Testing the efficacy of motor analogies designed to promote safe landing by older adults who fall accidentally

Brief Name: Motor analogy Measurements and instrumentation: A 2D video camera (Canon, 25 frames per second) and 15 Delsys TrignoTM (Delsys Inc., Natrick, MA) inertial measurement units (IMU) will be used for data collection. The video camera will be positioned 3 meters from the side of the participants on a tripod (height 1.3 meters). The researcher will place 15 Delsys TrignoTM (Delsys Inc., Natrick, MA) inertial measurement unit (IMU) sensors on different body segments, described in the ‘sensor placement’ section. Acceleration data from the IMU sensors will be recorded at a frequency of 148.15 Hz using EMGworks Acquisition software (Version 4.5.4). A hand-held dynamometer (MyoMeter, M550; range: 0-50 kg) will be used to record the force applied when nudging each participant to fall. Procedure: Participants will be invited to a data collection session at the Human Performance Science Lab (TT 0.05) at the School of Health at the University of Waikato. Overall, the whole experiment will take approximately 1 hour and 30 minutes to 1 hour and 45 minutes. The procedure will be performed at the participant’s most comfortable pace and there will be an assistant standing by the participant at all times. The participant’s safety will be observed before performing each test and if there is any sign of potential harm the procedure will be immediately stopped. Furthermore, chairs will be placed close to the participants during all the procedures and they will be able to sit on them at any point during the experiment and participants will be provided with as many breaks as they want. 1. Sensor placement Fifteen small IMU sensors (dimension: 27 x 37 x 13 mm) will be attached on the following body segments using double sided tape: head, chest (aligned with the sternum), lower back (aligned with L3), upper arms (dorsal), wrists (dorsal), hands (dorsal), hip (greater trochanter) thighs (lateral), lower legs (lateral). 2. Crossword puzzle Participants in the analogy condition will be required to complete a three-word crossword puzzle designed to prime them about how feathers land on the ground: soft, slow, silent. 3. Falling onto a soft surface Participants will stand on a surface surrounded by a fully padded area in the laboratory. The research assistant will unexpectedly apply a gentle impulse (nudge) to the shoulder of the participant in one of 4 different directions using a hand held dynamometer. Participants will be asked to fall onto a padded area in the direction in which the impulse (nudge) is applied. In order to avoid anticipation of the applied impulse (nudge), participants will be asked to engage in a secondary task – counting backwards in 3’s. To control for the nudge applied to the participants, the research assistant will be blinded to the conditions and a hand-held dynamometer will be used to record the force applied for each nudge. The participant will fall in four directions: backward, forward, left-side, and right-side. Participants in the analogy condition will be instructed to “land like a feather”. After the participants land on the soft mattress the assistant will help them to get up and they will have a 2 minutes interval between each fall. The order of the falls will be randomized using a random order generator. The experimental procedure will be repeated twice (with different order of falls each time); in total, each participant will fall eight times during the experimental procedure.