Substance and claimed effects

Barefoot shoes are a footwear category defined by three design constraints: zero heel-to-toe drop (the heel sits at the same height as the forefoot, versus the 8–12 mm drop typical of running shoes and the 20+ mm drop typical of dress and work shoes), a wide and anatomically shaped toe box (foot-shaped rather than tapered, allowing the toes to splay), and a thin, flexible sole with no arch support, no toe spring, and no midsole cushioning. Brands include Vivobarefoot, Vibram FiveFingers, Xero, Lems, Wildling, Be Lenka, and the somewhat-broader Altra (zero-drop and wide-toe but with conventional cushioning). The category sits on a spectrum: a "true" barefoot shoe has a 3–6 mm flexible sole; a "minimalist" running shoe has more cushion and a 0–4 mm drop. The claimed effects this entry covers, holistically: intrinsic foot muscle hypertrophy and toe-flexor strengthening, partial reversal of acquired arch collapse, a shift in walking and running gait (more forefoot/midfoot strike at speed, shorter stride, higher cadence), reduced peak knee adduction and patellofemoral loading at the cost of higher Achilles and plantar-flexor loading, improved static and dynamic balance via plantar mechanoreception, and toe-splay recovery / hallux valgus prevention. The transition period (typically 3–12 months) is itself a major editorial topic — the published injury literature is dominated by people who skipped it.

Evidence by addressing question

Mechanism

Science. The intrinsic foot muscles — abductor hallucis, flexor digitorum brevis, quadratus plantae, the lumbricals, and the four layers running between the metatarsals — are the muscular component of the foot's arch support and toe control. A cushioned arch-supported shoe substitutes for these muscles mechanically; they atrophy when not loaded, the same way any unloaded muscle atrophies. Cross-sectional imaging in habitually-shod versus habitually-unshod populations shows the difference clearly: intrinsic foot muscle cross-sectional area is larger in habitually-barefoot adults, arch height is generally preserved or higher, and foot width across the metatarsal heads is greater D'Aout 2009. In children, growing up barefoot produces measurably different foot morphology by age 6–18 — wider forefeet, higher arches in some metrics, and toes that point more straight ahead rather than being squeezed toward the midline Hollander et al. 2018.

The acute mechanism of a thin, flexible, zero-drop sole is twofold. First, removing the heel lift changes the foot's resting angle at the ankle, which propagates up the chain: less anterior pelvic tilt, less knee flexion at midstance, different hip mechanics. Second, removing the arch support and midsole forces the intrinsic muscles to do the load-bearing work they were doing before shoes were invented. A 2019 RCT randomized adults to walk in minimalist shoes for 8 weeks at incrementally increased durations versus a control group that wore conventional shoes; the minimalist group's intrinsic foot muscles increased in volume by amounts equivalent to a structured foot-exercise program, with no exercise prescription needed — just walking Ridge et al. 2019. A follow-up showed similar gains from minimalist daily-wear in a free-living population over 6 months Curtis et al. 2021.

Mechanism — gait. A habitually-shod heel-striking runner lands with the calcaneus first, transmitting a sharp impact transient (the rapid 1.5–3× bodyweight spike in the vertical ground reaction force) through the ankle, knee, hip, and spine. The cushion in a conventional running shoe attenuates the felt impact but the impulse still propagates. Habitually-barefoot runners — studied across populations from Kenyan Kalenjin to Tarahumara to instrumented treadmill cohorts — overwhelmingly land on the forefoot or midfoot, dorsiflexing the ankle to receive the load through the elastic Achilles–calf system rather than the bony heel Lieberman et al. 2010. The forefoot strike pattern eliminates the impact transient. This is the central mechanistic argument of the barefoot-running literature, and it generalises to walking only partially: most walking is heel-strike regardless of footwear, but the heel-strike is gentler in a flat, thin-soled shoe than in a cushioned heeled one.

Mechanism — knee and back. Heel-lift in a conventional shoe shifts the ground reaction force vector relative to the knee joint, increasing the external knee adduction moment (a well-validated proxy for medial-compartment knee loading and a risk marker for knee osteoarthritis progression). An instrumented study of walking in conventional running shoes versus barefoot in adults with knee OA found 11–12% higher knee adduction moments with shoes Kerrigan et al. 2009. The effect generalised to healthy adults as well. The back-loading story is less developed: forefoot-strike running reduces lumbar loading impulse versus heel-strike running, and zero-drop shoes flatten the pelvic tilt that high-heel and modest-heel footwear induces, but no large clinical trial has demonstrated low-back pain reduction from a footwear change alone.

