Surprisingly, stronger associations were found between improved upper leg muscle strength and reduced pain and activity limitations in the post-treatment period compared with peri-treatment periods. This could imply that some effects of exercise occur at a later stage (i.e. post-treatment). The study group was found to be highly adherent, with 78% of the participants continued to exercise after finishing the exercise programme. This high level of adherence may have played an impor- tant role in the stronger associations after treatment.