Mediators of physical activity behavior change: A multivariate approach.

Abstract

Using a multivariate extension of the Baron and Kenny (1986) mediation framework, we examined the simultaneous effect of psychosocial variables hypothesized to mediate the relationship between a motivationally-tailored physical activity intervention, and 6-month physical activity behavior in 239 healthy, under-active adults (mean age=47.5; 82% women). Participants were randomly assigned to 1) Print-based feedback; 2) Telephone-based feedback; or 3) Contact Control. All mediation criteria were satisfied for both intervention arms. In terms of effect size, a moderate indirect effect of Print (0.39, 95% CI=0.21, 0.57) was due to increases in behavioral processes (0.54, 95% CI= 0.29, 0.80) being attenuated by decreases due to cognitive processes (-0.17, 95%CI= -0.31,-.03). A moderate indirect effect was observed for Telephone (0.47, 95% CI=0.28, 0.66), with increases due to behavioral processes (0.61, 95% CI=0.34, 0.87) attenuated by decreases due to cognitive processes (0.15, 95% CI=-0.27, -0.02); self-efficacy and decisional balance mediational paths did not attain statistical significance. These findings highlight the importance of studies that deconstruct the theoretical components of interventions to determine which combination produces the greatest behavior changes at the lowest cost.

Psychosocial Mediators of Physical Activity and Fitness Changes in the Activity Counseling Trial

“…Three constructs are hypothesized to mediate the change process: decisional balance, cognitive and behavioral processes of change, and self-efficacy [10]. A number of studies have examined theoretical constructs from the TTM as mediators of PA change, and findings have been mixed [5,[12][13][14][15][16][17].…”

Sociopsychological Tailoring to Address Colorectal Cancer Screening Disparities: A Randomized Controlled Trial

“…[10][11][12][13][14][15][16][17][18][19][20][21][22] Whether enhancement of sociopsychological factors influences health behaviors is uncertain. 12,13,19,[22][23][24][25][26][27][28][29][30][31][32] Among trials comparing patients receiving sociopsychologically tailored colorectal cancer screening interventions with active control, 15,19,20,22,[25][26][27][28][29][30]33 only some found superior effects of tailoring 19,25,28,29,34 ; in all but 1 trial 34 screening was self-reported, 19,25,28,29 suggesting possible response bias. There is a need to examine further whether objectively measured colorectal cancer screening improves in response to sociopsychologi...…”

“…57 Nonetheless, these EHBM factor effect sizes are comparable to those in published trials. [10][11][12][13][14][15][16][17][18][19][20][21][22] In our sample, a 1 SD increase in self-efficacy was associated with a 5.4% greater likelihood of screening (data not shown, available upon request). Thus, the IMCP self-efficacy effect size of 0.16 would be expected to translate into a less than 1% increase in screening (5.4% × 0.16 = 0.86%).…”

Exploring Mediators of Physical Activity in Young Adult Cancer Survivors: Evidence from a Randomized Trial of a Facebook-Based Physical Activity Intervention

“…However, across groups, changes in self-monitoring were positively associated with PA increases as predicted by SCT and demonstrated in other studies. [20][21][22] The lack of increased social support among FITNET intervention participants may partially explain why no improvements in self-efficacy or self-monitoring were found in the FITNET intervention group relative to the self-help comparison group. The lack of FITNET intervention effects on self-monitoring could be due to both groups receiving a pedometer, FITNET intervention participants more accurately reporting their selfmonitoring behaviors (since they accessed the self-monitoring website), and/or self-help comparison group participants possibly over-reporting self-monitoring.…”

“…Self-efficacy, self-regulation, and environmental factors (e.g., social support) are key determinants of behavior described by SCT that have been targeted in several PA interventions. [19][20][21][22] In the context of PA, SCT suggests that a supportive environment may enhance individuals' self-efficacy (i.e., confidence in one's ability to perform exercise and to overcome barriers to exercise in specific settings) and in turn promote self-regulation (i.e., skills for personal regulation of goalsetting, planning, and self-monitoring) to effect behavior change.…”