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Shen B, Xiao S, Yu C, Zhang C, Zhan J, Liu Y, Fu W. Cerebral hemodynamics underlying ankle force sense modulated by high-definition transcranial direct current stimulation. Cereb Cortex 2024; 34:bhae226. [PMID: 38850217 DOI: 10.1093/cercor/bhae226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 05/07/2024] [Accepted: 05/14/2024] [Indexed: 06/10/2024] Open
Abstract
This study aimed to investigate the effects of high-definition transcranial direct current stimulation on ankle force sense and underlying cerebral hemodynamics. Sixteen healthy adults (8 males and 8 females) were recruited in the study. Each participant received either real or sham high-definition transcranial direct current stimulation interventions in a randomly assigned order on 2 visits. An isokinetic dynamometer was used to assess the force sense of the dominant ankle; while the functional near-infrared spectroscopy was employed to monitor the hemodynamics of the sensorimotor cortex. Two-way analyses of variance with repeated measures and Pearson correlation analyses were performed. The results showed that the absolute error and root mean square error of ankle force sense dropped more after real stimulation than after sham stimulation (dropped by 23.4% vs. 14.9% for absolute error, and 20.0% vs. 10.2% for root mean square error). The supplementary motor area activation significantly increased after real high-definition transcranial direct current stimulation. The decrease in interhemispheric functional connectivity within the Brodmann's areas 6 was significantly correlated with ankle force sense improvement after real high-definition transcranial direct current stimulation. In conclusion, high-definition transcranial direct current stimulation can be used as a potential intervention for improving ankle force sense. Changes in cerebral hemodynamics could be one of the explanations for the energetic effect of high-definition transcranial direct current stimulation.
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Affiliation(s)
- Bin Shen
- School of Exercise and Health, Shanghai University of Sport, 200 Hengren Road, Yangpu District, Shanghai 200438, China
| | - Songlin Xiao
- School of Exercise and Health, Shanghai University of Sport, 200 Hengren Road, Yangpu District, Shanghai 200438, China
| | - Changxiao Yu
- School of Exercise and Health, Shanghai University of Sport, 200 Hengren Road, Yangpu District, Shanghai 200438, China
| | - Chuyi Zhang
- School of Exercise and Health, Shanghai University of Sport, 200 Hengren Road, Yangpu District, Shanghai 200438, China
| | - Jianglong Zhan
- School of Exercise and Health, Shanghai University of Sport, 200 Hengren Road, Yangpu District, Shanghai 200438, China
| | - Ying Liu
- School of Psychology, Shanghai University of Sport, 399 Changhai Road, Yangpu District, Shanghai 200438, China
| | - Weijie Fu
- School of Exercise and Health, Shanghai University of Sport, 200 Hengren Road, Yangpu District, Shanghai 200438, China
- Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, 200 Hengren Road, Yangpu District, Shanghai 200438, China
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Pereira HM, Keenan KG, Hunter SK. Influence of visual feedback and cognitive challenge on the age-related changes in force steadiness. Exp Brain Res 2024; 242:1411-1419. [PMID: 38613669 DOI: 10.1007/s00221-024-06831-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 04/05/2024] [Indexed: 04/15/2024]
Abstract
Force steadiness can be influenced by visual feedback as well as presence of a cognitive tasks and potentially differs with age and sex. This study determined the impact of altered visual feedback on force steadiness in the presence of a difficult cognitive challenge in young and older men and women. Forty-nine young (19-30 yr; 25 women, 24 men) and 25 older (60-85 yr; 15 women; 10 men) performed low force (5% of maximum) static contractions with the elbow flexor muscles in the presence and absence of a cognitive challenge (counting backwards by 13) either with low or high visual feedback gain. The cognitive challenge reduced force steadiness (increased force fluctuation amplitude) particularly in women (cognitive challenge × sex: P < 0.05) and older individuals (cognitive challenge × age: P < 0.05). Force steadiness improved with high-gain visual feedback compared with low-gain visual feedback (P < 0.01) for all groups (all interactions: P > 0.05). Manipulation of visual feedback had no influence on the reduced force steadiness in presence of the cognitive challenge for all groups (all P > 0.05). These findings indicate that older individuals and women have greater risk of impaired motor performance of the upper extremity if steadiness is required during a low-force static contraction. Manipulation of visual feedback had minimal effects on the reduced force steadiness in presence of a difficult cognitive challenge.
