The influence of deformation height on estimating the center of pressure during level and cross-slope walking on sand

Xu, Hang; Yi, Wang; Greenland, Kasey; Bloswick, Donald S.

doi:10.1016/j.gaitpost.2015.04.015

Cited by 11 publications

(6 citation statements)

References 14 publications

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“…The unstable runway was filled with dry sand to simulate a common deformable surface environment. A Bertec force plate with a sampling rate of 1,000 Hz was embedded in the runway (20 cm underneath the sand; Xu et al, 2015 ) and used to collect GRF data. The frame consisted of two steel rectangles concentrically aligned with 6 mm clearance between the walls ( Figure 2 ).…”

Section: Methodsmentioning

confidence: 99%

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Effects of Running on Sand vs. Stable Ground on Kinetics and Muscle Activities in Individuals With Over-Pronated Feet

et al. 2022

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Background: In terms of physiological and biomechanical characteristics, over-pronation of the feet has been associated with distinct muscle recruitment patterns and ground reaction forces during running.Objective: The aim of this study was to evaluate the effects of running on sand vs. stable ground on ground-reaction-forces (GRFs) and electromyographic (EMG) activity of lower limb muscles in individuals with over-pronated feet (OPF) compared with healthy controls.Methods: Thirty-three OPF individuals and 33 controls ran at preferred speed and in randomized-order over level-ground and sand. A force-plate was embedded in an 18-m runway to collect GRFs. Muscle activities were recorded using an EMG-system. Data were adjusted for surface-related differences in running speed.Results: Running on sand resulted in lower speed compared with stable ground running (p < 0.001; d = 0.83). Results demonstrated that running on sand produced higher tibialis anterior activity (p = 0.024; d = 0.28). Also, findings indicated larger loading rates (p = 0.004; d = 0.72) and greater vastus medialis (p < 0.001; d = 0.89) and rectus femoris (p = 0.001; d = 0.61) activities in OPF individuals. Controls but not OPF showed significantly lower gluteus-medius activity (p = 0.022; d = 0.63) when running on sand.Conclusion: Running on sand resulted in lower running speed and higher tibialis anterior activity during the loading phase. This may indicate alterations in neuromuscular demands in the distal part of the lower limbs when running on sand. In OPF individuals, higher loading rates together with greater quadriceps activity may constitute a proximal compensatory mechanism for distal surface instability.

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Section: Methodsmentioning

confidence: 99%

“…The frame consisted of two steel rectangles concentrically aligned with 6 mm clearance between the walls ( Figure 2 ). Previous studies showed that this runway construction is well-suited to accurately assess GRFs while running ( Merryweather, 2008 ; Yoo, 2014 ; Xu et al, 2015 ). The force plate was embedded halfway through the 18 m runway.…”

Section: Methodsmentioning

confidence: 99%

Effects of Running on Sand vs. Stable Ground on Kinetics and Muscle Activities in Individuals With Over-Pronated Feet

et al. 2022

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“…For COP analysis, deformation height was computed. Of note, deformation height corresponds to the maximum vertical slippage depth while walking on sand [34]. The COP values were calculated in accordance with Xu et al [34].…”

Section: Methodsmentioning

confidence: 99%

Ground reaction forces and muscle activity while walking on sand versus stable ground in individuals with pronated feet compared with healthy controls

