Rengeruk ta samu nasararta ta farko a shekarar 2013, inda ta lashe tseren gwaji na matasa na Kenya kafin ta doke Berhan Demiesa na Habasha don daukar taken mita 3000 a gasar zakarun duniya na matasa a 2013. A shekara mai zuwa ta kasance ta biyar a tseren matasa a Gasar Zakarun Afirka
, rabawa a cikin tawagar zinariya. Ta riga ta sami nasara a gwajin matasa na Kenya tare da mafi kyawun mita 3000 na minti 8:53.41 a farkon gasar IAAF Diamond League a Doha. A gasar zakarun duniya ta matasa ta 2014, duk da haka, 'yar wasan Amurka Mary Cain ta fi ta, ta bar Rengeruk da lambar azurfa.