Comparison Of Moderate To Vigorous Physical Activity Assessed By Accelerometry And The EVS

Background: Physical activity (PA) questionnaires are an affordable and time efficient tool that can be used by physicians to determine if individuals meet PA recommendations (≥150 min/week of moderate to vigorous PA [MVPA] accumulated in bouts ≥10 minutes). The Exercise Vital Signs EVS (Coleman et al. MSSE 2012) questionnaire was recently developed for this purpose. However, little data exists on how it compares to objectively measured PA.

Purpose: To compare the agreement between MVPA measured objectively and MVPA determined by the EVS.

Methods: A total of 39 subjects (15 men and 24 women, 49.7±20.0 yr) and 38 subjects (20 men and 18 women, 41.7±21.3 yr) were recruited from Muncie IN, USA and Worcestershire, UK, respectively. Subjects wore an ActiGraph GT3X+ accelerometer on their right hip for a minimum of 4 days with 10 hours of valid wear-time per day and answered the EVS at the end of the observation week. Accelerometers were initialized in ActiLife v6.8.0 using 60Hz sampling rates and processed using 60 second epoch. Total MVPA time and MVPA accumulated in bouts of ≥10 minutes were quantified by applying Sasaki et al. (2011) cutpoints (≥2690 activity counts). Total MVPA/wk was determined from the EVS by multiplying the number of days by the length of time spent in MVPA/day reported by the subject. A dependent t-test, was used to assess for mean differences in MVPA assessed by the GT3X+ and EVS. Pearson correlations were performed between EVS and Sasaki cutpoint. Significance was set at p<0.05.

Results:: Time (min/wk) spent in MVPA quantifi ed by the EVS (184.1±156.5) was significantly different compared to total time and total bout time determined by Sasaki cutpoints (333.4±172.8 and 149.7±121.0, respectively). Pearson correlations for total MVPA time (.429) and total MVPA bout time (.551) were significant. There were 21 and 26 cases where the EVS and GT3X+ matched individuals to meeting or not meeting PA guidelines,respectively. This corresponds to a total agreement of 61.0%.

Conclusion: The level of agreement for meeting PA guidelines by the EVS and the GT3X+ was moderate. Therefore, future studies need to assess the validity and reliability of this questionnaire, in order to confidently classify patients’ PA status.