Running injuries have been reported in as many as 79% of runners. In a one-year randomized trial, recreational runners who trained their foot and ankle muscles were 2.4 times less likely to get injured than a group doing stretching alone. Toe-Rx is built for that training: open your toes wider than you can on your own, then close and grip against resistance to build the strength underneath every stride.
Taddei UT, Matias AB, Duarte M, Sacco ICN. Foot core training to prevent running-related injuries: a survival analysis of a single-blind, randomized controlled trial. The American Journal of Sports Medicine, 2020. 118 recreational runners, 8-week supervised program, 12-month follow-up. See how we read the evidence
Shoes hold the toes together and flat for most of the day. Toe-Rx restores the two motions that go missing — spreading the toes apart, and then closing them against something. One sets the position. The other builds the strength.
Toe-Rx sits between the toes and holds them apart at a width most people cannot reach on their own. Choose Firm for a deeper opening, Soft if your feet are stiff or tender to start with.
This part is the setup, not the workout. Opening the toes puts your foot in the position it needs to be in before you can train in it.
With the toes held open, squeeze them closed against the silicone. That contraction loads the plantar intrinsic muscles — abductor hallucis, flexor digitorum brevis, abductor digiti minimi and flexor hallucis brevis.
Those are the four muscles that measurably grew in the year-long running trial, and the same ones that hold the arch together while you are on the ground.
We would rather say this than have you find it later. In a controlled trial, adding a silicone toe spacer to a six-week foot strengthening programme produced no extra short-term benefit over the exercises on their own. Wearing something between your toes is not, by itself, the intervention.
The work is what changes a foot. Toe-Rx is built to make that work possible — to open the toes far enough to train them, and to give them something to close against.
Effects of foot strengthening exercises with or without a toe spacer on hallux alignment, foot mobility and balance: a randomized controlled trial. Applied Sciences, 2026. 25 healthy adults, 6-week programme, 22 sessions.Plenty of foot products cite science. Fewer show you the study design, the sample size, and the point where the findings run out. Here is everything we are leaning on, including the parts that do not help us.
Taddei and colleagues split 118 runners into two groups. One did an eight-week foot and ankle strengthening programme — twelve exercises a week supervised by a physical therapist, plus eight exercises at home three times a week — then kept going three times a week for the rest of the year. The other group did a static stretching routine.
Over twelve months, the strengthening group had 2.42 times fewer running-related injuries. The more foot strength a runner gained, the longer it took them to get hurt.
This is the study that changed how we talk about our own product. The comparison group in the best available trial was doing stretching, and stretching lost.
Where it stops The participants were recreational runners already covering real weekly mileage; whether the same holds for beginners or elite athletes needs further study. The programme was supervised by a therapist and ran for a year. And it tested exercises, not a device — no toe trainer of any brand was involved.
Read the study (doi: 10.1177/0363546520969205)One good trial is one good trial. Jaffri and colleagues went wider, searching four databases for randomized trials of intrinsic foot muscle training and rating each one for methodological quality before including it. Thirteen made the cut.
Across those trials, foot muscle training produced significant improvements in balance, foot strength, navicular drop — a measure of how far the arch collapses under load — and in what participants reported about their own foot function.
Where it stops Pain was measured and did not significantly improve. If you have come here because your feet hurt, that is the number to hold on to. The trials also used foot exercises in general, not any particular device, and only two of them measured sensory or motor control directly — one of those in participants aged 19 to 29.
Read the review (doi: 10.4085/1062-6050-0162.22)The same research group measured what the training had physically changed. Four plantar intrinsic muscles were stronger — abductor hallucis, flexor digitorum brevis, abductor digiti minimi and flexor hallucis brevis. The cross-sectional area of the intrinsic foot muscles increased, as did propulsive impulse during running.
The medial longitudinal arch also moved less through the stance phase, meaning it collapsed less under the runner's weight. These are the muscles Toe-Rx is designed to load when you close your toes against it.
Where it stops At eight weeks there was no change in impact force, braking force or vertical loading rate. Whatever protects these runners, it is not a softer landing. We have removed shock absorption from our claims for that reason.
Read the study (doi: 10.3389/fbioe.2022.890428)Nakai and Takeshita measured three things before and after: toe grip strength, toe gap strength — the force available to spread the toes apart — and reactive strength index. All three improved significantly. Long-distance runners are at raised risk of lower limb problems as intrinsic foot muscle function declines, which is what makes toe gap strength worth measuring at all.
This is the only trial we found that treats spreading the toes as a measurable strength quality rather than a stretch.
Where it stops Nineteen participants, all male university athletes, over five weeks. Both training groups improved and neither beat the other, so the gains are a change over time rather than proof that one method works better. Treat it as a signal, not a settled result.
Read the study (doi: 10.3390/app142210514)That it takes away foot pain. The meta-analysis above measured pain across thirteen trials and found no significant improvement. Strength, balance and arch behaviour moved. Pain did not. If your feet hurt, that is worth taking to a clinician rather than to a product page.
