Rate of Force Development as an Adjunctive Outcome Measure for Return-to-Sport Decisions After Anterior Cruciate Ligament Reconstruction

Return to play criteria following ACL reconstruction has been a debated topic, especially as of late. Unfortunately, we do not have clear cut objective tests that will tell us when an athlete is ready to go back onto the field safely and effectively.  Common tests, such as the single leg hop test, is often used as a test in the terminal phases of rehabilitation. Other objective data such as strength has been tested to determine the deficits between involved knee vs uninvolved knee. However, we are unsure whether strength translates over to field play.  

In this study, rate of force development was the primary focus. The authors define RFD as the ability to produce a muscle force quickly. The study used professional soccer players over a span of 6 seasons. The athletes who suffered an ACL tear underwent surgery and all started on the same rehabilitation program.  However, what was different was that at 6 months post-op the athletes underwent an additional 20 weeks of a training program focusing on RFD development.  The authors decided to recommend this additional 20 weeks due to significant deficits in RFD at 6 months.  Below are some of the key points of the article:  

-  One criterion that has been used to determine recovery and readiness to return to sport following an ACL recon- struction is achieving 85% or 90% of the maximal strength of the contralateral limb.  However, it has been shown that the time required to develop muscular strength in many types of daily2 and sports activities38 is considerably shorter (0-200 milliseconds) than that required to achieve maximal contraction strength (300 milliseconds or greater).

-  The RFD measured under isometric conditions has been identified as a key parameter characterizing the extent of neural drive to the muscle during explo- sive muscle actions.

-  The subsequent post hoc analysis indicated no significant difference in RFD30 values between the involved and uninvolved limbs measured at baseline (preinjury) and at 12 months postreconstruction. However, there was a significant difference between limbs at 6 months post-reconstruction.

-  For the involved limb, there was a significant difference in RFD30 values between baseline and 6 months, but not between baseline and 12 months

-  At 6 months post-reconstruction, the average RFD30 value for the involved side was only 80% of the baseline value (TABLE 1, FIGURE 3) and only 79% of the value of the uninvolved side, which was also mea- sured at 6 months postreconstruction

-  At 12 months postreconstruction, the mean RFD30 value for the involved side was 98% of the baseline value and 97% of the value of the uninvolved side.

So this asks the question: Should we be looking at RFD more closely as an indicator for return to sport?  Is it more applicable/transferable to sports play?  

For those of you who are part of the Sports Performance Special Interest Group in the Sports Section, this article was just brought up with a lot of good discussion!  

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