bobsledding is a winter sport in which sled teams make timed runs down narrow, twisting iced tracks at speeds of up to 140 kilometers per hour.

위 문장 분석이잘안되어서요.. twisting iced tracks at speeds of up to 140 kilometers per hour가 목적어이고
보어가 timed인 것 같은데 ,,runs down은 누슨 역할인가요?
분석 좀 해주세요~^^