First author Niklas Ivarsson (left), co-senior authors Johanna Lanner (center) and Håkan Westerblad (not shown), and colleagues found that mild Ca²⁺ leak through ryanodine receptors correlates with increased expression of markers for mitochondrial biogenesis (graph, right) and improved muscle function. Sadly, Ivarsson passed away on October 10, 2018. Photos courtesy of the authors.