Targeting Muscle Strength Loss Due to Hospitalization in Older Adults by Blood-flow Restriction Combined With an Electromyography-driven Serious Game.

This study investigates a new training method designed to help older adults preserve their muscle strength during hospitalization. When older adults are admitted to the hospital and spend long periods in bed, their muscles can weaken very quickly. This condition is known as hospital-associated disability (HAD), and it can lead to longer hospital stays, reduced independence, and an increased risk of complications or even death. Conventional strength training with heavy weights is often too demanding or unsafe for frail patients, especially just after surgery or illness. As a safer alternative, this study combines light muscle exercises with a medically validated technique called blood flow restriction (BFR), which gently reduces blood flow to the leg to boost the effects of light exercises. To make training more engaging and personalized, the GHOSTLY+ system was developed. This system consists of a game played on a tablet that responds to muscle activity through sensors placed on the skin. While playing, patients perform isometric muscle contractions (exercises where the muscles tighten without moving the joint) that help to maintain and rebuild strength. The system was carefully designed in collaboration with patients and therapists, and it has already been tested in a smaller pilot study at UZ Brussel. The current study is a multicenter randomized controlled trial, taking place at UZ Brussel, UZ Antwerpen, and UZ Leuven. A total of 120 patients aged 65 or older will be recruited, all of whom are hospitalized and are unable to bear weight or transfer (e.g., from lying to seated position). Participants will be randomly assigned to one of two groups. One group receives standard physiotherapy. The other group receives standard therapy plus the GHOSTLY+ training program. Those in the GHOSTLY+ group will train at least five times per week for two weeks, or until discharge from the hospital. Each training session lasts approximately 30 minutes and involves three sets of 12 muscle contractions, guided by the game. The difficulty is adapted to the individual's muscle strength, which is measured at the beginning of the training using a built-in calibration protocol. During the session, a smart cuff is applied to the upper leg to partially restrict blood flow - a technique shown to safely enhance muscle adaptation. The cuff is inflated to 50% of the individual's arterial occlusion pressure and deflated after the session ends. Before beginning, participants receive a short training session with a physiotherapist. Our pilot study (Debeuf et al., 2025) shows that most patients can use the system independently after about one hour of instruction. Measurements and evaluations take place at three timepoints: before starting the training, after one week, and again at discharge. The main goal is to assess leg muscle strength, which will be measured using a handheld device called a dynamometer. In addition, researchers will collect information on: * Muscle mass, via ultrasound of the thigh muscle * Functional capacity, using a 30-second sit-to-stand test and a walking scale (Functional Ambulation Category) * An index of independence in activities of daily living (Katz scale) * Cognitive functioning, using the Mini-Mental State Examination (MMSE) * Time spent bedridden and total length of hospital stay * Therapy adherence and user experience, via usage data and questionnaires * Muscle activity signals, such as fatigue, recorded during gameplay * Implementation outcomes (collected via surveys, interview, site logbooks) The study will also assess how easily the GHOSTLY+ system can be implemented in real hospital environments. This includes evaluations of user satisfaction, therapist feedback, and how consistently the system is used across hospital settings. Information will be gathered through structured interviews, surveys, and data logs from the app. These insights are crucial to understanding whether GHOSTLY+ can be broadly adopted in other hospitals in the future. Blood flow restriction training is considered very safe when applied correctly and is already used in rehabilitation clinics and sports medicine worldwide. Over 300,000 sessions have been conducted internationally, with a very low rate of complications. Minor discomfort, such as temporary tightness or muscle fatigue, may occur, but the risk of serious side effects is extremely small. By participating in this study, patients may benefit from improved muscle strength, reduced time spent in bed, and greater physical independence at discharge. The study also contributes to the development of more effective and enjoyable rehabilitation methods for older adults in hospitals.