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Affiliation(s)
- Hugo M Pereira
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA.
| | - Kevin G Keenan
- Joseph J. Zilber College of Public Health, University of Wisconsin-Milwaukee, Milwaukee, USA
| | - Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, USA
- Athletic and Human Performance Research Center, Marquette University, Milwaukee, USA
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Pereira HM, Hunter SK. Cognitive challenge as a probe to expose sex- and age-related differences during static contractions. Front Physiol 2023; 14:1166218. [PMID: 37260592 PMCID: PMC10227451 DOI: 10.3389/fphys.2023.1166218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 05/02/2023] [Indexed: 06/02/2023] Open
Abstract
Despite activities of daily living being frequently performed simultaneously with a cognitive task, motor function is often investigated in isolation, which can hinder the applicability of findings. This brief review presents evidence that 1) performing a cognitive challenge simultaneously with a motor task can negatively impact force steadiness and fatigability of limb muscles during a static contraction, 2) the negative impact on old adults (>65 years old), particularly older women is greater than young when a cognitive challenge is simultaneously performed with a static motor task, 3) age-related mechanisms potentially explain impairments in motor performance in the presence of a cognitive challenge, and 4) the mechanisms for the age-related decrements in motor performance can be distinct between men and women. These observations are highly relevant to the older adults, given the increased risk of accidents and injury when a motor task is performed with a high cognitive-demand task, especially in light of the expanding reliance on an aging workforce.
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Affiliation(s)
- Hugo M. Pereira
- Department of Health and Exercise Science, The University of Oklahoma, Norman, OK, United States
| | - Sandra K. Hunter
- Department of Physical Therapy, Marquette University, Milwaukee, WI, United States
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da Silva MC, da Silva CR, de Lima FF, Lara JR, Gustavson JP, Magalhães FH. Effects of Fatigue on Postural Sway and Electromyography Modulation in Young Expert Acrobatic Gymnasts and Healthy Non-trained Controls During Unipedal Stance. Front Physiol 2022; 13:782838. [PMID: 35222070 PMCID: PMC8864175 DOI: 10.3389/fphys.2022.782838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 01/14/2022] [Indexed: 11/13/2022] Open
Abstract
This study investigated whether expert acrobatic gymnasts respond differentially than their non-trained counterparts during a single-legged stance task performed before and after a protocol designed to induce fatigue in the ankle plantarflexor muscles in terms of (a) postural steadiness and (b) electromyography (EMG) activation. We hypothesized that neuromuscular adaptation due to training would lead to different behavior of center of pressure (COP) and EMG quantifiers after fatigue. Twenty eight female volunteers (aged 11 to 24 years) formed two groups: expert acrobatic gymnastics athletes (GYN, n = 14) and age-matched non-gymnasts [control (CTRL), n = 14]. Fatigue of the ankle plantarflexors (dominant leg) was induced by a sustained posture (standing on the toes) until exhaustion. Traditional COP parameters (area, RMS, mean velocity, and power spectrum at low and high frequency ranges) were obtained with a force plate, and time and frequency-domain EMG parameters were obtained by surface electrodes positioned on the tibialis anterior, soleus, lateral gastrocnemius, medial gastrocnemius, vastus lateralis, biceps femoris, spinal erector and rectus abdominis muscles. The main results showed that fatigue induced a significant increase in postural oscillations in the ML axis (including RMS, velocity and frequency components of the power spectrum), with no significant effects in the AP axis. In terms of postural sway parameters (i.e., COP quantifiers), no superior balance stability was found for the GYN group as compared to CTRL, irrespective of the fatigue condition. On the other hand, the modulation of EMG parameters (in both time and frequency domains) indicated that expert acrobatic gymnastics athletes (as compared to healthy untrained matched controls) used different neuromuscular control strategies to keep their postures on single-legged quiet standing after the fatiguing protocol. The present results improve our knowledge of the mechanisms behind the interplay between fatigue and postural performance associated with the neuromuscular adaptations induced by sport practice. The design of gymnastics training might consider strategies aimed at improving the performance of specific muscles (i.e., tibialis anterior, soleus, biceps femoris, spinal erector) for which particular activation patterns were used by the acrobatic gymnastics to control single-legged quiet standing.
