Zheng L, Feng Y, Wen DT, Wang H, Wu XS. Fatiguing exercise initiated later in life reduces incidence of fibrillation and improves sleep quality in Drosophila. Age (Dordr). 2015 Aug;37(4):9816. PMID: 26206392; PMCID: PMC4512962.
From the abstract: "As the human body ages, the risk of heart disease and stroke greatly increases. While there is evidence that lifelong exercise is beneficial to the heart's health, the effects of beginning exercise later in life remain unclear. This study aimed to investigate whether exercise training started later in life is beneficial to cardiac aging in Drosophila. ... We found that 2.0 and 2.5 h of exercise caused exercise-induced fatigue, and fatiguing exercise is beneficial for cardiac and healthy aging overall. This study provides a basis for further study in humans on the impact of beginning an exercise regimen later in life on cardiac health."