Gamarnik was world lightweight (67 kg) Greco-Roman wrestling champion at the 1955 World Wrestling Championships in Karlsruhe, Germany, beating out silver medalist Kyösti Lehtonen of Finland and bronze medalist Gustav Freij of Sweden. He came in second in the 1958 World Wrestling Championships in Budapest, Hungary, in welterweight (73 kg) Greco-Roman wrestling, behind gold medalist Kazim Ayvaz of Turkey and ahead of bronze medalist Valeriu Bularca of Romania.