and basal glucose (fasting glucose, the dawn phenomenon and night-time glucose) in Type 2 diabetes. METHODS: In a randomized three-treatment, two-period balanced incomplete block trial, 12 people with Type 2 diabetes (age, 60.0 ± 3.2 years; BMI, 30.2 ± 1.4 kg/m2 ) completed two of three conditions: sitting for 7 h interrupted every 60 min (Condition 1), 30 min (Condition 2), and 15 min (Condition 3) by 3-min light-intensity walking breaks. The activPAL3 and FreeStyle Libre were used to assess physical activity/sedentary behaviour and continuous glucose profile. Standardized meals were provided, and changes in basal glucose of the nights and early mornings before and after treatment conditions were calculated (mean ± SE). RESULTS: After treatment conditions, fasting glucose and duration of the dawn phenomenon were lower for Condition 3 (-1.0 ± 0.2 mmol/l, P < 0.02; -3.1 ± 1.3 h, P = 0.004) compared with Condition 1 (-0.1 ± 0.2 mmol/l; 1.9 ± 1.2 h). The magnitude of the dawn phenomenon was reduced in Condition 3 (-0.6 ± 0.4 mmol/l, P = 0.041) compared with Condition 2 (0.6 ± 0.3 mmol/l). Night-time glycaemic variability (coefficient of variation) was reduced in Condition 3 (-9.7 ± 3.9%) relative to Condition 2 (6.1 ± 4.8%, P < 0.03) and Condition 1 (2.5 ± 1.8%, P = 0.02). There was no change in night-time mean glucose. CONCLUSIONS: Frequent interruptions of prolonged sitting with 3 min of light-intensity walking breaks every 15 min improves fasting glucose, the dawn phenomenon and night-time glycaemic variability, and this might be a simple therapeutic intervention to improve glucose control. Clinicaltrials.gov Identifier: NCT02738996.

Differences in physical activity time-use composition associated with cardiometabolic risks.

This study investigates the association between the overall physical activity composition of the day (sedentary behavior (SB), light intensity physical activity (LIPA) and moderate-to-vigorous physical activity (MVPA)) and cardiometabolic health, and examines whether improved health can be associated with replacing SB with LIPA. A cross-sectional analysis of the Health Survey for England 2008 on N = 1411 adults was undertaken using a compositional analysis approach to examine the relationship between cardiometabolic risk biomarkers and physical activity accounting for co-dependency between relative amounts of time spent in different behavior. Daily time spent in SB, LIPA and MVPA was determined from waist-mounted accelerometry data (Actigraph GT1M) and modelled against BMI, waist circumference, waist-to-hip ratio, blood pressure, total and HDL cholesterol, HbA1c, and VO2 maximum. The composition of time spent in SB, LIPA and MVPA was statistically significantly associated with BMI, waist circumference, waist-to-hips ratio, HDL cholesterol and VO2 maximum (p < 0.001), but not HbA1c, systolic and diastolic blood pressure, or total cholesterol. Increase of relative time spent in MVPA was beneficially associated with obesity markers, HDL cholesterol, and VO2 maximum, and SB with poorer outcomes. The association of changes in LIPA depended on whether it displaced MVPA or SB. Increasing the proportion of MVPA alone may have the strongest potential association with adiposity outcomes and HDL cholesterol but similar outcomes could also be associated with a lower quantity of MVPA provided a greater quantity of SB is replaced overall with LIPA (around 10.5 min of LIPA is equivalent to 1 min of MVPA).

Systematic comparative validation of self-report measures of sedentary time against an objective measure of postural sitting (activPAL).

BACKGROUND: Sedentary behaviour is a public health concern that requires surveillance and epidemiological research. For such large scale studies, self-report tools are a pragmatic measurement solution. A large number of self-report tools are currently in use, but few have been validated against an objective measure of sedentary time and there is no comparative information between tools to guide choice or to enable comparison between studies. The aim of this study was to provide a systematic comparison, generalisable to all tools, of the validity of self-report measures of sedentary time against a gold standard sedentary time objective monitor. METHODS: Cross sectional data from three cohorts (N = 700) were used in this validation study. Eighteen self-report measures of sedentary time, based on the TAxonomy of Self-report SB Tools (TASST) framework, were compared against an objective measure of postural sitting (activPAL) to provide information, generalizable to all existing tools, on agreement and precision using Bland-Altman statistics, on criterion validity using Pearson correlation, and on data loss. RESULTS: All self-report measures showed poor accuracy compared with the objective measure of sedentary time, with very wide limits of agreement and poor precision (random error > 2.5 h). Most tools under-reported total sedentary time and demonstrated low correlations with objective data. The type of assessment used by the tool, whether direct, proxy, or a composite measure, influenced the measurement characteristics. Proxy measures (TV time) and single item direct measures using a visual analogue scale to assess the proportion of the day spent sitting, showed the best combination of precision and data loss. The recall period (e.g. previous week) had little influence on measurement characteristics. CONCLUSION: Self-report measures of sedentary time result in large bias, poor precision and low correlation with an objective measure of sedentary time. Choice of tool depends on the research context, design and question. Choice can be guided by this systematic comparative validation and, in the case of population surveillance, it recommends to use a visual analog scale and a 7 day recall period. Comparison between studies and improving population estimates of average sedentary time, is possible with the comparative correction factors provided.

Comparison of self-reported measure of sitting time (IPAQ) with objective measurement (activPAL).

