Uniaxial vs. Triaxial Force Plates: A Comparison
Digital, portable force plates are among the most valuable and versatile tools for physical therapists, sports medicine practitioners, strength and conditioning coaches, and athletic trainers. Force plates use load cells (e.g., beam load cells, strain gauge load cells, or piezoelectric elements) to capture ground reaction forces (GRFs) and generate quantitative data. PTs and trainers can […]
triaxial force plates
Digital, portable force plates are among the most valuable and versatile tools for physical therapists, sports medicine practitioners, strength and conditioning coaches, and athletic trainers. Force plates use load cells (e.g., beam load cells, strain gauge load cells, or piezoelectric elements) to capture ground reaction forces (GRFs) and generate quantitative data. PTs and trainers can use that data to inform a course of therapy or training, keep patients and clients engaged, and drive improved health and performance outcomes.
Each practice has its own unique needs and specializations, which means no one-size-fits-all solution exists when it comes to force plates. To meet users’ diverse needs, manufacturers have developed plates that vary in size, functionality, and the number of axes they measure along. Thanks to recent innovations, triaxial force plates, in addition to more common uniaxial force plates, are now available on the commercial market.
Here’s an introduction to uniaxial and triaxial force plates and guidance on choosing the right model for your practice.
What Are Uniaxial Force Plates?
Nearly all commercially available force plates are uniaxial (or single-axis). These popular tools measure force along the vertical (Z) axis. Uniaxial force plates come in a wide range of sizes: the smallest, most portable plates weigh a few pounds per plate, while large, stationary plates can weigh hundreds of pounds.
What they measure:
- Power
- Fatigue
- Balance
- Strength
- Peak force
- Jump height
- Limb symmetry
- Weight distribution
- Dynamic strength index
- Force/velocity spectrum profile
- Upper and lower limb proprioception
Ideal user:
Uniaxial force plates are popular among clinicians and professionals who work with athletes. They are an excellent solution for those who require portability (for example, a strength and conditioning coach who travels to train different teams).
Pros:
- Generally lightweight and portable
- Generate troves of valuable data, quickly
- More cost-effective than triaxial plates
Cons:
- Limited functionality as compared to triaxial plates
What Are Triaxial Force Plates?
Triaxial (also known as 3-axis or 3D) force plates (also known as triaxial or 3D force plates) are highly sophisticated instruments that generate multidirectional movement data. Unlike uniaxial force plates, triaxial force plates measure movement across three axes:
- Vertical (Z-Axis): Upward and downward movement
- Anterior-Posterior (Y-Axis): Forward and backwards movement
- Medial-Lateral (X-Axis): Side-to-side movement
What they measure:
- Force
- Speed
- Power
- Fatigue
- Balance
- Strength
- Peak force
- Jump height
- Explosiveness
- Limb symmetry
- Joint kinematics
- Weight distribution
- Dynamic strength index
- Center of pressure (CoP)
- Force/velocity spectrum profile
- Upper and lower limb proprioception
That data can be used to gain insight into an athlete’s performance, conduct sophisticated biomechanical analyses and injury risk assessments, make well-informed return to sport decisions, and devise individualized training plans.
Ideal user:
Anyone who needs to measure multi-directional movement can use triaxial force plates. They are especially popular among those who work with elite athletes (at the professional level, for example), researchers who conduct advanced biomechanical and sports science research, and rehabilitation professionals who need in-depth analyses of functional deficiencies and asymmetries.
Pros:
- Generate an unparalleled amount of valuable data
- Give users a comprehensive assessment of a patient’s or athlete’s physicality
Cons:
- Generally, not as portable as uniaxial force plates
- Costly, as compared to most models of uniaxial force plates
Are Uniaxial or Triaxial Force Plates Right for My Practice?
The “right” model will vary based on your needs, specialization and budget. Purchasing digital biofeedback devices and equipment is a significant investment that requires research and careful consideration.
If you require portability and know that more limited but still insightful data will suffice, single-axis force plates will likely suit your needs. However, if you need more comprehensive data and greater versatility, you will likely benefit from an investment in 3-axis plates.