Equidyn application tutorial v1

The Equidyn application was developed to evaluate dynamic balance through smartphone-based trunk accelerometry. The evaluation protocol had as main characteristic a reduced support base while having standardized movement amplitude and rhythm. The evaluation protocol was composed of a series of seven tasks: 1. One-leg motionless balance supported on the right leg, 2. One-leg motionless balance supported on the left leg, 3. Anteroposterior (AP) oscillation of the left leg while supported on the right leg, 4. AP oscillation of the right leg while supported on the left leg, 5. Mediolateral (ML) oscillation of the left leg while supported on the right leg, 6. ML oscillation of the right leg while supported on the left leg, 7. Sit-to-stand with bipedal support. Markers were made through adhesive strips, attached 20-cm apart in parallel on the ground. Proximal markers were used as reference for positioning the supporting foot, while the distal AP marker was attached in front of the participant, and the distal ML marker was attached laterally regarding participant’s spatial orientation. These markers were used to achieve the same leg movement amplitude across participants. The dynamic tasks were paced through beeps emitted by a digital metronome set at the frequency of 1-Hz. Each marker touching in the leg sway tasks, and either sitting or full standing phases of the sit-to-stand task were to be timed with metronome beeps. Tasks were assessed through three consecutive trials, lasting 15 s each.Intratest between-trial rest intervals were 30-s long, while 60-s intervals were provided between tests. The complete assessment lasted approximately 20 min. Participants’ responses are administered through a smartphone application named Equidyn, designed and developed for the Android system.The root mean square (RMS) of acceleration in the AP and ML directions was analyzed in each task.