Introduction Rapid progress has been made in relation to our understanding of the molecular and genetic basis of many mitochondrial disorders. Yet despite this, avenues for therapeutic intervention are limited. Low levels of habitual physical activity have been recognised to have a strong negative relationship with muscle mitochondrial capacity, disease development and mortality. The aims of this study were to systematically assess habitual physical activity in a cohort of mitochondrial patients.

Methods One hundred patients were enrolled in the study. Habitual physical activity was measured by a multisensor array and by completion of a self-report questionnaire. Disease severity was assessed using the Newcastle Mitochondrial Disability Adult Scale (NMDAS).

Results Low levels of habitual physical activity were common. Seventy-eight per cent of the patients achieved less than nationally advised levels of physical activity (10 000 steps per day) and almost half had an average daily energy expenditure of less than 1.4 METS. Higher physical activity was associated with lower BMI and lower clinical disease burden.

Conclusion Low levels of physical activity are prominent and constitute a significant and important modifiable risk factor in mitochondrial disease. These findings advocate the promotion of increased physical activity irrespective of genotype.