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Wu YK, Harel NY, Wecht JM, Bloom OE. Effects of Remote Ischemic Conditioning on Hand Engagement in individuals with Spinal cord Injury (RICHES): protocol for a pilot crossover study. F1000Res 2022; 10:464. [PMID: 35342620 PMCID: PMC8924555 DOI: 10.12688/f1000research.52670.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/06/2022] [Indexed: 11/20/2022] Open
Abstract
Background: Most spinal cord injuries (SCI) are not full transections, indicating that residual nerve circuits are retained. Rehabilitation interventions have been shown to beneficially reorganize motor pathways in the brain, corticospinal tract, and at the spinal level. However, rehabilitation training require a large number of repetitions, and intervention effects may be absent or show transient retention. Therefore, the need remains for an effective approach to synergistically improve the amount and duration of neuroplasticity in combination with other interventions. Remote ischemic conditioning (RIC) demonstrates several potential advantages as a candidate for such an approach. Therefore, we propose a protocol to investigate RIC coupled with physical training to promote neuroplasticity in hand muscles. Methods: This will be a prospective randomized-order crossover trial to be performed in eight able-bodied participants and eight participants with chronic cervical SCI. Patients will participate in two experimental sessions consisting of either active or sham RIC preceding a bout of pinch movement exercise. Serial evaluations will be conducted at baseline, after RIC, immediately after pinch exercise, and follow up 15-minutes later. The primary outcome is the change in corticospinal excitability (primarily measured by the motor evoked potential of abductor pollicis brevis muscle). Secondary outcomes will include maximal volitional pinch force, and inflammatory biomarkers. To ensure safety, we will monitor tolerability and hemodynamic responses during RIC. Discussion: This protocol will be the first to test RIC in people with cervical SCI and to investigate whether RIC alters corticospinal excitability. By sharing the details of our protocol, we hope other interested researchers will seek to investigate similar approaches – depending on overlap with the current study and mutual sharing of participant-level data, this could increase the sample size, power, and generalizability of the analysis and results. Trial registration: ClinicalTrial.gov, ID: NCT03851302; Date of registration: February 22, 2019
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Affiliation(s)
- Yu-Kuang Wu
- Rehabilitation and Human Performance, Icahn School of Medicine at Mount Sinai, New York, NY, 10003, USA
- Bronx Veterans Medical Research Foundation, Bronx, NY, 10468, USA
| | - Noam Y. Harel
- Rehabilitation and Human Performance, Icahn School of Medicine at Mount Sinai, New York, NY, 10003, USA
- Bronx Veterans Medical Research Foundation, Bronx, NY, 10468, USA
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, 10003, USA
| | - Jill M. Wecht
- Rehabilitation and Human Performance, Icahn School of Medicine at Mount Sinai, New York, NY, 10003, USA
- Bronx Veterans Medical Research Foundation, Bronx, NY, 10468, USA
| | - Ona E. Bloom
- Bronx Veterans Medical Research Foundation, Bronx, NY, 10468, USA
- The Feinstein Institute for Medical Research, Manhasset, NY, 11030, USA
- The Zucker School of Medicine at Hofstra Northwell, Hempstead, NY, 11549, USA
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State-of-the-art review: spinal and supraspinal responses to muscle potentiation in humans. Eur J Appl Physiol 2021; 121:1271-1282. [PMID: 33635383 DOI: 10.1007/s00421-021-04610-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 01/17/2021] [Indexed: 02/02/2023]
Abstract
Post-activation potentiation (PAP), described as a muscular phenomenon, refers to the enhancement of contractile properties following a voluntary or electrically stimulated short duration (< 10 s) high-intensity contraction. Mechanistic factors and subsequent effects on voluntary performance have been well documented. Associations between neural activation and PAP, however, are less understood and systematically have not been explored. Thus, the aim is to critically summarize the current understanding of PAP regarding the motor pathway from the corticospinal tract to spinal level factors including the H-reflex and motor unit activation. This review highlights aspects for further investigation by providing an integrative summary of the relationship between PAP and neural control. Contractile history affects neural control in subsequent contractions, (e.g. fatiguing tasks), however, by contrast acute contractile enhancement due to PAP in relation to neural responses are not well-studied. From the limited number of investigations, motor unit discharge rates are reduced subsequent to PAP and, although less consistently reported, generally H-reflexes are depressed. Additionally, corticomedullary evoked potentials are depressed and the cortical silent period is elongated. Thus, overall there is a depression of spinal and supraspinal responses following PAP. Although specific factors responsible and their pathways are unclear, this down-regulation may occur to conserve neural activation when muscle contraction is more responsive, and concurrently a strategy used to delay neuromuscular fatigue. Indeed, the co-existence of PAP and fatigue is not a novel concept, but the interactions between PAP and neural responses are not understood and likely are more than coincidental.
