Are Leg Muscle, Tendon and Functional Characteristics Associated with Medial Tibial Stress Syndrome? A Systematic Review.

Medial tibial stress syndrome, or MTSS, is a frustratingly common overuse injury in runners and athletes that doesn't yet have a clear, evidence-backed treatment approach. This systematic review looked at 17 studies involving over 1000 people to understand which leg muscle and tendon changes are linked to MTSS. The researchers found that two factors stood out most: people with MTSS tended to have less lean muscle in their legs, and their calf muscle (soleus) showed higher activity during the push-off phase of running.

Beyond those two findings, the evidence became more mixed. People with MTSS also showed weaker calf endurance, changes in how their muscles worked under tension, and different patterns of muscle activation compared to people without the condition. However, the authors were careful to note that we still don't know whether these muscle changes cause MTSS or whether MTSS itself causes these changes.

If you have MTSS, this research suggests that certain differences in your leg muscles and how they work may be connected to your pain. Studies found that people with MTSS often have less muscle bulk in the affected leg and their calf muscles tend to work harder during running.

They also had trouble with endurance in their calf and ankle muscles, and their muscles behaved differently when tested in the clinic. None of this necessarily explains why your particular pain started, and the research team was clear that we don't yet know whether these muscle changes came before the injury or happened because of it.

What we do know is that your leg's muscular strength and endurance appear relevant to how MTSS develops, which is useful information as research continues to clarify the best paths forward.

This is a summary of research, not medical advice. Talk to your own healthcare provider about anything affecting your care.

This systematic review brings together evidence on the structural and functional differences found in athletes with MTSS compared to uninjured controls. The strongest associations were decreased lean leg girth and elevated peak soleus activity during propulsion, though the authors appropriately call for prospective research to confirm causation.

Beyond those two factors, the evidence base shows deficits in ankle plantarflexor endurance, increased muscle shear modulus (tissue stiffness), and altered neuromuscular recruitment patterns, but with less robust correlation overall. The review included 17 predominantly case-control studies of moderate to good quality, meaning we're working with cross-sectional associations rather than causal evidence.

The heterogeneity of findings across the literature suggests that MTSS may have multiple muscular and functional phenotypes rather than a single unifying mechanism. This reinforces the need for more rigorous prospective designs to establish whether these characteristics are risk factors, consequences, or simply co-occurring features of the condition.