The goal of research of F. Rosenfeldt’s team was to study the mechanisms of age-related decrease in stress tolerance of the heart and search for possible ways allowing to fight them. Specifically, the scientists investigated the possibility to use coenzyme Q (CoQ), which is a component of the mitochondrial respiratory chain, and other antioxidants. In experiments on rats, F. Rosenfeldt and his colleagues showed that the tolerance for aerobic stress caused by fast heart beating decreased in aging heart. However, CoQ provided specific protection in that situation. It was shown in clinical studies (on 100 patients whose average age was 68 years) that 2 week long CoQ intake preceding an operation on the heart enhanced mitochondrial effectiveness in the myocardium and the myocardial condition (in vitro and in vivo). Then in the pilot study on 14 patients, the action of various food supplements (α-lipoic acid, magnesium orotate and omega-3 fatty acid) taking as a part of the diet containing CoQ was studied. It was found that the patients who had taken such food supplements were faster discharged from the hospital, had a lower level of oxidative stress, and improved in quality of life. Thus, the authors concluded that the organism’s stress tolerance decreasing with aging could be restored by adding some substances into the diet.