Hey PS+R Crew!
Fall is in full swing here in Florida—and so is our clinic! With a high volume of athletes currently pushing through ACL recovery, we are constantly evaluating the latest sports medicine research to ensure our return-to-sport protocols deliver the best possible outcomes.
When an athlete passes their strength tests with flying colors yet still shows an asymmetrical gait or hesitates on dynamic cuts, we often ask: what are we missing?
The latest research points to a clear answer: Rate of Force Development (RFD)— how fast a muscle can produce force, rather than just how much force it can produce.
Fast Strength vs. Heavy Strength
“The time has come to incorporate a greater focus on rate of force development training in the sports injury rehabilitation process” (Buckthorpe & Roi, 2017)
- The Problem: Being strong isn’t the same as being fast. Traditional gym exercises build maximal strength, but sports injuries happen in the blink of an eye—often in less than 50 milliseconds. Standard rehab gets muscles strong again, but leaves them far too slow to protect the joint in real-world sports situations.
- How the Brain Controls Speed: Quick force depends on how fast the brain sends signals to wake up muscle fibers, not just how big the muscle is. Slow, steady weightlifting doesn’t train the brain to fire those signals fast enough.
- The Fix: After basic healing and strength are built, rehab must include explosive movements. Patients need to practice contracting their muscles “as fast and hard as possible” from a relaxed state, alongside heavy lifting, jump training, and quick-stop drills.
Why Athletes Still Limp When Running
“The Influence of Quadriceps Strength and Rate of Torque Development on the Recovery of Knee Biomechanics During Running After ACL Reconstruction” (Knurr et al., 2023)
- The Key Finding: In college athletes recovering from ACL surgery, how quickly their thigh muscle produced power determined how normally they ran. Their total maximum strength had no effect on their running style.
- The Numbers: For every 10% boost in muscle speed symmetry between their legs, athletes ran with much better knee bend and natural spring.
- The Hidden Deficit: Most athletes regained about 78% of their maximum strength, but only 60% of their muscle speed. Because your foot is only on the ground for a fraction of a second while running, an athlete whose muscle is slow will naturally stiffen their knee to protect it—even if they look strong on weight machines.
Why Quality Rehabilitation Makes All the Difference
These findings serve as a powerful reminder that rehab quality is directly defined by how specifically we target functional demands.
Counting repetitions on leg extension machines or checking off basic 90% peak strength symmetry targets is simply not enough to protect an athlete’s long-term joint health. Quality rehab isn’t just about making a muscle bigger or stronger—it is about retraining the nervous system to react rapidly under pressure.
When we guide our athletes through high-quality, late-stage rehabilitation:
- We fix movement mechanics early: By restoring explosive force production (RTD), we help athletes shed compensatory habits like the “stiff-knee” running gait, restoring fluid, natural biomechanics.
- We aim to protect the joint from re-injury: Non-contact injuries occur in less than 50 ms. Delivering structured ballistic, heavy, and explosive training ensures their dynamic stabilizers can react fast enough to absorb joint loads on the field.
- We bridge the gap between “healed” and “ready to perform”: High-volume care must never mean assembly-line rehab. By intentionally cueing maximal-intent contractions, incorporating heavy power lifts, and assessing muscle speed alongside peak strength, we ensure our athletes return to sport fully equipped to succeed.
We continue bringing these principles into the clinic every day to deliver the highest standard of care and help our community return to doing what they love!
