Energy return in running shoes explained

The phrase “energy return” has only gained attention in the last decade as advanced materials like TPU, TPEE, PEBA, and A-TPU entered the scene. This guide covers every nuance about energy return based on our lab data (500+ shoes tested for energy return) and consultations with lots of experts on the topic.What is energy return and why it’s important in running shoesEnergy return in running shoes refers to how efficiently the midsole foam rebounds after being compressed during a step. Instead of absorbing all impact as heat, a running shoe stores some energy and releases it as the foot lifts off.This rebound helps reduce wasted effort and can improve running economy, though only if the shoe’s design, timing, and stiffness align well with the runner’s biomechanics and stride.Common misconceptions about energy return Your browser does not support the video tag. In this section, we’ll break down some of the most frequent misunderstandings surrounding energy return and how it’s often confused with other shoe characteristics.Energy return and running economyBetter energy return from a shoe can improve your running economy—but not always. For example, a heavier shoe with amazing energy return might still require more effort than a lighter shoe with slightly less energy return. Weight, stiffness, and geometry all shape the outcome, and it’s the interaction of these three variables that creates the performance equation, as demonstrated by this new study. Your browser does not support the video tag. Running economy is how efficiently your body uses energy while running at a steady pace. The better your running economy, the less oxygen or effort you need to maintain a given speed. It’s like a car when it uses less fuel to cover the same distance at the same speed. That saved energy can help you go farther, feel fresher, or run slightly faster.To measure running economy accurately, we need to use lab tests. The runner wears a mask connected to a machine that tracks oxygen use while running in different shoes at the same speed. This is how Nike proved that the Vaporfly 4% reduced energy use by about 4%. By the way, a 4% gain in running economy means your body uses 4% less energy to run at the same pace. However, only part of that saved energy becomes speed. Some of it helps reduce fatigue or smooth your stride.

That’s why the real-world time gains are usually closer to 2 or 3%, as demonstrated by this study. This gap exists because the relationship between energy use and speed isn’t perfectly linear.Energy return and shock absorptionThe rise of energy return in modern foams has led some runners to confuse bounce with shock absorption. But these are two very different things.As you can see in the chart, there’s no strong correlation between energy return and shock absorption. Some shoes with high energy return also offer high shock absorption, but others don’t. That's a clear indicator that the two qualities don’t go hand in hand.Running shoes with the best energy return don't necessarily have the best shock absorption.We also see plenty of overlap around the 60–65% energy return range, with shock absorption values ranging from about 100 to over 160 SA. This confirms that shock absorption depends on more than just the foam’s bounce, as other design elements like geometry, stack height, and midsole width play a big role.Picking four random shoes is another simple way to show that there’s no direct correlation between the two. Shoe Energy Return (Heel - %) Shock Absorption (Heel - SA) Hoka Bondi 9 60.2 146 ASICS Gel Nimbus 27 47.7 136 Nike Streakfly 2 76.3 106 Adidas Pureboost 23 69.5 108 It's also quite interesting to see that energy return and shock absorption change a lot between running shoe categories. This chart reveals a nuanced relationship between energy return and shock absorption across different shoe types. As shoes shift from daily trainers to supershoes, energy return increases steadily, from around 56% in daily trainers to over 70% in racing shoes. This reflects the progressive use of more bouncy foams like PEBA or A-TPU. Shock absorption also improves, but the trend is less steep and more irregular.In mid-tier shoes like those in the tempo category, shock absorption lags behind energy return slightly, hinting at a possible tradeoff when brands aim to balance weight, cost, and performance. Therefore, while energy return and shock absorption can rise together, their relationship is not strictly linear and depends heavily on foam quality.

