Aim 1: Primary Mitochondrial Disease Patients and Healthy Controls~Individuals will be screened for eligibility for study entry, and answer questions relating to their ability to perform study procedures and their physical activity levels. Individuals who meet study criteria will have 3 study visits, and each study visit will involve a different intervention.~At each of these study visits, individuals will complete one of the following interventions: Cardiopulmonary Exercise Testing (CPET), pGz administration through a bed or recliner, and pGz through a device called a Gentle Jogger. While participants will complete all three study visits, the order of the study visits will occur in random order.~During the study visits, participants will have blood draws before and after the study intervention, a vascular ultrasound with a Lumason contrast agent before and after the study intervention, and a Creatine Chemical Exchange Saturation Transfer (CrCEST) MRI of the lower leg.~Aim 2: Patients in the Pediatric Intensive Care Unit (PICU)~Individuals will be screened for eligibility for study entry. Individuals who meet study criteria will have 2 study visits during their admission to the PICU. The first study visit will involve a pedal exercise and the second study visit will involve pGz administration through a device called a Gentle Jogger.~During the study visits, participants will have blood draws before and after the study intervention, a vascular ultrasound with a Lumason contrast agent before and after the study intervention, and if able to safely complete, an CrCEST MRI of the lower leg.
This is a multi-aim study, studying the effects of conventional exercise (measured through Cardiopulomary Exercises Testing or an in-bed pedal exercise) and passive exercise through periodic acceleration (pGz). Aim 1 will focus on the differences between primary mitochondrial disease (PMD) patients and healthy volunteers. Aim 2 is an exploratory aim, which will be studying the effects in patients admitted to the Children's Hospital of Philadelphia Pediatric Intensive Care Unit (PICU).