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Affiliation(s)
- Marcos Camargo da Silva
- School of Arts, Sciences and Humanities, Universidade de São Paulo, EACH-USP, São Paulo, Brazil
| | - Cristiano Rocha da Silva
- Biomedical Engineering Laboratory and Neuroscience Program, Universidade de São Paulo, EPUSP, PTC, São Paulo, Brazil
| | - Felipe Fava de Lima
- Biomedical Engineering Laboratory and Neuroscience Program, Universidade de São Paulo, EPUSP, PTC, São Paulo, Brazil
| | - Jéssica Rodriguez Lara
- School of Arts, Sciences and Humanities, Universidade de São Paulo, EACH-USP, São Paulo, Brazil
| | - Jackson Paiva Gustavson
- School of Arts, Sciences and Humanities, Universidade de São Paulo, EACH-USP, São Paulo, Brazil
| | - Fernando Henrique Magalhães
- School of Arts, Sciences and Humanities, Universidade de São Paulo, EACH-USP, São Paulo, Brazil
- Biomedical Engineering Laboratory and Neuroscience Program, Universidade de São Paulo, EPUSP, PTC, São Paulo, Brazil
- *Correspondence: Fernando Henrique Magalhães, ;
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Zhang X, Wang W, Chen G, Ji A, Song Y. Effects of standing and walking on plantar pressure distribution in recreational runners before and after long-distance running. J Biomech 2021; 129:110779. [PMID: 34607282 DOI: 10.1016/j.jbiomech.2021.110779] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 10/20/2022]
Abstract
With marathon-running grew in popularity, the effect of long-distance running on plantar pressure has been more attractive. It has been proposed that long-distance running influences the deviation in the center of pressure (COP) during standing and the changes to plantar pressure during walking. The objective of this study was to observe the effects on the COP motion amplitude of static standing and the plantar pressure distribution of walking after long-distance running. The influence of a 10-km run on changes to plantar pressure was assessed during standing and walking. Plantar pressure was measured before and immediately after running. In the study, seven males and five females participated in barefoot tests of static standing and dynamic walking. In the static standing tests, COP was measured under the following four ordered conditions: (1) bipedal, eyes open, standing; (2) bipedal, eyes closed, standing; (3) unipedal, eyes open, standing and (4) unipedal, eyes closed, standing. Under each condition, the data was collected while a stable standing posture for 10 s. In the dynamic walking tests, the contact duration and plantar pressure were recorded. The standing tests results revealed no significant differences between males and females while slight differences before vs. after running. Running for a single time had no effect on COP deviation during standing. The walking tests results revealed an initial landing on the lateral heel. After landing on the lateral heel, the females quickly transferred to the medial heel. The movement of the pressure to the medial heel was slower in males than females. After running, the pressure of females was more inward, while that of males was more outward under the metatarsal zones in the propulsion phase.
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Affiliation(s)
- Xiyuan Zhang
- Lab of Locomotion Bioinspiration and Intelligent Robots, College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China; Olympic College, Communication University of China Nanjing, Nanjing, China; Department of Sports Health Sciences, Nanjing Sport Institute, Nanjing, China
| | - Wei Wang
- Lab of Locomotion Bioinspiration and Intelligent Robots, College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China
| | - Guangming Chen
- Lab of Locomotion Bioinspiration and Intelligent Robots, College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China
| | - Aihong Ji
- Lab of Locomotion Bioinspiration and Intelligent Robots, College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China.
| | - Yawei Song
- Department of Sports Health Sciences, Nanjing Sport Institute, Nanjing, China.
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Tavakkoli Oskouei S, Malliaras P, D Hill K, Garofolini A, Clark R, Perraton L. Assessment of ankle plantar flexor neuromuscular properties: A reliability study. J Electromyogr Kinesiol 2021; 61:102603. [PMID: 34563759 DOI: 10.1016/j.jelekin.2021.102603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/29/2021] [Accepted: 09/15/2021] [Indexed: 10/20/2022] Open
Abstract
This study aimed to determine test-retest reliability of ankle plantar flexor neuromuscular properties in healthy people to improve understanding of additional measurement and analysis procedures that may be used in outcome assessment. Ten healthy participants (age 29.60 ± 5.36 years) volunteered. Isometric torquemax, rate of torque development (RTD), rate of electromyography rise (RER), impulse, electromechanical delay (EMD), torque steadiness, and torque sensing were obtained during two testing sessions 60 min apart. ICC values ranged from 0.81 to 0.99, indicating good to excellent test-retest reliability. Lower bands of the 95% CIs were all above 0.75 apart from the early phase measures (≤50 ms) derived from explosive torque-time and EMG-time curves, which were between 0.32 and 0.73, indicating poor to moderate reliability. Heteroscedasticity was observed for RTD, impulse, and EMD. LOA as a function of the mean (X̅) for these measures ranged from meandifference ± 0.25X̅ to ± 0.68X̅. EMD showed excellent reliability (ICC = 0.90; 95% CI [0.63, 0.98]). Torque sensing and torque steadiness showed good reliability (0.81 ≤ ICC ≤ 0.89). Thus, ankle plantar flexor neuromuscular properties showed good to excellent test-retest reliability. However, reliability of measures in the early phase of muscle contraction were consistently lower than the late phase.