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Blazevich AJ, Babault N. Post-activation Potentiation Versus Post-activation Performance Enhancement in Humans: Historical Perspective, Underlying Mechanisms, and Current Issues. Front Physiol 2019; 10:1359. [PMID: 31736781 PMCID: PMC6838751 DOI: 10.3389/fphys.2019.01359] [Citation(s) in RCA: 217] [Impact Index Per Article: 43.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 10/14/2019] [Indexed: 12/31/2022] Open
Abstract
Post-activation potentiation (PAP) is a well-described phenomenon with a short half-life (~28 s) that enhances muscle force production at submaximal levels of calcium saturation (i.e., submaximal levels of muscle activation). It has been largely explained by an increased myosin light chain phosphorylation occurring in type II muscle fibers, and its effects have been quantified in humans by measuring muscle twitch force responses to a bout of muscular activity. However, enhancements in (sometimes maximal) voluntary force production detected several minutes after high-intensity muscle contractions are also observed, which are also most prominent in muscles with a high proportion of type II fibers. This effect has been considered to reflect PAP. Nonetheless, the time course of myosin light chain phosphorylation (underpinning “classic” PAP) rarely matches that of voluntary force enhancement and, unlike PAP, changes in muscle temperature, muscle/cellular water content, and muscle activation may at least partly underpin voluntary force enhancement; this enhancement has thus recently been called post-activation performance enhancement (PAPE) to distinguish it from “classical” PAP. In fact, since PAPE is often undetectable at time points where PAP is maximal (or substantial), some researchers have questioned whether PAP contributes to PAPE under most conditions in vivo in humans. Equally, minimal evidence has been presented that PAP is of significant practical importance in cases where multiple physiological processes have already been upregulated by a preceding, comprehensive, active muscle warm-up. Given that confusion exists with respect to the mechanisms leading to acute enhancement of both electrically evoked (twitch force; PAP) and voluntary (PAPE) muscle function in humans after acute muscle activity, the first purpose of the present narrative review is to recount the history of PAP/PAPE research to locate definitions and determine whether they are the same phenomena. To further investigate the possibility of these phenomena being distinct as well as to better understand their potential functional benefits, possible mechanisms underpinning their effects will be examined in detail. Finally, research design issues will be addressed which might contribute to confusion relating to PAP/PAPE effects, before the contexts in which these phenomena may (or may not) benefit voluntary muscle function are considered.
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Affiliation(s)
- Anthony J Blazevich
- School of Medical and Health Science, Centre for Exercise and Sports Science Research (CESSR), Edith Cowan University, Joondalup, WA, Australia
| | - Nicolas Babault
- Faculty of Sport Sciences, French National Institute of Health and Medical Research (INSERM), Unit 1093 Cognition, Action and Sensorimotor Plasticity, Centre for Performance Expertise, University of Burgundy and Franche-Comté, Dijon, France
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Aboodarda SJ, Fan S, Coates K, Millet GY. The short-term recovery of corticomotor responses in elbow flexors. BMC Neurosci 2019; 20:9. [PMID: 30871475 PMCID: PMC6419454 DOI: 10.1186/s12868-019-0492-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 03/06/2019] [Indexed: 11/10/2022] Open
Abstract
Background The recovery of neurophysiological parameters at various time intervals following fatiguing exercise has been investigated previously. However, the repetition of neuromuscular assessments during the recovery period may have interfered with the true corticomotor excitability responses. In this experiment, fatiguing contractions were combined with a single post-fatigue assessment at varying time points. Ten participants undertook 5 bouts of 60-s maximal voluntary contractions (MVC) of the elbow flexors, separated by 20 min. Before and after each 60-s fatiguing exercise (FAT), participants performed a series of 6-s contractions at 100, 75 and 50% of their MVC during which transcranial magnetic, transmastoid electrical and brachial plexus electrical stimuli were used to elicit motor evoked potentials (MEP), cervicomedullary motor evoked potentials (CMEP) and compound muscle action potentials (Mmax) in the biceps brachii muscle, respectively. Post-FAT measurements were randomly performed 0, 15, 30, 60, or 120 s after each FAT. Results MVC force declined to 65.1 ± 13.1% of baseline following FAT and then recovered to 82.7 ± 10.2% after 60 s. The MEP·Mmax−1 ratio recorded at MVC increased to 151.1 ± 45.8% and then returned to baseline within 60 s. The supraspinal excitability (MEP·CMEP−1) measured at MVC increased to 198.2 ± 47.2% and fully recovered after 30 s. The duration of post-MEP silent period recorded at MVC elongated by 23.4 ± 10.6% during FAT (all P < 0.05) but fully recovered after 15 s. Conclusions The current study represents the first accurate description of the time course and pattern of recovery for supraspinal and spinal excitability and inhibition following a short maximal fatiguing exercise in upper limb.
