Training for a first marathon allows for significant rejuvenation of the cardiovascular system, although this improvement is potentially offset by premature wear of the lower joints.

noli's read

The community is converging toward a nuanced skepticism, welcoming the cardiac benefit while immediately highlighting the musculoskeletal risk. The cited study (Journal of the American College of Cardiology, 2020) is a prospective observational study showing that a six-month marathon training program can reduce arterial stiffness, equivalent to a vascular rejuvenation of four years. While the cardiovascular benefit is supported by solid evidence, the claim regarding accelerated aging of the knees and hips is a popular and exaggerated extrapolation. In reality, research on running suggests that regular practice, even intense, does not necessarily increase the risk of osteoarthritis in healthy individuals, contrary to conventional wisdom. There is no evidence that running causes linear mechanical 'wear' on joints as one would with a motor part. The forum consensus reflects a cautious balance between metabolic gain and physical prudence.

the sources

1. 1r/AdvancedFitness