This study compared sitting time measured by a questionnaire (International Physical Activity Questionnaire; IPAQ) with concurrently measured objective sitting time from an accelerometer-based measure of thigh inclination (activPAL).Adults (n = 69), wore an activPAL for a week, and then completed the long-form 7 d recall IPAQ questionnaire. IPAQ reported sitting time (including and excluding transportation sitting) for the week, weekdays and weekend days were compared to activPAL (criterion measure) sitting time using intraclass correlation coefficients and Bland Altman plots.Confidence intervals between the IPAQ and the activPAL were wide, while correlations between the two measures were low and non-significant (0.112-0.275). Compared to a direct measure of postural sitting (activPAL), the IPAQ underestimated sitting time across the group for the whole week, both when including (mean 2.2 h d(-1)) and excluding (mean 3.4 h d(-1)) transportation sitting. Sitting was less accurately reported on weekend days than weekdays, and at lower levels of sitting on weekdays.Agreement between the IPAQ and the activPAL, a direct measure of sitting, in this study was poor. The direction of group agreement was different to comparisons using a measure of low accelerometer counts (Actigraph) as the criterion measure in previous research. Future studies should use a direct measure of sitting as a criterion measure to validate subjective measurement tools.

Associations between objectively-measured sedentary behaviour and physical activity with bone mineral density in adults and older adults, the NHANES study.

BACKGROUND: Lack of physical activity (PA) is an important modifiable risk factor for bone mineral density (BMD). Time spent in sedentary behaviour (SB), or time spent in non-exercising seated and reclining postures, has recently emerged as a new public health risk, independent of the amount of time someone spends being active. As national surveys report that adults spend on average 8h per day being sedentary, rising to 10h a day in older age, it has been hypothesised that a repeated exposure to sitting in modern daily life, whether it is for travelling, working or leisure, might have a deleterious effect on bone health in a way that mirrors the results of studies into the effect of lengthy periods of bed-rest. The aim of this study was to investigate for the first time a) how time spent in SB is associated with bone mineral density (BMD), b) whether this association changes depending on the amount of time spent engaging in different intensity levels of PA, and c) if the pattern of accumulation of SB and long uninterrupted periods of SB are associated with BMD. METHODS: The 2005/2006 National Health and Nutrition Examination Survey (NHANES), is a cross-sectional study of a representative sample of the US population that is conducted biannually by the National Centers for Disease Control. PA and SB were assessed objectively over 7 days using an Actigraph accelerometer and BMD was measured via dual-energy X-ray absorptiometry. In this study, data are presented on four regions of the femur (femoral neck, trochanter, inter trochanter and total femur) and total spine (L1-L4). The associations between BMD, SB and PA levels were examined using multiple linear regressions stratified by gender. In addition, the association between the pattern of accumulation of SB (quantified as frequency and duration of SB) and BMD was also investigated. All models were adjusted for known risk factors associated with BMD. In total, data for 2117 individuals, aged 23-90+years (males N=1158), were available to analyse SB and femur BMD and 1942 individuals (males N=1053) for analysis of SB and spine BMD. RESULTS: There was no evidence of an association between SB time and hip or spinal BMD in men. For men, time spent doing moderate to vigorous activity (MVPA) and vigorous activity (VIG) was associated with higher total femur and the other hip sub-region BMD. The regression coefficient was BMVPA=0.306 (95% CI: 0.021-0.591)g/cm2 for each 10 minute increment in daily MVPA. For VIG, the regression coefficient is BVIG=0.320 (95% CI: 0.058-0.583) but this cannot be interpreted linearly as time spent in vigorous activity was square root transformed. In women, SB was negatively associated with total femur BMD and all sub-regions but not MVPA nor VIG. The regression coefficient for total femur BMD was BSB = -0.159 (95% CI: -0.241-0.076)g/cm2 for each 10 minute increment spent being sedentary each day. In addition, the duration of SB bouts was deleteriously associated with BMD for the total femur and of other hip sub-regions, but the number of bouts of SB did not have a significant effect. These associations were found to be independent of the amount of MVPA and VIG that women engage in. No associations were found between SB or PA and spinal BMD for either men or women. CONCLUSIONS: These results provide the first evidence that repeated exposure to sitting (SB), measured objectively in daily life, is deleteriously associated with BMD of the total femur and of all hip sub-regions in women, independent of the amount of time women engage in moderate and vigorous activity. This suggests that SB might be a risk factor for bone health in women independent of whether they engage in physical activity. In addition, the duration of SB bouts, rather than their frequency, appears to be deleteriously associated with BMD of the total femur and of all hip sub-regions. Future research should investigate the effect on bone health of interventions which set out to reduce SB and the duration of SB bouts in comparison, and as adjunct, to the promotion of PA. For men, SB is not significantly associated with BMD of the femur or spine and the results appear to confirm that moderate and vigorous activity has a protective effect.

Methods for objective measure, quantification and analysis of sedentary behaviour and inactivity.

The purpose of this study was to develop and test a generic technique to robustly quantify the pattern of sedentary behaviour from objective records. The technique was applied to four groups of subjects: a healthy group with an active occupation (N=54), a healthy group with a sedentary occupation (N=53), a group of subjects with chronic low back pain (N=5) and a group of subjects with chronic fatigue syndrome (N=14). This study presents the first evidence that bouts of sedentary activity are power law distributed. Results showed that there was no significant difference in total sedentary time between the groups, however, the patterns of accumulation of sedentary time were significantly different for the groups. Sedentary groups accumulated their total sedentary time from a small number of longer sedentary bouts. Active groups tended to break their sedentary time into a greater number of shorter bouts. This suggests that the power law exponent alpha and the GINI index G, used to describe the pattern of accumulation of sedentary time, could be used to evaluate and quantify sedentary behaviour.