bensales –
Although it’s be ‘illegal’ to use in a race as there’s some rule about not having springs in shoes.
thisisnotaspoon –
What’s the definition? Is it really that different to shoes like Nike air with pressurized air bladders?
Apparently rule 143 covers it:
http://www.iaaf.org/download/download?filename=fa556b18-c75f-4b3d-b952-7348645bccb5.pdf&urlslug=IAAF%20Competition%20Rules%202016-2017%2C%20in%20force%20from%201%20November%202015
“Shoes
2. Athletes may compete barefoot or with footwear on one or both feet. the purpose of shoes for competition is to give protection and stability to the feet and a firm grip on the ground. Such shoes, however, must not be constructed so as to give an athlete any unfair additional assistance, including by the incorporation of any technology which will give the wearer any unfair advantage. A shoe strap over the instep is permitted. All types of competition shoes must be approved by iAAF.”
The IAAF looked into Nike’s shoes using the Breaking 2, but I don’t know what the outcome was.
https://www.theguardian.com/sport/2017/mar/07/iaaf-investigation-concerns-springs-running-shoes-marathon