Mechanism — balance. The sole of the foot is densely populated with cutaneous mechanoreceptors (Meissner corpuscles, Pacinian corpuscles, Merkel cells, free nerve endings) feeding rapid proprioceptive signal to the central nervous system about ground contact, slope, and texture. A 15 mm cushioned EVA midsole acts as a low-pass filter on this signal. A trial in older adults at fall risk found that switching to minimal footwear improved static balance and reduced sway during dynamic tasks, attributed to restored mechanoreceptive input Cudejko et al. 2020.

Evidence

Foot strengthening — the cleanest finding. Multiple RCTs and prospective cohort studies show that wearing minimalist or barefoot shoes for daily activities produces measurable hypertrophy of the intrinsic foot muscles within 8 weeks to 6 months, with effect sizes comparable to a structured foot-exercise program Ridge et al. 2019 Miller et al. 2014 Curtis et al. 2021. The mechanism is clean (load the muscle, it grows), the imaging is direct (ultrasound and MRI cross-sectional area), and the result has replicated. This is the strongest evidence claim in the barefoot category.

Gait changes. Forefoot strike rate in habitually-barefoot runners is ~75% versus ~5–25% in habitually-shod heel-strikers Lieberman et al. 2010. Shod runners can shift toward forefoot strike when running barefoot or in minimal shoes, but the shift is incomplete in shod runners wearing minimalist shoes — they tend to retain some heel-strike pattern, indicating that the shoe is only part of the gait input Bonacci et al. 2013. Cadence rises, stride length shortens, and contact time decreases in minimal shoes versus conventional shoes during running Squadrone & Gallozzi 2009. Walking changes are subtler: ankle joint range increases, toe push-off contribution increases, peak plantar pressure under the heel is lower Franklin et al. 2015.

Knee loading. Reduced peak knee adduction moments in barefoot versus shod walking, replicated across multiple labs, with effect sizes of ~10–15% Kerrigan et al. 2009. The clinical relevance — does this translate to reduced incident knee OA over decades? — has not been tested in an RCT and probably cannot be, since the population-scale randomisation would be infeasible.

Injury risk and transition. This is where the evidence gets uncomfortable for enthusiasts. A controlled 10-week transition study had adult runners transition from conventional to Vibram FiveFingers running shoes following the manufacturer's progression schedule. MRI at 10 weeks found that 10 of 19 runners in the minimalist group had developed bone marrow edema in the metatarsals, with two outright stress fractures — none in the control group Ridge et al. 2013. A clinical case series of minimalist runners presenting with injuries reported a distinct pattern: metatarsal stress fractures (especially second and third), Achilles tendinopathy, plantar fasciitis, and calf strain — injuries that map cleanly onto the new load pattern Salzler et al. 2012. A systematic review of long-term habitually-barefoot or minimalist runners (i.e., those past the transition) found lower rates of patellofemoral injury and lower-leg overuse than habitually-shod runners, but the populations are self-selected and the comparison group differs in many ways beyond footwear Hollander et al. 2017.

Performance. Six weeks of structured transition to minimalist running shoes improved running economy and 5 km time-trial performance versus controls in trained runners Fuller et al. 2017. This is a narrow performance question and the effect is real for runners who complete the transition, but it doesn't bear on the daily-wear use case.

Balance and falls. An RCT in older adults with a history of falls found improved standing balance, faster timed-up-and-go, and reduced sway during functional reach tasks after switching to minimal footwear, versus controls in conventional supportive footwear Cudejko et al. 2020. The mechanism is plausible (mechanoreceptor restoration), the effect is meaningful (the OR for falls in older adults is sensitive to balance metric improvements of this magnitude), and the population is one where the evidence is most directly actionable.