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Affiliation(s)
- Sanam Tavakkoli Oskouei
- Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University, Victoria, Australia.
| | - Peter Malliaras
- Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University, Victoria, Australia
| | - Keith D Hill
- Ageing and Independent Living (RAIL) Research Centre, Monash University, Victoria, Australia
| | | | - Ross Clark
- School of Health and Behavioural Sciences, University of the Sunshine Coast, Queensland, Australia
| | - Luke Perraton
- Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University, Victoria, Australia
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Test-Retest Reliability of Plantar Flexion Torque Generation During a Functional Knee Extended Position in Older and Younger Men. J Aging Phys Act 2020; 29:626-631. [PMID: 33361497 DOI: 10.1123/japa.2020-0288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 09/20/2020] [Accepted: 09/23/2020] [Indexed: 11/18/2022]
Abstract
Measuring ankle torque is of paramount importance. This study compared the test-retest reliability of the plantar flexion torque-generating capacity between older and younger men. Twenty-one older (68 ± 6 years) and 22 younger (25 ± 5 years) men were tested twice for maximal isometric plantar flexion. Peak torque (PT), rate of torque development, and contractile impulses (CI) were obtained from 0 to 50 ms (rate of torque development0-50; CI0-50) and from 100 to 200 ms (rate of torque development100-200; CI100-200). Typical error as the coefficient of variation (CVTE) and intraclass correlation coefficient were used to assess test-retest reliability. Student's t test was applied to investigate systematic errors. The CVTE ratio was used for between-group comparisons. Only PT demonstrated acceptable reliability (intraclass correlation coefficient ≥ .75 and CV ≤ 10%). Older men demonstrated greater CVTE than younger men for PT (ratio = 2.24), but lesser for rapid torque (ratio ≤ 0.84). Younger men demonstrated systematic error for PT (6.5%) and CI100-200 (-8.9%). In conclusion, older men demonstrated greater variability for maximal torque output, but lesser for rapid torque.
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Magalhães FH, Mello EM, Kohn AF. Association Between Plantarflexion Torque Variability In Quiet Stance And During Force And Position Tasks. Somatosens Mot Res 2019; 36:241-248. [PMID: 31583939 DOI: 10.1080/08990220.2019.1673720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This study examined the association between plantarflexion torque variability during quiet bipedal standing (QS) and during plantarflexion force- and position-matching tasks (FT and PT, respectively). In QS, participants stood still over a force plate, and the mean plantarflexion torque level exerted by each subject in QS (divided by 2 to give the torque due to a single leg) served as the target torque level for right leg FT and PT (performed with the participants seated with their right knee fully extended). During FT participants controlled the force level exerted by the foot against a rigid restraint, while during PT they controlled the angular position of the ankle when sustaining equivalent inertial loads. Standard deviation (SD) of plantarflexion torque was computed from torque signals acquired during periods with and without visual feedback. Significant correlations were found between plantarflexion torque variability in QS and FT (r = 0.8615, p < 0.0001 and r = 0.8838, p = 0.0003 for visual and no visual conditions, respectively) as well as between QS and PT (r = 0.8046, p = 0.003 and r = 0.7332, p = 0.0103 for visual and no visual conditions, respectively), regardless of vision availability. No significant differences were found between the correlations for Qs vs FT and QS vs PT (t(8) = 0.4778, p = 0.6455 and t(8) = 1.6819, p = 0.1310 for visual and no visual conditions, respectively), as assessed by "Hotelling-Williams" tests for equality among dependent correlations. The results indicate that simple measurements of plantarflexion torque fluctuations during FT and PT may be used to estimate balance ability. From a practical standpoint, it is suggested that rehabilitation protocols designed to regain/improve balance function may be based on the performance of FTs or PTs executed in a seated position.
