Background/Purpose:   To determine the relationship over time between beliefs, motivation, and worries about physical activity and physical activity participation in persons with knee osteoarthritis (KOA). 

Methods:   Longitudinal data from 155 adults with KOA enrolled in a randomized clinical trial to assess the effectiveness of a behavioral intervention to promote physical activity were analyzed. Data included participant self-reported beliefs that physical activity can be beneficial for their disease, motivation for physical activity participation, worries about physical activity participation, and objective average daily accelerometer counts over a week’s time at baseline, 3 months, 6 months, and 12 months. The relationships of physical activity with beliefs, motivation and worries about physical activity were examined by multiple regression models using general estimating equations adjusting for age, gender, body mass index, disease activity, and treatment group.

Results:   Results from the adjusted analyses showed a strong significant concurrent relationship between beliefs and physical activity, as well as between motivation and physical activity (Figure 1). The predictive relationships of beliefs, motivation, and worries with subsequent physical activity were each not significant.

Figure 1. Adjusted^a average daily activity counts for dynamic variables^b (N=155)

^a Modeling average daily activity counts on concurrent dynamic variables adjusted for age, gender, body mass index, disease activity, and treatment group.

^b Belief score: not strong 0~21, strong 22~33; Motivation score: not strong 6~20, strong 21~24; Worry score: not strong -7~0, strong 1~7.

^*  P-value comparing not strong versus strong.

Conclusion:

Ø  Higher levels of physical activity participation in persons with KOA were concurrently related to stronger beliefs that physical activity can be helpful for managing disease and to greater motivation for being active.

Ø  Prior beliefs, motivation, and worries did not predict subsequent physical activity.

Ø  These findings suggest that persistent attention to motivation and beliefs are needed to sustain higher levels of physical activity.