Aimar et al. 2024, Midsole foam mechanical fatigue

Bench fatigue test of five commercial midsole foams (EVA, TPU and PEBA) under cyclic compression to 200,000 cycles, roughly equivalent to 400–700 km of running (Footwear Science 2024). Simulated fatigue substantially softened the foams — on average a 42 ± 6% loss of maximum specific stress and a 66 ± 15% loss of specific energy absorption, with residual strain rising sharply — and the foams with the best initial cushioning performance (the lightest, most porous) degraded the fastest, while the densest TPU foam was the most durable. Strong (materials testing).