That Toe-Rx makes you faster. Foot strength and running economy are not the same thing. One study of competitive distance runners found running economy unchanged even after intrinsic foot muscle strength went up. If you see a foot product promising a personal best, ask which trial measured it.
That it softens your landing. Eight weeks of foot strengthening left impact and loading rates untouched. The protection appears to come from a foot that tolerates load better, not from less load arriving.
That wearing it is enough. Adding a silicone toe spacer to a six-week strengthening programme produced no additional short-term benefit over the exercises alone. The exercises are the intervention. Toe-Rx is what makes them possible to do.
In the trial, the runners did their foot work three times a week. Every other day lands on roughly that. Daily is fine if your feet like it, but nothing we have read says daily beats every other day — so pick the one you will actually keep doing.
Work each toe fully into its slot and sit with the toes held open. No effort required — let the silicone do the work. Sets the position. This is the part that gets your foot into a shape you can train in, not the part that trains it.
With Toe-Rx still in, use your hand to rotate the tips of your toes in small controlled circles, ten in each direction. Moves the toe joints through a range they rarely see inside a running shoe.
Still wearing it, lift your toes up, then press them down firmly into the floor. Squeeze against the silicone as they close. This is the working set. Gripping while the toes are held apart is what loads the plantar intrinsic muscles — the ones that grew in the trial.
Around ten minutes per foot, sitting down. Toe-Rx is waterproof, so the first two steps work in the bath or a foot soak. Full instructions and photos
Nothing to work around. This is how the training was done in the trial — as its own session, not attached to a run.
Once you are done for the day, the timing question disappears. After a long run or a day in stiff shoes is when most people want it anyway.
Holding a stretch for 60 seconds or more has been shown to temporarily reduce maximal force and power, and the effect gets larger the longer you hold. A 3–5 minute spread sits well past that threshold. We have not seen this tested on the toes specifically, so treat it as a reason to be cautious rather than a proven effect — but there is no reason to schedule it there when a rest day works better.
We want to be straight about the gap. The runners in the study did twelve exercises a week supervised by a physical therapist, plus eight more at home three times a week, for eight weeks — and then kept going for a year. Ten minutes with Toe-Rx is not that programme.
What it does is cover the movement at the centre of it: spreading the toes and gripping while they are spread. If you want the full protocol, it is worth asking a physical therapist about foot core training by name. If you want something you will actually do on a Tuesday evening, start here.
Two decisions: how firm you want it, and what size fits your foot. Both are worth getting right — a Toe-Rx that doesn't fit is uncomfortable to wear, and you won't keep using something that hurts.
More resistance to grip against, and a wider opening. If you are training your feet rather than just resting them, this is the one.
A gentler spread. Choose it if your toes are stiff or don't separate much yet, or if this is your first pair. You can move up to Firm later.
| Toe-Rx size | Women's US | Men's US |
|---|---|---|
| Small | 4.5 – 7 | CONFIRM_BEFORE_PUBLISHING |
| Medium | 7 – 9.5 | 7 – 8.5 |
| Large | 9.5 – 12 | 8.5 – 14 |
On an iPhone or iPad, open any product page in Safari and tap the 3D image to place a full-size Toe-Rx on the floor in AR. Line it up against your own foot before you order — it is the closest thing to trying one on.
Shoe size gets most people to the right size, but it measures length, and what has to fit here is the width and thickness of your toes. Two runners with the same shoe size can need different Toe-Rx.
Sizes 7 and 9.5 in women's, and 8.5 in men's, sit on the line between two sizes. If that's you, let your toe shape decide.
Sizing by shoe size is a good estimate, not a guarantee, and we would rather you had the right pair than the pair you first ordered. If your Toe-Rx pinches or slips once you try it, get in touch and we will exchange it for the size that fits.
Please do this rather than pushing through it. Wearing the wrong size is uncomfortable and can cause injury, and a pair that hurts is a pair you will stop using. Contact us about an exchange
Running injuries are common and genuinely hard to prevent. The strongest trial we could find says that runners who spent eight weeks strengthening their feet, and kept going, got hurt far less often over the following year — and that it was the strength they gained, not the stretch they held, that tracked with staying healthy.
Toe-Rx opens your toes wider than you can on your own, and gives them something to close against. Ten minutes, every other day, sitting down.
Every figure on this page comes from one of these. Where a study's findings run out, we have said so in the section that cites it.
The studies above tested foot and toe strengthening exercises. None of them tested Toe-Rx, and no trial has been run on this product. We cite them because they describe the movement Toe-Rx is built for, not because they measured it.
Toe-Rx is not a medical device. Nothing here is intended to diagnose, treat, cure or prevent any condition. If you have foot pain, a current injury, diabetes or reduced sensation in your feet, talk to a clinician before starting.
