Barefoot Shoes Studies: Effects on Foot Strength and Health?

Wearing minimalist or “barefoot” shoes does strengthen the feet. A systematic review of the research found that intrinsic foot muscle strength increased between 9% and 57%, while muscle size grew between about 7% and 11%, depending on the study and the measurement used.¹ But strength gains are only part of a much larger picture that includes changes to your arches, gait, tendons, balance, and injury risk. The evidence is encouraging in some areas and cautionary in others, and the speed of your transition matters more than most people realize.

What Happens to Foot Muscles

Your feet contain dozens of small muscles that conventional shoes largely do the work for. Thick soles, arch supports, and rigid midsoles brace the foot so those muscles rarely fire at full capacity. Minimalist shoes strip away most of that support, forcing intrinsic foot muscles to stabilize the arch and control the toes with every step. The systematic review cited above pooled results from multiple trials and found consistent gains in muscle cross-sectional area and thickness after weeks to months of minimalist shoe use.¹ The authors noted that simply wearing the shoes during daily activities could be more practical than dedicated foot-strengthening exercises, because the stimulus is built into every step rather than requiring a separate workout.

Arch Structure Gets Stiffer and Higher

One of the more striking findings in this field comes from comparisons between populations that habitually wear minimal footwear and those that wear conventional shoes. In a cross-population study, people who regularly wore minimal footwear had arches that were about 9% higher and 27% stiffer than those of conventionally shod participants. Only 1% of the minimally shod group had low arches, compared with 31% of the conventional group.² A stiffer arch stores and returns energy more efficiently during walking and running, which may explain part of the performance benefits some runners report.

A separate intervention study tracked runners who switched to minimalist shoes and found that longitudinal arch stiffness increased by roughly 60% in the minimalist group over the study period, while a control group wearing conventional shoes showed no change.³ These are not small differences. The arch essentially becomes a firmer spring, which has downstream effects on how the rest of the leg absorbs and transmits force.

How Minimalist Shoes Change Your Gait

When you put on a shoe with little or no heel-to-toe drop and minimal cushioning, your body reflexively adjusts how your foot meets the ground. Research shows that minimalist footwear shifts runners toward a more plantarflexed foot strike, meaning the forefoot or midfoot lands first rather than the heel.⁴ This change is not all-or-nothing; minimalist shoes produce a foot-strike pattern that falls somewhere between barefoot and traditional shoes. The lower the heel height and the less cushioning, the closer the gait resembles true barefoot running.⁵

This shift redistributes forces through the leg. Ankle joint demands increase while knee joint demands tend to decrease. One study looking at barefoot running across different surfaces found ankle moments rose by 5% to 26% while knee moments dropped by up to 11%.⁶ That tradeoff is the fundamental bargain of minimalist footwear: you offload the knee but ask more of the foot, ankle, and calf.

The Transition Problem

This is where the research gets uncomfortable for barefoot shoe enthusiasts who want to switch overnight. Your bones, tendons, and muscles need time to adapt to the new loading pattern, and the consequences of rushing are well documented.

An MRI-based study found that after just ten weeks of running in Vibram FiveFingers, over half the participants in the minimalist group showed increased bone marrow edema in at least one foot bone, a precursor to stress fractures. The control group showed significantly less of this.⁷ Case reports describe experienced runners with no other risk factors developing metatarsal stress fractures within weeks of switching to barefoot-simulating shoes.⁸

A 12-week trial comparing neutral shoes, partial minimalist shoes, and full minimalist shoes found that the partial minimalist design actually produced the highest injury rate, with shin and calf pain being particularly common in the full minimalist group.⁹ A prospective comparison between barefoot and shod runners found fewer total injuries per runner in the barefoot group, but the barefoot runners also ran significantly fewer miles, making direct injury-rate comparisons inconclusive.¹⁰

A systematic review of transition protocols found that most studies increased minimalist shoe exposure up to an average of about 60% of total running by the end of the transition period, but fewer than half included injury prevention exercises and fewer than half included gait retraining.¹¹ The takeaway from the transition literature is blunt: go slowly, and consider supplementing with calf and foot strengthening work during the changeover.