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Affiliation(s)
- Saied Jalal Aboodarda
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Dr NW, Calgary, AB, T2N 1N4, Canada
| | - Selina Fan
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Dr NW, Calgary, AB, T2N 1N4, Canada
| | - Kyla Coates
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Dr NW, Calgary, AB, T2N 1N4, Canada
| | - Guillaume Y Millet
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Dr NW, Calgary, AB, T2N 1N4, Canada.
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Collins BW, Gale LH, Buckle NCM, Button DC. Corticospinal excitability to the biceps brachii and its relationship to postactivation potentiation of the elbow flexors. Physiol Rep 2017; 5:5/8/e13265. [PMID: 28455452 PMCID: PMC5408290 DOI: 10.14814/phy2.13265] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 03/30/2017] [Accepted: 04/05/2017] [Indexed: 11/24/2022] Open
Abstract
We examined the effects of a submaximal voluntary elbow flexor contraction protocol on measures of corticospinal excitability and postactivation potentiation of evoked muscle forces and if these measures were state‐dependent (rest vs. voluntary muscle contraction). Participants completed four experimental sessions where they rested or performed a 5% maximum voluntary contraction (MVC) of the elbow flexors prior to, immediately, and 5 min following a submaximal contraction protocol. During rest or 5% MVC, transcranial magnetic stimulation, transmastoid electrical stimulation, electrical stimulation of biceps brachii motor point and Erb's point were elicited to induce motor‐evoked potentials (MEPs), cervicomedullary MEPs (CMEPs), potentiated twitch (PT) force, and maximal muscle compound action potential (Mmax), respectively prior to, immediately, and 5 min postcontraction protocol. MEP amplitudes increased (215 and 165%Mmax, P ≤ 0.03) only at 1 and 6s postcontraction protocol, respectively during rest but not 5% MVC. CMEP amplitudes decreased during rest and 5% MVC (range:21–58%Mmax, P ≤ 0.04) for up to 81 sec postcontraction protocol. Peak twitch force increased immediately postcontraction protocol and remained elevated for 90 sec (range:122–147% increase, P < 0.05). There was a significant positive correlation between MEP and PT force during rest (r = 0.88, P = 0.01) and a negative correlation between CMEP and PT force during rest (r = −0.85, P < 0.02 and 5% MVC (r = −0.96, P < 0.01) immediately postcontraction protocol. In conclusion, the change in corticospinal and spinal excitability was state‐ and time‐dependent whereas spinal excitability and postactivation potentiation were time‐dependent following the contraction protocol. Changes in corticospinal excitability and postactivation potentiation correlated and were also state‐dependent.
