Energy return in running shoes explained (2025)
3 days ago
- #energy-return
- #running-shoes
- #lab-testing
- Energy return in running shoes refers to how well the midsole foam rebounds after compression, storing and releasing energy to aid forward motion.
- Higher energy return can improve running economy by reducing wasted effort, but it's not the only factor; weight, stiffness, and geometry also matter.
- There's no strong correlation between energy return and shock absorption; shoes with high energy return may not offer the best impact protection.
- Stack height alone doesn't determine energy return; foam material (e.g., PEBA, A-TPU, EVA) and engineering are more critical.
- Supershoes combine high-energy-return foam, a stiffening plate (like carbon), and lightweight construction for performance gains, but energy return alone isn't enough.
- Strike pattern affects energy return: heel strikers need stable transitions, while midfoot/forefoot strikers benefit more from rebound during push-off.
- Foam is the primary influencer of energy return, with PEBA and A-TPU offering high return (around 80%), while EVA is lower (around 50-60%).
- Other shoe parts like the plate (distributes pressure), insole (thin for max foam space), and outsole (thinner for better bounce) also impact energy return.
- Energy return is less important for slow/recovery runs or short sprints, where shock absorption and comfort take priority.
- Premium foams retain energy return better in cold weather, while standard foams like EVA lose significant bounce.
- Elite runners may gain more efficiency from supershoes due to higher forces, but recreational runners can still save time due to longer race durations.
- Testing methods for energy return (e.g., ASTM F1976) vary, and results can differ, emphasizing the need for standardized lab data over marketing claims.
- High energy return isn't always beneficial; it can lead to instability, timing issues with rebound, or conflict with minimalist running principles.
- Future improvements in energy return will be gradual, with foams unlikely to reach 100% due to energy loss as heat and material limitations.