Sepp Miles posted an update 4 months ago
Figure 2 shows unadjusted mean min/wk of self-reported MVPA after completion of the 6-month intervention. Mean MVPA at 6 months ranged from 73.0 min/wk in Seamos Saludables to 169.7 min/wk in Activas. When data was aggregated across studies, there was a marginal overall effect of demonstration walk (b=24.9, SE=12.5, p=0.06). Looking at study pairs separately, this Biotin-tyramide was mostly driven by differences in the Spanish pair, in which those who completed the demonstration walk reported significantly fewer minutes of MVPA per week at 6 months than those not completing the walk (mean difference=99.9±32.2; p<0.05). The difference between the English studies, however, was not significant.To test whether the demonstration walk improved the accuracy of the self-report MVPA measure, we compared the correlations between self-report and objectively measured MVPA amongst participants who did and did not complete the demonstration walks at baseline and in the 6 months following the MVPA intervention. At baseline, a total of 585 participants wore the accelerometer across the three studies. For Stride I participants who did not complete the demonstration walk, we observed correlations with the 3-day PAR of 0.05 (p=0.85) at baseline and 0.24 (p=0.35) at 6 months. Correlating prorated accelerometer data with the 7-day PAR produced nearly identical results to the 3-day PAR at baseline (0.04) and 6 months (0.24). For Stride II participants who did complete the demonstration walk, we observed correlations of 0.28 at baseline and 0.31 at 6 months (for both, p<0.01). Participants in Activas did not use accelerometers, thus we were not able to compare correlations between the Spanish language studies, but for Seamos Saludables, which included the demonstration walk, correlations were 0.26 at baseline and 0.44 at 6 months (p<0.01 for both).DiscussionImportantly, there was a higher degree of agreement between self-reported MVPA and objectively measured MVPA among participants who completed the 10-minute demonstration walk compared to those who did not complete the walk. For participants not completing the demonstration walk at baseline, correlations between objective and self-report MVPA were markedly low (0.04), while participants completing the demonstration walk had higher and statistically significant correlations at baseline (0.28 and 0.26). This suggests the experiential demonstration may have improved self-report accuracy through improved understanding of what constitutes MVPA. The agreements between the 7-Day PAR and the objective data measured via Actigraph accelerometers in our studies are similar, albeit slightly lower than those reported in a previous study. Sloane et al reported moderate agreement between data collected from a telephone administered 7-Day PAR and an RT3 accelerometer with correlation coefficients ranging from 0.24 to 0.54. As Sloane et al pointed out, a potential reason for the poor agreement between the 7-Day PAR and accelerometry is the fact that they measure different dimensions of PA. While the PAR measures recalled minutes of activity, accelerometry measures accelerations, which are then used to approximate minutes of activity using count thresholds.These data suggest that a 10-minute experiential demonstration walk may serve as an effective and practical calibration of both duration and intensity of MVPA prior to conducting self-report MVPA assessments. These findings also suggest the typical over-reporting of MVPA may not simply be due to social desirability, but at least in part to an incomplete understanding of what a 10-minute bout of MVPA actually feels like. The common practice of providing simple verbal descriptions (e.g., “you may be slightly out of breath and sweat a bit”) and examples (e.g., “brisk walking or biking on a flat surface”) of MVPA, as is done in many self-report MVPA assessments including the 7-Day PAR, may be an insufficient means of educating previously sedentary individuals on the duration and intensity of MVPA for accurate reporting. Given the low baseline levels of MVPA in the participants in the current studies, ovule is likely they had a low initial understanding of MVPA. For instance, after completing the demonstration walk, several participants noted that they had never completed any MVPA of that intensity or duration before. However, given previous reports of < 5% of US adults engaging in regular MVPA, it is likely that the experiential demonstration would be useful for improving understanding of MVPA in most populations.