Mahaki, M. | bioRxiv Science

bioRxiv2021

The effect of external lateral stabilization on energy cost of walking - A systematic review and meta-analysis

Previous studies have estimated the energy cost required for the control of medio-lateral stability in human walking by means of external lateral stabilization. Results were inconsistent, possibly due to differences in task constraints or stabilization devices. To better understand the effects of lateral stabilization on energy cost, we conducted a systematic review with meta-analysis of studies, which directly assessed effects of lateral stabilization on energy cost in healthy young adult participants (18-41 years old). We obtained individual participant data on net energy cost (J kg-1 m-1) from previously published studies. Across all studies reviewed, the net energy cost reduction during stabilized walking at preferred and zero step widths equaled to 0.05 {+/-} 0.35 (~2-3% reduction) and 0.25 {+/-} 0.29 J kg-1 m-1 (mean {+/-} s.d.) (~8-9% reduction), respectively. The effect of external lateral stabilization was significant only for walking at zero step width and without arm swing. Lateral stabilization devices with short rope length increased energy cost reduction. However, spring stiffness and habituation time did not influence energy cost reduction. We provide recommendations for improvement of lateral stabilization devices to avoid some of the confounding effects. External lateral stabilization reduces energy cost during walking by a small amount. It can be concluded that a small proportion of total energy cost is required to control medio-lateral stability; this proportion is larger when walking with narrow steps and without arm swing.

physiology↗

bioRxiv2020

How does external lateral stabilization constrain normal gait, apart from improving medio-lateral gait stability?

BackgroundThe effect of external lateral stabilization on medio-lateral gait stability has been investigated previously. However, existing lateral stabilization devices not only constrains lateral motions, but also transverse and frontal pelvis rotations. This study aimed to investigate the effect of external lateral stabilization with and without constrained transverse pelvis rotation on mechanical and metabolic gait features. MethodsWe undertook 2 experiments with eleven and ten young adult subjects, respectively. Experiment 2 supplemented experiment 1, as it considered several potential confounding factors in the design and set-up of experiment 1. Kinematic, kinetic, and breath-by-breath oxygen consumption data were recorded during 3 walking conditions (normal walking (Normal), lateral stabilization with (Free) and without transverse pelvis rotation (Restricted)) and at 3 speeds (0.83, 1.25, and 1.66 m/s) for each condition. ResultsExternal lateral stabilization significantly reduced the amplitudes of the transverse and frontal pelvis rotations, medio-lateral pelvis displacement, transverse thorax rotation, arm swing, and step width. The amplitudes of free vertical moment, anterior-posterior and vertical pelvis displacements, step length, and energy cost were not significantly influenced by external lateral stabilization. The removal of transverse pelvis rotation restriction by our experimental set-up resulted in significantly higher transverse pelvis rotation, although it remained significantly less than Normal condition. In concert, concomitant gait features such as transverse thorax rotation and arm swing were not significantly influenced by our new set-up. ConclusionExisting lateral stabilization set-ups not only constrain medio-lateral motions (i.e. medio-lateral pelvis displacement), but also constrains other movements such as transverse and frontal pelvis rotations, which leads to several other gait changes such as reduced transverse thorax rotation, and arm swing. Our new setup allowed for more transverse pelvis rotation, however, this did not result in more normal pelvis rotation, arm swing, etc. Hence, to provide medio-lateral support without constraining other gait variables, more elaborate set-ups are needed. Unless such a set-up is realized the observed side effects need to be taken into account when interpreting the effects of lateral stabilization as reported in previous studies.

bioengineering↗