Virtual Reality Balance Games Provide Little Muscular Challenge to Prevent Muscle Weakness in Healthy Older Adults

Objective: Muscle weakness is an important risk factor for falls in older adults. Intensity and duration of muscle activity are important determinants of exercise effectiveness in combating muscle weakness. The aim of this article was to assess the intensity and duration of muscle activity in virtual reality (VR) balance games. Materials and Methods: Thirty young and 30 healthy older adults played seven different VR balance games. Muscle activity of the vastus lateralis, vastus medialis, soleus, and gluteus medius was obtained using surface electromyography (EMG). The processed EMG signals were divided into 200-ms blocks, after which each block was categorized by its average normalized EMG activity, that is, >80%, 60%-80%, 40%-60%, or 40% MVC, to identify prolonged muscle activity. Results: Muscle activity during game play was mostly