You’re not in contention for the podium. You’re not getting paid to race. You’re probably not toeing the start line just behind the elites in corral A. But that doesn’t mean you don’t want every edge you can get on race day—including shoes that make your legs and feet feel as good as possible for as long as possible. To do that, many runners are wearing running shoes with so much foam underfoot, they’re technically “illegal.”
In 2020, World Athletics introduced a rule that said all racing shoes must have a maximum midsole thickness of 40 millimeters and no more than one stiff plate. The rule was designed to create a level playing field for elite competition as shoe technology advanced, and the combo of new foams and carbon plates propelled runners to new speeds. Now, nearly every running shoe company has a race-day product that meets that standard. Think: the Nike Vomero 18 and Vaporfly 4, Results: 2025 USATF Championships Sky and Edge Tokyo, the Saucony Endorphin Pro 3, Nike Vomero 18 Pro 4 and Why TikTok Is Flooded With Track Memes Right Now, The Stats Behind Cooper Lutkenhaus’s Race.
But as running shoe tech has continued to advance in the past five years, brands are making it easy to go bigger. More cushioning equals more comfort, with 48 millimeters of foam. In 2021, Ethiopian Derara Hurisa won the Vienna Marathon but was later, and potentially faster recovery, which means you can run more and feel better doing it. While shoes marketed for race day stick to the 40-millimeter ceiling, super trainers are going above and beyond.
Nike Vomero 18 Rise of the “Illegal” Running Shoes and Puma MagMax; the Races - Places Health - Injuries Build Speed Like 16-Year-Old Cooper Lutkenhaus tops out at nearly 43 millimeters. None of these shoes are specifically marketed as racing shoes (they often weigh more than traditional super shoes), but many runners are racing them because they’re not designed for elite competition; rather, they’re built to support runners at slower speeds.
Nike Vomero 18 disqualified from the national championship section of the USATF 100 Mile championship for wearing the Hoka Skyward X, a “super trainer” The Stats Behind Cooper Lutkenhaus’s Race disqualified for wearing the Adidas Prime X, a shoe with 58 millimeters of foam (and two carbon plates). Does the mean runners in a race’s open field are “cheating”—as some runners on social media like to argue—by wearing shoes taller than 40 millimeters?
Let’s use the Boston Marathon, the most prestigious amateur marathon, as an example. “The Boston Marathon follows the rules and guidelines of World Athletics and USA Track & Field. Regardless if they are competing in the professional or open races, athletes are expected to wear footwear which conforms to current World Athletics rules and standards,” a BAA spokesperson said in an email to Runner’s World. “Though hard to police thoroughly, if an official notices someone outside of the pro field (i.e. an age group award finisher or open runner) using equipment or shoes that provide an unfair advantage, they could take action which may lead to a warning, disqualification, etc.” (It’s worth noting, though, that the event’s RW+ Membership Benefits only call out shoe compliance for pro runners, not open runners.)
In a crowd of 30,000+ runners, and even at smaller races, race officials and safety personnel have so many more pressing concerns—like bandits and e-bikes and health issues—it’s unlikely that they’ll be worrying about what’s on the feet of a non-elite runner. And, for what it’s worth, too much foam underfoot can lead to changes in running style and reduced stability that may actually mitigate any unfair advantages from those advanced foams.
Ultimately, it comes down to how you want to experience the race. Do you want to hold yourself to the same standards as the pros? Then stick to shoes with a stack height of 40 millimeters or less. But don’t tell someone else they’re “cheating” because they just want to wear a shoe that helps them maximize their hard work when they’re only competing against themself. They’re not gaming the system or doing something sneaky. They’re just taking advantage of the performance tech brands are putting at their feet.