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Affiliation(s)
- Fernando Henrique Magalhães
- School of Arts, Sciences and Humanities, Universidade de São Paulo, EACH-USP, São Paulo, Brazil.,Biomedical Engineering Laboratory and Neuroscience Program, Universidade de São Paulo, EPUSP, PTC, São Paulo, Brazil
| | - Emanuele Moraes Mello
- Biomedical Engineering Laboratory and Neuroscience Program, Universidade de São Paulo, EPUSP, PTC, São Paulo, Brazil
| | - André Fabio Kohn
- Biomedical Engineering Laboratory and Neuroscience Program, Universidade de São Paulo, EPUSP, PTC, São Paulo, Brazil
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9
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Barbosa RN, Silva NR, Santos DP, Moraes R, Gomes MM. The variability of the force produced by the plantar flexor muscles does not associate with postural sway in older adults during upright standing. Hum Mov Sci 2018; 60:115-121. [DOI: 10.1016/j.humov.2018.05.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 05/03/2018] [Accepted: 05/19/2018] [Indexed: 12/26/2022]
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10
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Papegaaij S, Hortobágyi T, Godde B, Kaan WA, Erhard P, Voelcker-Rehage C. Neural correlates of motor-cognitive dual-tasking in young and old adults. PLoS One 2017; 12:e0189025. [PMID: 29220349 PMCID: PMC5722310 DOI: 10.1371/journal.pone.0189025] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 11/17/2017] [Indexed: 02/07/2023] Open
Abstract
When two tasks are performed simultaneously, performance often declines in one or both tasks. These so-called dual-task costs are more pronounced in old than in young adults. One proposed neurological mechanism of the dual-task costs is that old compared with young adults tend to execute single-tasks with higher brain activation. In the brain regions that are needed for both tasks, the reduced residual capacity may interfere with performance of the dual-task. This competition for shared brain regions has been called structural interference. The purpose of the study was to determine whether structural interference indeed plays a role in the age-related decrease in dual-task performance. Functional magnetic resonance imaging (fMRI) was used to investigate 23 young adults (20–29 years) and 32 old adults (66–89 years) performing a calculation (serial subtraction by seven) and balance-simulation (plantar flexion force control) task separately or simultaneously. Behavioral performance decreased during the dual-task compared with the single-tasks in both age groups, with greater dual-task costs in old compared with young adults. Brain activation was significantly higher in old than young adults during all conditions. Region of interest analyses were performed on brain regions that were active in both tasks. Structural interference was apparent in the right insula, as quantified by an age-related reduction in upregulation of brain activity from single- to dual-task. However, the magnitude of upregulation did not correlate with dual-task costs. Therefore, we conclude that the greater dual-task costs in old adults were probably not due to increased structural interference.
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Affiliation(s)
- Selma Papegaaij
- Center for Human Movement Sciences, Groningen University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
- * E-mail: (SP); (CV)
| | - Tibor Hortobágyi
- Center for Human Movement Sciences, Groningen University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Ben Godde
- Jacobs Center on Lifelong Learning and Institutional Development, Jacobs University Bremen, Bremen, Germany
| | - Wim A. Kaan
- Center for Human Movement Sciences, Groningen University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Peter Erhard
- Brain Research Institute, University of Bremen, Bremen, Germany
| | - Claudia Voelcker-Rehage
- Jacobs Center on Lifelong Learning and Institutional Development, Jacobs University Bremen, Bremen, Germany
- * E-mail: (SP); (CV)
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Keenan KG, Huddleston WE, Ernest BE. Altered visual strategies and attention are related to increased force fluctuations during a pinch grip task in older adults. J Neurophysiol 2017; 118:2537-2548. [PMID: 28701549 DOI: 10.1152/jn.00928.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 06/19/2017] [Accepted: 07/08/2017] [Indexed: 11/22/2022] Open
Abstract
The purpose of the study was to determine the visual strategies used by older adults during a pinch grip task and to assess the relations between visual strategy, deficits in attention, and increased force fluctuations in older adults. Eye movements of 23 older adults (>65 yr) were monitored during a low-force pinch grip task while subjects viewed three common visual feedback displays. Performance on the Grooved Pegboard test and an attention task (which required no concurrent hand movements) was also measured. Visual strategies varied across subjects and depended on the type of visual feedback provided to the subjects. First, while viewing a high-gain compensatory feedback display (horizontal bar moving up and down with force), 9 of 23 older subjects adopted a strategy of performing saccades during the task, which resulted in 2.5 times greater force fluctuations in those that exhibited saccades compared with those who maintained fixation near the target line. Second, during pursuit feedback displays (force trace moving left to right across screen and up and down with force), all subjects exhibited multiple saccades, and increased force fluctuations were associated (rs = 0.6; P = 0.002) with fewer saccades during the pursuit task. Also, decreased low-frequency (<4 Hz) force fluctuations and Grooved Pegboard times were significantly related (P = 0.033 and P = 0.005, respectively) with higher (i.e., better) attention z scores. Comparison of these results with our previously published results in young subjects indicates that saccadic eye movements and attention are related to force control in older adults.NEW & NOTEWORTHY The significant contributions of the study are the addition of eye movement data and an attention task to explain differences in hand motor control across different visual displays in older adults. Older participants used different visual strategies across varying feedback displays, and saccadic eye movements were related with motor performance. In addition, those older individuals with deficits in attention had impaired motor performance on two different hand motor control tasks, including the Grooved Pegboard test.
