Corner height influences center of mass kinematics and path trajectory during turning

Abstract

Despite the prevalence of directional changes during every-day gait, relatively little is known about turning compared to straight gait. While the center of mass (COM) movement during straight gait is well characterized, the COM trajectory, and the factors that influence it, are less established for turning. This study investigated the influence of a corner’s height on the COM trajectory as participants walked around the corner. Ten participants (25.3 ± 3.74 years) performed both 90° step and spin turns to the left at self-selected slow, normal, and fast speeds while walking inside a marked path. A pylon was placed on the inside corner of the path. Four different pylon heights were used to correspond to heights of everyday objects: 0 cm (no object), 63 cm (box, crate), 104 cm (desk, table, counter), 167 cm (shelf, cabinet). Obstacle height was found to significantly affect the COM trajectory. Taller obstacles resulted in more distance between the corner and the COM, and between the corner and the COP. Taller obstacles also were associated with greater curvature in the COM trajectory, indicating a smaller turning radius despite the constant 90° corner. Taller obstacles correlated to an increased required coefficient of friction (RCOF) due to the smaller turning radii. Taller obstacles also tended towards greater mediolateral (ML) COM-COP angles, contrary to the initial hypothesis. Additionally, the COM was found to remain outside the base of support (BOS) for the entire first half of stance phase for all conditions indicating a high risk of falls resulting from slips.

Comparison of the COM-FCP inclination angle and other mediolateral stability indicators for turning

“…10). Only a few researchers have used the COM-COP angle in turning or circular walking tasks [32, 33]. The peak ML COM-COP angle is around 7.0° for healthy subjects, while the ML angle (FCP) in our study for CW1 m with NSL is around 6.9° (Fig.…”

State of science: occupational slips, trips and falls on the same level

“…A slip occurs at the shoe and floor interface when the friction required (required coefficient of friction, RCOF) to support walking exceeds the friction available (available coefficient of friction, ACOF) at the shoe and floor interface (Hanson, Redfern, and Mazumdar 1999). The RCOF for straight walking has been investigated extensively (Hanson, Redfern, and Mazumdar 1999; Cham and Redfern 2002a; Kim, Lockhart, and Yoon 2005; Chang, Matz, and Chang 2012; Anderson, Franck, and Madigan 2014; Beringer, Nussbaum, and Madigan 2014; Fino and Lockhart 2014; Fino, Lockhart, and Fino 2015). The transverse component of the ground reaction force obtained with a force plate has been ignored in most of the RCOF calculations, but a study conducted by Chang, Chang, and Matz (2011) demonstrated that the transverse shear force could significantly increase RCOF and result in a much earlier occurrence of RCOF in the gait cycle.…”

“…The transverse component of the ground reaction force obtained with a force plate has been ignored in most of the RCOF calculations, but a study conducted by Chang, Chang, and Matz (2011) demonstrated that the transverse shear force could significantly increase RCOF and result in a much earlier occurrence of RCOF in the gait cycle. Recent studies showed that the RCOF for turning could be as high as 0.36, while that for straight walking was of the order of 0.2 (Burnfield, Tsai, and Powers 2005; Yamaguchi et al 2013; Fino, Lockhart, and Fino 2015). The RCOF for carrying out different tasks under different situations, such as walking on different floor surfaces with different footwear, needs to be investigated further.…”

Classifying Step and Spin Turns Using Wireless Gyroscopes and Implications for Fall Risk Assessments

“…Additionally, Yamada et al [ 13 ] reported a greater frequency of spin turns during a multi-target stepping task in elderly with a high risk of falling compared to healthy elderly. The higher frequencies of spin turns are concerning because the COM is laterally displaced outside the BOS more during spin turns than step turns [ 9 , 10 ] indicating a high risk of lateral falls if a perturbation (slip, trip) occurs.…”

“…Spin turns are characterized by turning on the ipsilateral limb (e.g., left turn while the left limb is the stance limb) and step turns are characterized by turning on the contralateral limb (e.g., left turn while the right limb is the stance limb). Of these two strategies, spin turns are considered less stable than step turns because the whole-body center-of-mass (COM) remains outside the base-of-support (BOS) for the majority of the stance phase [ 9 , 10 ]. Because of this COM displacement, one could expect step turns to be more prevalent.…”