Career
Kayange is well known within the rugby sevens community, as he has produced some of the best performances for the Kenya national sevens side. He is the captain of the team Kayange played for the military team Ulinzi Reconstruction Finance Corporation in the Kenya Cup league.
The team was later disbanded, and he moved to Mwamba Reconstruction Finance Corporation. He was part of the Kenyan squad at the 2009 Rugby World Cup Sevens, reaching the semifinals.
Kayange has also played for the Kenya national rugby union team (15s), playing at the 2011 World Cup Qualifiers. He is the older brother of top tries Kenya scorer Collins Injera who also plays for Mwamba Reconstruction Finance Corporation. Their younger brother Michael Agevi also plays rugby for the Sevens.
In 2012 Humphrey moved to Bristol, United Kingdom to undertake research into tenellin biosynthesis with Professor Christine L. Willis at the University of Bristol.