This retrospective cohort study focused on cardiac health in lifelong, veteran endurance athletes through cardiac MRI. Participants were recruited through solicitations placed in endurance race newsletters. Selection was based on over 100 proven marathons or an equivalent exercise diary verified by the authors. Twelve veteran endurance athletes participated in the study, with an average age of 57 years and a standard deviation of 6 years. Twenty age-matched controls also participated, with an average age of 60 and a standard deviation of 5. In a separate group, 17 younger athletes were also compared, with an average age of 31 and a standard deviation of 5. None of these athletes smoked, none reported a history of diabetes or cardiovascular disease, none reported a family history of diabetes or cardiovascular disease, and none exercised 1 week prior to the MRI.
Cardiac MRI was followed in 5 to 10 minutes by a late gadolinium phase and was analyzed by 2 readers looking for evidence of myocardial fibrosis. Six athletes from the veteran group (50%) showed evidence of myocardial fibrosis, while none of the comparison groups showed fibrosis on MRI. In the veteran group, there was no correlation between evidence of fibrosis and age, height, or weight, but there was a statistically significant correlation with years of training, number of marathons run, and marathons greater than 50 miles. Though the clinical significance of myocardial fibrosis in this cohort is unclear, this study raises suspicion about possible deleterious effects of extreme exercise. Other limitations include its small size and the accuracy with which exercise volume was documented.
(J Appl Physiol. 2011 [Epub ahead of print]) MG Wilson, R O'Hanlon, S Prasad, et al.
Prepared by Anil Menon, MD, UTMB/NASA Aerospace Medicine Fellow, Galveston, TX, USA