Martlew will race in the KL2 and VL3 at the Paris 2024 Paralympic Games. He finished fourth and eighth in the former and latter, respectively, at Tokyo 2020. The three-time world medallist was a rugby player in school and has a bronze in the K4 500m and K4 200m at the Oceania Championships in 2019. He became the first New Zealand paddler to compete at the Paralympic Games when he participated at Rio 2016, finishing eighth in the KL3.