More cushion is not automatically better for running. In fact, research shows that maximally cushioned shoes can increase impact forces on your body rather than reduce them, which is the opposite of what most runners expect. The relationship between cushioning and performance is more nuanced than shoe marketing suggests, and the “right” amount depends on what you’re trying to optimize: comfort, speed, injury prevention, or stability.
Why Extra Cushioning Can Increase Impact
The biggest surprise in cushioning research is that thick, soft midsoles don’t necessarily absorb more shock. A study published in the Orthopaedic Journal of Sports Medicine compared maximalist shoes (the thickly cushioned kind) to traditional neutral shoes before and after a 5K run. Runners in the maximalist shoes hit the ground harder, with impact peaks of 1.76 times their body weight compared to 1.58 in neutral shoes. The rate at which force loaded onto their legs was also about 33% higher in the maximalist shoes.
This held true both before and after the 5K, meaning fatigue didn’t change the pattern. Heel-strikers showed the effect most clearly: they landed with greater force and faster loading rates in the cushioned shoes compared to traditional ones.
Why would softer shoes produce harder impacts? Your body adjusts its landing mechanics based on what it feels underfoot. When you sense a thick, soft platform beneath you, you tend to land with a straighter leg and strike the ground more aggressively, as if your neuromuscular system is trying to “find” the ground through all that foam. The cushion compresses, but your leg compensates by being less compliant, so the net force your skeleton absorbs stays the same or even increases. Researchers call this the “shoe cushioning paradox.”
What Actually Makes Modern Shoes Faster
If raw cushion thickness isn’t the key, why are today’s thickly soled racing shoes breaking records? The answer is less about cushioning and more about energy return and shoe geometry. A systematic review and meta-analysis in Frontiers in Sports and Active Living found that carbon-plated shoes with advanced foam reduced metabolic demand by roughly 2.75%, with individual studies showing improvements ranging from about 1% to 4.5%. That translates to real time savings: a 2.75% improvement could shave more than a minute off a 40-minute 10K.
Two features drive most of that benefit. First, the foam itself matters more than its thickness. PEBA-based foams (the material in most elite racing shoes) return around 76 to 78% of the energy your foot puts into them. Traditional EVA foam returns only 40 to 65%. So a thinner layer of PEBA can outperform a thicker slab of EVA. Second, a curved carbon plate embedded in the midsole acts like a lever, helping your foot roll forward more efficiently. Research suggests the plate and the foam each contribute roughly similar gains in running economy.
In other words, a shoe can be thick and fast, but the speed comes from what the cushion is made of and how the shoe is engineered, not from stacking more material underfoot.
The Stability Tradeoff
Every millimeter of stack height raises your foot further from the ground, and that creates a longer lever arm for your ankle to roll. Shoes with stack heights above 36mm tend to feel squishier and less stable, particularly on turns, uneven surfaces, or when you’re fatigued and your form breaks down. This is why World Athletics caps competition shoe thickness at 40mm for road races and 20mm for track spikes.
Shoe companies have started engineering around this problem with wider bases, flared midsoles, and beveled heels that provide what some brands call “adaptive stability.” These features can help, but they add complexity and weight. The fundamental physics remain: a taller platform is inherently less stable than a lower one. If you run on trails, do speed work with sharp turns, or have a history of ankle sprains, a maximally cushioned shoe introduces risk that a lower-profile option wouldn’t.
How Your Body Adapts to Different Cushion Levels
Research on leg stiffness across shoe types reveals something important about how your body self-regulates. When runners wore minimalist shoes (very little cushion), they ran with stiffer legs, shorter ground contact, and higher loading rates. But when they switched between traditional and maximalist shoes, their leg stiffness and overall strategy stayed remarkably similar. The body didn’t become meaningfully more relaxed or compliant just because there was more foam beneath it.
This suggests your musculoskeletal system has a preferred stiffness setting for a given speed, and it adjusts leg mechanics to maintain that setting regardless of how much cushion the shoe provides. Extra foam changes where the compression happens (more in the shoe, less in your joints), but the total system behavior is largely preserved. For most runners, the perceived softness of a maximally cushioned shoe is real in terms of comfort, but it doesn’t necessarily translate into reduced skeletal loading.
When More Cushion Helps
None of this means thick cushioning is bad. There are clear situations where more foam underfoot is genuinely useful:
- Long, slow runs on pavement. When you’re running for two or more hours at easy pace, comfort matters. A softer ride can reduce the perception of fatigue in your feet and lower legs, even if the measurable impact forces are similar.
- Heavier runners. Runners carrying more body weight compress foam faster and more completely. A shoe that feels moderately cushioned to a 130-pound runner may bottom out for someone at 200 pounds. In that case, more material provides a functional buffer.
- Runners with joint pain or arthritis. If you have knee or hip pain that worsens with running, a cushioned shoe can change the feel of each footstrike enough to keep you running comfortably, even if the biomechanical forces are comparable.
- Recovery runs. Many competitive runners use maximalist shoes for easy days specifically because the soft landing feels forgiving when their legs are tired from hard training.
When Less Cushion Helps
Lower-profile shoes have their own advantages, particularly for runners who want better ground feel and stability:
- Speed work and intervals. A firmer, lower shoe gives you a more direct connection to the ground, which helps with quick turnover and precise foot placement.
- Trail and technical terrain. Less stack height means a lower center of gravity and better proprioception, both of which reduce ankle roll risk on rocks and roots.
- Building foot and lower leg strength. Running in less cushioned shoes forces your foot muscles and Achilles tendon to do more work, which can strengthen those structures over time.
Transitioning Between Cushion Levels
If you want to move toward either more or less cushion than you’re used to, do it gradually. Research on footwear transitions suggests increasing your time in the new shoe by about 5% of your weekly running each week. At that rate, you’d be fully transitioned in roughly 20 weeks. That sounds slow, but abrupt changes in shoe cushioning alter how forces distribute through your feet, shins, and knees, and your tissues need time to adapt.
A practical approach is to start wearing the new shoes for one short, easy run per week, then add volume over several months. Keep your current shoes in rotation during the transition. This is especially important when moving to less cushioning, since the higher loading rates associated with minimal shoes can stress your Achilles tendon and metatarsals if you ramp up too quickly.
Choosing the Right Amount of Cushion
Rather than defaulting to the most cushioned shoe on the shelf, consider matching cushion level to the type of run. Many experienced runners rotate between two or three shoes: a well-cushioned trainer for easy and long runs, a lighter and firmer shoe for tempo and interval work, and a racing shoe with high energy-return foam for competition. This rotation also extends the life of each pair, since no single shoe accumulates all your mileage.
When evaluating a shoe, pay less attention to how thick the sole looks and more attention to how the foam performs. A 35mm midsole made of PEBA-based foam will feel livelier and return more energy than a 40mm slab of basic EVA. Stack height is one number. Energy return, weight, stability features, and how the shoe matches your foot strike pattern all matter at least as much. The best cushioning for your running is the amount that keeps you comfortable, stable, and injury-free at the paces and distances you actually train.