Biology subjects

Lee-Confer, J. S.

Publications and source records attributed to Lee-Confer, J. S..

3 recordsLinked to original sources

bioRxiv2025

Peak Anteroposterior Heel Slip Acceleration Predicts Lateral Trunk Flexion During Unexpected Slip Perturbations

Slip-induced falls are a major contributor to hip fractures and injury, particularly during sideways falls where lateral trunk flexion drives impact to the hip. While past studies have focused on sagittal-plane slip mechanics, the mechanisms of inducing frontal-plane trunk excursion remain poorly understood. This study investigated which slip foot kinematic variables predict lateral trunk flexion during unexpected slips. Twenty-six healthy young adults experienced an unexpected slip while walking in a laboratory setting. Peak anteroposterior (AP) heel slip distance, velocity, and acceleration, as well as mediolateral (ML) slip distance, velocity, and acceleration, were measured using three-dimensional motion capture. A stepwise multiple linear regression identified peak AP heel slip acceleration as the sole significant predictor of lateral trunk flexion (p = .026, R2 = 0.19). One-way repeated measures ANOVA and one-tailed paired t-tests further revealed that peak heel acceleration occurred significantly earlier than both peak heel velocity (p = .012) and the onset of lateral trunk flexion (p < .001), supporting its role as an early destabilizing mechanism. In contrast, neither velocity nor slip distance predicted lateral trunk flexion magnitude. These findings suggest that peak AP heel acceleration is associated with inducing lateral trunk flexion movements that likely precede lateral falls. Reducing heel acceleration through slip-resistant flooring or footwear, or enhancing compensatory strategies such as reactive arm movements, may reduce the likelihood of losing sideways balance. This work highlights the need for balance training interventions that emphasize rapid responses to early-phase slip dynamics. HighlightsO_LIEvery 1000 cm/s2 increase in AP heel acceleration leads to 6 degrees more lateral trunk flexion C_LIO_LIHeel acceleration occurs significantly earlier than heel velocity or the onset of lateral trunk flexion C_LIO_LIFindings highlight the importance in reducing forward heel acceleration to reduce sideways loss of balance C_LI

bioengineering↗

bioRxiv2024

High G-Forces in Unintentionally Improper Infant Handling: Implications for Shaken Baby Syndrome Diagnosis

IntroductionAbusive head trauma (AHT), commonly referred to as Shaken Baby Syndrome (SBS), is diagnosed in approximately 33 per 100,000 infants annually in the United States. Traditional diagnostic criteria for SBS include subdural, subarachnoid, and retinal hemorrhages. While intentional shaking is a known cause, the potential for similar forces acting on the head resulting from accidental trauma has not been fully explored. This study investigates the biomechanical forces on a model infants head during improper handling to determine if such forces could contribute to SBS without malicious intent. MethodsA realistic silicone infant model was equipped with an inertial measurement unit (IMU) to quantify head accelerations during two conditions: (1) placement of the infant model on a table with the head unsupported, and (2) manual shaking at maximum effort by 2 participants holding the model by the torso. Peak head accelerations were recorded for both conditions, and the results were analyzed for comparative assessment of the forces involved. ResultsThe average peak head acceleration when placing the infant model on a table with the head unsupported was +30,952.67 {+/-} 6,540.79 mg, with a range of +19,234.40 to +43,406.30 mg across trials. The average peak head accelerations during maximum effort shaking were significantly lower than placing the infant on the table, averaging 11,430.48 {+/-} 9,539.06,867 vs. 30,952.67 {+/-} 6,540.79 mg, p < 0.0001). There were no significant differences in head accelerations between participants when placing the infant model on the table with the head unsupported (p = 0.93) nor with shaking the baby with maximum effort (p = 0.97). DiscussionThe G-force in this study resulted in higher forces than experienced in an 18-mph car crash and a 5-mph bumper car collision. The study highlights that even accidental non-recommended handling of infants can result in high G-forces to the head, potentially leading to injuries similar to those observed in SBS. These findings highlight the necessity of supporting an infants head during handling and warrants caution against prematurely attributing physical abuse in SBS cases without considering unintentional causes.

bioengineering↗

bioRxiv2023

Overground walking slip perturbations induce frontal plane motion of the trunk indicating that slips are not just a backwards but also a sideways loss of balance

Slip and fall incidents are a serious health care concern globally. Previous research describes a backwards loss of balance during a slip incident, however hip fractures only occur if individuals fall on their side. Therefore, this study is investigating and quantifying the trunk motion in the sagittal and frontal plane. 13 healthy young participants trunk kinematics were analyzed during a slip incident. Peak trunk angle of the trunk in the sagittal and frontal plane were calculated. There was no significant difference between sagittal and frontal plane peak trunk angles suggesting that there is frontal plane motion during an overground slip incident. Our findings suggest research should investigate frontal plane mechanics during a slip incident as there is trunk frontal plane motion which if uncontrolled can result in falling on the femoral neck. Understanding and preventing falls based upon frontal plane mechanics may be more useful for preventing hip fractures from a slip incident. Lastly, the findings of this study are confirmatory results as the frontal plane trunk motion was quantified and reported in 2008.

bioengineering↗