Fast responses to stepping‐target displacements when walking

Zhang, Yajie; Smeets, Jeroen B. J.; Brenner, Eli; Verschueren, Sabine; Duysens, Jacques

doi:10.1113/jp278986

Cited by 26 publications

(44 citation statements)

References 49 publications

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“…Note that the scales differ from those of a similar plot for the young adults in our previous paper ( Fig. 6 in Zhang et al (2020)) direction of the perturbation has little or no effect on the adjustments (Oostwoud Wijdenes et al 2013). In contrast, in the present study it was found that corrections for lateral shifts were more complete than those for medial shifts.…”

Section: Arm Reaching Versus Foot Steppingcontrasting

confidence: 85%

“…The main difference with the young adults (not shown; for their patterns see Fig. 6 in Zhang et al 2020) is that all muscles in the older adults were more active. This might reflect the reduced muscle strength in the elderly, because activity was expressed in relation to that when exerting maximal force.…”

Section: Resultsmentioning

confidence: 87%

“…We anticipate that the older adults will have later adjustments than the young adults. We expect the age-related delay in leg adjustments to be similar to such delay in arm adjustments, since the leg adjustments are extremely fast, similar to arm adjustments (Zhang et al 2020). In reaching tasks, the response latency to a target shift is 100-160 ms (Oostwoud Wijdenes et al 2013;Smeets et al 2016;Zhang et al 2018b), and older adults have a delay of about 15-20 ms (Kadota and Gomi 2010;Kimura et al 2015;Zhang et al 2018a).…”

Section: Introductionmentioning

confidence: 95%

“…Therefore, in the present study, we used EMG measures in conjunction with kinetics and kinematics. According to our previous study, young adults can start such an adjustment within as little as about 123 ms for muscle activation and about 155 ms for kinematics (Zhang et al 2020). We knew that gluteus medius (GlM), semitendinosus (ST), biceps femoris (BF), tibialis anterior (TA) and gastrocnemius medialis (GaM) from both the swing and stance leg respond quickly to medio-lateral target shifts (Zhang et al 2020).…”

Section: Introductionmentioning

confidence: 99%

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Effects of ageing on responses to stepping-target displacements during walking

et al. 2020

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Purpose Human sensory and motor systems deteriorate with age. When walking, older adults may therefore find it more difficult to adjust their steps to new visual information, especially considering that such adjustments require control of balance as well as of foot trajectory. Our study investigates the effects of ageing on lower limb responses to unpredictable target shifts. Methods Participants walked on a treadmill with projected stepping targets that occasionally shifted in the medial or lateral direction. The shifts occurred at a random moment during the early half of the swing phase of either leg. Kinematic, kinetic and muscle activity data were collected. Results Older adults responded later and corrected for a smaller proportion of the shift than young adults. The order in which muscle activation changed was similar in both groups, with responses of gluteus medius and semitendinosus from about 120 to 140 ms after the shift. Most muscles responded slightly later to lateral target shifts in the older adults than in the young adults, but this difference was not observed for medial target shifts. Ageing delayed the behavioural responses more than it did the electromyographic (EMG) responses. Conclusions Our study suggests that older adults can adjust their walking to small target shifts during the swing phase, but not as well as young adults. Furthermore, muscle strength probably plays a substantial role in the changes in online adjustments during ageing.

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Section: Arm Reaching Versus Foot Steppingcontrasting

confidence: 85%

Section: Resultsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Effects of ageing on responses to stepping-target displacements during walking

et al. 2020

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“…Consequently, foot placement adjustments had to be realized during swing, which we expected to undermine the relationship between foot placement and CoM state. Evidence exists that rapid foot placement adjustments are feasible during a stepping task [39], although stability constraints appear to negatively affect responses to large jumps of foot placement targets [40]. In our study, foot placement appeared to be more effectively constrained by the projections during slow walking as compared to normal walking, as reflected by a lower step width variability at the slower speed (see S4).…”

Section: Foot Placement Constrained Walkingmentioning

confidence: 47%

Active foot placement control ensures stable gait: Effect of constraints on foot placement and ankle moments

Leeuwen

Dieën

Daffertshofer

et al. 2020

Preprint

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15Step-by-step foot placement control, relative to the center of mass (CoM) kinematic state, is 16 generally considered a dominant mechanism for maintenance of gait stability. By adequate 17 (mediolateral) positioning of the center of pressure with respect to the CoM, the ground 18 reaction force generates a moment that prevents falling. In healthy individuals, foot 19 placement is complemented mainly by the ankle strategy ensuring stability. To evaluate 20 possible compensatory relationships between step-by-step foot placement and 21 complementary ankle moments, we investigated the degree of (active) foot placement control 22 during steady-state walking and under either foot placement or ankle moment constraints. 23Thirty healthy participants walked on a treadmill, while full-body kinematics, ground reaction 24 forces and EMG activities were recorded. As a replication of earlier findings, we first showed 25 step-by-step foot placement is associated with preceding CoM state and hip ab-/adductor 26 activity during steady-state walking. Tight control of foot placement appears to be important 27 at normal walking speed because there was a limited change in the degree of foot placement 28 control despite the presence of a foot placement constraint. At slow speed, the degree of foot 29 placement control decreased substantially, suggesting that tight control of foot placement is 30 less essential when walking slowly. Foot placement control was not tightened to compensate 31 for constrained ankle moments. Instead compensation was achieved through increases in step 32 width and stride frequency. 33 34 35On every step we take, our center of mass (CoM) accelerates laterally towards the new stance 36 foot. In order not to fall, this motion of the CoM has to be reversed, preventing the CoM to 37 move beyond the lateral border of the base of support [1]. The moment that accelerates the 38 CoM in the opposite direction can be controlled by adjusting the center of pressure (CoP) [2]. 39During gait, the dominant mechanism to control the CoP is the so-called foot placement 40 strategy [1, 3]. 41 42 Wang and Srinivasan [4] captured this control strategy in a linear model, indicating that foot 43 placement can be predicted by the CoM kinematic state (i.e. CoM position and velocity) during 44the preceding swing phase. The association between foot placement and CoM was shown to 45 be less pronounced during walking with external lateral stabilization [5], which supports the 46 notion that step-by-step foot placement control promotes mediolateral gait stability. 47

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Tapping on a target: dealing with uncertainty about its position and motion

2022

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Reaching movements are guided by estimates of the target object’s location. Since the precision of instantaneous estimates is limited, one might accumulate visual information over time. However, if the object is not stationary, accumulating information can bias the estimate. How do people deal with this trade-off between improving precision and reducing the bias? To find out, we asked participants to tap on targets. The targets were stationary or moving, with jitter added to their positions. By analysing the response to the jitter, we show that people continuously use the latest available information about the target’s position. When the target is moving, they combine this instantaneous target position with an extrapolation based on the target’s average velocity during the last several hundred milliseconds. This strategy leads to a bias if the target’s velocity changes systematically. Having people tap on accelerating targets showed that the bias that results from ignoring systematic changes in velocity is removed by compensating for endpoint errors if such errors are consistent across trials. We conclude that combining simple continuous updating of visual information with the low-pass filter characteristics of muscles, and adjusting movements to compensate for errors made in previous trials, leads to the precise and accurate human goal-directed movements.

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Fast responses to stepping‐target displacements when walking

Cited by 26 publications

References 49 publications

Effects of ageing on responses to stepping-target displacements during walking

Effects of ageing on responses to stepping-target displacements during walking

Active foot placement control ensures stable gait: Effect of constraints on foot placement and ankle moments

Tapping on a target: dealing with uncertainty about its position and motion

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