Protocol

Practice / clinical consensus. The published transition protocols from physical therapists working in the barefoot space share a common shape:

• Daily-wear transition (the relevant one for most adults): Start with barefoot time at home — walking around the house barefoot, ideally for 1–2 hours/day. Add barefoot-style shoes for short outings (errands, walks under 30 min) for 2–4 weeks. Extend to ~50% of daily wear over 1–3 months. Full transition (most of waking life) over 6–12 months. Keep cushioned shoes for prolonged standing on hard surfaces and long-walking days until the foot is ready.
• Running transition: Drop to 10% of usual running volume in minimalist shoes for week 1. Add ~10% per week, monitoring for forefoot soreness, calf tightness, and Achilles pain. A full transition takes 3–6 months minimum for habitual heel-strikers. Returning to conventional shoes after transition is fine; the foot adaptation persists.
• Concurrent foot work: Short foot exercises (towel scrunches, toe yoga, single-leg balance), calf eccentrics, and intrinsic-foot-muscle activation drills accelerate adaptation and reduce stress-injury risk during the transition window Ridge et al. 2019.

Manufacturer-printed transition schedules tend to be more aggressive than the clinical literature supports; the Ridge 2013 stress-fracture study used the Vibram-printed schedule and saw harm Ridge et al. 2013.

Contraindications

Practice / clinical consensus. Conditions where barefoot transition is contraindicated or requires medical supervision:

• Diabetic peripheral neuropathy. Loss of foot sensation means loss of the protective signal that prevents unnoticed injury; a small cut from gravel that a healthy foot would notice in seconds can become an ulcer. Cushioned, supportive footwear is the standard of care.
• Charcot foot (neuropathic arthropathy) — same reasoning, more severe.
• Active plantar fasciitis or Achilles tendinopathy — barefoot shoes increase load on exactly the structures that are inflamed. Treat the injury first, then transition.
• Recent foot or ankle surgery — defer until cleared by the operating surgeon.
• Severe pes planus (flat foot) with symptomatic posterior tibial tendon dysfunction — case-by-case; some symptomatic flat-footed adults benefit from minimalist transition (the intrinsic-strengthening rebuilds arch support actively), others worsen. Physical therapy guidance is appropriate.
• Pregnancy in the third trimester — ligamentous laxity from relaxin makes the foot more susceptible to overuse injury; not a hard contraindication, but a poor time to start a transition.

Misconceptions

• "Barefoot shoes are for running." Most of the daily-wear benefit (foot strengthening, gait, balance) accrues from walking, standing, and ordinary activity, not running. The running literature dominates the publication count, which warps perception Ridge et al. 2019 Curtis et al. 2021.
• "They'll fix my plantar fasciitis." Not during an acute flare. After resolution, they're a reasonable part of preventing recurrence; during, they generally make it worse.
• "You need arch support." The foot has an arch because of the muscles, bones, and ligaments holding it up — the shoe's arch is supplementary. Most healthy feet do not need passive support; the arch responds to active loading like any musculoskeletal structure Ridge et al. 2019. The exception is structural foot pathology where the arch system has failed (severe symptomatic pes planus, certain post-traumatic states).
• "Minimalist shoes = barefoot." Even thin-soled minimalist shoes don't replicate true barefoot biomechanics — runners in minimalist shoes retain more heel-strike pattern than runners actually barefoot, and the small amount of cushioning still attenuates ground feedback Bonacci et al. 2013.
• "The transition is fast." The Vibram-printed schedule (3–6 weeks for runners) produced bone edema and stress fractures at high rates Ridge et al. 2013. Realistic timelines for daily-wear adults are 6–12 months.
• "My feet are too far gone." Adult foot strength and arch metrics responded to minimalist training across age groups studied, including older adults at fall risk Cudejko et al. 2020 Curtis et al. 2021. The plasticity persists.

Failure modes

Practice / community. The pattern of "tried barefoot shoes, got hurt, gave up" is well-documented and almost always traceable to specific errors:

• Too much too fast. By far the dominant failure. Running 5K in Vibrams on day one, wearing them to a marathon expo for 6 hours of standing — the load jump exceeds what the deconditioned foot can tolerate Salzler et al. 2012.
• Hard surfaces with no acclimation. Concrete and tile transmit ground reaction force the foot has never had to absorb. Grass, trail, and indoor floors are gentler starting surfaces.
• Maintaining a heel-strike pattern in minimalist running shoes. The shoe is designed to be landed on flat or forefoot-first; landing on the heel of a thin sole at running speed punishes the heel directly. Many adopters never make the gait shift and suffer accordingly.
• Ignoring calf and Achilles signals. The plantar-flexor complex carries new load during transition; soreness escalating to sharp pain is the signal to back off, not push through.
• Skipping concurrent foot work. The transition is faster and lower-injury-risk when paired with explicit intrinsic-foot exercises rather than left to passive adaptation alone.

