Search Results

You are looking at 1 - 3 of 3 items for

  • Author: Bronwyn K. Clark x
Clear All Modify Search
Restricted access

Sjaan R. Gomersall, Toby G. Pavey, Bronwyn K. Clark, Adib Jasman and Wendy J. Brown

Background:

Sedentary behavior is continuing to emerge as an important target for health promotion. The purpose of this study was to determine the validity of a self-report use of time recall tool, the Multimedia Activity Recall for Children and Adults (MARCA) in estimating time spent sitting/lying, compared with a device-based measure.

Methods:

Fifty-eight participants (48% female, [mean ± standard deviation] 28 ± 7.4 years of age, 23.9 ± 3.05 kg/m2) wore an activPAL device for 24-h and the following day completed the MARCA. Pearson correlation coefficients (r) were used to analyze convergent validity of the adult MARCA compared with activPAL estimates of total sitting/lying time. Agreement was examined using Bland-Altman plots.

Results:

According to activPAL estimates, participants spent 10.4 hr/day [standard deviation (SD) = 2.06] sitting or lying down while awake. The correlation between MARCA and activPAL estimates of total sit/lie time was r = .77 (95% confidence interval = 0.64–0.86; P < .001). Bland-Altman analyses revealed a mean bias of +0.59 hr/day with moderately wide limits of agreement (–2.35 hr to +3.53 hr/day).

Conclusions:

This study found a moderate to strong agreement between the adult MARCA and the activPAL, suggesting that the MARCA is an appropriate tool for the measurement of time spent sitting or lying down in an adult population.

Restricted access

Winnie Y.H. Lee, Bronwyn K. Clark, Elisabeth Winkler, Elizabeth G. Eakin and Marina M. Reeves

Background:

This study evaluated the responsiveness to change in physical activity of 2 self-report measures and an accelerometer in the context of a weight loss intervention trial.

Methods:

302 participants (aged 20 to 75 years) with type 2 diabetes were randomized into telephone counseling (n = 151) or usual care (n = 151) groups. Physical activity (minutes/week) was assessed at baseline and 6-months using the Active Australia Survey (AAS), the United States National Health Interview Survey (USNHIS) walking for exercise items, and accelerometer (Actigraph GT1M; ≥1952 counts/minute). Responsiveness to change was calculated as responsiveness index (RI), Cohen’s d (postscores) and Cohen’s d (change-scores).

Results:

All instruments showed significant improvement in the intervention group (P < .001) and no significant change for usual care (P > .05). Accelerometer consistently ranked as the most responsive instrument while the least responsive was the USHNIS (responsiveness index) or AAS (Cohen’s d). RIs for AAS, USNHIS and accelerometer did not differ significantly and were, respectively: 0.45 (95% CI: 0.26–0.65); 0.38 (95% CI: 0.20–0.56); and, 0.49 (95% CI: 0.23–0.74).

Conclusions:

Accelerometer tended to have the highest responsiveness but differences were small and not statistically significant. Consideration of factors, such as validity, feasibility and cost, in addition to responsiveness, is important for instrument selection in future trials

Restricted access

Bronwyn K. Clark, Nyssa T. Hadgraft, Takemi Sugiyama and Elisabeth A. Winkler

The office is a key setting for intervening to reduce sitting, therefore office-specific activity measures are needed to evaluate interventions. We tested whether valid measures of office time and office-specific activities could be obtained using Bluetooth sensing with a variety of sampling intervals, receiver wear positions, and beacon placements. Workers from one building (n = 29, 72% female, age 23–68 years) wore, for one workday, the activPAL3 on the thigh (measured sitting, standing and stepping) and the Bluetooth-enabled ActiGraph Link on the wrist and thigh. Location (office/not) was estimated by Bluetooth signal presence/absence at two beacons in the wearer’s office (desk, wall), with chest-worn video cameras as the criterion. Accuracy in location classification was assessed and compared across 60-s, 30-s, and 10-s sampling intervals. The validity of Bluetooth-derived measures of total time in the office and in office-specific activities was assessed. For both the wrist and thigh-worn Link, with various beacon placements, accurate classification of location (office/not) was obtained, with a significant (p < .05) but trivial difference in accuracy across sampling interval options (F scores all ≈ .98). With the 60-s sampling interval, mean absolute percent error was very small for office time and office sitting time (<5%), but higher for infrequent activities: standing (17%–23%), incidental stepping (30%–49%), and purposeful walking (57%–86%). The ActiGraph Link can be used to validly measure office time and office location of activity with a 60-s Bluetooth setting. Higher resolution improves accuracy but not to a meaningful degree.