Trajectories of physical activity following digital education and exercise therapy-a longitudinal registry study among 15,197 persons with knee or hip osteoarthritis.
Kiadaliri A, Mahmoudian A, et al. • BMC musculoskeletal disorders • 2026
Group-based trajectory modelling identified four distinct physical activity trajectories among persons with knee or hip osteoarthritis participating in a digital education and exercise therapy program, with BMI and physical function as the most important associated factors, and clinically comparable improvements in patient-reported outcomes across all trajectories.
Key Findings
Results
The proportion of participants reaching recommended physical activity levels increased from enrolment to one-year follow-up.
Recommended PA level was defined as ≥150 min/week of moderate to vigorous physical activity.
At enrolment, 51.4% (95% CI: 50.6, 52.2) met recommended PA levels.
At one year, 58.5% (95% CI: 57.1, 59.9) met recommended PA levels.
Approximately 60% of participants reached or maintained recommended PA levels over the study period.
Sample size was n=15,197 individuals aged 40+ years with knee or hip OA.
Results
Group-based trajectory modelling identified four distinct physical activity trajectories among participants.
The four trajectories were: persistently high (41.2%), persistently low (30.4%), increasing (16.5%), and declining (11.9%).
Trajectories were modelled using group-based trajectory modelling (GBTM) with PA measured at enrolment and at 3-month intervals up to 1 year.
PA was measured as a binary outcome (meeting or not meeting ≥150 min/week of moderate to vigorous physical activity).
The largest single trajectory group was 'persistently high' at 41.2% of participants.
Results
BMI was the most important factor associated with physical activity trajectory group membership, followed by physical function.
Multinomial logistic regression was used to explore factors associated with trajectory membership.
BMI was identified as the primary predictor of PA trajectory.
Physical function was the second most important associated factor.
Results suggest that targeted PA promotion strategies for individuals with higher BMI and poorer function may be beneficial.
These findings imply that interventions could be tailored based on BMI and baseline function to promote PA.
Results
All four physical activity trajectory groups experienced clinically comparable improvements in patient-reported outcomes from enrolment to one-year follow-up.
Changes in patient-reported outcomes (PROs) across PA trajectories were analysed using random intercept models.
PROs were measured from enrolment up to 1-year follow-up.
Improvements were described as 'clinically comparable' across all four PA trajectories.
The finding that PROs improved regardless of PA trajectory was noted as supporting provision of education and exercise therapy to all individuals with OA.
This result held across the persistently high, persistently low, increasing, and declining trajectory groups.
Methods
The study included 15,197 individuals with knee or hip osteoarthritis participating in a digital education and exercise therapy program with longitudinal follow-up.
Participants were aged 40+ years with a diagnosis of knee or hip OA confirmed through referral documentation or based on NICE guidelines and Swedish national criteria.
Inclusion required responses to validated self-reported PA questions at enrolment and at least one follow-up.
Follow-up assessments occurred at 3-month intervals for up to 1 year after enrolment.
This was a longitudinal registry-based study design.
The digital program provided education and exercise therapy.
What This Means
This research examined how physical activity levels change over time among more than 15,000 people with knee or hip osteoarthritis who participated in a digital program providing education and exercise therapy. Participants reported their physical activity at enrollment and every three months for up to one year. The researchers used a statistical method to group participants into distinct patterns of physical activity over time, and they found four groups: those who consistently stayed active (about 41%), those who consistently remained less active (about 30%), those whose activity increased over time (about 17%), and those whose activity declined (about 12%). Overall, the share of participants meeting recommended physical activity guidelines (at least 150 minutes per week of moderate to vigorous activity) rose from about 51% at the start to about 59% after one year.
The study found that body weight (measured by BMI) was the strongest factor linked to which activity pattern a person followed, with physical function being the second most important factor. This suggests that people with higher BMI or poorer physical function at the start may need more targeted support to increase or maintain their activity levels. Importantly, all four groups — whether they were consistently active, consistently less active, or changed over time — showed similar and clinically meaningful improvements in patient-reported outcomes such as pain and quality of life.
This research suggests that digital education and exercise therapy programs for osteoarthritis may benefit people across the full range of physical activity levels, not just those who are already active. The finding that health outcomes improved regardless of activity trajectory supports making these programs broadly available to people with osteoarthritis. At the same time, the link between BMI, physical function, and activity patterns points to the potential value of tailoring support for those who face more barriers to becoming or staying physically active.
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Kiadaliri A, Mahmoudian A, Dahlberg L, Dell'Isola A, Ageberg E, Lohmander L. (2026). Trajectories of physical activity following digital education and exercise therapy-a longitudinal registry study among 15,197 persons with knee or hip osteoarthritis.. BMC musculoskeletal disorders. https://doi.org/10.1186/s12891-026-10590-w