Career
He has a personal best of 44.27 seconds for the distance. He was a silver medallist at the 2015 IAAF World Relays. Gardiner, from Central Abaco in the Bahamas, competed in the sport in his teenage years and ran in the 400 m at the national championships in 2013.
He entered three events at the 2014 CARIFTA Games: he only managed fourth in the individual 200 metres but claimed a silver in the 4×100 metres relay and a bronze in the 4×400 metres relay.
An appearance at the 2014 World Junior Championships in Athletics resulted in a semi-final run in the 200 m and a sixth-place finish in the 4×400 m. His first senior medal came at the 2015 IAAF World Relays, held on home turf, where he gave American Jeremy Wariner a close run in the 4×400 m, helping the Bahamas to the silver medal alongside Ramon Miller, Michael Mathieu and Chris Brown.
He began to focus on the 400 m in the 2015 season and this proved a successful transition. He rapidly improved to become the youngest Bahamian ever, at 19 years old, to run the distance under 45 seconds and moved up to fourth on the Bahamian all-time lists with a best of 44.64 seconds.
He set the time at the Bislett Games, which brought him victory on his debut on the IAAF Diamond League circuit, finishing ahead of Matthew Hudson-Smith and Pavel Maslak.
200 metres – 20.66 seconds (2014)
400 metres – 44.27 seconds (2015).