scholarly journals Effect of blood flow occlusion on corticospinal excitability during sustained low-intensity isometric elbow flexion

2020 ◽  
Vol 123 (3) ◽  
pp. 1113-1119 ◽  
Author(s):  
D. B. Copithorne ◽  
C. L. Rice ◽  
C. J. McNeil
Keyword(s):  
Blood Flow ◽  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Elbow Flexion ◽  
Group Iii ◽  
Low Intensity ◽  
Blood Flow Occlusion ◽  
Motor Cortical ◽  
Flow Occlusion ◽  
Contractile Failure

Blood flow occlusion (BFO) has been used to study the influence of group III/IV muscle afferents after fatiguing exercise, but it is unknown how BFO-induced activity of these afferents affects motor cortical and motoneuronal excitability during low-intensity exercise. Therefore, the purpose of this study was to assess the acute effect of BFO on peripheral [maximal M wave (Mmax)], spinal [cervicomedullary motor evoked potential (CMEP) normalized to Mmax], and motor cortical [motor evoked potential (MEP) normalized to CMEP] excitability. Nine healthy men completed a sustained isometric contraction of the elbow flexors at 20% of maximal force under three conditions: 1) contractile failure with BFO, 2) a time-matched trial without restriction [free flow (FFiso)], and 3) contractile failure with free flow (FFfail). Time to failure for BFO (and FFiso) were ~80% shorter than that for FFfail ( P < 0.05). For FFfail and FFiso, Mmax area decreased ~17% and ~7%, respectively ( P < 0.05), with no change during BFO. CMEP/Mmax area increased ~226% and ~80% during BFO and FFfail, respectively ( P < 0.05), with no change during FFiso ( P > 0.05). The increase in normalized CMEP area was greater for BFO and FFfail compared with FFiso and for BFO compared with FFfail. MEP/CMEP area was not different among the protocols ( P > 0.05) and increased ~64% with time ( P < 0.05). It is likely that group III/IV muscle afferent feedback to the spinal cord modulates the large increase in motoneuronal excitability for the BFO compared with FFfail and FFiso protocols. NEW & NOTEWORTHY We have observed how blood flow occlusion modulates motor cortical, spinal, and peripheral excitability during and immediately after a sustained low-intensity isometric elbow flexion contraction to failure. We conclude that blood flow occlusion causes a greater and more rapid increase in motoneuronal excitability.

Effects of post-exercise blood flow occlusion on quadriceps responses to transcranial magnetic stimulation

2021 ◽  
Author(s):  
Christopher Latella ◽  
Matheus Daros Pinto ◽  
James L. Nuzzo ◽  
Janet Louise Taylor
Keyword(s):  
Blood Flow ◽  
Transcranial Magnetic Stimulation ◽  
Muscle Pain ◽  
Magnetic Stimulation ◽  
Muscle Group ◽  
Knee Extensors ◽  
Post Exercise ◽  
Group Iii ◽  
Blood Flow Occlusion ◽  
Flow Occlusion

For a fatigued hand muscle, group III/IV afferent firing maintains intracortical facilitation (ICF) without influencing corticospinal excitability. Exercise of larger muscles produces greater afferent firing. Thus, this study investigated if fatigue-related firing of group III/IV afferents from a large muscle group (quadriceps) modulates intracortical and corticospinal networks. In two sessions, participants (n=18) completed a 2-minute maximal voluntary isometric contraction (MVIC) of knee extensors with (OCC) or without (CON) post-exercise blood flow occlusion to maintain afferent firing. Pre- and post-exercise, single- and paired-pulse transcranial magnetic stimulation (TMS) elicited motor evoked potentials (MEPs) from vastus lateralis (VL), vastus medialis and rectus femoris. Test pulse intensities evoked VL MEPs of ~0.5 mV and were adjusted post-exercise. The conditioning stimulus for ICF and short interval intracortical inhibition (SICI) was constant and set to evoke ~50% of maximum ICF. Muscle pain was also assessed (0-10 scale). Post-exercise, muscle pain was greater for OCC than CON (Median = 8.6 vs. 1.0; P<0.001). MEPs were depressed for CON (all muscles: ∆ -24.3 to -34.1%; P≤0.018) despite increased stimulus intensity (~10%, P<0.001), but both MEPs and intensity remained unchanged for OCC. ICF was depressed post-exercise in OCC (VL and RF: ∆ -59.8% and -28.8%, respectively P=0.016-0.018) but not CON (all muscles: ∆ -3.8 to -44.3%, P=0.726-1.0), but was not different between conditions (interactions: P=0.143-0.252). No interactions were observed for SICI (all muscles: P≥0.266). Group III/IV afferent firing counteracts the post-contraction depression of MEPs in quadriceps. However, intracortical inhibitory and facilitatory networks are not implicated in this response.

