Axel Muller, now a member of the Argentina National Sevens side, grew up in Phoenix, Arizona after having moved from Argentina to the US at the age of 8. There, Muller played American football where he was praised by coaches and teammates alike for his athleticism. This athleticism was made further apparent by his strong performances in youth decathlons. At the age of 16 he moved back to Argentina and his focus turned to rugby, but he credits much of his tackling knowledge to the coaching he received in the States. Muller has since gone on to receive 9 caps for the Argentinian sevens side.