Practicalities

Cost. A pair of well-made barefoot shoes runs ~$90–180 USD; the category has a high-end (Vivobarefoot, Wildling) and a budget end (Xero, Be Lenka). A two- to three-pair rotation (a sneaker for daily wear, something dressier or boot-style for work/cold weather) is the realistic setup. Annual cost is comparable to or modestly above conventional shoe spending for someone who buys quality footwear.

Setting fit. A wide-toe, thin-soled shoe is a hard sell in many professional contexts; the dressier options (Vivobarefoot Ra, Vivobarefoot Geo, Lems Chillum) are passable but visibly different from a polished oxford. Boot-style barefoot options work better for cold-weather and rugged-terrain settings. Hard-floor retail workers and warehouse workers report mixed experience — some appreciate the toe room, others find the thin sole punishing on concrete for full shifts.

Sizing. Barefoot shoe sizing maps roughly to conventional sizes but the width and toe-box differences mean trying on (or careful measurement-based ordering with a known-good return policy) is important. Many brands publish foot-tracing templates for at-home sizing.

Payoff

Timeline. The published cross-sectional and longitudinal data give a rough timeline:

• Weeks 1–4. Calf and foot soreness, occasional sharp pain in metatarsal heads. Some people report immediate gait feeling (better posture, more grounded sense). Others find them uncomfortable. No measurable physiological change yet.
• Weeks 4–12. Intrinsic foot muscle volume measurably increases Ridge et al. 2019. Toes begin to splay. Calves and Achilles strengthen. Foot proprioception sharpens. Many adopters notice subjectively better balance.
• Months 3–6. Gait changes become habitual. Forefoot-strike pattern in running consolidates for those running in minimalist shoes Fuller et al. 2017. Knee and back complaints, where present and footwear-driven, often resolve.
• Year 1+. Foot strength stabilises at a new baseline. Toe splay continues to develop; in cases with mild bunion deformity, alignment can partially improve (often paired with toe spacers). Long-term habitually-barefoot adults show preserved foot strength into older age D'Aout 2009 Hollander et al. 2017.
• Decades. The longevity hypothesis — that maintained foot strength and balance reduce fall incidence in old age, with downstream impact on independence and mortality — is mechanistically plausible and supported by the Cudejko 2020 short-term balance data Cudejko et al. 2020, but no long-running cohort has tested it directly.

The credibility range

The optimist case

The optimist case is largely the mechanistic case, and it is unusually strong by the standards of consumer health interventions. The human foot evolved over ~6 million years of bipedal walking and running on natural surfaces; cushioned arch-supported footwear is roughly 50 years old at scale. The intrinsic foot muscles atrophy under unloading, the same as any unloaded muscle — the studied populations who don't wear shoes have stronger, wider, more functional feet, and the adults who switch from conventional to minimalist footwear gain measurable intrinsic muscle volume within 8 weeks Ridge et al. 2019 Curtis et al. 2021 D'Aout 2009. The downstream effects — gait change, knee unloading, restored balance — all have plausible biomechanical paths and are individually documented even if the long-term clinical endpoints aren't. For the older-adult falls case, the mechanism (restored plantar mechanoreception) is direct and the intervention is essentially free compared to the cost of one bad fall.

The community signal is also unusually consistent in shape: barefoot adopters who survive the transition tend to stay, report stable improvement in foot comfort and posture, and resist returning to conventional shoes. This is consistent with a real effect, not just placebo — people who tried it and didn't like it leave the population (selection), but the survival bias is partly informative because the "I lasted 3 months and felt nothing" failure mode is also reported and rare.

The skeptic case

The skeptic case has three legs. First, the injury data: the most-controlled transition trial showed bone marrow edema in over half the minimalist-shod group and frank stress fractures in 10% at 10 weeks — a serious harm signal for a wellness intervention Ridge et al. 2013. The clinical case series of minimalist-runner injuries describes a distinctive pattern (metatarsal stress fractures, Achilles tendinopathy, plantar fasciitis) that is genuinely caused by the intervention rather than being incidental Salzler et al. 2012. The transition is non-trivial and many people who attempt it fail in ways that leave them worse off.