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Affiliation(s)
- Brandon W Collins
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Newfoundland and Labrador Canada
| | - Laura H Gale
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Newfoundland and Labrador Canada
| | - Natasha C M Buckle
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Newfoundland and Labrador Canada
| | - Duane C Button
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Newfoundland and Labrador Canada .,BioMedical Sciences, Faculty of Medicine Memorial University St. John's, Newfoundland and Labrador, Canada
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Concerto C, Babayev J, Mahmoud R, Rafiq B, Chusid E, Aguglia E, Coira D, Battaglia F. Modulation of prefrontal cortex with anodal tDCS prevents post-exercise facilitation interference during dual task. Somatosens Mot Res 2017; 34:80-84. [DOI: 10.1080/08990220.2017.1292238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Carmen Concerto
- Department of Interprofessional Health Sciences & Health Administration, Seton Hall University, South Orange, NJ, USA
| | - Jacqueline Babayev
- Pre-clinical Sciences, New York College of Podiatric Medicine, New York, USA
| | - Rowan Mahmoud
- Pre-clinical Sciences, New York College of Podiatric Medicine, New York, USA
| | - Basil Rafiq
- Pre-clinical Sciences, New York College of Podiatric Medicine, New York, USA
| | - Eileen Chusid
- Pre-clinical Sciences, New York College of Podiatric Medicine, New York, USA
| | - Eugenio Aguglia
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Diego Coira
- Department of Psychiatry and Behavioral Medicine, Hackensack University Medical Center, Hackensack, NJ, USA
| | - Fortunato Battaglia
- Department of Interprofessional Health Sciences & Health Administration, Seton Hall University, South Orange, NJ, USA
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Aboodarda SJ, Copithorne DB, Pearcey GE, Button DC, Power KE. Changes in supraspinal and spinal excitability of the biceps brachii following brief, non-fatiguing submaximal contractions of the elbow flexors in resistance-trained males. Neurosci Lett 2015; 607:66-71. [DOI: 10.1016/j.neulet.2015.09.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 08/28/2015] [Accepted: 09/23/2015] [Indexed: 11/28/2022]
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Weavil JC, Sidhu SK, Mangum TS, Richardson RS, Amann M. Intensity-dependent alterations in the excitability of cortical and spinal projections to the knee extensors during isometric and locomotor exercise. Am J Physiol Regul Integr Comp Physiol 2015; 308:R998-1007. [PMID: 25876651 DOI: 10.1152/ajpregu.00021.2015] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/08/2015] [Indexed: 11/22/2022]
Abstract
We investigated the role of exercise intensity and associated central motor drive in determining corticomotoneuronal excitability. Ten participants performed a series of nonfatiguing (3 s) isometric single-leg knee extensions (ISO; 10-100% of maximal voluntary contractions, MVC) and cycling bouts (30-160% peak aerobic capacity, W peak). At various exercise intensities, electrical potentials were evoked in the vastus lateralis (VL) and rectus femoris (RF) via transcranial magnetic stimulation (motor-evoked potentials, MEP), and electrical stimulation of both the cervicomedullary junction (cervicomedullary evoked potentials, CMEP) and the femoral nerve (maximal M-waves, M max). Whereas M max remained unchanged in both muscles (P > 0.40), voluntary electromyographic activity (EMG) increased in an exercise intensity-dependent manner for ISO and cycling exercise in VL and RF (both P < 0.001). During ISO exercise, MEPs and CMEPs progressively increased in VL and RF until a plateau was reached at ∼ 75% MVC; further increases in contraction intensity did not cause additional changes (P > 0.35). During cycling exercise, VL-MEPs and CMEPs progressively increased by ∼ 65% until a plateau was reached at W peak. In contrast, RF MEPs and CMEPs progressively increased by ∼ 110% throughout the tested cycling intensities without the occurrence of a plateau. Furthermore, alterations in EMG below the plateau influenced corticomotoneuronal excitability similarly between exercise modalities. In both exercise modalities, the MEP-to-CMEP ratio did not change with exercise intensity (P > 0.22). In conclusion, increases in exercise intensity and EMG facilitates the corticomotoneuronal pathway similarly in isometric knee extension and locomotor exercise until a plateau occurs at a submaximal exercise intensity. This facilitation appears to be primarily mediated by increases in excitability of the motoneuron pool.
