Kinetic-functional Analysis of an Immersive Virtual Reality Serious Game and Investigation of Cybersickness Symptoms

Virtual reality has moved beyond gaming arcades and into the quiet, focused world of physical rehabilitation. For years, therapists have used computer-generated environments to help patients retrain their bodies, offering safe spaces to practice balance and movement without the risk of falling. However, a persistent shadow follows this technology: a phenomenon known as cybersickness. Much like motion sickness on a boat, it occurs when the eyes see movement that the inner ear does not feel, leaving the user dizzy, nauseous, or disoriented. This side effect has often limited how widely these tools can be used in clinics, as therapists struggle to know if a patient's struggle is due to a physical weakness or simply the discomfort of the virtual world. To move forward, researchers need a way to watch how people actually move inside these digital spaces and to understand exactly when and why that virtual dizziness strikes.

A team of researchers at the Federal University of Rio Grande do Norte in Brazil set out to examine these questions using a specific virtual reality game called VIRTUALTER. This game was designed to help people practice sitting balance by reaching out to catch glowing fireflies in a digital forest. The researchers invited thirty-two healthy young adults, mostly students studying physical therapy, to wear a headset and play the game. They wanted to see two things: first, how the players' bodies moved and adjusted while trying to catch the targets, and second, whether the game made them feel sick. To measure the sickness, the team asked the players to fill out questionnaires before they put on the headset and again immediately after they took it off. These surveys asked about nausea, dizziness, and eye strain. The researchers also watched the players closely, noting how they held their heads, how they shifted their weight in their chairs, and how smoothly they reached for the virtual targets.

The results offered a reassuring picture for the future of this technology. The study found that playing the immersive version of VIRTUALTER did not cause a significant increase in sickness symptoms for the group as a whole. While a few participants reported mild dizziness or nausea that lasted for a short time after the session, the vast majority tolerated the experience well. The researchers noticed that people who had played with virtual reality before felt less sick than those who were new to the technology, suggesting that familiarity helps the brain adjust to the strange mix of visual and physical signals. Interestingly, the study found no difference in sickness levels between men and women, challenging the idea that one gender is naturally more prone to these symptoms in this context.

Beyond the question of sickness, the team developed a detailed way to describe how the players moved, connecting their actions to a standard system used by doctors to classify human function. They observed that the players used their bodies in a coordinated and efficient way. To catch the fireflies, players would turn their heads, twist their torsos, and reach with their arms in a smooth, continuous motion. They maintained a stable posture in their chairs, keeping their heads and spines aligned even as they leaned forward or sideways to reach targets. The researchers noted that the players' movements were symmetrical, meaning they used both sides of their bodies equally, and that they could accurately judge where to reach without stumbling. This kind of detailed observation allows therapists to see not just if a patient can complete a task, but how they organize their body to do it.

The study concludes that this specific virtual reality game is a safe and effective tool for observing and training movement. It did not generate the severe discomfort that often stops patients from using such technology. The researchers suggest that the game's design, which kept the camera steady and let the player control the action, likely helped prevent the sensory confusion that causes sickness. By combining the observation of physical movement with the tracking of symptoms, the team showed that virtual reality can be used to understand human function more deeply. They emphasize that while this initial test was successful, more research with larger groups and different types of patients is needed to refine how these tools are used in real-world therapy. For now, the findings suggest that with careful design, the virtual forest can be a safe place for the body to learn and heal.