In July, shortly after relocation to Star City, two of the six were replaced on medical grounds. Firstly, during a centrifuge test of 8 "g", Kartashov experienced some internal damage, causing minor hemorrhaging on his back. Despite Gagarin's requests for him to stay, the doctors decided to remove Kartashov from the group of six. Later in July, Varlamov was involved in a swimming accident. During a dive into a lake near the training center, he hit his head on the bottom, displacing a cervical vertebra. So by the end of July, the Vanguard Six were: Gagarin, Bykovskiy, Nelyubov, Nikolayev, Popovich, and Titov.