Validity and Accuracy of Step Count as an Indicator of a Sedentary Lifestyle in People With Chronic Obstructive Pulmonary Disease.

OBJECTIVE: To determine the validity and accuracy of <5000 steps/day as a sedentary lifestyle indicator, and the optimal step count cut point value for indicating a sedentary lifestyle in people with chronic obstructive pulmonary disease (COPD). DESIGN: Analysis of baseline data from a randomized clinical trial. SETTING: Sydney, Australia. PARTICIPANTS: Stable COPD on the waitlist for pulmonary rehabilitation. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Step count and time in sedentary behavior (SB) were assessed using thigh-worn accelerometry. A sedentary lifestyle was defined as <5000 steps/day. Pearson correlation coefficients were analyzed between step count and time spent in SB. Sensitivity, specificity, and accuracy were calculated for the <5000 steps/day threshold. Receiver operating characteristic curves with the area under the curve were computed for step count in identifying a sedentary lifestyle. RESULTS: 69 people with COPD (mean age=74 years, SD=9; forced expiratory volume in 1 second, mean=55%, SD=19 predicted) had sufficient wear data for analysis. There was a moderate inverse correlation between step count and time spent in SB (r=-0.58, P<.001). Step count had a fair discriminative ability for identifying a sedentary lifestyle (area under the curve=0.80, 95% confidence interval [CI], 0.68-0.91). The <5000 steps/day threshold had a sensitivity, specificity, and accuracy of 82% (95% CI, 70-94), 70% (95% CI, 54-86), and 78%, respectively. A lower threshold of <4300 steps/day was more accurate for ruling in a sedentary lifestyle. CONCLUSIONS: Compared with thigh-worn accelerometry, <5000 steps/day is a valid and reasonably accurate indicator of a sedentary lifestyle in this population.

Patterns and Correlates of Sedentary Behaviour Accumulation and Physical Activity in People with Chronic Obstructive Pulmonary Disease: A Cross-Sectional Study.

Few studies have used 24-hour accelerometery to characterise posture and movement patterns in people with chronic obstructive pulmonary disease (COPD). This study aimed to quantify sedentary behaviour (SB), patterns of SB accumulation and physical activity (PA) in people with COPD, and to examine physiological and functional capacity correlates of total SB and patterns of SB accumulation. SB and PA were assessed continuously over seven days using thigh-worn accelerometery in people with COPD. Participants were regarded as "sedentary" if combined sitting/reclining time accounted for ≥70% of waking wear time. Differences in patterns of SB accumulation and PA were compared between "sedentary" and "non-sedentary" participants. Physiological and functional capacity correlates of SB were explored using univariate analysis. Sixty-nine people with COPD (mean (SD) age 74 (9) years, FEV1 55% (19) predicted) had sufficient wear data for analysis. Mean sedentary time was 643 (105) minutes/day (71% (11) of waking wear time), of which 374 (142) minutes/day were accumulated in prolonged bouts of ≥30 min. "Sedentary" participants had a more unfavourable pattern of SB accumulation and spent less time in PA of any intensity. Sedentary time, expressed as a proportion of waking wear time, was inversely correlated with light (r = -0.97, p < .01) and moderate-to-vigorous intensity PA (r = -0.55, p < .01) and exercise capacity (r = -0.33, p < .01), but not with age, body mass index or lung function. People with COPD had high total SB and accumulated the majority of SB in prolonged bouts. High total SB was correlated with low physical activity and exercise tolerance.

An observational study of self-reported sedentary behaviour in people with chronic obstructive pulmonary disease and bronchiectasis.

