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Preventing falls and improving quality of life for older adults are key challenges in promoting health in an increasingly long-lived population. One promising approach is to strengthen dynamic balance – the ability to maintain bodily stability even while moving. With this in mind, researchers at USP’s School of Physical Education and Sport, from the Human Motor Systems Laboratory, developed Equidyn, an app that uses a smartphone’s accelerometer to assess balance in a simple, fast, and accessible way.
The project was carried out in partnership with the National Institute of Technology (INT) in Rio de Janeiro, responsible for the technical development of the app commissioned by the USP team. The goal was to create a standardized body balance assessment protocol that could be performed entirely with the help of a cell phone, reducing the need for expensive equipment or complex procedures.
According to Luís Augusto Teixeira, a professor at EEFE and one of the developers of the tool, an examiner needs to be present to place the device on the person being assessed and give basic instructions. After that, the app guides the user and takes care of almost the entire process.
How to use
The process is simple: the smartphone with Equidyn installed is secured to the participant’s mid-back with an elastic strap. The app then guides the person through a series of tests, starting with a stationary single-leg stance – balancing on one leg for 30 seconds. During the test, the phone’s sensor records torso sway, which serves as the main measure of balance.
After the static test, the protocol moves on to dynamic challenges. The participant performs leg swings – forward and backward, then side to side – and finally completes a sit-to-stand task. All movements are guided by audio cues from the app, which uses a built-in metronome to standardize rhythm and ensure data consistency. Floor markings also limit the range of motion, further reinforcing standardization. “The metronome standardizes movement timing, which is one of the biggest challenges in assessing dynamic balance”, Teixeira explains. “If timing is left open, individual differences are too large, making it difficult to compare results”.
According to him, this standardization makes Equidyn especially interesting for clinical application and comparative studies. Unlike other approaches that assess balance indirectly – for example, by asking the person to move their leg as far as possible, which also involves strength and flexibility – the app directly measures the torso acceleration during the test, which provides a more accurate measure of body stability.
Innovation
While acceleration-tracking apps are available online, Teixeira emphasizes that Equidyn’s distinguishing feature is its validated protocol, specifically tested for assessing balance in different contexts. “Perhaps something similar exists abroad, but not with this proposal of a complete protocol for both static and dynamic balance”, the researcher says.
The professor explains that the tests carried out with Equidyn were applied to more than 50 elderly people, with good results. Everyone was able to follow the instructions, maintain the rhythm and complete the movements successfully. The data collected showed expected variations in torso accelerations depending on the type of movement, which reinforces the reliability of the tool.
There are, however, some limitations. People with severe balance issues – such as very frail older adults or individuals with neurological disorders – may be unable to perform the proposed tasks. For this reason, Equidyn was designed to assess individuals who can maintain balance on one leg for at least 30 seconds. Teixeira notes that, although the tests were conducted with an older population, the tool can be used for people of any age, including younger adults.
Update
“The app is already complete, but Luís Augusto Teixeira notes that the team is developing a lite version with fewer trials per leg and half the duration. The goal is to make the test even faster and suitable for clinical use. “The technology remains the same – we’re simply moving to another programming language, a process handled by INT”, the professor explains. “We’re just waiting to finish this second phase to expand access and allow broader use. It has become very simple and user-friendly”.
English version: Nexus Traduções, edited by Denis Pacheco
