MSK Doctors uses force plates that measure force production over time, providing insight into the kinetics of function movement, in other words the action of forces in producing or changing motion. We use a clinician-friendly force plate system specifically designed for MSK issues, alongside software’s that analyse and report kinetic performance with dual plates in real-time. We analyse kinetic performance by conducting simple activities that requires patients to perform a certain movement, in which performance and asymmetry metrics are evaluated. The application of force plate testing includes, baseline kinetic profiling, monitoring rehabilitation and an assessment of the patient’s response to treatments/rehab.
What are Forces?
Force plates measure the so-called ground reaction force. According to Newton’s third law, this is the force that acts on a human body during movement. At rest, the ground reaction force corresponds to the weight of the body, during movements, this force changes due to acceleration effects. Ground reaction forces are among the most measured biomechanical parameters where movement patterns can be easily identified.
How do we Test Patients using Force Plates?
At MSK Doctors we have a dual force plate system that allows each limb to be assessed or can be used individually for single-leg movements. The most studied protocols include a Countermovement Jump (CMJ) and a Squat Jump (SJ) as these movements provide reproducible performance metrics which is well suited for profiling and monitoring purposes. However, over the past couple of years, force plate testing has become a lot more popular amongst clinicians due to its adaptability and importance. Certain movement patterns can be adapted which takes in consideration the severity of the injury/condition, physical activity levels and the general health of the patient. For instance, the Sit-To-Stand (STS Test) or Squat Assessment (SQT) protocols are designed to reach the wider population.
How is Kinetic Performance Measured?
The force-time curve is used to measure kinetic performance of a patient. Force-Time is compared with the kinematics of the patient to quantify force application during specific phases of the movement. For instance, certain movements can have phase specific metrics such as eccentric forces (blue area) or concentric forces (orange area) (see fig 1.1). Dual force plate system allows the practitioner to understand how ground reaction forces differ between limbs and phase specific metrics help us understand where in the movement these asymmetries occur. These deficits are targeted in rehabilitation or training plans and monitored as outcome measures.
How important are Force Plates clinically?
Our understanding of the relationship between dual force plate performance and musculoskeletal health is rapidly evolving. The ideal scenario for our bodies is to have a perfect symmetry between limbs when exposed to certain activities, unfortunately that is not how it works. Human bodies will always create adaptations where asymmetries will be present. However, these asymmetries only become a problem when they reach a certain number. Typically, patients will encounter big asymmetries when injured and these asymmetries may keep rising until rehabilitation stages. After treatments, patients may be pain free allowing them to walk/run better, however, asymmetries could still be present that are not detectable through our naked eyes. These asymmetries could still be causing too much stress on the affected limb creating a barrier for optimal performance, but more importantly increasing the risk of future injuries/conditions. There is a growing body of literature describing normative symmetry in specific sport populations that can be used to guide clinical decisions.
To summaries, force plate testing assists clinicians to obtain evidence of progression and helps identify whether further treatment needs to be put in place. Whether you are an active person or not, understating the alignment of the body is important to monitor and improve asymmetries which will lead to better gait mechanics, better performance, and a reduced risk of future MSK injuries/conditions.