Simple breath and urine tests could track muscle energy in rare diseases

This small study looked at whether simple breath and urine tests can measure how well muscles produce energy in children with metabolic myopathies—rare disorders that cause exercise intolerance. Three participants completed a 12-week at-home physiotherapy program, and researchers used non-invasive tests before and after to see if energy metabolism changed. The goal was to develop better ways to monitor future treatments, not to test a new therapy itself.