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Affiliation(s)
- Kevin G Keenan
- Department of Kinesiology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin; and .,Center for Aging and Translational Research, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Wendy E Huddleston
- Department of Kinesiology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin; and.,Center for Aging and Translational Research, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Bradley E Ernest
- Department of Kinesiology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin; and
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Suda EY, Sacco ICN, Hirata RP, Samani A, Kawamura TT, Madeleine P. Later stages of diabetic neuropathy affect the complexity of the neuromuscular system at the knee during low-level isometric contractions. Muscle Nerve 2017; 57:112-121. [PMID: 28224646 DOI: 10.1002/mus.25627] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 02/13/2017] [Accepted: 02/19/2017] [Indexed: 12/19/2022]
Abstract
INTRODUCTION This study evaluates the complexity of force and surface electromyography (sEMG) during knee extension and flexion at low-level isometric contractions in individuals with different degrees of diabetic peripheral neuropathy (DPN). METHODS Ten control and 38 diabetic participants performed isometric contractions at 10%, 20%, and 30% of maximal voluntary contraction. Knee force and multichannel sEMG from vastus lateralis (VL) and biceps femoris were acquired. The SD of force and sample entropy (SaEn) of both force and sEMG were computed. RESULTS Participants with moderate DPN demonstrated high force-SD and low force-SaEn. Severely affected participants showed low SaEn in VL at all force levels. DISCUSSION DPN affects the complexity of the neuromuscular system at the knee for the extension task during low-level isometric contractions, with participants in the later stages of the disease (moderate and severe) demonstrating most of the changes. Muscle Nerve 57: 112-121, 2018.
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Affiliation(s)
- Eneida Y Suda
- Laboratory of Biomechanics of Human Movement, Department of Physical Therapy, Speech and Occupational Therapy, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil
| | - Isabel C N Sacco
- Laboratory of Biomechanics of Human Movement, Department of Physical Therapy, Speech and Occupational Therapy, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil
| | - Rogerio P Hirata
- SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220, Aalborg East, Denmark
| | - Afshin Samani
- SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220, Aalborg East, Denmark
| | - Thiago T Kawamura
- Laboratory of Biomechanics of Human Movement, Department of Physical Therapy, Speech and Occupational Therapy, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil
| | - Pascal Madeleine
- SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220, Aalborg East, Denmark
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13
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Errors in the ankle plantarflexor force production are related to the gait deficits of individuals with multiple sclerosis. Hum Mov Sci 2016; 51:91-98. [PMID: 27923175 DOI: 10.1016/j.humov.2016.11.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 11/09/2016] [Accepted: 11/11/2016] [Indexed: 11/27/2022]
Abstract
BACKGROUND Individuals with multiple sclerosis (MS) often have limited mobility that is thought to be due to the neuromuscular impairments of the ankle. Greater isometric motor control of the ankle has been associated with better standing postural balance but its relationship to mobility is less understood. The objectives of this investigation were to quantify the motor control of the ankle plantarflexors of individuals with MS during a dynamic isometric motor task, and explore the relationship between the ankle force control and gait alterations. METHODS Fifteen individuals with MS and 15 healthy adults participated in both a dynamic isometric ankle plantarflexion force matching task and a biomechanical gait analysis. FINDINGS Our results displayed that the subjects with MS had a greater amount of error in their dynamic isometric force production, were weaker, walked with altered spatiotemporal kinematics, and had reduced maximal ankle moment at toe-off than the control group. The greater amount of error in the dynamic force production was related to the decreases in strength, step length, walking velocity, and maximal ankle moment during walking. INTERPRETATION Altogether these results imply that errors in the ankle plantarflexion force production may be a limiting factor in the mobility of individuals with MS.