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Affiliation(s)
- J C Weavil
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - S K Sidhu
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - T S Mangum
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - R S Richardson
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah; Department of Internal Medicine, University of Utah, Salt Lake City, Utah; Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center, Salt Lake City, Utah
| | - M Amann
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah; Department of Internal Medicine, University of Utah, Salt Lake City, Utah; Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center, Salt Lake City, Utah
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Sarkar B, Das PG, Equebal A, Mitra PK, Kumar R, Anwer S. Efficacy of low-energy extracorporeal shockwave therapy and a supervised clinical exercise protocol for the treatment of chronic lateral epicondylitis: A randomised controlled study. Hong Kong Physiother J 2013. [DOI: 10.1016/j.hkpj.2012.12.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Tallent J, Goodall S, Hortobágyi T, St Clair Gibson A, French DN, Howatson G. Recovery time of motor evoked potentials following lengthening and shortening muscle action in the tibialis anterior. J Clin Neurosci 2012; 19:1328-9. [PMID: 22721891 DOI: 10.1016/j.jocn.2012.01.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 01/29/2012] [Indexed: 11/29/2022]
Abstract
Motor evoked potentials (MEP) at rest remain facilitated following an isometric muscle contraction. Because the pre-synaptic and post-synaptic control of shortening (SHO) and lengthening (LEN) contractions differs, the possibility exists that the recovery of the MEP is also task specific. The time course of MEP recovery was assessed in the tibialis anterior following SHO and LEN (0.26 rad/s) at 25% and 80% of maximal voluntary contraction. Following LEN and SHO contractions, the MEP recovered to baseline levels within 10s. Despite task-specific differences between SHO and LEN contractions, the MEP facilitation from the augmented neurotransmitter release appears to be short lasting and not influenced by contraction type.
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Affiliation(s)
- J Tallent
- School of Life Sciences, Northumbria University, Northumberland Road, Newcastle-upon-Tyne NE1 8ST, United Kingdom
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Thompson CK, Lewek MD, Jayaraman A, Hornby TG. Central excitability contributes to supramaximal volitional contractions in human incomplete spinal cord injury. J Physiol 2011; 589:3739-52. [PMID: 21610138 DOI: 10.1113/jphysiol.2011.212233] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Despite greater muscle fatigue in individuals with spinal cord injury (SCI) when compared to neurologically intact subjects using neuromuscular electrical stimulation (NMES)protocols, few studies have investigated the extent of volitional fatigue in motor incomplete SCI. Using an established protocol of 20 repeated, intermittent, maximal volitional effort (MVE) contractions, we previously demonstrated that subjects with incomplete SCI unexpectedly demonstrated a 15% increase in peak knee extensor torques within the first five MVEs with minimal evidence of fatigue after 20 contraction. In the present study, we investigated potential segmental mechanisms underlying this supramaximal torque generation. Changes in twitch properties and maximum compound muscle action potentials (M-waves) were assessed prior to and following one, three and five MVEs, revealing a significant 17% increase only in maximum twitch torques after a single MVE. Despite this post-activation potentiation of the muscle, use of conventional NMES protocols to elicit repeated muscular contractions resulted in a significant decrease in evoked torque generation, suggesting limited the muscular contributions to the observed phenomenon. To evaluate potential central mechanisms underlying the augmented torques, non-linear responses to wide-pulse width (1 ms), low-intensity, variable-frequency (25–100 Hz) NMES were also tested prior to and following repeated MVEs.When variable-frequency NMES was applied following the repeated MVEs, augmented and prolonged torques were observed and accompanied by sustained quadriceps electromyographic activity often lasting > 2s after stimulus termination. Such data suggest a potential contribution of elevated spinal excitability to the reserve in volitional force generation in incomplete SCI.
