High-Intensity Interval Exercise in Young Adult Survivors of Pediatric Brain Tumors: A Pilot Feasibility Study

Inclusion Criteria: * Written informed consent prior to any study-related procedures. * At time of study are a young adult, aged 18-45 years. * Histologically diagnosed brain tumor during childhood, or currently diagnosed with an IDH-mutant glioma (diagnosed \> 18 years). * Are at least 2 years post tumor-directed therapy for pediatric brain tumor survivors, or at least 1 year since their most recent surgery, radiation or chemotherapy treatment for IDH-mutant glioma patients (or are deemed able to participate in the study based on the assessment of their treating physician). IDH-mutant glioma patients can participate while on maintenance therapy with an IDH inhibitor. * The effects of exercise on the developing fetus are unknown. For this reason, people of child-bearing potential must verify pregnancy status by providing first day of their last menstrual cycle and agree to use adequate contraception (hormonal or barrier method of birth control or abstinence) prior to study entry. Should a person become pregnant or suspect that they are pregnant while participating on the trial, they should inform their treating physician immediately. * Medically cleared to participate in exercise by their referring physician or a certified clinical exercise physiologist. * If participants have a diagnosis of tumor-related epilepsy, they must have good seizure control, with no generalized seizures in the 6 months preceding enrollment. * Are without any other medical conditions that could exacerbate with exercise, such as bone disease (excluding bone metastases) at imminent risk of fracture or uncontrolled cardiopulmonary or metabolic diseases. * Speak English and/or Spanish. * Currently participate in less than or equal to 60 minutes of moderate or vigorous structured exercise/week. * Does not smoke cigarettes or e-cigarettes (no smoking during the previous 12 months). Those who infrequently smoke in social settings will be included. Those who vape will also be included. * Willing to travel to DFCI for necessary data collection. * Ability to understand and the willingness to sign a written informed consent document Exclusion Criteria: * Diagnosis of primary spinal cord tumor. * Pre-existing medical conditions such as uncontrolled tumor-related epilepsy, cardiopulmonary disease, or metabolic diseases that could exacerbate with exercise. * Patients with evidence of progressive CNS or systemic cancer in the last 3 months. * People who are pregnant, or plan to become pregnant during study duration will be excluded due to the unknown nature of exercise on developing fetuses. * Actively on a weight loss diet. * Participate in more than 60 minutes of moderate or vigorous structured exercise/week. * Currently and regularly smokes. * Unable to travel to DFCI for necessary data collection. * May not be able to comply with the safety monitoring requirements of the study in the opinion of the investigator.