Abstract
Background:Physical inactivity is a key contributor to the global burden of disease and disproportionately impactsthe wellbeing of people experiencing mental illness. Increases in physical activity are associated with improvementsin symptoms of mental illness and reduction in cardiometabolic risk. Reliable and valid clinical tools that assessphysical activity would improve evaluation of intervention studies that aim to increase physical activity and reducesedentary behaviour in people living with mental illness.Methods:The five-item Simple Physical Activity Questionnaire (SIMPAQ) was developed by a multidisciplinary,international working group as a clinical tool to assess physical activity and sedentary behaviour in people livingwith mental illness. Patients with a DSM or ICD mental illness diagnoses were recruited and completed the SIMPAQon two occasions, one week apart. Participants wore an Actigraph accelerometer and completed brief cognitiveand clinical assessments.Results:Evidence of SIMPAQ validity was assessed against accelerometer-derived measures of physical activity. Datawere obtained from 1010 participants. The SIMPAQ had good test-retest reliability. Correlations for moderate-vigorous physical activity was comparable to studies conducted in general population samples. Evidence of validityfor the sedentary behaviour item was poor. An alternative method to calculate sedentary behaviour had strongerevidence of validity. This alternative method is recommended for use in future studies employing the SIMPAQ.Conclusions:The SIMPAQ is a brief measure of physical activity and sedentary behaviour that can be reliably andvalidly administered by health professionals.