Shin Splints: What Predicts Them, What Doesn't Help, and Where Your Feet Come In

Shin splints — medial tibial stress syndrome, or MTSS — is pain along the inner edge of the shinbone that comes on with running and eases with rest. It is one of the commonest running injuries, it hits beginners hardest, and it has been studied for forty years. The honest summary of those forty years is shorter than you would expect.

How common it is

MTSS affects somewhere between 5% and 35% of runners depending on the population studied.¹ It is more common in people new to running, in people ramping up their mileage, and in women.

What predicts it

A 2013 systematic review and meta-analysis pooled the studies that had measured runners before they developed MTSS and compared those who did with those who didn't.¹ The factors that came out significantly associated:

• Having had it before. Risk ratio 3.74 — the strongest single predictor.
• Being female. Risk ratio 1.71.
• Fewer years of running experience.
• Higher body mass index.
• Greater navicular drop — the arch sinking further when you stand on it.
• Greater hip external rotation range, in men.
• Orthotic use — which the authors read as a marker of people who already had foot problems, not as a cause.

A 2020 systematic review focused on novice and recreational runners found the same picture — navicular drop and foot pronation among the intrinsic factors — and added that the underlying studies were of mixed quality, so the conclusions are firmer on direction than on size.²

Training load matters too, and here the evidence is clearer. Novice runners who increased weekly distance by more than 30% over two weeks had higher rates of distance-related injuries, MTSS among them.³ The more recent finding — that a single run more than 10% longer than your longest in the past 30 days is what predicts injury, rather than the weekly total — is written up on our 10% rule page.

What doesn't help — or rather, what hasn't been shown to

This is the part the 2013 review put in its opening lines and most articles leave out:

"Research over the last 40 years investigating a range of interventions has not established any clearly effective management for MTSS that is better than prolonged rest."¹

Ice, stretching, taping, orthoses, shockwave — each has its advocates and its case series. None has been shown, in a trial, to beat simply stopping running for long enough. That does not mean they are useless. It means that if someone tells you they have the fix for shin splints, the evidence has not caught up with them. The reliable intervention is rest and a slower return.

When it is not shin splints

MTSS sits on a continuum with tibial stress reaction and tibial stress fracture, and the 2013 review proposed exactly that model.¹ The difference matters, because a stress fracture that is run on gets worse. See a clinician promptly if the pain is:

• Focal — one spot you can point to with a fingertip, rather than a band along the bone.
• Present at rest or at night, not only with running.
• Sharp on a single-leg hop.
• Getting worse despite a week or two of reduced running.

None of what follows applies until that has been ruled out.

Where your feet come in

Of the risk factors above, most are not things you can change. You cannot alter your sex, your history, or your years of experience. Body mass and training load are within reach. And one of the remaining factors — navicular drop, how far the arch sinks under load — turns out to be something foot training measurably affects.

A 2023 meta-analysis of 13 randomised trials found that training the small muscles of the foot significantly reduced navicular drop.⁴ In runners specifically, eight weeks of foot-core training reduced how far the arch moved during the stance phase of running.⁵ And in the year-long trial that followed, runners who did that training were 2.4 times less likely to sustain a running-related injury than a group doing static stretching.⁶

So the chain runs: navicular drop predicts MTSS; foot training reduces navicular drop; foot training reduced running injuries overall. That is three solid findings pointing the same way. What it is not is a trial that trained runners' feet and counted their shin splints. Nobody has run that study. We think the chain is reasonable. We are not going to call it proof, and we are not going to call a foot exercise a shin-splint preventer on the strength of it.

Where Toe-Rx fits

Toe-Rx is a tool for the foot training in the chain above. It holds the toes open wider than you can unassisted and gives them something to close against. In the one trial that isolated it, wearing a separator passively changed nothing over eight weeks; adding the closing movement changed every measure taken.⁷ Ten minutes, seated, after a run rather than before, every other day — and after any bone stress has been ruled out, not instead of ruling it out.

If you are currently in a bout of shin splints, the order is: see someone if it matches the list above; rest it properly; come back slowly under the 10% line; and then, if you want to work on the one foot-side risk factor that training changes, the protocol is on the runners' page.

*These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.

References

1. Newman P, Witchalls J, Waddington G, Adams R. Risk factors associated with medial tibial stress syndrome in runners: a systematic review and meta-analysis. Open Access Journal of Sports Medicine. 2013;4:229–241. doi:10.2147/OAJSM.S39331. PMID: 24379729. Read it
   Source for the prevalence range, the risk ratios, the "nothing better than rest" statement, and the continuum model.
2. Menéndez C, Batalla L, Prieto A, Rodríguez MÁ, Crespo I, Olmedillas H. Medial tibial stress syndrome in novice and recreational runners: a systematic review. International Journal of Environmental Research and Public Health. 2020;17(20):7457. doi:10.3390/ijerph17207457. Read it
   Eleven studies; the authors note design biases and poor methodological quality in most. Confirm author list.
3. Nielsen RØ, Parner ET, Nohr EA, Sørensen H, Lind M, Rasmussen S. Excessive progression in weekly running distance and risk of running-related injuries: an association which varies according to type of injury. Journal of Orthopaedic & Sports Physical Therapy. 2014;44(10):739–747. doi:10.2519/jospt.2014.5164.
4. Jaffri AH, Koldenhoven R, Saliba S, Hertel J. Evidence for intrinsic foot muscle training in improving foot function: a systematic review and meta-analysis. Journal of Athletic Training. 2023;58(11–12):941–951. doi:10.4085/1062-6050-0162.22. Read it
5. Matias AB, Watari R, Taddei UT, et al. Effects of foot-core training on foot-ankle kinematics and running kinetics in runners: secondary outcomes from a randomized controlled trial. Frontiers in Bioengineering and Biotechnology. 2022. doi:10.3389/fbioe.2022.890428
6. 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. doi:10.1177/0363546520969205
   Injuries were counted overall; MTSS was not reported as a separate outcome.
7. Kim MH, Yi CH, Weon JH, Cynn HS, Jung DY, Kwon OY. Effect of toe-spread-out exercise on hallux valgus angle and cross-sectional area of abductor hallucis muscle in subjects with hallux valgus. Journal of Physical Therapy Science. 2015;27(4):1019–1022. doi:10.1589/jpts.27.1019. Read it