et al. 2019

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BackgroundSand is an easy-to-access, cost-free resource that can be used to treat pronated feet (PF). Therefore, the aims of this study were to contrast the effects of walking on stable ground versus walking on sand on ground reaction forces (GRFs) and electromyographic (EMG) activity of selected lower limb muscles in PF individuals compared with healthy controls.MethodsTwenty-nine controls aged 22.2±2.5 years and 30 PF individuals aged 22.2±1.9 years were enrolled in this study. Participants walked at preferred speed and in randomized order over level ground and sand. A force plate was included in the walkway to collect GRFs. Muscle activities were recorded using EMG system.ResultsNo statistically significant between-group differences were found in preferred walking speed when walking on stable ground (PF: 1.33±0.12 m/s; controls: 1.35±0.14 m/s; p = 0.575; d = 0.15) and sand (PF: 1.19±0.11 m/s; controls: 1.23±0.18 m/s; p = 0.416; d = 0.27). Irrespective of the group, walking on sand (1.21±0.15 m/s) resulted in significantly lower gait speed compared with stable ground walking (1.34±0.13 m/s) (p<0.001; d = 0.93). Significant main effects of “surface” were found for peak posterior GRFs at heel contact, time to peak for peak lateral GRFs at heel contact, and peak anterior GRFs during push-off (p<0.044; d = 0.27–0.94). Pair-wise comparisons revealed significantly smaller peak posterior GRFs at heel contact (p = 0.005; d = 1.17), smaller peak anterior GRFs during push-off (p = 0.001; d = 1.14), and time to peak for peak lateral GRFs (p = 0.044; d = 0.28) when walking on sand. No significant main effects of “group” were observed for peak GRFs and their time to peak (p>0.05; d = 0.06–1.60). We could not find any significant group by surface interactions for peak GRFs and their time to peak. Significant main effects of “surface” were detected for anterior-posterior impulse and peak positive free moment amplitude (p<0.048; d = 0.54–0.71). Pair-wise comparisons revealed a significantly larger peak positive free moment amplitude (p = 0.010; d = 0.71) and a lower anterior-posterior impulse (p = 0.048; d = 0.38) when walking on sand. We observed significant main effects of “group” for the variable loading rate (p<0.030; d = 0.59). Pair-wise comparisons revealed significantly lower loading rates in PF compared with controls (p = 0.030; d = 0.61). Significant group by surface interactions were observed for the parameter peak positive free moment amplitude (p<0.030; d = 0.59). PF individuals exhibited a significantly lower peak positive free moment amplitude (p = 0.030, d = 0.41) when walking on sand. With regards to EMG, no significant main effects of “surface”, main effects of “group”, and group by surface interactions were observed for the recorded muscles during the loading and push-off phases (p>0.05; d = 0.00–0.53).ConclusionsThe observed lower velocities during walking on sand compared with stable ground were accompanied by lower peak positive free moments during the push-off phase and loading rates during the loading pha...

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“…where F x , F y and F z are the lateral, fore-aft and vertical GRFs, respectively; M x and M y the moment components in the force transducer coordinate system; and h is the vertical distance between the force transducers and the tread-surface (Xu et al 2015). The stride width was then defined as max (d y ) -min (d y ) over a stride.…”

Section: Division Of Stridementioning

confidence: 99%

Intra-limb and muscular coordination during walking on slopes

2020

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Purpose Intra-limb and muscular coordination during gait are the result of the organisation of the neuromuscular system, which have been widely studied on a flat terrain. Environmental factors, such as the inclination of the terrain, is a challenge for the postural control system to maintain balance. Therefore, we hypothesised that the central nervous system flexibly modifies its control strategies during locomotion on slopes. Methods Ten subjects walked on an inclined treadmill at different slopes (from − 9° to + 9°) and speeds (from 0.56 to 2.22 m s −1 ). Intra-limb coordination was investigated via the Continuous Relative Phase, whereas muscular coordination was investigated by decomposing the coordinated muscle activation profiles into Basic Activation Patterns. Results A greater stride to stride variability of kinematics was observed during walking on slopes, as compared to walking on the level. On positive slopes, the stride period and width present a greater variability without modification of the timepattern of the muscular activation and of the variability of intersegmental coordination. On negative slopes, the stride width is larger, the variability of the stride period and of the inter-segmental coordination is greater and the basic activation patterns become broader, especially at slow speeds. Conclusion Our findings suggest that the control strategy of downhill walking corresponds to a more conservative gait pattern, which could be adopted to lower the risk of falling at the cost of a greater energy consumption. In uphill walking, where metabolic demands are high, the strategy adopted may be planned to minimise energy expenditure. Keywords Coordination • Neuromuscular control • Basic activation pattern • Continuous relative phase Abbreviations CRP Continuous relative phase GRF Ground reaction force EMG Records of the electrical activity produced by skeletal muscles TO Toe off COP Centre of pressure FC Foot contact F x , F y , F z Lateral, fore-aft and vertical component of the GRF d y , d x Lateral and fore-aft position of the COP ω i , θ i Lower-limb segment angular velocity and position φ iN Phase angle ϕ iN CRP angle MARP Mean absolute relative phase DP Deviation phase of the CRP FWHM Full width at half maximum CI Co-activation index NNMF Non-negative matrix factorisation P, W Basic activation patterns and associated weighting components VAF Variability accounted for

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The influence of deformation height on estimating the center of pressure during level and cross-slope walking on sand

Cited by 11 publications

References 14 publications

Effects of Running on Sand vs. Stable Ground on Kinetics and Muscle Activities in Individuals With Over-Pronated Feet

Effects of Running on Sand vs. Stable Ground on Kinetics and Muscle Activities in Individuals With Over-Pronated Feet

Ground reaction forces and muscle activity while walking on sand versus stable ground in individuals with pronated feet compared with healthy controls

Intra-limb and muscular coordination during walking on slopes

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