Establishing construct validity of a stages-of-change algorithm for physical activity

Area of Science:

• Exercise Science
• Behavioral Medicine
• Rehabilitation Psychology

Background:

• The transtheoretical model (TTM) provides a framework for understanding behavior change.
• Assessing physical activity (PA) stages is crucial for designing effective interventions in individuals with physical disabilities.
• Validating measurement tools is essential for reliable research and clinical application.

Purpose of the Study:

• To examine the construct validity of a modified stages-of-change (SOC) scale in adults with physical disabilities.
• To investigate the relationships between TTM constructs, PA levels, and SOC.
• To compare the modified SOC algorithm with previously recommended scales.

Main Methods:

• A cross-sectional online survey was administered to 271 adults with physical disabilities.
• Standardized questionnaires were used to measure TTM constructs and PA.
• Multivariate analysis of variance and discriminant function analysis were employed.

Main Results:

• The hypothesized relations between SOC and TTM constructs were supported, indicating strong construct validity.
• Physical activity levels increased linearly across the SOC stages, from precontemplation to action.
• TTM constructs like behavioral processes, self-efficacy, and cognitive processes were significant predictors of SOC.

Conclusions:

• The modified SOC scale demonstrates strong construct validity for adults with physical disabilities.
• The scale effectively differentiates PA levels and TTM constructs across stages.
• Health promoters can utilize this validated SOC scale and TTM for developing stage-matched PA interventions.