In September 2014, a 3-tit3-time Bosotn Marathon winner, Jeptoo, tested positive for blood booster EPO in an out of competition test in Kenya.
Kenyan Athletics governing body (Athletics Kenya) gave Jeptoo a two year doping ban that will expire at the end of Ocotber.
However Jeptoos return to competition depends on the result of her appeal to the Court of Arbitration for Sport (CAS), which is set to rule on her case on October 26, after the IAAF requested that the ban be doubled to four years.
"I have returned to serious training with the hope that I will return to the marathon soon," Jeptoo told AFP news agency on Tuesday.
"I am optimistic my appeal to CAS will go through," she added Jeptoo.