Deceleration: There's More To It

mTrigger co-founder Russ Paine and his colleagues recently published a Clinical Viewpoint in the International Journal of Sports Physical Therapy on the role of the quadriceps muscle during deceleration movements. Previously, deceleration has been associated with non-contact knee injuries; however, the current battery of return-to-sport tests we have negates the importance of deceleration movements.(1) In their research, Russ’ team used the mTrigger device to help address and quantify what they call “The Deceleration Dilemma.” Let’s take a closer look at what they found.

Why Deceleration is Important

Deceleration is a critical athletic skill that allows athletes to slow down and control momentum before changing direction or after sprinting. This movement places 161% of the maximum voluntary isometric contraction (MVIC) on the quad.(1)  To combat this, high levels of eccentric strength are required to adequately control the knee joint during cutting, jumping, and deceleration movements.(1) 

Stiff-leg landings, which are often seen in athletes following an injury during the return-to-sport phase, heavily rely on the hip and trunk (flexion) landing strategies. Athletes do this because they can achieve the task at hand without sufficient knee flexion on landing. Unfortunately, this means that current methods of hop testing often overestimate limb symmetry, as significant quad deficits are still present in many patients who “pass” testing.(1) 

To overcome this discrepancy, the authors suggest performing a deceleration task and a single-leg retro hop to access deceleration by forcing greater knee flexion and quadriceps demand. 

Using mTrigger to Quantify

When performing a retro hop, the authors used mTrigger sEMG biofeedback to quantify and compare quad activation, a practice they strongly encourage for all practitioners. In line with the article, for this athlete, a retro hop required greater quad activation (~1700mV) than a forward hop (~1500mV), as demonstrated by a greater peak MVC during the retro hop.

Clinical Implications and Exercise Examples 

Eccentric exercise helps build the capacity required to absorb and control forces inherent in sport. The necessity of adding eccentric exercise to an athlete's training plan should be evident for physical therapists and athletic trainers. Thankfully, there are lots of options, with the authors highlighting several.

Furthermore, using mTrigger sEMG biofeedback during exercises can help assure maximal eccentric quad activation is being obtained during the exercise to further improve deceleration capacity. Take a look at these examples.

For more exercise ideas and detailed instructions regarding clinical tests, read the full Deceleration Dilemma article here.

Summary

Deceleration is a skill—it is a critical component of a safe, effective return to sport. By incorporating deceleration-specific testing, targeted eccentric training, and objective tools like mTrigger sEMG biofeedback, clinicians can better identify residual quadriceps deficits and make more informed return-to-sport decisions. The Deceleration Dilemma challenges us to raise the standard of how we assess readiness for sport.

More on Deceleration from Russ Paine

 Reliability and Validity of mTrigger Biofeedback

References

1. Higbie S, Gallina C, Paine R, Bailey L, Lowe WR. The Deceleration Dilemma: Leveraging The Relationship Between Quadriceps Function and Deceleration to Optimize Return to Sport. Int J Sports Phys Ther. 2025;20(5):762-765. Published 2025 May 1. doi:10.26603/001c.137030