Oct 30, 2019
How to use force plates in sports (sponsored)
By Pete Leno, contributing writer

Coaching has always been part science, part art. Coaching always will be. For today’s coach, the science looks a little different than in the past.

The use of force plates as part of the envelope of athlete care is becoming more common. Force plates are the “Gold Standard” for the measurement of force production, power, and landing dynamics in human movement. Today’s sport scientists and sports medicine professionals know that reliable measurements of 3-dimensional forces are essential to monitor performance, assess potential risk of lower extremity injury, and track the effect of training interventions.

A force platform is designed to continuously measure the force exerted on it. Forces in three perpendicular directions are usually plotted against time, these being the vertical force and, in the horizontal plane, the anterior-posterior (front–back) and medial-lateral (inside to outside) forces. Measuring forces applied by an athlete provide value to the coach by serving any or all the following reasons:

  • Allows a quick and reliable assessment of how an athlete applies force when accelerating or decelerating their center of mass.
  • Well-designed protocols allow for quick and repeatable measurement during standard athletic movements.
  • A useful force plate analysis provides coaches and trainers guidance for detecting subtle differences in athletes over time. Typical uses include basic movement screen, neuromuscular readiness, recovery over time and return to play decisions.
  • Dual force plates allow for detection of asymmetry when generating force, which provides coaches and trainers with immediate actionable data.
  • Allow precise measurement of force trajectory.

In other words, force plates are a tool that display what the coach’s eye can’t see. They do not replace the coach’s eye, just enhance it.

More questions arise regarding which data are immediately actionable. Initially, you will make decisions based on your gut and the eye test, then start to use historical data to glean information from, and finally trusting the data to help make real time decisions. Too often we get focused on just trying to collect data, but then once we have it, we are not quite sure how we want to extract value out of the data to benefit our decision making.

Effective testing with force plates

The most fundamental application of a force plate analysis involves noting how an athlete changes over time. Thus, a primary focus with force plate testing should be establishing baseline values for each athlete. Deviations from baseline values are the essence of useful athlete monitoring and provides the most value to coaches and trainers. Deviations from baseline values can help drive decisions for performance, readiness and return-to-play situations.

Many products exist to quantify stress applied to the athletes — heart rate and GPS, to name a couple; force plate data provides excellent insight into the effects of the stress on each athlete. Regular testing allows your staff to connect force plate data with other metrics to observe developing trends within each athlete. This provides you with a means for evaluating the effect of all loads applied, ultimately allowing you to define your own best practices for your athlete development model.

Below are points to consider when designing a baseline testing protocol:

    • Clearly defined purpose. The primary focus with force plate testing should be establishing baseline values for each athlete. The baseline testing procedure should address questions that can be answered through your testing protocols.  The best coaches and scientists are the ones who can ask relevant questions that can be answered with data.
    • A consistent and repeatable testing protocol. A consistent protocol allows you to establishing baseline values for your athletes. My suggestion is to begin testing with a limited number of tests and limit the variables of interest to those you feel have the most immediate value. As your testing needs evolve, you could expand on the number of tests and variables of interest. Your workflow should be dialed in to 45 to 60 seconds per athlete. Testing one to two times per month should be adequate during the season.
    • Reliable measures. Reliability refers to the consistency or reproducibility of measurements. When deciding upon which tests and variables to use, select those with high reliability of the data (ICC= 0.90+). A force plate analysis is more reliable if the movement phases are well defined. To do so requires a very reliable calculation of velocity rather than making assumptions of the direction the body is moving based solely on the force signal. If we want to measure an athlete’s ability to decelerate or accelerate, we need to be certain which direction the center of mass is moving.
    • Relevant measures. Is force generated by the athlete impacting movement in a meaningful way? Force drives motion; thus, relevant measures will not only quantify force but reliably quantify the effect of that force on the athlete’s motion. Much of the research in exercise science and strength has shown the importance of measuring force, impulse, power and work output profiles during rather simple movements. Force plate analysis allows the user to better understand an athlete’s capabilities during a dynamic movement sequence and has the benefit of excellent day to day reliability.
    • No ‘black box’ analysis. Remember, you and your staff are the experts regarding the training of your athletes. You should be making the training and recovery decisions for your athletes. The collection of force plate data should be part of a dynamic process to continually answer your current questions and drive you to ask the next question. A “black box” analysis implies that all the questions have been answered. Don’t get caught chasing red herring.

For more information and research about using force plates, visit AccuPower Solutions.

Pete Leno, MS is Vice President of AccuPower Solutions and Associate Professor, Director of Human Performance Center at Dickinson State University, Dickinson, North Dakota.

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