The effect of blood flow on tibialis anterior motor unit firing rates during sustained low-intensity isometric contractions

2021 ◽  
Vol 46 (1) ◽  
pp. 63-68
Author(s):  
David B. Copithorne ◽  
Kalter Hali ◽  
Charles L. Rice
Keyword(s):  
Blood Flow ◽  
Motor Unit ◽  
Tibialis Anterior ◽  
Free Flow ◽  
Neural Activation ◽  
Firing Rates ◽  
Low Intensity ◽  
Motor Unit Firing ◽  
Blood Flow Occlusion ◽  
Flow Occlusion

Low-intensity contractions with blood flow occlusion (BFO) result in neuromuscular adaptations comparable with high-intensity (>70% maximal voluntary contraction, MVC) exercise. Because BFO exercise can only be applied to limb muscles, it is of interest to explore whether muscles proximal to the occlusion site are affected. Therefore, the purpose of this study was to assess neural activation of the tibialis anterior (TA) when flow is occluded proximal and distal to the active muscle. Five males completed three protocols to observe the effect of BFO on motor unit firing rates (MUFR) of the TA at a fatiguing contraction intensity of ∼15% MVC. Two occlusion protocols, one proximal (BFOprox) to and one distal (BFOdis) to the TA, were compared with a control (free-flow) protocol time-matched to BFOdis. MVC was significantly reduced following the BFOprox (∼41%; P < 0.001) and BFOdis (∼27%, P < 0.001), but not following the control protocol (∼15%; P = 0.13). Surface electromyography (EMG) during BFOdis and BFOprox increased ∼14% and ∼28%, respectively, but was not different among protocols. MUFRs for BFOdis and BFOprox were significantly reduced (by ∼33% and ∼23%, respectively; P < 0.01) at task failure. Results indicate that although BFOprox results in the largest reductions of MUFRs, BFOdis shows greater impairments compared with the free-flow control condition. Novelty Effects on motor unit firing rates of proximal versus distal blood flow occlusion were compared during low-intensity fatiguing task. Proximal occlusion results in greatest fatigue and reduction in motor unit rates, but distal occlusion elicits more fatigue and rate reduction than a control task.

scholarly journals Exercise and Repeated Testing Improves Accuracy of Laser Doppler Assessment of Microvascular Function Following Shortened (1-minute) Blood Flow Occlusion

2016 ◽  
Vol 23 (4) ◽  
pp. 293-300 ◽  
Author(s):  
Brian D. Tran ◽  
Abraham Chiu ◽  
Charlene Tran ◽  
Danica Rose Rogacion ◽  
Nicole Tfaye ◽  
...  
Keyword(s):  
Blood Flow ◽  
Microvascular Function ◽  
Laser Doppler ◽  
Repeated Testing ◽  
Blood Flow Occlusion ◽  
Flow Occlusion

Blood Flow Occlusion Pressure At Rest And Immediately After A Bout Of Low Load Exercise

2015 ◽  
Vol 47 ◽  
pp. 548
Author(s):  
Scott J. Dankel ◽  
Brian E. Barnett ◽  
Brittany R. Counts ◽  
Allison L. Nooe ◽  
Takashi Abe ◽  
...  
Keyword(s):  
Blood Flow ◽  
Occlusion Pressure ◽  
Low Load ◽  
Blood Flow Occlusion ◽  
Flow Occlusion

Effect of Blood Flow Occlusion on Laser Hyperthermia for Liver Metastases

2002 ◽  
Vol 103 (2) ◽  
pp. 165-174 ◽  
Author(s):  
V. Muralidharan ◽  
C. Malcontenti-Wilson ◽  
Chris Christophi
Keyword(s):  
Blood Flow ◽  
Liver Metastases ◽  
Laser Hyperthermia ◽  
Blood Flow Occlusion ◽  
Flow Occlusion

The Pharmacokinetic Response of Succinylcholine from Blood Flow occlusion

1994 ◽  
Vol 27 (2) ◽  
pp. 155
Author(s):  
Suk Jun Yoon ◽  
Chun Sook Kim ◽  
Young Deog Cha ◽  
Yong Ik Kim ◽  
Kyu Sik Kang ◽  
...  
Keyword(s):  
Blood Flow ◽  
Blood Flow Occlusion ◽  
Flow Occlusion

scholarly journals The effect of resting blood flow occlusion on exercise tolerance and W′

2015 ◽  
Vol 309 (6) ◽  
pp. R684-R691 ◽  
Author(s):  
Ryan M. Broxterman ◽  
Jesse C. Craig ◽  
Carl J. Ade ◽  
Samuel L. Wilcox ◽  
Thomas J. Barstow
Keyword(s):  
Blood Flow ◽  
Critical Power ◽  
Work Capacity ◽  
Mechanical Work ◽  
Handgrip Exercise ◽  
Constant Amount ◽  
Severe Intensity ◽  
Anaerobic Work ◽  
Blood Flow Occlusion ◽  
Flow Occlusion

It has previously been postulated that the anaerobic work capacity (W′) may be utilized during resting blood flow occlusion in the absence of mechanical work. We tested the hypothesis that W′ would not be utilized during an initial range of time following the onset of resting blood flow occlusion, after which W′ would be utilized progressively more. Seven men completed blood flow occlusion constant power severe intensity handgrip exercise to task failure following 0, 300, 600, 900, and 1,200 s of resting blood flow occlusion. The work performed above critical power (CP) was not significantly different between the 0-, 300-, and 600-s conditions and was not significantly different from the total W′ available. Significantly less work was performed above CP during the 1,200-s condition than the 900-s condition ( P < 0.05), while both conditions were significantly less than the 0-, 300-, and 600-s conditions ( P < 0.05). The work performed above CP during these conditions was significantly less than the total W′ available ( P < 0.05). The utilization of W′ during resting blood flow occlusion did not begin until 751 ± 118 s, after which time W′ was progressively utilized. The current findings demonstrate that W′ is not utilized during the initial ∼751 s of resting blood flow occlusion, but is progressively utilized thereafter, despite no mechanical work being performed. Thus, the utilization of W′ is not exclusive to exercise, and a constant amount of work that can be performed above CP is not the determining mechanism of W′.

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