Shoe foam durability
Evidence: moderate
The super-shoe economy advantage fades with mileage, largely gone by around 450 km. Separate roles: train in durable shoes, race in the super-shoes.
The performance advantage of super-shoe foam is not permanent: it decays with mileage. New PEBA improves economy by about 1.8% over new EVA, but after roughly 450 km of road wear that advantage disappears, with worn PEBA raising energy cost while worn EVA barely changes (Rodrigo-Carranza et al. 2024). The low-density foam that performs best when new wrinkles and loses resilience faster than denser foam, a durability-performance trade-off confirmed by bench testing in which the best-when-new foams degraded fastest (Aimar et al. 2024).
The evidence is not unanimous: one bench test of a worn PEBA shoe found only a small loss of energy return, so the exact rate is contested and depends on foam, runner and surface (Burns & Joubert 2024). Manufacturer guidance, such as a stated “up to 250 miles” for one model, is marketing without a published method.
The practical implication is clear enough to act on. The economy benefit is concentrated in the early life of the foam, so the cost-effective approach is to separate roles: train in durable shoes and reserve the expensive super-shoes for races and key sessions, retiring them from racing well before the foam has flattened. This also bears on the recovery claim: a flattened super-shoe offers neither the performance nor any hypothetical cushioning benefit.
Rotate your shoes
Keep the expensive super-shoes for races and key sessions, and do the bulk of easy mileage in durable trainers. A rotation of two or three pairs spreads wear, lets foam recover its shape between runs, and means the super-shoes still have their “pop” on race day rather than being flattened by daily training. Retire a racing super-shoe from racing well before it feels dead underfoot, since the economy edge fades before the cushioning visibly does.