An eight-year-old boy carried his disabled brother through three challenging stages of a triathlon.

Lucas Aldrich suffers from a rare brain disorder that affects development and growth called lissencephaly, which has left him unable to walk or talk.

But this didn't stop his brother Noah from stepping in to help Lucas take part in the gruelling sport event.

Working together as a team, the two brothers from Idaho, US, have managed to complete several marathons and now a youth triathlon. 

Noah pushed and pulled his younger brother through a 200 metre swim, a three mile bicycle ride and a one mile run in the scorching summer heat. 

The brothers were recently featured on the Today show in the states, where Noah was quoted saying about his brother, "I like everything about him. I think he is perfect."

A charity has now been set up in Lucas' name called the Lucas House Organization aimed to help the families and children affected by similar disabilities as Lucas.