Considering that only 18% of adults with disabilities participate in moderate or higher-intensity activities (USDHHS, 2000), physical activity (PA) motivational programs must be targeted toward one's stage of change (SOC; stage-matched programs; Kosma, 2007). The current SOC measures have several limitations, including lack of assessment of PA intention and behavior within each stage, limited distinction of the two active stages (action and maintenance), and brief PA definitions (Kosma, 2007). Therefore the purpose was to test the construct validity of a modified SOC scale – its initial version was published as an expert commentary in Motivation of Exercise and Physical Activity (Kosma, 2007) – among adults with physical disabilities by investigating differences in the transtheoretical model (TTM) constructs (processes of change [POC], self-efficacy, pros, and cons) and PA across the SOC and the most important TTM predictors of the SOC.
Method
Standardized self-report scales were used to assess the TTM constructs and PA among 273 adults with physical disabilities (Mage = 49.30; 73.6% females; 51% multiple sclerosis and 33% spinal cord injury).
Analysis/Results
Based on descriptive statistics, participants were well-represented across the four proposed SOC (i.e., precontemplation = 68; contemplation = 65; preparation = 48; and action = 92). Based on the MANOVA, the POC, self-efficacy, and pros increased across the SOC in an almost linear fashion. Additionally, active participants perceived fewer cons than precontemplators. According to the One-Way ANOVA, PA levels increased linearly across the SOC. Precontemplators (Mean = 8.53 MET-hrs/day) had lower PA scores than contemplators (Mean = 14.27 MET-hrs/day) and preparators (Mean = 17.3 MET-hrs/day), who in turn had lower scores than active people (Mean = 22.82 MET-hrs/day). Based on the first function of the direct discriminant function analysis, the most important predictors of the SOC were the behavioral POC (r = .85), self-efficacy (r = .69), the cognitive POC (r = .58), and pros (r = .48). In the second discriminant function, the cons also emerged as significant SOC predictors (r = .54). The most accurately predicted SOC were action (76.1%), precontemplation (69.1%), contemplation (44.6%), and preparation (22.9%), with an overall classification accuracy of 57.5%.
Conclusions
The construct validity of the SOC scale was supported. Compared to previous scales (e.g., Kosma et al., 2006), the current SOC scale differentiated almost linearly the levels of PA and the TTM constructs. Health promoters need to use the proposed SOC scale and the TTM to implement stage-matched PA motivational programs.