What Happens to the Achilles Tendon

Because minimalist shoes shift more work to the calf and ankle, the Achilles tendon bears substantially more load. Over time, this can be a good thing. A cross-sectional study found that habitual minimalist runners had thicker, stiffer Achilles tendons that could handle greater stress than those of traditionally shod runners.¹² A 12-week training study confirmed that minimalist shoe running increased mechanical loading of the Achilles tendon and improved its energy storage and release properties.¹³

However, a separate 12-week study found that while the mechanical loading of the tendon changed, the actual structural adaptation of the tendon had not yet caught up in that time frame.¹⁴ The loading increases before the tissue remodels, and that gap is when injuries happen. A survey of officers transitioning to minimalist footwear or barefoot walking found that about 23% reported Achilles strain, and plantar fasciitis was even more common, present in roughly 56% of those who had transitioned compared with 18% of those who hadn’t.¹⁵

Plantar Fascia Under New Demands

The plantar fascia, the thick band of tissue along the bottom of your foot, works harder in minimalist shoes. Barefoot running produces greater toe extension at push-off, which stretches the plantar fascia more than shod running does.¹⁶ An elastography study found that habitual forefoot strikers, the landing pattern minimalist shoes encourage, had less elastic plantar fascia tissue, making it more susceptible to overstrain.¹⁷ The researchers specifically recommended that forefoot strikers strengthen their foot muscles to protect the plantar fascia, which aligns with the broader theme: the strength gains minimalist shoes produce may be partly a necessary defense against the new stresses they impose.

Balance and Fall Prevention in Older Adults

One of the more promising areas of minimalist shoe research is in older adults at risk of falling. A randomized trial of people with a history of falls found that wearing minimal shoes improved postural stability during standing (measured by center-of-pressure sway) and walking stability compared with conventional supportive shoes. Stability in minimal shoes was comparable to being barefoot for standing, and actually better than barefoot for walking.¹⁸

A longer-term trial followed older adults for a full year. The minimal footwear group improved on a validated fall-risk assessment by an additional 2.6 points compared with the control group at one year. While the difference in actual falls did not reach statistical significance, the numbers trended in a meaningful direction: about 35% of the minimalist shoe group experienced at least one fall over the year, versus about 59% in the control group.¹⁹ Biomechanical analysis of why minimal shoes help with walking stability pointed to changes at the hip, specifically increased hip rotation at heel strike, rather than changes at the foot or ankle.²⁰

For younger adults, a four-week trial found that walking in minimalist shoes improved static single-leg balance, with improvements that continued even after the intervention ended.²¹ One nuance worth noting: a separate study found that for dynamic balance tasks, textured insoles inside conventional shoes actually outperformed both minimalist shoes and barefoot conditions, suggesting that sensory feedback to the sole matters but can be delivered in more than one way.²²

Children’s Feet Respond Quickly

Children’s developing feet may be especially responsive to footwear choices. A study of primary school students who wore minimalist shoes daily to school found significantly increased muscle size in two key intrinsic foot muscles, stronger toes, higher arches, and even improved standing long jump distance compared with a control group in standard school shoes.²³ A different randomized trial in children found increases in muscle size and toe strength from moderately minimalist shoes, but the differences did not reach statistical significance in that sample.²⁴ The discrepancy might come down to how minimal the shoes actually were, since “minimalist” is a spectrum rather than a single product category. Still, the overall direction of the evidence is that less structured footwear during childhood allows foot muscles and arches to develop more robustly.

Running Economy and Shoe Weight

If minimalist shoes strengthen the foot and change the gait, do they make you a more efficient runner? A meta-analysis of controlled trials found a small but statistically significant advantage in running economy for minimalist shoes over conventional shoes.²⁵ A more recent systematic review with meta-analysis also found significant improvements, with the effect being larger for minimalist shoes compared with shod running than for barefoot compared with shod.²⁶ Shoe mass is a significant factor: lighter shoes consistently improve metabolic cost.

