New Research on Achilles Tendinopathy
Rethinking Achilles Tendinopathy: Targeting the Nervous System and the Lateral Gastrocnemius
Achilles tendinopathy has long been treated as a purely local tissue problem—primarily through tendon-focused protocols like eccentric loading. But emerging research suggests the condition is far more complex, involving significant changes in the central nervous system (CNS) and muscle-specific neural deficits. A 2025 PhD Academy Award-winning study by Fernandes et al., published in the British Journal of Sports Medicine, sheds new light on the neurophysiological underpinnings of Achilles tendinopathy in runners and provides compelling evidence for targeted interventions that go beyond the tendon.
This article explores those findings and further discusses how treatments like acupuncture and dry needling at Morningside Acupuncture may support recovery by influencing both local and central mechanisms.
Achilles tendinopathy
Key Points
Achilles tendinopathy in runners involves increased cortical inhibition and reduced neural drive.
These CNS changes cause bilateral endurance deficits, even in unilateral injuries.
The lateral gastrocnemius is disproportionately affected.
A novel "feet-in" plantarflexion technique increases activation of the lateral gastrocnemius.
Treatment should address central and muscular factors, not just tendon loading.
Study Summary
Recent research by Fernandes and colleagues reveals that Achilles tendinopathy is not merely a local tendon injury but a condition involving systemic neuromuscular changes. Through three carefully designed studies, the researchers show that both brain-level inhibition and muscle-specific activation deficits are central to the endurance issues runners experience—even when pain or injury is isolated to one leg. This paradigm shift moves the focus from solely mechanical loading to addressing underlying motor control dysfunction.
1. Cortical Inhibition and Bilateral Deficits
In the first study (Fernandes et al., 2022), runners with unilateral Achilles tendinopathy were found to have increased intracortical inhibition and reduced plantarflexor endurance in both legs. Importantly, maximal strength remained intact, pointing toward central nervous system modulation—rather than just tendon dysfunction—as a key contributor.
2. Muscle-Specific Neural Drive Loss
The second study (Fernandes et al., 2022) identified the lateral gastrocnemius as the muscle most affected by the neurophysiological changes. Reduced neural drive to this specific head of the triceps surae complex could compromise coordination and endurance, even if other muscles like the medial gastrocnemius and soleus remain relatively unaffected.
3. Feet-In Positioning for Better Activation
The third study revealed that performing plantarflexion exercises with the feet turned inward significantly increases lateral gastrocnemius activation. This offers a simple, practical strategy to better target the muscle most impacted by CNS changes and improve outcomes in rehab programs.
| Findings | What It Means (in Plain English) |
|---|---|
| Increased intracortical inhibition in runners with Achilles tendinopathy | The brain sends weaker signals to the calf muscles, making them tire faster. |
| Bilateral endurance deficits despite one-sided injury | Both legs are affected, so both should be part of rehab—not just the painful one. |
| Reduced neural drive specifically to the lateral gastrocnemius | This part of the calf is underperforming, which could limit recovery if ignored. |
| Feet-in plantarflexion boosts lateral gastrocnemius activation | Turning the feet inward during calf exercises helps target the weak muscle. |
What This Means for Treatment
The implications for treatment are clear: a successful Achilles tendinopathy rehab plan must go beyond traditional eccentric loading. It should include CNS-targeted strategies that reduce intracortical inhibition and restore muscle-specific function—especially in the lateral gastrocnemius. Interventions like dry needling and motor retraining exercises using inward foot positioning offer practical tools to address both brain and muscle-level dysfunction. Treating both limbs, even when only one is symptomatic, is also supported by the findings.
How Dry Needling Can Help Achilles Tendinopathy
Dry needling is a style of acupuncture that targets myofascial trigger points and neuromuscular dysfunction using a solid filiform acupuncture needle. It may play an important role in treating Achilles tendinopathy by complementing the findings from Fernandes et al. in the following ways:
Addressing Neural Drive Deficits
Dry needling the lateral gastrocnemius, particularly in the affected leg, may help restore motor control by reducing abnormal muscle tone and improving neuromuscular coordination. This is especially relevant given the study's identification of reduced drive to this muscle.
Modulating Central Sensitization
Research shows that acupuncture and dry needling can alter central sensitization and cortical excitability—potentially reducing intracortical inhibition as described in the study. Techniques targeting the spinal segments (S1–S2) and peripherally along the sciatic and tibial nerve pathways may support these neuroplastic changes.
Complementing Functional Rehab
When combined with exercises like feet-in plantarflexion, dry needling may enhance motor retraining by preparing the muscle for more effective recruitment. This combined approach—addressing both local muscle dysfunction and CNS-mediated inhibition—can be especially powerful in persistent cases.
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Related Questions:
Sources:
Fernandes, G. L., et al. (2022). Intracortical inhibition is associated with plantar flexor endurance deficits in runners with Achilles tendinopathy. British Journal of Sports Medicine, 56(3), 170–175. https://pubmed.ncbi.nlm.nih.gov/34897835/
Fernandes, G. L., et al. (2022). Muscle-specific neural deficits in runners with Achilles tendinopathy: Implications for rehabilitation. British Journal of Sports Medicine, 56(12), 615–621. https://pubmed.ncbi.nlm.nih.gov/36418751/
Fernandes, G. L. (2025). Neurophysiological characteristics accompanying runners with Achilles tendinopathy and their influence in triceps surae performance. British Journal of Sports Medicine. https://pubmed.ncbi.nlm.nih.gov/40484446/
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