Thick or thin? Walk into any outdoor shop and you’ll hear both: more foam saves your legs on long days, or less foam makes your feet stronger. I wanted a straight answer for hikers, so I went back to the research and to the podiatrists and physical therapists who have already answered our questions about footwear.
The short version: sole thickness matters less than the weight that comes with it, how well the shoe fits, and how ready your feet are for it. Below is what the studies show, where they stop, and how to choose.
OutdoorAdept note: An earlier version of this page reported a 2023 field test with 22 hikers. When we re-audited it in November 2026 we could not verify its raw data: the published numbers follow patterns that real trail measurements do not produce. We have withdrawn that study and rebuilt the page on published research and named experts. Our editorial standards explain how we handle corrections.
What Sole Thickness Actually Means
Brands call it stack height: the total material between your foot and the ground, measured at the heel and at the forefoot. The difference between the two is the drop. Stack height and drop are given in millimeters by convention.
Stack height is measured at the heel and at the forefoot; the drop is the difference between them. Diagram: OutdoorAdept
Category limits as used in our barefoot shoes guide. Zero drop is a separate question: the Lone Peak and Olympus are both zero drop.
We measure our test pairs with a digital caliper instead of relying on the spec sheet. Photo: OutdoorAdept
Weight on Your Feet Costs More Than Weight on Your Back
This is the best-established finding in the whole debate. In a backpacking study by Legg and Mahanty (Ergonomics, 1986), men walked with a pack of 35% of their body weight in boots of increasing weight. Every extra 3.5 oz100 g of boot raised their oxygen cost by about 0.96%. Adding the same weight to the pack raised it by only 0.15%, which makes weight on the feet about 6.4 times as expensive.
Thick soles are not always heavy, but more foam and more rubber usually add weight. Over a long day, that weight is a more reliable source of fatigue than the thickness itself. Our footwear leaderboard lists the weight of every pair we test, so you can compare like for like.
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Does More Cushioning Reduce Impact?
Not as much as the marketing suggests. The research is on runners, not hikers, so treat it as a direction rather than a rule, but the two best-known studies point in different directions for a reason.
Law and colleagues (Journal of Sports Sciences, 2019) built one test shoe in midsole thicknesses from 1 to 29 mm. The thinnest versions (1 and 5 mm) raised vertical loading rates compared with 25 and 29 mm.
Kulmala and colleagues (Scientific Reports, 2018) compared a conventional running shoe with a maximalist one. In the maximalist shoe, impact peaks were 6.4% higher at an easy pace and 10.7% higher at a faster pace, because runners stiffened their legs on landing.
Put together: going from almost no sole to a normal sole softens loading, but piling on more foam after that does not keep helping, and can even make your legs land harder. Our panel explains why.
Dr. Ashley Katzenback describes the foot as “a richly innervated sensory organ critical for postural control and locomotion” in our barefoot shoes guide. The better your brain can feel the ground, the better it organizes each step. In her view, thick padding blunts that signal, and with it the warning that your feet are getting tired.
Thicker Soles and Ankle Stability
Height under the foot also changes how an ankle reacts when it rolls. Ramanathan and colleagues (Foot and Ankle Surgery, 2011) tipped 38 people’s feet into a sudden 20-degree roll in a barefoot condition, a standard shoe, and shoes with 25 and 50 mm soles. The muscle that fights an ankle roll, the peroneus longus, had to work harder as the sole got thicker. The authors warn that a thick sole raises the risk of a lateral ligament injury once that response is overwhelmed.
A Georgia State thesis by Ahn (2020) found a similar trade-off for slips: thicker soles made the first recovery step less stable. Neither study used hiking boots on a trail, but both matter on rocky ground, where an ankle roll is the most common footwear-related problem.
Dr. David A. Laurino DPM, Marvel Foot & Ankle Centers
“These shoes don’t reduce load, they relocate it.”
Dr. Laurino said this about thin barefoot shoes, and it works in both directions. A thin sole moves load away from the knee toward the ankle, Achilles and the bones of the forefoot. A thick sole does the reverse. Neither removes it.
What About Your Knees on the Way Down?
Descents are where knees take the most load. In a study by Kuster and colleagues (Journal of Bone and Joint Surgery, 1997), peak force in the knee joint averaged 3.9 times body weight on level ground and 8 times body weight walking downhill.
