Mediators of physical activity behavior change: a multivariate approach.
OBJECTIVE
Using a multivariate extension of the Baron and Kenny (1986) mediation framework, we examined the simultaneous effect of variables hypothesized to mediate the relationship between a motivationally tailored physical activity intervention, and 6-month physical activity behavior in 239 healthy, underactive adults (M age = 47.5; 82% women).


METHODS
Participants were randomly assigned to (a) print-based feedback; (b) telephone-based feedback; or (c) contact control.


METHODS
Psychosocial variables, including self-efficacy, decisional balance, and processes of change.


RESULTS
All mediation criteria were satisfied for both intervention arms. A moderate indirect effect of print (0.39, 95% CI = 0.21, 0.57) was found 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.


CONCLUSIONS
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.
Napolitano
Melissa A
MA
Temple University, Department of Kinesiology, USA. napolita@temple.edu
Papandonatos
George D
GD
Lewis
Beth A
BA
Whiteley
Jessica A
JA
Williams
David M
DM
King
Abby C
AC
Bock
Beth C
BC
Pinto
Bernardine
B
Marcus
Bess H
BH
D000328:Adult; D000368:Aged; D001521:Behavior Therapy; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D020377:Self Efficacy; D012919:Social Behavior; D011795:Surveys and Questionnaires