Energy return and stack heightThis scatter plot clearly shows that stack height and energy return aren’t strongly linked. In fact, some shoes with towering 40 mm midsoles deliver under 55% energy return, while others with more moderate stacks come close to 80%.So it's very clear that thickness alone isn’t the key, and what really matters is the foam itself. The material, its formulation, and how it's engineered make the biggest difference in bounce and responsiveness. That’s why a 28 mm shoe with a PEBA midsole can easily outperform a 45-mm model packed with standard EVA in terms of energy return.The key role of energy return in modern supershoesChances are that if you ran a race in 2017, most shoes around you were red, as almost every serious runner was wearing the Nike Vaporfly 4% Flyknit. Fast forward to 2019, and the scene turned green and pink with the Nike Vaporfly Next%. But now, almost every brand offers a supershoe with comparable (or even better) performance.If you have a good memory and consider yourself a running shoe geek like us, you might remember how some brands rushed to counter Nike with lightweight models featuring carbon plates—like the Adidas Adizero Pro (not to be confused with the Adizero Adios Pro) or the Hoka Carbon X 3. But those early attempts didn’t work at all, the legs still felt trashed during and after marathons and times weren’t dropping at all.The Carbon X 3 had the looks and the carbon plate but missed out on a true superfoam.This shows that modern superfoams with high energy return are essential in today’s supershoes. When Adidas launched Lightstrike Pro or ASICS developed FF Turbo, suddenly you looked around during races and saw more options than just Nike. And elite marathoners started to post Vaporfly-like times.But even in 2025, we still don’t fully understand why supershoes are so effective. However, what studies have shown is that a true supershoe combines three elements: a foam with high energy return, a stiffening agent (usually a carbon plate), and lightweight construction. In other words—energy return alone won’t make you faster.Lighter running shoes usually have more energy return.

But, why?One of the best parts of testing hundreds of shoes at RunRepeat is uncovering trends from real data—and one of the clearest is that lighter shoes often deliver higher energy return.But that doesn’t mean simply reducing weight will make a shoe bouncier. What really happens is that supershoes usually feature advanced foams like PEBA or A-TPU, which are both lighter and more responsive than EVA.At the same time, it’s important to remember that lower weight alone still brings benefits. It won’t boost energy return, but it can improve running economy—shaving 100g from a shoe is widely linked to a ~1% gain.Does your strike pattern matter for energy return?Yes, it does. Aside from Altra and a few niche brands, nearly every running shoe on the market is built with a higher heel than forefoot. That might make you assume there’s more foam in the heel. Well, it depends.Take the Adidas Prime X 2 Strung as an example. We found in the lab that it stacks up with 45.7 mm in the heel and 36.9 mm in the forefoot, creating an 8.8 mm drop. However, its platform tells a different story: the forefoot is 115.2 mm wide, while the heel is just 81.6 mm. So the forefoot may be shorter in height, but its width gives it more foam to store and release energy.Let's take a look at this chart. It shows a strong correlation between heel and forefoot energy return—when one is high, the other tends to be as well. Also most shoes deliver slightly better energy return in the forefoot, which makes sense given how important push-off is during running.Interestingly, we also found more variability in the mid-range segment, where some shoes show a noticeable imbalance between heel and forefoot performance. Meanwhile, the top-performing superfoams maintain consistently high energy return across the entire midsole, highlighting how premium materials deliver more uniform rebound for both landing and propulsion phases.Heel strikersWhile it’s not the natural way of running for the human body, heel striking is incredibly common, especially at slower paces.

In fact, a broad 2021 meta-analysis found that 79% of runners use a rearfoot strike early in races—and that number climbs to 86% as the run goes on, since fatigue often shifts footstrike patterns.Most high energy-return shoes come with well-cushioned heels, which means they absorb a lot of impact when your foot lands. But what happens to that energy? Ideally, the foam would bounce back and help roll your foot forward. In reality, much of that rebound happens while the foot is still transitioning to midstance, so not all of it helps you move ahead.That’s why many modern shoes have a noticeable rockered shape, something we also measure in our lab and that we’ve already covered in a guide. You can see this in models like the HOKA Cielo X1 for road running or the Adidas Terrex Agravic Speed Ultra for trail—both designed to convert heel impact into forward momentum rather than letting it sink.Another key factor is timing and pronation control. When a heel striker lands and compresses the foam, the foot is flexing and the midsole starts to deform. If the foam is too soft, the heel might sink too deep. If the shoe also lacks stability, that can lead to overpronation or a shaky transition. This not only wastes energy through unwanted lateral motion, but it may also increase injury risk. That’s why for heel strikers, a high energy return only matters if the shoe supports a stable heel-to-toe transition. Your browser does not support the video tag. So, what should you look for in a high-energy-return running shoe? If you’re a heel striker, we strongly recommend choosing a model with a supportive heel counter—rated 3-out-of-5 or higher in our lab—avoiding ultra-soft foams, and probably going for an average or wide heel width. Two solid examples are the ASICS Superblast 2 and the Adidas Adizero EVO SL—both offer higher-than-average energy return and heel counters that provide added support.Midfoot / Forefoot strikersMidfoot or forefoot striking usually results in shorter ground contact and more ankle compliance at landing—since the heel barely touches down, the calf and Achilles absorb much of the impact. Therefore, a good shoe for forefoot runners should work with the natural recoil of the Achilles tendon.