Method and system for monitoring exercises with elastic elements

The execution of training in rehabilitation programs is usually carried out as supervised programs based on gyms and home training programs. Exercise variables related to prescription, such as type, frequency, intensity, and duration, are critical in the implementation of exercise in a clinical setting. Managing these training variables in a clinical environment is typically done by physiotherapists, with a specific objective, depending on each patient's condition. Among the different methods of applying load in strength training within home-based programs, elastic bands have proven to be an effective modality due to their low cost, adaptability to different environments, and simple progression capability. Along with type, frequency, and intensity, time under tension (TUT) is a specific and important training variable for elastic band exercises. Total TUT reflects the duration of an exercise and refers to the sum of concentric, quasi-isometric, and eccentric contractions. A device capable of estimating the actual force exerted by a subject and calculating TUTs is based on a series of prior data: the length of the lever arm, the initial length of the elastic band, and the angle of incidence of the elastic band on the lever arm at the start of the exercise. Various alternatives have been proposed to measure either the tension of elastic bands or TUTs during home exercises. However, the main limitation of these types of sensors is that they only serve for temporary measurements, such as TUTs, but are not capable of recording tensile force. In our proposal, during the execution of an exercise, a wristband-like device records and sends to an app (on a tablet or smartphone) the inclination angle of the limb (arm, forearm, or leg) that acts as a lever relative to the mobile joint (shoulder, elbow, or knee). Subsequently, the app calculates the elongation of the elastic band based on the instantaneous angle, depending on the type of band and the initial position of the elastic band, which can be longitudinal to the lever arm, at 45º, or perpendicular. Finally, the system can estimate the actual force exerted by the subject and calculate the TUTs.