Gathimba emerged at international level in 2014, taking a silver medal at the 2014 African Championships in Athletics behind Lebogang Shange of South Africa. He set a personal best of 1:23:59 hours to place second at the national championships that year, behind David Kimutai Rotich.[1][2] He topped the podium at the 2015 national trials with a new best of 1:23:12 hours, which ranked him in the world's top 100 for the first time.[3][4] He again demonstrated his place among the continent's best at the 2015 African Games where he lost out on the gold to Shange by a margin of one second.[5]
