Shin Splints (MTSS).
Shin splints — medically known as medial tibial stress syndrome (MTSS) — are the most common running injury in beginners, accounting for up to 35% of all running injuries. The pain presents along the inner edge of the shinbone (tibia) and is caused by overload of the bone and surrounding tissue, typically from doing too much too soon.
Overview
Medial tibial stress syndrome is a bone stress injury affecting the tibia (shinbone) and its periosteum — the membrane covering the bone that contains pain-sensing nerve fibres. MTSS exists on a clinical continuum with tibial stress fracture: MTSS represents diffuse bone stress (the milder end), while stress fracture represents localised bone failure (the severe end). Early recognition and appropriate load modification prevent progression along this continuum. MTSS accounts for 13-17% of all running injuries and up to 35% of injuries in beginner runners, making it the most common injury in new runners by a significant margin.
Causes and biomechanics
The primary cause is training load error — increasing weekly running volume or intensity faster than the tibial bone and periosteum can adapt through the bone remodelling cycle (which takes 6-8 weeks per cycle). Contributing biomechanical and risk factors include running on hard surfaces (concrete produces 30% more tibial impact force than grass), worn-out shoes with degraded cushioning, excessive overpronation, weak calf muscles (both gastrocnemius and soleus), weak foot intrinsic muscles (tibialis posterior in particular), low bone mineral density, female sex (women are 1.5-3x more likely to develop MTSS), prior history of MTSS, and insufficient calcium or vitamin D intake.
Symptoms
Diffuse, aching pain along the medial (inner) border of the tibia, typically spanning 5 cm or more of the bone surface. Pain is characteristically worse at the start of a run, may partially improve as the area warms up during the session, and returns with increased intensity after cooling down. The key clinical distinction: diffuse tenderness along a broad area of the shin suggests MTSS, while point tenderness at a specific spot (reproducible with one-finger palpation) may indicate a tibial stress fracture and requires imaging (MRI is the gold standard). If point tenderness is present, stop running immediately and seek medical assessment.
Treatment
Reduce running volume by 40-60% and replace running days with low-impact cross-training that does not reproduce the pain — cycling, swimming, deep-water running and elliptical are all effective alternatives. Apply ice for 15 minutes after any weight-bearing activity. Begin progressive calf strengthening: standing calf raises with straight legs (3x15), seated calf raises with bent knees (3x15), and toe walks (3x30 seconds) to strengthen the tibialis posterior and foot intrinsic muscles. If pain persists beyond 3 weeks despite load reduction, see a sports medicine physician for imaging to rule out tibial stress fracture.
Prevention
Follow the 10% rule for weekly volume increases — no exceptions during the first 6 months of running. Rotate two pairs of running shoes with different cushioning profiles and midsole geometries to vary the loading pattern on the tibia. Run on softer surfaces (grass, trail, track) when possible — even 1-2 sessions per week on soft ground reduces cumulative tibial stress. Maintain calf strength year-round with standing and seated calf raises (3x15, twice per week). For new runners: use a structured walk-to-run programme like STRIDD's beginner plan that builds volume gradually over 8-12 weeks with built-in adaptation time.
Return to running
Resume running only when you can walk briskly for 30 minutes completely pain-free on consecutive days. Then progress through a structured run-walk protocol over 2-3 weeks: start with 1-minute run intervals separated by 2-minute walks, progressing to 3-minute runs with 1-minute walks. Increase continuous running time by no more than 5 minutes per session. Return to full pre-injury training volume gradually over 4-6 weeks. Maintain calf and tibialis posterior strengthening exercises as a permanent part of your routine — they are not optional and should continue indefinitely to prevent recurrence.
This article is for educational purposes only and does not constitute medical advice. If you are experiencing pain or injury, consult a qualified sports medicine physician or physiotherapist before modifying your training. Read our full medical disclaimer.
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