25/09/2025
🚨 Quadriceps Inhibition After ACL Injury: What You Need to Know 🚨
Did you know that even after successful ACL reconstruction, many athletes struggle with a hidden problem that delays recovery and raises reinjury risk? It’s called arthrogenic muscle inhibition (AMI) – and it mainly affects the quadriceps.
👉 What is AMI?
AMI is a neurological response where the body “shuts down” muscle activation after knee trauma or surgery. It’s not just about weakness — the nervous system limits how much you can voluntarily contract your quad.
👉 Why does it happen?
• Peripheral factors: joint swelling, damaged receptors in the ACL, and pain.
• Central factors: changes in brain and spinal cord control that reduce motor drive.
👉 How does it affect recovery?
• Persistent quadriceps weakness and delayed muscle activation.
• Abnormal gait mechanics and compensatory movement patterns.
• Increased risk of reinjury (including graft rupture or injury to the other knee).
• Long-term: higher chance of early knee osteoarthritis.
👉 Signs to look out for
Even months after surgery, you might notice:
• Difficulty regaining quad strength despite training.
• Limping or favoring one leg during running.
• Trouble with single-leg hops, landing, or stability exercises.
👉 What helps?
Research highlights the need for targeted rehabilitation, not just standard strength training:
• Neuromuscular electrical stimulation (NMES) and cryotherapy in early rehab.
• Eccentric training and blood flow restriction (BFR) in mid-phase recovery.
• Cognitive–motor and dual-task training later, to re-train the brain and improve movement quality.
• Advanced tools like gait analysis, EMG testing, and neurostimulation may also play a role in the future.
⚠️ Takeaway: AMI is one of the main reasons athletes struggle to get back to pre-injury performance after ACL surgery. Proper assessment and rehab targeting neuromuscular control, not just strength, are critical for a safe return to sport.
💡 If you’re rehabbing from an ACL injury, talk with your physio about AMI-specific strategies. Early detection and treatment can make all the difference!
Additional information: https://www.mdpi.com/2077-0383/14/8/2633
