[1][2][3][4] Grøndahl is renowned for his tactical understanding, and despite his young age he is often seen taking care of time-outs in GOG Håndbold instead of the head coach.
[5] Grøndahl started playing handball at Haslum HK, where his father was a youth coach.
He debuted for the senior teamed in the 2017/2018 season with a single game.
In the 2021/2022 season he was the top scorer in the EHF Champions League.
His father was also a handball player for Haslum HK and Elverum Håndball.