Balance Assessment Using a Smartwatch Inertial Measurement Unit with Principal Component Analysis for Anatomical Calibration.

Balance assessment, or posturography, tracks and prevents health complications for a variety of groups with balance impairment, including the elderly population and patients with traumatic brain injury. Wearables can revolutionize state-of-the-art posturography methods, which have recently shifted focus to clinical validation of strictly positioned inertial measurement units (IMUs) as replacements for force-plate systems. Yet, modern anatomical calibration (i.e., sensor-to-segment alignment) methods have not been utilized in inertial-based posturography studies. Functional calibration methods can replace the need for strict placement of inertial measurement units, which may be tedious or confusing for certain users. In this study, balance-related metrics from a smartwatch IMU were tested against a strictly placed IMU after using a functional calibration method. The smartwatch and strictly placed IMUs were strongly correlated in clinically relevant posturography scores (r = 0.861-0.970, p < 0.001). Additionally, the smartwatch was able to detect significant variance (p < 0.001) between pose-type scores from the mediolateral (ML) acceleration data and anterior-posterior (AP) rotation data. With this calibration method, a large problem with inertial-based posturography has been addressed, and wearable, "at-home" balance-assessment technology is within possibility.

A Pilot Feasibility Randomized Controlled Trial of Effects of Opaque Bottles on Maternal Sensitivity, Infant Intake, and Infant Weight Status.

BACKGROUND: Conventional clear infant feeding bottles provide visual cues about the amount of milk consumed, which may decrease caregivers' sensitivity to infant cues, increase infant intake, and lead to greater infant weight gain. OBJECTIVE: This study examined feasibility, adherence, acceptability, and preliminary effectiveness of an intervention in which families received clear vs opaque bottles. DESIGN: A pilot feasibility randomized controlled trial was conducted. PARTICIPANTS/SETTING: Participants included mothers (N = 76) with young infants (2.9 ± 1.4 months old). Data collection occurred between December 2018 and July 2022 and within San Luis Obispo and Santa Barbara Counties, California. All assessments occurred within participants' homes. INTERVENTION: Participants were randomized to use clear (Clear group, n = 38) or opaque (Opaque group, n = 38) bottles for 12 weeks. MAIN OUTCOME MEASURES: We assessed feasibility of recruitment and retention, participant perceptions of study bottles, participant adherence to the intervention, maternal sensitivity to cues, infant intake (mL and mL/kg), and infant weight-for-length z-scores (WLZ). STATISTICAL ANALYSES PERFORMED: Data were analyzed using linear regression, χ2 analysis, and repeated-measures analysis of variance (ANOVA). RESULTS: Of 842 potential participants, 295 (35%) could not be reached after initial contact, 166 (20%) declined to participate, and 305 (36%) were ineligible. Of those who declined, 16 (10%) declined because they did not want to use study bottles. No differences were observed for loss to follow-up for Clear (8 of 38; 21%) vs Opaque (5 of 38; 13%) groups (P = 0.36) or for reported use of assigned bottles for Clear (89.8% ± 24.5% of daily feedings) vs Opaque (90.1% ± 22.1%) groups (P = 0.96). No group differences were observed for sensitivity to cues (P = 0.52) or intake (mL, P = 0.53 or mL/kg, P = 0.56) at follow-up. Opaque group infants had lower WLZ at follow-up compared with Clear group infants (mean difference, 0.47; 95% confidence interval, 0.08, 0.86; ηp2 = 0.17), adjusting for baseline WLZ. CONCLUSIONS: Relative to providing clear bottles, providing families with opaque bottles appeared feasible and acceptable, with good adherence. Although preliminary, study findings suggest the potential of opaque bottles to support healthier weight outcomes for bottle-fed infants.