Koba made most of her international appearances in the mid 1990s for Ukraine. She was a bronze medallist in the 10,000 metres at the 1993 European Cup, though her selection for that event at the 1993 World Championships in Athletics was brought to a halt due to injury. In 1994 she was a member of the national team for the Yokohama Women's Ekiden, 1994 IAAF World Cross Country Championships and 1994 European Cross Country Championships (placing tenth at the latter). She led the rankings for the Ukrainian women at the 1995 IAAF World Cross Country Championships in 60th place and took the 5000 m bronze at the 1995 European Cup. She was eliminated in the heats in her final major international appearance, at the 1995 World Championships in Athletics 5000 m race.