Amusan, who was wearing Adidas Adizero Avanti shoes designed for runners who compete in 5-10 km races, cruised to the 100m hurdles gold in what was announced as a world record 12.06 seconds but later ruled ineligible due to excessive wind speed.
She had already broken the world record earlier in the day by running 12.12 in her semi-final at Hayward Field.
"My abilities are not centred around spikes," Amusan told The Guardian, revealing that she had hit upon the idea to use customised shoes with bouncy foam due to an injury.
"I had patella fasciitis at the beginning of the season so that set me back for a while. I spoke to Adidas and requested if I could get spikes with a softer sole," Amusan said.
"They recommended a lot of stuff and I feel comfortable in that, so I was using them basically the entire time."
Shoe technology has come into focus since records started tumbling last year, with governing body World Athletics trying to draw a line between innovation and giving athletes an unfair advantage.
Current regulations allow for shoes to have a maximum thickness of between 20-25mm depending on the event, while they can go up to 40mm for road races.
Sprint spikes cannot have soles that are thicker than 20mm, which is the same as the shoes Amusan was wearing on Sunday.
Sole thicknesses for all athletic shoes in track and field events will be simplified to a stack height of 20mm from November 1, 2024, World Athletics said in December.
