Intensive Tailored Exercise Training With NAD+ Precursor Supplementation to Improve Muscle Mass and Fitness in Adolescent and Young Adult Hematopoietic Cell Transplant Survivors

This will be a randomized, placebo-controlled trial with a 2x2 factorial design testing the effects of an NAD+ precursor (NR) and exercise on skeletal muscle quality and VO2max in AYA HCT survivors. The primary outcome is the change in muscle strength (isometric knee extension) from baseline to 16 weeks. Key secondary outcomes are the change in muscle strength (ankle plantarflexion) from baseline to 16 weeks, the change in grip strength from baseline to 16 weeks, the change in lower extremity muscle mass from baseline to 16 weeks, the change in muscle OXPHOS capacity from baseline to 16 weeks, and the change in aerobic capacity (VO2 max) from baseline to 16 weeks.