Brazilian Ivonette Balthazar felt jittery ahead of a recent Rio de Janeiro road race, but her heart – transplanted from a German Olympian a year ago – spurred her on. In the midst of a long recovery from a transplant operation last year, the three-kilometre fun run alongside Rio's Copacabana Beach seemed like a marathon to 67-year-old Balthazar.
That heart, though, wouldn't let her sit back. “The heart of an athlete beats inside me, the heart of a young person,” she said at the start line. “This heart demands more from my body than I was used to.”