Valeri Polyakov did not suffer any serious health problems after spending 437 days in space aboard the Mir space station from 1994 to 1995. Despite concerns about the long-term effects of microgravity, he was able to walk unaided shortly after landing, demonstrating that extended space missions could be feasible for human exploration. However, like other long-duration astronauts, he likely experienced temporary effects such as muscle atrophy, bone density loss, and fluid redistribution, but he recovered over time.