Lawford BJ, Bennell KL, Allison K, et al. - Challenges linked with implementing a home-based strengthening exercise program for patients with knee osteoarthritis and comorbid obesity included a fear of pain, having false assumptions about exercise, difficulties with exercise performance, application of cuff weights, and adverse effects of other health conditions. Many psychological and physical challenges to exercise were encountered by patients and physical therapists.

• In this qualitative study within a randomized controlled trial, two home-based strengthening programs (weight-bearing functional exercise vs non–weight-bearing quadriceps strengthening exercise) for patients with knee osteoarthritis and comorbid obesity were compared.

• In both exercise programs, patients received 5 consultations with a physical therapist and undertook a home-based exercise program for 12 weeks.

• Psychological, physical, and overcoming challenges were experienced.

• Psychological challenges included false assumptions regarding exercise; fear of pain; disliking exercise; mental effort of the weight-bearing functional program; underestimating capability.

• Physical challenges included complexity of the weight-bearing functional program; cuff weights and straight leg raise being problematic in non–weight-bearing quadriceps program; other health problems.

• Overcoming challenges involved incentives to exercise; accountability; education and reassurance; tailoring the exercise program.