Science & Approach

Why Quads Stay Weak After Knee Surgery

Even after months of rehab, many athletes still feel their surgical leg isn’t as strong as it should be. One major reason is a reflex called Arthrogenic Muscle Inhibition (AMI). After an injury or surgery, swelling and joint trauma send abnormal signals to the nervous system, which in turn ‘turns down’ the ability of your quadriceps to fully activate. This isn’t simply weakness from disuse, it’s a protective response where the brain and spinal cord limit motor unit recruitment around the knee to guard the joint. The problem is that AMI can persist long after the joint has healed, making it difficult to fully rebuild quad strength and leaving patients feeling unstable or underpowered. This phenomenon is often more severe if the quad tendon is utilized for an autograft in ACL reconstruction, especially if quad tendon pain persists for several months or longer.

A skier in red and gray winter gear, black helmet and goggles, descending a snowy slope.

Side view of male legs with skin side and anatomical muscle and bone diagrams overlayed on the thigh muscles.

Science-Based Recovery That Works

We use targeted strategies to force the dormant quad muscle fibers to contract through isolated movements/holds, cueing for quad bias during compound movements, and working the muscle through its’ entire range - shortened and lengthened positions. If needed to produce a stronger contraction, we use electrical stimulation and blood flow restriction in conjunction to ‘wake up’ the quads and override arthrogenic muscle inhibition. From there, we progress into hypertrophy and strength training to rebuild muscle, then dynamic power, deceleration, and cutting drills to restore full athletic function and confidence.

Our 4-Phase Training Model