A systematic review of the impact of long-term endurance training on negative cardiac remodelling in athletes: can we do too much exercise?

Background The benefits of undertaking regular physical exercise in lowering the risk of cardiovascular disease is recognised. However, there is concern surrounding the negative cardiac remodelling that can ensue from excessive training. The systematic review aimed to examine the point at which endurance training becomes detrimental to the left ventricle and whether risk reduction guidelines should be introduced. Methods From 5th to 19th February 2024, studies were identified from Scopus and MEDLINE. Inclusion criteria focused on endurance athletes and negative cardiac remodelling specific to the left side. Only studies from period 2004 to 2024, involved human participants, and included original data were considered. Results Of the 389 articles identified, 17 studies met the selection criteria. ROBINS-I was used to assess overall risk of bias, where determined 3 were found to have serious, 10 moderate, and 4 low bias. The studies showed that frequent endurance training could lead to significant left ventricular remodelling with high volume training regimens and high cumulative training hours being associated with greater derangement in left ventricular morphology and function. Remodelling was observed in as little as two years with notable changes in adolescents. Conclusion Participants in high volume training over a sustained period of as little as two years, appeared to have a greater extent of changes to the left ventricle compared to those who trained a lesser amount. This review highlights the necessity of additional research to understand fully the association between volume and total lifetime hours of endurance training and their effects on heart morphology. This understanding will be essential in developing guidelines to address the potential risks of high-volume endurance training.