The paper by Roshanravan et al. “In vivo mitochondrial ATP production is improved in older adult skeletal muscle after a single dose of elamipretide in a randomized trial”, appeared in the journal PLoS one in July 2021. Older subjects were selected for low in vivo mitochondrial function, but were otherwise healthy. In vivo ATPmax was measured by 31P MRS in the Translational Bioenergetics Laboratory at baseline, following a single IV treatment with ELAM (or placebo), then again a week later. ELAM improved ATPmax immediately after infusion, compared to placebo. This improvement returned to placebo levels a week later. Results from this randomized trial indicate that depressed mitochondrial function in skeletal muscle in older adults is reversible by targeted interventions.