Second, the long-term clinical endpoint data — does barefoot footwear reduce knee OA incidence, low back pain, or falls in randomised samples followed for years? — does not exist. The optimist case stacks plausible mechanism on plausible mechanism, but the chain of inference from "knee adduction moment 12% lower" to "lower OA incidence over decades" is not directly tested. Population-scale RCT is infeasible, and observational comparisons of habitually-barefoot versus habitually-shod populations are confounded by income, geography, weight, surface, and almost everything else.

Third, the population the trials actually study is narrow. Most of the intrinsic-foot-strength RCTs are in younger, healthier, often athletic adults. The general adult population includes people with diabetes, neuropathy, severe pes planus, prior foot surgeries, and structural pathologies for whom the conventional supportive shoe is the standard of care for good reasons. The barefoot literature does not address these subgroups directly, and the enthusiastic community sometimes flattens these distinctions.

The author's call

Barefoot shoes are a real intervention with a clean mechanism, replicated short-term physiological effects (foot strengthening, balance), and a transition period that is the dominant source of harm and the dominant editorial topic. For a healthy adult willing to do a patient 6–12 month transition, the upside is genuine and the downside is recoverable. The injury literature is mostly a story of skipped transitions, not an indictment of the intervention. The long-term clinical outcomes are mechanistically supported but unproven. evidence: 3 reflects the strong short-term physiology evidence and the weaker long-term clinical evidence; controversy: 3 reflects the genuine field disagreement (podiatry sceptics vs. evolutionary-biology enthusiasts) and the loud community on both sides.

Stakeholder and incentive map

• Commercial — barefoot brands. Vivobarefoot, Vibram, Xero, Lems, Wildling, Be Lenka. Industry size is modest (sub-$1B globally) but growing. Marketing leans on evolutionary framing and felt-experience testimonials.
• Commercial — conventional footwear industry. Massive ($100B+ globally). Strong incentive to maintain the "support and cushion" frame that justifies high-margin features. Athletic shoe brands have hedged with minimalist sub-lines (Nike Free, Adidas Adipure) but the core lineup remains heavily cushioned.
• Clinical — podiatry. Mixed and shifting. Older podiatric guidance emphasised arch support; the profession has become more nuanced as the foot-strengthening literature matured. Custom orthotics is a meaningful revenue stream that creates a minor structural conflict with the barefoot frame, though most podiatrists today distinguish between cases that need orthotics (structural pathology) and cases that don't (deconditioning).
• Clinical — sports physical therapy. Generally favourable, especially for the foot-strengthening and balance-restoration cases. PT clinics specialising in foot/ankle and running gait have been early adopters.
• Community — running. The 2009–2012 Christopher McDougall Born to Run wave drove the first mass-market enthusiasm and the first wave of stress-fracture injuries. The running community has since calibrated: minimalist as a useful tool, transition as the critical variable.
• Community — lookmaxxing / fitness influencer. Recent (2022+) wave around toe-splay, foot mobility, "primal" framing. Enthusiastic, evidence-light on some specific claims (e.g., bunion reversal in adults).

Population variability

• Children and adolescents. The clearest signal: foot development is plastic during growth, and habitually-barefoot children develop different foot morphology than habitually-shod children Hollander et al. 2018. Many child-development specialists now recommend barefoot or barefoot-shoe wear during early walking years.
• Younger active adults. The best-studied group; foot strengthening and gait adaptation are reproducible across multiple RCTs and cohorts.
• Older adults. The balance and falls-prevention case is most directly actionable for this group Cudejko et al. 2020, but the transition needs to be even more conservative due to slower tissue adaptation and higher baseline injury risk.
• People with structural foot pathology. Symptomatic pes planus with posterior tibial tendon dysfunction, severe hallux rigidus, Charcot foot, peripheral neuropathy — these are case-by-case clinical decisions, not blanket "everyone should switch" cases.
• People with high training loads. Recreational runners can transition with care; competitive distance runners face a non-trivial performance question (the Fuller 2017 data show economy gains Fuller et al. 2017 but the transition cost in training disruption is real).
• People with desk-based jobs. Low daily wear hours mean slow adaptation; the offsetting benefit is fewer cumulative load hours during transition, so injury risk is lower.
• People with high standing-on-concrete jobs. The hardest transition group. The thin sole transmits load that the deconditioned foot cannot disperse; long acclimation with cushioned shoes maintained for shifts is appropriate until the foot adapts.

