['Reduced activity of the sarcoplasmic reticulum Ca ATPase-2a (SERCA-2a) contributes to myocardial dysfunction. Exercise training improves myocardial Ca-handling, but SERCA-2a function is uncertain. We assessed SERCA-2a activity after exercise training.', 'SERCA-2a function was assessed by sarcoplasmic reticulum Ca uptake in cardiomyocytes with other Ca uptake mechanisms blocked, in mice after aerobic interval training versus sedentary controls.', 'We established protocols to assess SERCA-2a function, and show that aerobic interval training increases the maximal rate of Ca uptake by 30%. This is at least partly explained by reduced phospholamban-to-SERCA-2a ratio.'] Does myocardial sarcoplasmic reticulum Ca2+ ATPase function is increase by aerobic interval training?