Cross-Education Training to Strengthen Quads during ACL Rehab

Cross-education is the phenomenon of strength training your uninjured limb and experiencing strength benefits to your injured limb. 

What does the research say? 

A study performed by Harput et al (2018) included 48 patients who had undergone ACL reconstruction with a hamstring tendon graft. The patients were randomly selected into 3 groups when they reached 4 weeks post surgery. Group 1 performed standardized ACL rehab in addition to concentric knee extension strengthening of the non-operated knee. Group 2 performed standardized ACL rehab in addition to eccentric knee extension strengthening of the non-operated knee. And group 3 was the control group that stuck to a standardized ACL rehab with no additional loading of the non-operated knee. 

Quadricep maximum voluntary isometric contraction strength (MVIC) was measured during the 4th week (pre-training), 12th week (post training), and 24th week post surgery on the operated knee

The results were significant strength improvements for the experiment groups. Strength gains were 28% and 31% in the concentric and eccentric groups respectively when compared to the control group. 

Resisted seated knee extension of the non-operated leg

How does cross education work? 

By stimulating and training the uninjured limb it is believed that the neural drive of the injured limb is enhanced. Therefore, leading to reduced atrophy of the injured limb. 

How does cross education training affect ACLR rehab? 

Cross eduction training is directly applicable to ACLR patients that may have restrictions in their post-op protocols that do not allow for seated knee extension exercises. The absence of seated knee extension from ACLR rehab prevents the patient from isolating quad strength which can create a significant challenge in restoring full quad strength post-op. 

How should cross education training be incorporated into ACLR rehab? 

Following the procedure of the protocol, cross education training of the uninjured limb should be included 3x/week using the seated knee extension until seated knee extension of the operated ACL is allowed. By omitting this training from your ACL rehab plan you are creating a much higher risk of quad atrophy that will have to be overcome later in the rehab plan. 

For more information on ACL rehab at Modern Physiotherapy and Training contact the author at 


Harput G, Ulusoy B, Yildiz TI, Demirci S, Eraslan L, Turhan E, Tunay VB. Cross-education improves quadriceps strength recovery after ACL reconstruction: a randomized controlled trial. Knee Surg Sports Traumatol Arthrosc. 2019 Jan;27(1):68-75.