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Affiliation(s)
- Christopher K Thompson
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL 60612, USA
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Hornby TG, Lewek MD, Thompson CK, Heitz R. Repeated maximal volitional effort contractions in human spinal cord injury: initial torque increases and reduced fatigue. Neurorehabil Neural Repair 2009; 23:928-38. [PMID: 19478056 PMCID: PMC5603074 DOI: 10.1177/1545968309336147] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Substantial data indicate greater muscle fatigue in individuals with spinal cord injury (SCI) compared with healthy control subjects when tested by using electrical stimulation protocols. Few studies have investigated the extent of volitional fatigue in motor incomplete SCI. METHODS Repeated, maximal volitional effort (MVE) isometric contractions of the knee extensors (KE) were performed in 14 subjects with a motor incomplete SCI and in 10 intact subjects. Subjects performed 20 repeated, intermittent MVEs (5 seconds contraction/5 seconds rest) with KE torques and thigh electromyographic (EMG) activity recorded. RESULTS Peak KE torques declined to 64% of baseline MVEs with repeated efforts in control subjects. Conversely, subjects with SCI increased peak torques during the first 5 contractions by 15%, with little evidence of fatigue after 20 repeated efforts. Increases in peak KE torques and the rate of torque increase during the first 5 contractions were attributed primarily to increases in quadriceps EMG activity, but not to decreased knee flexor co-activation. The observed initial increases in peak torque were dependent on the subject's volitional activation and were consistent on the same or different days, indicating little contribution of learning or accommodation to the testing conditions. Sustained MVEs did not elicit substantial increases in peak KE torques as compared to repeated intermittent efforts. CONCLUSIONS These data revealed a marked divergence from expected results of increased fatigability in subjects with SCI, and may be a result of complex interactions between mechanisms underlying spastic motor activity and changes in intrinsic motoneuron properties.
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Affiliation(s)
- T George Hornby
- Department of Physical Medicine and Rehabilitation, Northwestern University Medical School, Chicago, Illinois 60612, USA.
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Blicher JU, Nielsen JF. Cortical and spinal excitability changes after robotic gait training in healthy participants. Neurorehabil Neural Repair 2008; 23:143-9. [PMID: 19047360 DOI: 10.1177/1545968308317973] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND Recent studies have proposed a role for robotic gait training in participants with acquired brain injury, but the effects on the excitability of cortical and spinal neurons even in healthy participants are uncertain. OBJECTIVE To investigate changes in corticospinal excitability in healthy participants after active and passive robotic gait training in a driven gait orthosis (DGO), the Lokomat. METHODS Thirteen healthy participants took part in 2 experiments. Each participant performed 20 minutes of active and passive gait training in a DGO. Motor evoked potentials (MEP), short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), F-wave frequency, and Mmax were measured in the right tibialis anterior muscle before and after training. RESULTS Active training led to a decline in MEP amplitude and F-wave frequency. The MEP decline was associated with subjective muscle fatigue. Passive training induced a decrease in SICI lasting for 20 minutes after training. CONCLUSIONS The decline in MEP after active training is most likely because of central fatigue, whereas the decreased F-wave frequency might represent short-term plastic changes in the spinal cord. The decrease in SICI after passive training probably reflects a decrease in intracortical GABA activity, which could benefit the acquisition of new motor skills.
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Affiliation(s)
- Jakob U Blicher
- Hammel Neurorehabilitation and Research Centre, Aarhus University Hospital, Denmark.
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Slater H, Arendt-Nielsen L, Wright A, Graven-Nielsen T. Effects of a manual therapy technique in experimental lateral epicondylalgia. ACTA ACUST UNITED AC 2006; 11:107-17. [PMID: 15914074 DOI: 10.1016/j.math.2005.04.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Revised: 03/03/2005] [Accepted: 04/07/2005] [Indexed: 12/21/2022]
Abstract
In patients with lateral epicondylalgia, mobilization-with-movement (MWM) is used as an intervention aimed at achieving analgesia and enhancing grip force, although the mechanisms underlying these effects are unclear. The present study investigated the acute sensory and motor effects of an MWM intervention in healthy controls with experimentally induced lateral epicondylalgia. Twenty-four subjects were randomly allocated to either a MWM or a placebo group (n=12). In both groups, to generate the model of lateral epicondylalgia, delayed onset muscle soreness (DOMS) was provoked in one arm 24h prior (Day 0) to hypertonic saline-induced pain in the extensor carpi radialis brevis muscle (Day 1). Either a MWM or placebo intervention was applied during the saline-induced pain period. Saline-induced pain intensity (visual analogue scale: VAS), pain distribution and pain quality were assessed quantitatively. Pressure pain thresholds (PPTs) were recorded at the common extensor origin and the extensor carpi radialis brevis muscle. Maximal measures of grip and wrist extension force were recorded. In both groups (pooled data), DOMS was efficiently induced as demonstrated by a significant decrease in pre-exercise to pre-injection PPT at the common extensor origin (-45+/-19%) and at the extensor carpi radialis brevis (-61+/-23%; P<0.05), and a significant decrease in maximal grip force (-25+/-6%) and maximal wrist extension force (-40+/-12%; P<0.001). Moreover, both groups experienced a significant increase in muscle soreness (3.9+/-0.2; P<0.0001) at Day 1 compared to pre-exercise. During saline-induced pain and in response to intervention, there were no significant between-group differences in VAS profiles, pain distributions, induced deep tissue hyperalgesia or force attenuation. These data suggest that the lateral glide-MWM does not activate mechanisms associated with analgesia or force augmentation in subjects with experimentally induced features simulating lateral epicondylalgia.
