Background: Physical activity is important for general health and facilitates sputum expectoration in people with primary ciliary dyskinesia (PCD). We studied physical activity in people with PCD participating in the international COVID-PCD study.

Methods: An online questionnaire assessed baseline physical activity levels and weekly questionnaires assessed duration of mild, moderate, and vigorous activity on the previous day. We studied number of active days and number of days participants reached the WHO recommended minutes (min) of moderate-to-vigorous activity (MVA) per day (60 min for children and 43 min for adults). We used multilevel mixed effects linear regression to study factors associated with MVA.

Results: We included 521 people with PCD. 313 (60%) were female; median age 30 years [range 3-85]. At baseline, 130 (24%) reported not being active, 153 (30%) reported being active irregularly, and 238 (46%) regularly. During a median of 33 (range 4-79) weeks of follow-up, children were active on 78% of days and reached the WHO recommended 60 min MVA on 28% of days. Adults were active 59% of days and reached WHO recommendations on 16% of days. Several factors were associated with less daily MVA. Adjusted for season and weekday, female sex (-16 min, 95%CI -23to-8), age ?18 years (-17 min, 95%CI -25to-9), FEV1 ? 50% predicted (-16 min, 95%CI -29to-3), and body mass index>30 (-14 min, 95%CI -27to-2) (only in adults) were associated with less daily min of MVA.

Conclusion: Many participants were less active than recommended by the WHO, especially adults. Increasing physical activity in people with PCD is recommended to reach the WHO guidelines.

Funding:SNSF 320030B_192804, SLA 2021-08_Pedersen. A BEAT-PCD collaboration.