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Magalhães FH, Elias LA, da Silva CR, de Lima FF, de Toledo DR, Kohn AF. D1 and D2 Inhibitions of the Soleus H-Reflex Are Differentially Modulated during Plantarflexion Force and Position Tasks. PLoS One 2015; 10:e0143862. [PMID: 26599909 PMCID: PMC4658029 DOI: 10.1371/journal.pone.0143862] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 11/10/2015] [Indexed: 01/05/2023] Open
Abstract
Presynaptic inhibition (PSI) has been shown to modulate several neuronal pathways of functional relevance by selectively gating the connections between sensory inputs and spinal motoneurons, thereby regulating the contribution of the stretch reflex circuitry to the ongoing motor activity. In this study, we investigated whether a differential regulation of Ia afferent inflow by PSI may be associated with the performance of two types of plantarflexion sensoriomotor tasks. The subjects (in a seated position) controlled either: 1) the force level exerted by the foot against a rigid restraint (force task, FT); or 2) the angular position of the ankle when sustaining inertial loads (position task, PT) that required the same level of muscle activation observed in FT. Subjects were instructed to maintain their force/position at target levels set at ~10% of maximum isometric voluntary contraction for FT and 90° for PT, while visual feedback of the corresponding force/position signals were provided. Unconditioned H-reflexes (i.e. control reflexes) and H-reflexes conditioned by electrical pulses applied to the common peroneal nerve with conditioning-to-test intervals of 21 ms and 100 ms (corresponding to D1 and D2 inhibitions, respectively) were evoked in a random fashion. A significant main effect for the type of the motor task (FT vs PT) (p = 0.005, η2p = 0.603) indicated that PTs were undertaken with lower levels of Ia PSI converging onto the soleus motoneuron pool. Additionally, a significant interaction between the type of inhibition (D1 vs D2) and the type of motor task (FT vs PT) (p = 0.038, η2p = 0.395) indicated that D1 inhibition was associated with a significant reduction in PSI levels from TF to TP (p = 0.001, η2p = 0.731), whereas no significant difference between the tasks was observed for D2 inhibition (p = 0.078, η2p = 0.305). These results suggest that D1 and D2 inhibitions of the soleus H-reflex are differentially modulated during the performance of plantarflexion FT and PT. The reduced level of ongoing PSI during PT suggests that, in comparison to FT, there is a larger reliance on inputs from muscle spindles primary afferents when the neuromuscular system is required to maintain position-controlled plantarflexion contractions.
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Affiliation(s)
- Fernando Henrique Magalhães
- School of Arts, Sciences and Humanities, Universidade de São Paulo, EACH-USP, São Paulo, SP, Brazil.,Biomedical Engineering Laboratory, Universidade de São Paulo, EPUSP, Avenida Professor Luciano Gualberto, Travessa 3, n.158, São Paulo, SP, Brazil.,Neuroscience Program, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Leonardo Abdala Elias
- Biomedical Engineering Laboratory, Universidade de São Paulo, EPUSP, Avenida Professor Luciano Gualberto, Travessa 3, n.158, São Paulo, SP, Brazil.,Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil
| | - Cristiano Rocha da Silva
- Biomedical Engineering Laboratory, Universidade de São Paulo, EPUSP, Avenida Professor Luciano Gualberto, Travessa 3, n.158, São Paulo, SP, Brazil.,Neuroscience Program, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Felipe Fava de Lima
- Biomedical Engineering Laboratory, Universidade de São Paulo, EPUSP, Avenida Professor Luciano Gualberto, Travessa 3, n.158, São Paulo, SP, Brazil
| | - Diana Rezende de Toledo
- Biomedical Engineering Laboratory, Universidade de São Paulo, EPUSP, Avenida Professor Luciano Gualberto, Travessa 3, n.158, São Paulo, SP, Brazil
| | - André Fabio Kohn
- Biomedical Engineering Laboratory, Universidade de São Paulo, EPUSP, Avenida Professor Luciano Gualberto, Travessa 3, n.158, São Paulo, SP, Brazil.,Neuroscience Program, Universidade de São Paulo, São Paulo, SP, Brazil
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Spinal mechanisms may provide a combination of intermittent and continuous control of human posture: predictions from a biologically based neuromusculoskeletal model. PLoS Comput Biol 2014; 10:e1003944. [PMID: 25393548 PMCID: PMC4230754 DOI: 10.1371/journal.pcbi.1003944] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 09/27/2014] [Indexed: 01/07/2023] Open
Abstract
Several models have been employed to study human postural control during upright quiet stance. Most have adopted an inverted pendulum approximation to the standing human and theoretical models to account for the neural feedback necessary to keep balance. The present study adds to the previous efforts in focusing more closely on modelling the physiological mechanisms of important elements associated with the control of human posture. This paper studies neuromuscular mechanisms behind upright stance control by means of a biologically based large-scale neuromusculoskeletal (NMS) model. It encompasses: i) conductance-based spinal neuron models (motor neurons and interneurons); ii) muscle proprioceptor models (spindle and Golgi tendon organ) providing sensory afferent feedback; iii) Hill-type muscle models of the leg plantar and dorsiflexors; and iv) an inverted pendulum model for the body biomechanics during upright stance. The motor neuron pools are driven by stochastic spike trains. Simulation results showed that the neuromechanical outputs generated by the NMS model resemble experimental data from subjects standing on a stable surface. Interesting findings