The influence of ankle muscle activation on postural sway during quiet stance

Warnica, Meagan J.; Weaver, Tyler B.; Prentice, Stephen D.; Laing, Andrew C.

doi:10.1016/j.gaitpost.2014.01.019

Cited by 89 publications

(73 citation statements)

References 25 publications

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“…Although only early or middle severity PD individuals were included in the present study, these findings were reasonable considering that postural instability may occur in the early stages of PD [2,21]. Concomitantly, the CoP based values observed were similar to the ones found in previous studies [4,21,22].…”

Section: Discussionsupporting

confidence: 87%

Standing balance in individuals with Parkinson's disease during single and dual-task conditions

et al. 2015

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This study aimed to examine the differences in standing balance between individuals with Parkinson's disease (PD) and subjects without PD (control group), under single and dual-task conditions. A cross-sectional study was designed using a non-probabilistic sample of 110 individuals (50 participants with PD and 60 controls) aged 50 years old and over. The individuals with PD were in the early or middle stages of the disease (characterized by Hoehn and Yahr as stages 1-3). The standing balance was assessed by measuring the centre of pressure (CoP) displacement in single-task (eyes-open/eyes-closed) and dual-task (while performing two different verbal fluency tasks). No significant differences were found between the groups regarding sociodemographic variables. In general, the standing balance of the individuals with PD was worse than the controls, as the CoP displacement across tasks was significantly higher for the individuals with PD (p<0.01), both in anteroposterior and mediolateral directions. Moreover, there were significant differences in the CoP displacement based parameters between the conditions, mainly between the eyes-open condition and the remaining conditions. However, there was no significant interaction found between group and condition, which suggests that changes in the CoP displacement between tasks were not influenced by having PD. In conclusion, this study shows that, although individuals with PD had a worse overall standing balance than individuals without the disease, the impact of performing an additional task on the CoP displacement is similar for both groups.

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Section: Discussionsupporting

confidence: 87%

Standing balance in individuals with Parkinson's disease during single and dual-task conditions

et al. 2015

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“…MPF is a measure of the average sway frequency calculated from the spectral power of the COP data. An increase in sway frequency reflects increased production of corrective torque around the ankle joint [37], with higher values indicative of greater joint stiffness and possibly muscle co-contraction [49,50] whereas a decrease in sway frequency reflects reduced production of corrective torque around the ankle joint [37]. MPF was calculated from the Power Spectral Density of each 30s window of the AP COP data using Welch's overlapped segment averaging estimator function (‘pwelch’ in Matlab).…”

Section: Methodsmentioning

confidence: 99%

Anodal Transcranial Direct Current Stimulation Shows Minimal, Measure-Specific Effects on Dynamic Postural Control in Young and Older Adults: A Double Blind, Sham-Controlled Study

Craig

Doumas

2017

PLoS ONE

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We investigated whether stimulating the cerebellum and primary motor cortex (M1) using transcranial direct current stimulation (tDCS) could affect postural control in young and older adults. tDCS was employed using a double-blind, sham-controlled design, in which young (aged 18–35) and older adults (aged 65+) were assessed over three sessions, one for each stimulatory condition–M1, cerebellar and sham. The effect of tDCS on postural control was assessed using a sway-referencing paradigm, which induced platform rotations in proportion to the participant’s body sway, thus assessing sensory reweighting processes. Task difficulty was manipulated so that young adults experienced a support surface that was twice as compliant as that of older adults, in order to minimise baseline age differences in postural sway. Effects of tDCS on postural control were assessed during, immediately after and 30 minutes after tDCS. Additionally, the effect of tDCS on corticospinal excitability was measured by evaluating motor evoked potentials using transcranial magnetic stimulation immediately after and 30 minutes after tDCS. Minimal effects of tDCS on postural control were found in the eyes open condition only, and this was dependent on the measure assessed and age group. For young adults, stimulation had only offline effects, as cerebellar stimulation showed higher mean power frequency (MPF) of sway 30 minutes after stimulation. For older adults, both stimulation conditions delayed the increase in sway amplitude witnessed between blocks one and two until stimulation was no longer active. In conclusion, despite tDCS’ growing popularity, we would caution researchers to consider carefully the type of measures assessed and the groups targeted in tDCS studies of postural control.

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“…While co-contraction is not a PD-specific phenomenon [10], its elevation with age and PD and its effects on functional balance make it relevant to understanding balance impairment in PD. In adults without PD, muscle co-contraction is associated with functional changes in behavior, including increased sway [11][12][13][14], increased risk of falls [15,16], and decreased functional reach distance and functional stability boundaries [13].…”

Section: Introductionmentioning

confidence: 99%

Antagonist muscle activity during reactive balance responses is elevated in Parkinson's disease and in balance impairment

Lang

Hackney

Ting

et al. 2018

Preprint

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Highlights:• We quantified abnormal antagonist muscle activation during balance in PD.• Abnormalities were related to PD severity as well as to overall balance ability.• Abnormalities were similar across PD phenotypes with and without tremor.• Balance antagonist activation may be a useful rehabilitative outcome measure.. CC-BY-ND 4.0 International license It is made available under a was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint (which . http://dx.doi.org/10.1101/343004 doi: bioRxiv preprint first posted online Jun. 8, 2018; Antagonist muscle activity in PD balance 1 Abstract BACKGROUND: Abnormal antagonist leg muscle activity could indicate increased muscle cocontraction and clarify mechanisms of balance impairments in Parkinson's disease (PD). Prior studies in carefully selected patients showed PD patients demonstrate earlier, longer, and larger antagonist muscle activation during reactive balance responses to perturbations.RESEARCH QUESTION: Here, we tested whether antagonist leg muscle activity was abnormal in a group of PD patients who were not selected for phenotype, and most of whom had volunteered for exercise-based rehabilitation. METHODS: We compared antagonist activation during reactive balance responses to multidirectional support-surface translation perturbations in 31 patients with mild-moderate PD (age 68±9; H&Y 1-3; UPDRS-III 32±10) and 13 matched individuals (age 65±9). We quantified modulation of muscle activity (i.e., the ability to activate and inhibit muscles appropriately according to the perturbation direction) using modulation indices (MI) derived from minimum and maximum EMG activation levels observed across perturbation directions. RESULTS: Antagonist leg muscle activity was abnormal in unselected PD patients compared to controls. Linear mixed models identified significant associations between impaired modulation and PD (P<0.05), PD severity (P<0.01), and balance ability

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The influence of ankle muscle activation on postural sway during quiet stance

Cited by 89 publications

References 25 publications

Standing balance in individuals with Parkinson's disease during single and dual-task conditions

Standing balance in individuals with Parkinson's disease during single and dual-task conditions

Anodal Transcranial Direct Current Stimulation Shows Minimal, Measure-Specific Effects on Dynamic Postural Control in Young and Older Adults: A Double Blind, Sham-Controlled Study

Antagonist muscle activity during reactive balance responses is elevated in Parkinson's disease and in balance impairment

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