Biomechanics and Motor Control of Human Movement

Winter, David

doi:10.1002/9780470549148

Cited by 5,709 publications

(6,204 citation statements)

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“…A fourth-order, zero phase-lag, low-pass Butterworth filter with a cut-off frequency of 20 Hz [32] was applied to all CoP displacement time series. Only the CoP displacements in the AP direction will be reported, as the perturbations were induced symmetrically.…”

Section: Reciprocal Activation Emgnorm Emgnormmentioning

confidence: 99%

Influence of long-term wearing of unstable shoes on compensatory control of posture: An electromyography-based analysis

et al. 2014

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Purpose: This study investigated the influence of long-term wearing of unstable shoes (WUS) on compensatory postural adjustments (CPA) to an external perturbation.Methods: Participants were divided into two groups: one wore unstable shoes while the other wore conventional shoes for 8 weeks. The ground reaction force signal was used to calculate the anterior-posterior (AP) displacement of the centre of pressure (CoP) and the electromyographic signal of gastrocnemius medialis (GM), tibialis anterior (TA), rectus femoris (RF) and biceps femoris (BF) muscles was used to assess individual muscle activity, antagonist co-activation and reciprocal activation at the joint (TA/GM and RF/(BF+GM) pairs) and muscle group levels (ventral (TA+RF)/dorsal (GM+BF) pair) within time intervals typical for CPA. The electromyographic signal was also used to assess muscle latency. The variables described were evaluated before and after the 8-week period while wearing the unstable shoes and barefoot. Results: Long-term WUS led to: an increase of BF activity in both conditions (barefoot and wearing the unstable shoes); a decrease of GM activity; an increase of antagonist co-activation and a decrease of reciprocal activation level at the TA/GM and ventral/dorsal pairs in the unstable shoe condition. Additionally, WUS led to a decrease in CoP displacement. However, no differences were observed in muscle onset and offset. Conclusion: Results suggest that the prolonged use of unstable shoes leads to increased ankle and muscle groups' antagonist co-activation levels and higher performance by the postural control system.

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Section: Reciprocal Activation Emgnorm Emgnormmentioning

confidence: 99%

Influence of long-term wearing of unstable shoes on compensatory control of posture: An electromyography-based analysis

et al. 2014

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“…Data were sampled at 60 Hz and low pass filtered using a 2nd order, dual pass Butterworth filter with a cut-off frequency of 5 Hz. The position of the centre of mass (COM) of each body segment in the antero-posterior (AP) direction was calculated using the kinematic data and anthropometric data provided by Winter (1990). Whole body COM position (in space) in the AP direction was derived from the weighted sum of the individual segment COM locations.…”

Section: Data Recordingmentioning

confidence: 99%

Compensatory postural adaptations during continuous, variable amplitude perturbations reveal generalized rather than sequence-specific learning

et al. 2008

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We examined changes in the motor organization of postural control in response to continuous, variable amplitude oscillations evoked by a translating platform and explored whether these changes reflected implicit sequence learning. The platform underwent random amplitude (maximum ± 15 cm) and constant frequency (0.5 Hz) oscillations. Each trial was composed of three 15-second segments containing seemingly random oscillations. Unbeknownst to participants, the middle segment was repeated in each of 42 trials on the first day of testing and in an additional seven trials completed approximately 24 hours later. Kinematic data were used to determine spatial and temporal components of total body centre of mass (COM) and joint segment coordination. Results showed that with repeated trials, participants reduced the magnitude of horizontal body COM displacement, shifted from a COM phase lag to a phase lead relative to platform motion and increased correlations between ankle/platform motion and hip/platform motion as they evolved from an ankle strategy to a multi-segment control strategy involving the ankle and hip. Maintenance of these changes across days provided evidence for learning. Similar improvements for the random and repeated segments, however, indicate that participants did not exploit the sequence of perturbations to improve balance control. Rather, the central nervous system (CNS) may have been tuning into more general features of platform motion. These findings provide important insight into the generalizabilty of improved compensatory balance control with training.jsfrank@uwindsor.ca,

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“…Before each experimental session, we placed 72 reflective markers on the legs, trunk, and arms using a modified Cleveland Clinic marker set to measure whole body kinematics based on standard techniques [7,9,10,24]. Clusters of at least four markers were placed on the feet, shanks, thighs, pelvis, trunk, upper arms, and forearms, and individual markers were placed on the medial and lateral joint centers between each segment.…”

Section: Methodsmentioning

confidence: 99%

Does Use of a Powered Ankle-foot Prosthesis Restore Whole-body Angular Momentum During Walking at Different Speeds?

D’Andrea

Wilhelm

Silverman

et al. 2014

Clinical Orthopaedics &Amp; Related Research

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Background Whole-body angular momentum (H) influences fall risk, is tightly regulated during walking, and is primarily controlled by muscle force generation. People with transtibial amputations using passive-elastic prostheses typically have greater H compared with nonamputees. Questions/purposes (1) Do people with unilateral transtibial amputations using passive-elastic prostheses have greater sagittal and frontal plane H ranges of motion during walking compared with nonamputees and compared with using powered prostheses? (2) Does use of powered anklefoot prostheses result in equivalent H ranges in all planes of motion compared with nonamputees during walking as a result of normative prosthetic ankle power generation? Methods Eight patients with a unilateral transtibial amputation and eight nonamputees walked 0.75, 1.00, 1.25, 1.50, and 1.75 m/s while we measured kinematics and ground reaction forces. We calculated H for participants using their passive-elastic prosthesis and a powered anklefoot prosthesis and for nonamputees at each speed. Results Patients using passive-elastic prostheses had 32% to 59% greater sagittal H ranges during the affected leg stance phase compared with nonamputees at 1.00 to 1.75 m/s (p \ 0.05). Patients using passive-elastic prostheses had 5% and 9% greater sagittal H ranges compared with using powered prostheses at 1.25 and 1.50 m/s, respectively (p \ 0.05). Participants using passive-elastic prostheses had 29% and 17% greater frontal H ranges at 0.75 and 1.50 m/s, respectively, compared with nonamputees (p \ 0.05). Surprisingly, patients using powered prostheses had 26% to 50% greater sagittal H ranges during the affected leg stance phase compared with nonamputees at 1.00 to 1.75 m/s (p \ 0.05). Patients using powered prostheses also had 26% greater frontal H range compared with nonamputees at 0.75 m/s (p \ 0.05). Conclusions People with a transtibial amputation may more effectively regulate H at two specific walking speeds when using powered compared with passive-elastic prostheses.

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Biomechanics and Motor Control of Human Movement

Cited by 5,709 publications

References 0 publications

Influence of long-term wearing of unstable shoes on compensatory control of posture: An electromyography-based analysis

Influence of long-term wearing of unstable shoes on compensatory control of posture: An electromyography-based analysis

Compensatory postural adaptations during continuous, variable amplitude perturbations reveal generalized rather than sequence-specific learning

Does Use of a Powered Ankle-foot Prosthesis Restore Whole-body Angular Momentum During Walking at Different Speeds?

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