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Affiliation(s)
- Helen Slater
- Laboratory for Experimental Pain Research, Center for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark.
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Hopkinson NS, Sharshar T, Ross ET, Nickol AH, Dayer MJ, Porcher R, Jonville S, Moxham J, Polkey MI. Corticospinal control of respiratory muscles in chronic obstructive pulmonary disease. Respir Physiol Neurobiol 2004; 141:1-12. [PMID: 15234671 DOI: 10.1016/j.resp.2004.04.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2004] [Indexed: 11/17/2022]
Abstract
Patients with chronic obstructive pulmonary disease (COPD) face an increased respiratory load and in consequence have an elevated respiratory drive. We used transcranial magnetic stimulation (TMS) to investigate associated changes in corticospinal excitability both at rest and during voluntary facilitation at different levels of inspiratory effort. Diaphragm and abdominal motor thresholds were significantly lower in COPD than healthy controls, but the quadriceps response was the same. In patients there was a significant increase in diaphragm response from rest during 20% inspiratory efforts but no further increase with greater efforts. In controls there was a further stepwise increase at 40% and 60% of inspiratory effort. The cortical silent period was significantly shorter in COPD. Using paired stimulation to study intracortical inhibitory and excitatory circuits we found significantly less excitability of intracortical facilitatory circuits in patients at long (>7 ms) interstimulus intervals. These results suggest that there is a ceiling effect in motor control output to the respiratory muscles of patients with COPD.
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Straus C, Locher C, Zelter M, Derenne JP, Similowski T. Facilitation of the diaphragm response to transcranial magnetic stimulation by increases in human respiratory drive. J Appl Physiol (1985) 2004; 97:902-12. [PMID: 15133007 DOI: 10.1152/japplphysiol.00989.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human respiratory neural drive has an automatic component (bulbospinal pathway) and a volitional component (corticospinal pathway). The aim of this study was to assess the effects of a hypercapnia-induced increase in the automatic respiratory drive on the function of the diaphragmatic corticospinal pathway as independently as possible of any other influence. Thirteen healthy volunteers breathed room air and then 5 and 7% hyperoxic CO2. Cervical (cms) and transcranial (tms) magnetic stimulations were performed during early inspiration and expiration. Transdiaphragmatic pressure (Pdi) and surface electromyogram of the diaphragm (DiEMG) and of the abductor pollicis brevis (apbEMG) were recorded in response to cms and tms. During inspiration, Pdi,cms was unaffected by CO2, but Pdi,tms increased significantly with 7% CO2. During expiration, Pdi,cms was significantly reduced by CO2, whereas Pdi,tms was preserved. DiEMG,tms latencies decreased significantly during early inspiration and expiration (air vs. 5% CO2 and air vs. 7% CO2). DiEMG,tms amplitude increased significantly in response to early expiration-tms (air vs. 5% CO2 and air vs. 7% CO2) but not in response to early inspiration-tms. DiEMG,cms latencies and amplitudes were not affected by CO2 whereas 7% CO2 significantly increased the apbEMG,cms latency. The apbEMG,tms vs. apbEMG,cms latency difference was unaffected by CO2. In conclusion, increasing the automatic drive to breathe facilitates the response of the diaphragm to tms, during both inspiration and expiration. This could allow the corticospinal drive to breathe to keep the capacity to modulate respiration in conditions under which the automatic respiratory control is stimulated.