Cushioning can help some knees. In a double-blind trial (Sensors, 2023), 26 people with knee osteoarthritis wore cushioned sport shoes for three months and 12 wore identical shoes without the cushioning. Pain went down and function went up in the cushioned group only. If you hike with arthritic knees, a cushioned shoe is a reasonable choice. If your knees are healthy, our guide to knee pain when hiking downhill covers what helps more: poles, strength and a shorter stride.
What Our Podiatrists and Physical Therapists Say
We put the cushioning question to five clinicians for our barefoot shoes guide, and to Dr. Ashley Katzenback again for our shin splints guide. They do not agree on everything, which is useful in itself.
Dr. Kelton Cullenberg PT, DPT, Steady State Health
“Barefoot shoes don’t make your feet stronger. Your feet get stronger when they’re forced to work hard.”
Dr. Ashley Katzenback PT, DPT, CMTPT, Cape Concierge Physical Therapy
“The biggest misconception about shin splints is that people think they can fix them with footwear. Footwear is a tool. Strengthening is the actual fix.”
Dr. Katzenback’s own pick for most of her patients is a zero-drop shoe with 24 mm of cushioning, what she calls “low cushion”. It is a middle ground, not a barefoot shoe.
How to Choose Sole Thickness for Your Hike
Your situation
Lean toward
Why
Long days with a heavy pack
Moderate stack, the lightest pair that fits
Weight on the feet costs about 6.4 times more than in the pack
Rocky, technical ground, ankle rolls in the past
Lower, more stable sole
Thicker soles made the ankle work harder after a sudden roll
Knee osteoarthritis
More cushioning
Cushioned shoes reduced knee pain in a three-month trial
Strong feet, used to minimal shoes
Thin or low cushion
Better ground feel; our panel sees fewer problems in adapted feet
New to hiking, or managing a foot injury
Supportive, moderate cushion
Dr. Menke and Dr. Cullenberg advise against a big load change here
Our summary of the studies and quotes above. It is a starting point, not a diagnosis.
Fit still matters more than any number on a spec sheet. Our guide on how to choose hiking boots covers sizing, toe room and break-in.
Switching to a Thinner Sole Safely
Every clinician on our panel said the same thing in a different way: the switch is where people get hurt. The steps they gave us for barefoot shoes work for any move to a lower stack:
Wear the new pair around the house first, with no exercise in it (Dr. Laurino).
Then short walks on flat, even ground (Dr. Laurino, Dr. Menke, Dr. Pinker).
Then swap the shoes on your shortest, easiest outing of the week only, and keep everything else the same for about two weeks (Dr. Cullenberg).
Do foot and calf strength work alongside it. Our shin splints guide has Dr. Katzenback’s exercises.
Dr. Ashley Katzenback PT, DPT, CMTPT, Cape Concierge Physical Therapy
“Wearing barefoot shoes without strengthening your intrinsic/extrinsic muscles will likely lead to shin splints. Wearing barefoot shoes GRADUALLY while ALSO strengthening your muscles will help shin splints.”
If you have diabetes, poor circulation, a past metatarsal stress fracture or an unstable flat foot, talk to a podiatrist before going thinner. Our barefoot shoes guide lists who should not make the switch at all.
Not automatically. Thicker soles add weight, and every 3.5 oz100 g on your feet raised oxygen cost by about 0.96% in a backpacking study, 6.4 times more than the same weight in your pack. More foam also did not lower impact forces in a lab study of runners. A moderate, well-fitting sole usually beats a very thick or very thin one.
Do Thin Soles Make You More Tired?
They can at first, because your feet and calves do more of the work. Our panel sees that as training load, not a flaw: it builds strength if you switch gradually, and causes injuries if you switch too fast.
What Is a Good Stack Height for Hiking Shoes?
There is no single number. For reference, barefoot designs sit under about 15 mm, many trail runners and hiking shoes sit in the mid 20s, and max-cushion shoes start around 30 mm. Pick by terrain, load and how strong your feet are.
Is Cushioning Good for Knee Pain on Descents?
For people with knee osteoarthritis, one double-blind trial found cushioned shoes reduced pain over three months. For healthy hikers, poles, strength and a shorter stride on descents matter more than extra foam.
Melvin Claassen
Based in the Netherlands, and an avid outdoorsman, mountain addict, and hiking enthusiast. When he isn’t hiking, Melvin is passionate about running, trail running, hitting the dirt on his mountain bike, and scaling rock faces.
He has successfully climbed several peaks around the world, including Mt Taranaki and Pico Duarte. His deep-rooted passion for the outdoors and mountaineering helps inspire numerous people to hit the trails and fulfill their own adventurous spirit.
Dr. Ashley Katzenback
