Angular momentum regulation may dictate the slip severity in young adults

Abstract

Falls cause negative impacts on society and the economy. Slipping is a common initiating event for falling. Yet, individuals differ in their ability to recover from slips. Persons experiencing mild slips can accommodate the perturbation without falling, whereas severe slipping is associated with inadequate or slow pre-or post-slip control that make these individuals more prone to fall. Knowing the discrepancies between mild and severe slippers in kinematic and kinetic variables improves understanding of adverse control responsible for severe slipping. This study examined differences across these participants with respect to center of mass (COM) height, sagittal angular momentum (H), upper body kinematics, and the duration of single/double phase. Possible causality of such relationships was also studied by observing the time-lead of the deviations. Twenty healthy young adults performed walking trials in dry and slippery conditions. They were classified into mild and severe slippers based on their heel slipping speed. No inter-group differences were observed in the upper extremity kinematics. It was found that mild and severe slippers do not differ in the studied variables during normal gait; however, they do show significant differences through slipping. Compared to mild slippers, sever slippers lowered their COM height following a slip, presented higher H, and shortened their single support phase (p-value<0.05 for all). Based on the time-lead observed in H over all other variables suggests that failure to control angular momentum may influence slip severity.

Regulation of whole-body and segmental angular momentum in persons with Parkinson's disease on an irregular surface

“…This meant that the PD group experienced a greater lateral shift onto their leading limb that would lead their center of pressure to travel closer to the lateral edge of their base of support (Chiovetto et al, 2018;Herr and Popovic, 2008). Poor regulation of frontal angular momentum has been shown to have implications regarding severity of a slip should one occur (Nazifi et al, 2020). During weight transfer, the hip extensors and ankle dorsiflexors are most active in the sagittal plane (Neptune and McGowan, 2011), and in the frontal plane, the leg abductors are most active (Neptune and McGowan, 2016).…”

“…This study was further limited by the choice to normalize WBAM using walking velocity. Though this is the technique most used in the literature (Herr and Popovic, 2008;Silverman et al, 2012;Martelli et al, 2013;Nolasco et al, 2019;Nazifi et al, 2020), it should be noted that due to the cross product in Eq.1, sagittal walking velocity does not contribute to the frontal plane angular momentum. Normalizing frontal plane angular momentum by disparate walking velocities can artificially skew the magnitude of the results.…”

Severity of Unconstrained Simultaneous Bilateral Slips: The Impact of Frontal Plane Feet Velocities Relative to the Center of Mass to Classify Slip-Related Falls and Recoveries

“…Hence, we presented our second hypothesis and demonstrated that the peak sagittal and frontal plane angular momentum of the trunk and non-dominant arm during the slipping timeline, respectively, were significant in classifying falls and recoveries. Despite extensive literature on the significance of peak trunk extension angle to both falls and recoveries (9,13,17,19,23,29,(42)(43)(44)(45), our variable selection process generated a model based on arm adduction angular momentum. This would indicate that bracing for impact by increasing arm adduction angular momentum is associated with higher fall probability.…”

Identifying differences in gait adaptability across various speeds using movement synergy analysis

“…It is therefore unsurprising to find a movement synergy identified during the double-support phase of normal-walking was most relevant to DP as this gait-phase plays a proactive role in dynamic balance control. Interestingly [ 51 ], was unable to find differences between mild- and severe-slippers in terms of baseline sagittal plane angular momentum, centre-of-mass height, single/double-support duration or upper-body extremity kinematics but did find differences between groups during perturbed-walking. The results of the current study suggest PCA derived movement synergies may be useful in identifying such differences relevant to slip severity during normal-walking trials.…”