However, when researchers tested whether training in minimalist shoes over time improves economy even when tested in conventional shoes, the results were less clear. One randomized trial found small to moderate effect sizes favoring the minimalist training group, but the differences were not statistically significant.²⁷ In other words, some of the economy benefit disappears when you put conventional shoes back on, suggesting the advantage comes partly from wearing lighter shoes in the moment rather than from lasting changes to your running mechanics.

Knees and Osteoarthritis

The gait shift that minimalist shoes produce, with less knee loading and more ankle loading, has attracted interest from researchers studying knee osteoarthritis. Studies have examined whether minimalist footwear could reduce the external knee adduction moment, a biomechanical measure linked to the progression of medial knee osteoarthritis. Research in older women with knee osteoarthritis has investigated the mechanisms behind reported reductions in this knee load when wearing minimalist footwear long-term.²⁸

But the picture is not straightforward. A study examining different footwear types and knee biomechanics found that walking in minimalist footwear without sufficient accommodation, meaning without enough time for the body to adapt, could actually affect kinetic and kinematic parameters in ways that increase the risk of early knee osteoarthritis development.²⁹ The familiar theme of gradual transition surfaces again: what helps in the long run can hurt during the adjustment period.

Toe Shape and Narrow Shoe Damage

Separate from the minimalist-versus-cushioned question is the matter of toe-box shape. Most conventional shoes taper to a point at the front, squeezing the toes together. An anatomical study found that wearing constrictive V-shaped toe-box shoes, even only occasionally, changed hallux (big toe) alignment from a young age and increased the prevalence of bony growths on the toe, likely from friction against the shoe’s inner wall.³⁰ Cross-population comparisons between habitually shod and unshod groups have found significant differences in hallux angle and the spacing between the big and second toes.³¹

Many barefoot shoe brands emphasize wide toe boxes as a core feature, and for good reason. However, a study of older women with hallux valgus (bunions) found that toe-box shape and fit were not associated with increased medial forefoot pressures in their sample, suggesting that once bunions have already formed, simply switching to a wider shoe may not change the pressure dynamics as much as people hope.³² Prevention and treatment may be different conversations.

Why the Surface You Walk On Matters Too

Most minimalist shoe studies are conducted on treadmills or flat pavement, but surface stiffness interacts with footwear in ways that matter. Research on barefoot running across surfaces of different hardness found that the gait adjustments people make in minimal footwear, like greater plantarflexion, were amplified on harder surfaces. Ankle muscle demands increased on harder ground, while knee demands decreased. The effects of surface stiffness were stronger in barefoot running than in shod running, because cushioned shoes blunt the feedback from the ground.⁶

A meta-analysis found that peak tibial acceleration, a measure linked to stress injuries of the shin bone, was significantly lower on softer surfaces.³³ If you are running in minimalist shoes and worried about impact-related injuries, choosing softer terrain like grass, trails, or rubberized tracks can provide some of the shock absorption your shoes are not offering. It also increases the stimulus to the intrinsic foot muscles, since uneven terrain demands more stabilization work.

Loading Rates and the Cushioning Debate

One of the original selling points of barefoot running was that a forefoot strike avoids the sharp impact spike of a heel strike, reducing the rate at which force hits the body. The evidence on this is surprisingly mixed. A systematic review found only limited evidence of differences in loading rates among barefoot, minimalist, and shod conditions.³⁴ A comparison of minimal, traditional, and maximal shoes found that loading rate was greater in the minimal shoe than in the maximally cushioned shoe, but no other ground-reaction-force differences emerged.³⁵ The narrative that minimalist shoes reduce impact by encouraging a forefoot strike oversimplifies what actually happens. Forces get redistributed, but they do not disappear. Whether the redistribution is beneficial depends on which tissues you are most worried about and whether those tissues have had time to adapt.