Treating disability in knee osteoarthritis with exercise therapy: a central role for self-efficacy and pain.
OBJECTIVE
To examine the effects of aerobic and resistance exercise on self-efficacy beliefs in older adults with knee osteoarthritis (OA) and to determine whether self-efficacy and knee pain mediated the effects of the treatments on stair time performance and health perceptions.


METHODS
Measures of self-efficacy, knee pain, stair climbing performance, and health perceptions were collected prior to randomization and again at an 18-month followup in older adults with knee OA who were assigned to 1 of 3 treatment conditions: aerobic exercise, resistance training, or health education control. All analyses were conducted on the intention-to-treat principle.


RESULTS
Both exercise treatments increased self-efficacy for stair climbing in comparison to the health education control group. Both knee pain and self-efficacy mediated the effect of the treatments on stair climb time, whereas only knee pain mediated health perceptions.


CONCLUSIONS
The findings suggest that control beliefs and changes in physical symptoms such as knee pain are important outcomes in physical activity programs with patients who have OA of the knee. Moreover, these variables mediate the effects that such programs have on disability and health perceptions.
Department of Health and Exercise Science, Wake Forest University, Winston-Salem, NC 27109, USA.
W J
WJ
Rejeski
W H
WH
Ettinger
K
K
Martin
T
T
Morgan
D000328:Adult; D000368:Aged; D001294:Attitude to Health; D005080:Exercise Test; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications / Q000523:psychology / Q000628:therapy*; D010146:Pain / Q000209:etiology*; D020377:Self Efficacy; D016896:Treatment Outcome