Physical inactivity is a major risk behaviour with a potential for causing premature death, particularly among people with mobility limitations, such as knee osteoarthritis.

Digital motivational interventions (such as SMS) can motive to a healthy behaviour including increased physical activity.

The purpose of this study is to investigate if motivational text messages following an exercise intervention to improve mobility limitations will change the physical activity level in patients with knee osteoarthritis.

This study is designed as pilot randomized controlled trial, with equal randomization (1:1). Eligible participants will be randomised into one of two groups (intervention or control) after completing their baseline measurements. The intervention group will receive weekly motivational text messages and the control group will not receive any attention from the study.

Inclusion Criteria:

• Age ≤18
• Diagnosed with knee osteoarthritis
• Owner of a smart phone or tablet
• Have just finished an exercise program for knee osteoarthritis

Exclusion Criteria:

• Not able to read and understand Danish
• Any condition, which in the opinion of the investigator would put the subject at increased safety risk by participation, or otherwise make the subject unsuitable for this study.