Return to Sport Testing Using Force Plates

ACL Return to Sport Testing Using Force Plates

At Union PT in Seattle we specialized in sports physical therapy. We are excited to bring a new tool into the clinic that can significantly help and improve the way we assess and implement unique and personalized rehabilitation plans.  To improve our objective understanding of your progress and to aid us in return to sport decision making we have integrated Force Plates into the practice.  While there is a lot of information that we can gather using traditional tools like video recording and analysis, watching our patient move, or testing range of motion and strength, there are many things that the eye simply cannot pick up. The Vald force plates that we use in-clinic are able to measure a number of different metrics from jump height, force production, landing and take off force, center of mass movement and a number of other variables.  The information we gather using a force plate can help us make crucial decisions about returning to sport following an ACL. Returning to sport too early can result in a failure of ACL reconstruction which is something we are working hard to prevent. 

How does this help us with returning to sport testing?

When we are coming back from an ACL injury it is important to take an objective look at performance to see if the patient can start returning to sport safely.  Certainly traditional tools like range of motion and manual muscle tests are important but simply “that looks pretty good” is not enough and we need to know what specifically the deficits are and how the patient is performing tasks that correspond to their given sport.

How does a force plate help with sports physical therapy?

The force plate allows us to measure 3 main categories of the stretch shortening cycle of muscles and performance. 

Category one: Maximum Strength Testing

Max strength is the foundation upon which return to sport and athletic performance is built. Force plates can  play a key role in objectively assessing an individual’s maximum strength. While we can use hand or dynamometry testing for individual muscles or joints, the plates allow us to measure force in more complex and compound exercises like squats, deadlifts, or or bridges. We can precisely measure the force exerted by each limb. Such data aids in identifying strength deficits between sides, indicating potential muscle imbalances that could lead to injuries or hinder future performance.

Personalized Rehab Training Programs

Once these strength deficits are recognized, we can better tailor personalized home exercise  programs to address those specific weaknesses. The real-time feedback provided by the force plates helps track progress and modify training intensity, ensuring a safe and gradual progression.

Tracking Rehab Progress

Something that is additionally helpful is that when we measure these attributes we can upload them to your chart and see how they change over time.  The plates and the associated web & app interface can create easy to read charts or graphs to see how progress is being made throughout the entire rehab process.

A screenshot showing an 18.4% asymmetry in landing force from a jump test

Category 2: Power

Power = work/time. Explosive strength, often referred to as power, is essential for athletes participating in sports requiring quick bursts of speed, agility, and force. Measuring this accurately without force plates is near impossible. For sports like basketball, soccer, and volleyball, where explosive movements play a pivotal role, force plates offer invaluable insights into an individual’s readiness for return to sport.  

Plyometric Training in ACL Rehab

Plyometric exercises involve rapid stretching and contracting of muscles, building explosive strength. Force plates help measure ground reaction forces during jumps, bounding, and other plyometric drills. This information guides physical therapists in designing safe and effective plyometric training regimens tailored to each athlete’s unique needs.  Using the plates we can measure the force applied in takeoff and landing during jumps between different feet; even the height of each jump and compare right versus left!

Jump Mechanics Analysis

Athletes and patients can improve their jumping mechanics with the aid of force plates. By analyzing take-off and landing forces, therapists can identify inefficiencies or improper movement patterns that might lead to injuries or suboptimal performance. Subsequent interventions and targeted exercises can then be prescribed to optimize jumping mechanics.

Category 3: Reactive Ability aka Agility and Stability

Reactive ability or agility and stability is the capacity to rapidly absorb and produce forces in response to external stimuli. This aspect of performance is particularly critical in sports that require sudden changes of direction and quick responses to unpredictable situations.

Injury Prevention and Balance Training

Force plates can be used to assess an athlete’s balance and stability.  Part of what they may measure is where your center of mass and velocity is as you perform different trials.  By measuring postural sway and balance deficits, physical therapists can identify potential injury risks and implement targeted balance training programs. Improved reactive ability enhances an athlete’s ability to adjust and stabilize during high-intensity movements, reducing the likelihood of injuries.

Neuromuscular Control Assessment

Neuromuscular control, the coordination between the nervous and muscular systems, plays a significant role in reactive ability. Force plates help measure and analyze neuromuscular responses, guiding therapists in designing neuromuscular control drills that enhance an athlete’s ability to react swiftly and efficiently during competition or even daily life.

Real Time visualization of force through right vs left foot


Clinic force plates have changed our ability to accurately gauge and tailor home programs and in-clinic interventions for rehab and sports performance. Their ability to measure and analyze an athlete’s maximum strength, explosive strength, and reactive ability empowers therapists and patients alike to design personalized and relevant training programs.

Whether it’s optimizing maximum strength to build a solid foundation, develop explosive strength to improve speed and power, or enhancing reactive ability for agility and stability, force plates have become an indispensable tool.

Knowing that an athlete has met specific goals that have been accurately measured are essential steps to successful return to sport following an ACL injury.

What makes Union the best physical therapy in Seattle

It’s not all fancy tools… At Union PT we are athletes ourselves and skilled in finding out what the cause of an injury or deficit may be. We understand the unique challenges faced by your sport or daily life. We are trained in manual therapy, exercise prescription and movement analysis making sure you will get the most out of each visit.  Not only will we address the immediate issue but we’ll also look “upstream” to see WHY you are here with that problem.  We are constantly looking to improve how we deliver care to deliver the best outcome possible for your rehabilitation. 

About the author

Jon Sparks, PT, DPT, CSCS is a physical therapist at Union PT in Seattle. He is experienced in treating acute and chronic industrial injuries, postoperative rehabilitation and orthopedic injuries. He enjoys staying up-to-date with evidence-based treatments. Outside the clinic Jon is thoroughly obsessed with rock climbing. When not climbing, he enjoys traveling, exploring new restaurants and snowboarding.