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Affiliation(s)
- C Straus
- UPRES EA 2397, Faculté de Médecine Pitié-Salpêtrière, Université Paris VI Pierre et Marie Curie, Paris, France
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Perretti A, Balbi P, Orefice G, Trojano L, Marcantonio L, Brescia-Morra V, Ascione S, Manganelli F, Conte G, Santoro L. Post-exercise facilitation and depression of motor evoked potentials to transcranial magnetic stimulation: a study in multiple sclerosis. Clin Neurophysiol 2004; 115:2128-33. [PMID: 15294215 DOI: 10.1016/j.clinph.2004.03.028] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/28/2004] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To evaluate motor cortex excitability changes by transcranial magnetic stimulation (TMS) following repetitive muscle contractions in patients with multiple sclerosis (MS); to state whether a typical pattern of post-exercise motor evoked potentials (MEPs) is related to clinical fatigue in MS. METHODS In 41 patients with definite MS (32 with fatigue and 9 without fatigue according to Fatigue Severity Scale) and 13 controls, MEPs were recorded at rest: at baseline condition, following repetitive contractions until fatigue, and after fatigue, to evaluate post-exercise MEP facilitation (PEF) and depression (PED). RESULTS After exercise, MEP amplitude significantly increased both in patients and controls (PEF). When fatigue set in, MEP amplitude was significantly reduced in normal subjects (PED), but not in patients. Post-exercise MEP findings were similar both in patients with and without fatigue. CONCLUSIONS Our findings suggest an intracortical motor dysfunction following a voluntary contraction in MS patients, possibly due to failure of depression of facilitatory cortical circuits, or alternatively of inhibitory mechanisms.
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Affiliation(s)
- A Perretti
- Department of Neurological Sciences, Servizio di Neurofisiopatologia, University of Naples Federico II, Via Sergio Pansini 5, 80131 Naples, Italy.
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Nielsen JF, Nørgaard P. Increased post-exercise facilitation of motor evoked potentials in multiple sclerosis. Clin Neurophysiol 2002; 113:1295-300. [PMID: 12140010 DOI: 10.1016/s1388-2457(02)00153-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVES To study post-exercise facilitation following a non-fatigue exercise in a homogenous group of multiple sclerosis (MS) patients with complaints of muscle fatigue. METHODS In 15 MS patients and matched controls motor evoked potentials (MEP) were recorded from the biceps brachii muscle at time delays of 0.5-30s after an isometric contraction with a torque of 50% of maximal voluntary contraction (MVC) maintained for 2-6s. In addition, MEP was recorded after isometric torque of 25, 50, and 100% of MVC maintained for 6s. RESULTS Isometric non-fatigue contraction induced significant post-exercise increase in MEP amplitude in MS patients compared with controls being most pronounced after a contraction for 6s. The post-exercise increase in MEP lasted for longer than 30s in MS patients. CONCLUSIONS Post-exercise increase of MEP amplitude following a non-fatigue exercise was significant in MS patients with complaints of muscle fatigue compared with healthy subjects.
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Balbi P, Perretti A, Sannino M, Marcantonio L, Santoro L. Postexercise facilitation of motor evoked potentials following transcranial magnetic stimulation: a study in normal subjects. Muscle Nerve 2002; 25:448-52. [PMID: 11870725 DOI: 10.1002/mus.10066] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The size of the motor evoked potential (MEP) elicited by transcranial magnetic stimulation increases soon after a nonexhaustive voluntary contraction of the target muscle (postexercise facilitation). Our aim was to determine whether the duration or intensity of voluntary muscle contraction influenced postexercise facilitation in normal subjects. We recorded the MEP from the thenar muscles following contractions of different durations (5, 15, and 30 s) and intensities (10%, 25%, and 50% of maximal voluntary contraction). We found that every combination of the tested intensities and durations of physical effort could induce postexercise MEP facilitation. Although the degree of postexercise MEP facilitation was comparable across the different durations and intensities, the maximal facilitation was observed with the shortest and strongest muscle contraction. Our study thus defines the optimal setting to study postexercise facilitation for clinical purposes.
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Affiliation(s)
- Pietro Balbi
- Department of Rehabilitation, Fondazione "Salvatore Maugeri," Istituto di Ricovero e Cura a Carattere Scientifico, Centro Medico di Telese Terme, Loc. S. Stefano in Lanterria, 82037 Telese Terme, BN, Italy.
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