were that: i) an intermittent pattern of muscle activation emerged from this posture control model for two of the leg muscles (Medial and Lateral Gastrocnemius); and ii) the Soleus muscle was mostly activated in a continuous manner. These results suggest that the spinal cord anatomy and neurophysiology (e.g., motor unit types, synaptic connectivities, ordered recruitment), along with the modulation of afferent activity, may account for the mixture of intermittent and continuous control that has been a subject of debate in recent studies on postural control. Another finding was the occurrence of the so-called “paradoxical” behaviour of muscle fibre lengths as a function of postural sway. The simulations confirmed previous conjectures that reciprocal inhibition is possibly contributing to this effect, but on the other hand showed that this effect may arise without any anticipatory neural control mechanism. The control of upright stance is a challenging task since the objective is to maintain the equilibrium of an intrinsically unstable biomechanical system. Somatosensory information is used by the central nervous system to modulate muscle contraction, which prevents the body from falling. While the visual and vestibular systems also provide important additional sensory information, a human being with only somatosensory inputs is able to maintain an upright stance. In this study, we used a biologically-based large-scale neuromusculoskeletal model driven only by somatosensory feedback to investigate human postural control from a neurophysiological point of view. No neural structures above the spinal cord were included in the model. The results showed that the model based on a spinal control of posture can reproduce several neuromechanical outcomes previously reported in the literature, including an intermittent muscle activation. Since this intermittent muscular recruitment is an emergent property of this spinal-like controller, we argue that the so-called intermittent control of upright stance might be produced by an interplay between spinal cord properties and modulated sensory inflow.
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Magalhães FH, Kohn AF. Effectiveness of electrical noise in reducing postural sway: a comparison between imperceptible stimulation applied to the anterior and to the posterior leg muscles. Eur J Appl Physiol 2014; 114:1129-41. [DOI: 10.1007/s00421-014-2846-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 02/04/2014] [Indexed: 11/24/2022]
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Watanabe RN, Magalhães FH, Elias LA, Chaud VM, Mello EM, Kohn AF. Influences of premotoneuronal command statistics on the scaling of motor output variability during isometric plantar flexion. J Neurophysiol 2013; 110:2592-606. [DOI: 10.1152/jn.00073.2013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study focuses on neuromuscular mechanisms behind ankle torque and EMG variability during a maintained isometric plantar flexion contraction. Experimentally obtained torque standard deviation (SD) and soleus, medial gastrocnemius, and lateral gastrocnemius EMG envelope mean and SD increased with mean torque for a wide range of torque levels. Computer simulations were performed on a biophysically-based neuromuscular model of the triceps surae consisting of premotoneuronal spike trains (the global input, GI) driving the motoneuron pools of the soleus, medial gastrocnemius, and lateral gastrocnemius muscles, which activate their respective muscle units. Two types of point processes were adopted to represent the statistics of the GI: Poisson and Gamma. Simulations showed a better agreement with experimental results when the GI was modeled by Gamma point processes having lower orders (higher variability) for higher target torques. At the same time, the simulations reproduced well the experimental data of EMG envelope mean and SD as a function of mean plantar flexion torque, for the three muscles. These results suggest that the experimentally found relations between torque-EMG variability as a function of mean plantar flexion torque level depend not only on the intrinsic properties of the motoneuron pools and the muscle units innervated, but also on the increasing variability of the premotoneuronal GI spike trains when their mean rates increase to command a higher plantar flexion torque level. The simulations also provided information on spike train statistics of several hundred motoneurons that compose the triceps surae, providing a wide picture of the associated mechanisms behind torque and EMG variability.
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Affiliation(s)
- Renato N. Watanabe
- Biomedical Engineering Laboratory, Department of Telecommunication and Control Engineering, Escola Politécnica, University of São Paulo, São Paulo, Brazil
| | - Fernando H. Magalhães
- Biomedical Engineering Laboratory, Department of Telecommunication and Control Engineering, Escola Politécnica, University of São Paulo, São Paulo, Brazil
| | - Leonardo A. Elias
- Biomedical Engineering Laboratory, Department of Telecommunication and Control Engineering, Escola Politécnica, University of São Paulo, São Paulo, Brazil
| | - Vitor M. Chaud
- Biomedical Engineering Laboratory, Department of Telecommunication and Control Engineering, Escola Politécnica, University of São Paulo, São Paulo, Brazil
| | - Emanuele M. Mello
- Biomedical Engineering Laboratory, Department of Telecommunication and Control Engineering, Escola Politécnica, University of São Paulo, São Paulo, Brazil
| | - André F. Kohn
- Biomedical Engineering Laboratory, Department of Telecommunication and Control Engineering, Escola Politécnica, University of São Paulo, São Paulo, Brazil
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