What Makes a 97-Year-Old Man Cycle 5,000 km a Year?

<b><i>Background:</i></b> The nature versus nurture debate is one of the oldest issues in the study of longevity, health and successful aging. <b><i>Objective:</i></b> We present a 97-year-old man (I.K.) as an example of the effects of habitual exercise on the aging process. <b><i>Methods:</i></b> Extensive assessments included medical examinations, interviews, musculoskeletal structure, performance characteristics, cognitive function and gut microbiota composition. <b><i>Results:</i></b> I.K. suffers from iatrogenic hypogonadism, prostate cancer, hypothyroidism and a history of deep popliteal th…