Knowledge gaps

• Long-term clinical endpoints. No RCT of sufficient duration tests whether barefoot/minimalist daily wear changes incidence of knee OA, low back pain, falls, or hallux valgus progression over years to decades. The mechanism is there; the outcome data are not.
• The optimal transition protocol. Most published transition schedules are author-opinion or manufacturer-issued. A head-to-head RCT of different transition rates with stress-injury monitoring would settle a lot of practical debate.
• Population variation in adaptation rate. Why some adults adapt in months and others fail to adapt at all is unexplained. Genetic factors (collagen type), prior foot morphology, body weight, surface exposure, and concurrent foot-strength work are all candidates.
• Bunion reversal in adults. Strongly claimed in community settings, weakly supported in published data. The structural deformity of late-stage hallux valgus is unlikely to fully reverse without surgery, but earlier-stage soft-tissue contributions probably can. The literature here is thin.
• The dress-shoe-equivalent problem. Professional and formal-wear contexts mostly lack good barefoot-style options; the practical effect is that even committed adopters spend significant hours in conventional footwear. The dose-response question — how many hours/day of barefoot wear is needed to maintain the foot-strength gain — is largely unanswered.
• Concurrent exercise vs. daily-wear-alone. Daily wear alone produces foot strengthening; structured exercise alone produces foot strengthening; the comparison is rarely done. Whether the combination is synergistic, additive, or partly redundant is open.

Scope vs. brief. The brief named foot strength, arch mechanics, gait, knee and back loading, balance, and the transition. All six are covered. The back-loading angle is the thinnest in the literature — the section folds it into the broader knee/kinetic-chain story rather than getting its own addressing section, because no clinical trial isolates footwear as the variable for low-back pain. Flagged in the dossier knowledge gaps.

Category call. Chose exercise over lookmaxxing, msk-conditions, and home. Barefoot shoes are footwear used during walking, standing, and movement — most of the catalogue's benefit case is mechanical/movement, not aesthetic and not condition-specific. The lookmaxxing-adjacent foot-aesthetic angle is real but a small piece of the substance.

Rating difficulties.

• effort_burden: 2 not 3. The transition is genuinely a 6–12-month patient commitment with sustained attention; the ongoing post-transition effort is essentially zero beyond shoe selection. Scored against the steady state with the transition called out in the pitch and justification.
• evidence: 3 not 4. The foot-strengthening RCTs (Ridge 2019, Curtis 2021, Miller 2014) and the gait/knee-loading biomechanics are solid; the long-term clinical endpoints (OA incidence, fall reduction over decades, low back pain) are mechanism-only. Held at 3 to honour the gap.
• longevity: 2. The Cudejko 2020 short-term balance signal in older fall-risk adults is the strongest direct evidence, and the indirect mortality path (falls → 65+ mortality) is real. Held at 2 because no long-term outcome trial exists.
• mood: 0. Community claims around "grounding" and felt connection exist but lack any real evidence backing — scored honestly rather than splitting the difference.

Contraindications field empty by design. None of the closed-vocabulary tokens (pregnancy, diabetes-medication, etc.) cleanly map to the actual barefoot contraindications — peripheral neuropathy, active plantar fasciitis / Achilles tendinopathy, severe symptomatic posterior tibial tendon dysfunction, recent foot surgery, Charcot foot. These are conditions, not medications or life stages in the existing vocabulary. The full list lives in the article's contraindications addressing section, wrapped as a warning callout. If the closed vocabulary later admits a peripheral-neuropathy token, this entry should be back-edited.

Separate-entry candidates.

• Toe spacers — distinct enough product, separate user population (people with progressing hallux valgus); pairs with this entry but warrants its own.
• Foot mobility and intrinsic-foot exercise routine — short-foot, toe yoga, calf eccentrics. The five-minute-a-day routine that accelerates barefoot adaptation; useful on its own for sedentary feet.
• Older-adult fall prevention — multi-input (balance training, vision, home environment, grip, footwear). Mentioned here as one input; warrants its own entry.
• Running gait and cadence work — the gait shift is a meaningful intervention separable from the footwear.

Future-link candidates. Once they exist, link toe spacers, foot mobility, and older-adult fall prevention via related. The article's out-of-scope section already points readers at these conceptually.

Hard call — minimalist running performance. Fuller 2017 shows real running-economy gains from a structured minimalist transition. The article mentions this briefly under payoff and protocol but doesn't lead with it, because the daily-wear case is broader and the running case is a sub-population. Flagged if the entry ever needs to be retargeted to a runner-first audience.