BACKGROUND: Few studies have examined sedentary behaviour in chronic respiratory disease. The limited evidence suggests that increased levels of sedentary behaviour are associated with increased mortality. OBJECTIVES: This study aimed to compare the level of self-reported sedentary behaviour in people with chronic obstructive pulmonary disease (COPD) and bronchiectasis as well as to identify associations between sedentary time with functional performance measures and health-related quality of life in the chronic respiratory disease group. METHODS: An observational study design was used. Participants completed the Sedentary Behaviour Questionnaire from which average sedentary time (hours/day) was determined. Functional performance was measured using the six-minute walk test, the four-metre gait speed test and the five sit-to-stand test. Health-related quality of life was measured using the St George's Respiratory Questionnaire. Sedentary time was compared between groups using an unpaired t-test. Univariate analysis explored relationships amongst variables. RESULTS: The convenience sample consisted of 103 people with COPD [52% male; mean±SD age: 73±9 years, FEV1% predicted: 56±23] and 33 people with bronchiectasis [52% male; 74±8 years, FEV1% predicted: 69±25]. Average self-reported sedentary time in COPD was 7.6±2.7 hours/day and in bronchiectasis was 8.0±4.1 hours/day, with no between-group difference (-0.4, 95% CI -1.7, 0.8). No associations were found between sedentary time and any functional performance outcome or with health-related quality of life. CONCLUSION: There was no difference in the high sedentary time between people with COPD and bronchiectasis. Sedentary behaviour was not associated with functional performance or disease-related health-related quality of life in people with chronic respiratory disease.

Physical Activity and Health-Related Quality of Life in People With Back Pain: A Population-Based Pooled Study of 27,273 Adults.

BACKGROUND: To investigate the association between moderate- to vigorous-intensity physical activity (MVPA) and health-related quality of life (HRQoL) in people with back pain. METHODS: The sample comprised adults aged 16 years and older who participated in the Welsh Health Survey (2011-2015). The HRQoL was evaluated using the 36-item short form. Participants were categorized into 4 groups based on minutes per week of MVPA: inactive (no MVPA), insufficiently active (<150 min/wk), sufficiently active (≥150 and <300 min/wk), and very active (≥300 min/wk). The authors investigated the association between MVPA and HRQoL using generalized linear models and multiple linear regression. RESULTS: Of the 74,578 adults in the survey cohorts, 27,273 participants diagnosed with back pain were included in the analyses. Consistent direct curvilinear associations between MVPA and HRQoL were demonstrated for all 36-item short form domains (P < .001), in both the minimally and fully adjusted models, with the highest scores observed for sufficiently active and very active participants. Compared with the inactive group, those who were insufficiently active; sufficiently active; and very active had an average difference of 6.31 (95% confidence interval, 5.70-6.92), 7.72 (95% confidence interval, 7.04-8.41), and 8.00 (95% confidence interval, 7.12-8.89) points in the overall HRQoL, respectively. CONCLUSION: The authors found a consistent direct curvilinear association between MVPA and HRQoL.

Physical activity and chronic back conditions: A population-based pooled study of 60,134 adults.

BACKGROUND: Little is known about the association between different types of physical activity (PA) and chronic back conditions (CBCs) at the population level. We investigated the association between levels of total and type-specific PA participation and CBCs. METHODS: The sample comprised 60,134 adults aged ≥16 years who participated in the Health Survey for England and Scottish Health Survey from 1994 to 2008. Multiple logistic regression models, adjusted for potential confounders, were used to examine the association between total and type-specific PA volume (walking, domestic activity, sport/exercise, cycling, football/rugby, running/jogging, manual work, and housework) and the prevalence of CBCs. RESULTS: We found an inverse association between total PA volume and prevalence of CBCs. Compared with inactive participants, the fully adjusted odds ratio (OR) for very active participants (≥15 metabolic equivalent h/week) was 0.77 (95% confidence interval (CI): 0.69-0.85). Participants reporting ≥300 min/week of moderate-intensity activity and ≥75 min/week of vigorous-intensity activity had 24% (95%CI: 6%-39%) and 21% (95%CI: 11%-30%) lower odds of CBCs, respectively. Higher odds of CBCs were observed for participation in high-level manual domestic activity (OR = 1.22; 95%CI: 1.00-1.48). Sport/exercise was associated with CBCs in a less consistent manner (e.g., OR = 1.18 (95%CI: 1.06-1.32) for low levels and OR = 0.82 (95%CI: 0.72-0.93) for high levels of sport/exercise). CONCLUSION: PA volume is inversely associated with the prevalence of CBCs.