Carrying asymmetric loads while walking on an uneven surface

Abstract

Background Individuals often carry asymmetric loads over challenging surfaces such as uneven or irregular terrain, which may require a higher demand for postural control than walking on an even surface. Research Question The purpose of this study was to assess postural stability in the medial-lateral (ML) direction while carrying unilateral versus bilateral loads when walking on even versus uneven surfaces. Methods Nineteen healthy young adults walked on even and uneven surface treadmills under three load conditions: no load, 20% body weight (BW) bilateral load, and 20% BW unilateral load. A Pedar in-shoe pressure system (Novel, Munich, Germany) was used to evaluate center of pressure (COP)-based parameters. Results Carrying 20% BW bilateral or unilateral loads significantly increased double support ratio. In addition, carrying a 20% BW unilateral load significantly increased coefficient of variation (CV) of double support ratio, CV of ML COP excursion, and CV of ML COP velocity. Walking on an uneven surface significantly increased double support ratio, ML COP excursion, ML COP velocity, and CV of double support ratio. When carrying a 20% BW unilateral load, unloaded limb stance had significantly increased double support ratio and ML COP velocity, although it appears that the loaded limb may be used to make step-by-step adjustments as evidenced by the higher CV of ML COP velocity. Significance Unilateral load carriage, walking on uneven surfaces, and unloaded leg stance are of particular concern when considering postural stability.

Mediolateral postural stability when carrying asymmetric loads during stair negotiation

“…ML COP positions, velocities, and accelerations were used to calculate ML TTC using the equation in Figure 2. Since the COP shifts between the boundaries of each foot during walking, a modified version of TTC was utilized (Wang and Gillette, 2018b). In brief, TTC was calculated at each data point and then compared to the remaining single stance time (Figure 3).…”

“…Previous studies have reported that an asymmetric load resulted in increased mediolateral (ML) center of pressure (COP) velocity during quiet standing (Anker et al, 2008;Zultowski and Aruin, 2008) and higher ML COP displacement during gait initiation (Fraga et al, 2016) as compared to bilateral loads. More recently, a study has found that asymmetric load carriage with a hand-held bag required more rapid ML postural adjustments as compared to bilateral load carriage during gait (Wang and Gillette, 2018b). However, two studies did not find differences in ML COP parameters between asymmetric and bilateral load carriage during gait (Bampouras and Dewhurst, 2016;Hill et al, 2018).…”

“…Furthermore, it has been suggested that ML COP parameters are linked to higher risk of falls (Maki et al, 1994). Time to contact (TTC) appeared to be effective to evaluate postural stability when carrying asymmetric and bilateral loads (Wang and Gillette, 2018b). In fact, the ML TTC measures were decreased while other COP parameters were not changed when comparing to asymmetric load carriage to symmetric load carriage.…”

Cosmetic and functional results of a newly reconstructed thumb by combining the phalanx of second toe and the great toenail flap transplantation

“…The great toe transfer is recognized as being able to achieve both esthetic appearance and good function in the reconstructed thumb, while the second toe transfer is thought to result in less donor site morbidity [4]. The current specific considerations regarding the selection of the toe(s) are greatly based on the surgeon's experience and patient's need [5].…”

Cosmetic and Functional Results of a Newly Reconstructed Thumb by Combining the Phalange of Second Toe and the Great Toenail Flap Transplantation

“…The great toe transfer is recognized as being able to achieve both aesthetic appearance and good function in the reconstructed thumb, while the second toe transfer is thought to result in less donor site morbidity [4]. The current speci c considerations regarding the selection of the toe(s) are greatly based on the surgeon's experience and patient's need [5].…”