The Relationship Between Blood Flow and Motor Unit Firing Rates in Response to Fatiguing Exercise Post-stroke
We quantified the relationship between the change in post-contraction blood flow with motor unit firing rates and metrics of fatigue during intermittent, sub-maximal fatiguing contractions of the knee extensor muscles after stroke. Ten chronic stroke survivors (>1-year post-stroke) and nine c...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2019-05-01
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| Series: | Frontiers in Physiology |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fphys.2019.00545/full |
| _version_ | 1818391371335073792 |
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| author | Spencer Murphy Matthew Durand Francesco Negro Dario Farina Sandra Hunter Brian Schmit David Gutterman Allison Hyngstrom Allison Hyngstrom |
| author_facet | Spencer Murphy Matthew Durand Francesco Negro Dario Farina Sandra Hunter Brian Schmit David Gutterman Allison Hyngstrom Allison Hyngstrom |
| author_sort | Spencer Murphy |
| collection | DOAJ |
| description | We quantified the relationship between the change in post-contraction blood flow with motor unit firing rates and metrics of fatigue during intermittent, sub-maximal fatiguing contractions of the knee extensor muscles after stroke. Ten chronic stroke survivors (>1-year post-stroke) and nine controls participated. Throughout fatiguing contractions, the discharge timings of individual motor units were identified by decomposition of high-density surface EMG signals. After five consecutive contractions, a blood flow measurement through the femoral artery was obtained using an ultrasound machine and probe designed for vascular measurements. There was a greater increase of motor unit firing rates from the beginning of the fatigue protocol to the end of the fatigue protocol for the control group compared to the stroke group (14.97 ± 3.78% vs. 1.99 ± 11.90%, p = 0.023). While blood flow increased with fatigue for both groups (p = 0.003), the magnitude of post-contraction blood flow was significantly greater for the control group compared to the stroke group (p = 0.004). We found that despite the lower magnitude of muscle perfusion through the femoral artery in the stroke group, blood flow has a greater impact on peripheral fatigue for the control group; however, we observed a significant correlation between change in blood flow and motor unit firing rate modulation (r2 = 0.654, p = 0.004) during fatigue in the stroke group and not the control group (r2 = 0.024, p < 0.768). Taken together, this data showed a disruption between motor unit firing rates and post-contraction blood flow in the stroke group, suggesting that there may be a disruption to common inputs to both the reticular system and the corticospinal tract. This study provides novel insights in the relationship between the hyperemic response to exercise and motor unit firing behavior for post-stroke force production and may provide new approaches for recovery by improving both blood flow and muscle activation simultaneously. |
| first_indexed | 2024-12-14T05:12:27Z |
| format | Article |
| id | doaj.art-78407c9d45504d3b82fe4a160517beb8 |
| institution | Directory Open Access Journal |
| issn | 1664-042X |
| language | English |
| last_indexed | 2024-12-14T05:12:27Z |
| publishDate | 2019-05-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Physiology |
| spelling | doaj.art-78407c9d45504d3b82fe4a160517beb82022-12-21T23:15:56ZengFrontiers Media S.A.Frontiers in Physiology1664-042X2019-05-011010.3389/fphys.2019.00545438617The Relationship Between Blood Flow and Motor Unit Firing Rates in Response to Fatiguing Exercise Post-strokeSpencer Murphy0Matthew Durand1Francesco Negro2Dario Farina3Sandra Hunter4Brian Schmit5David Gutterman6Allison Hyngstrom7Allison Hyngstrom8Integrative Neural Engineering and Rehabilitation Laboratory, Department of Biomedical Engineering, Marquette University, Milwaukee, WI, United StatesDepartment of Physical Medicine and Rehabilitation, Medical College of Wisconsin, Milwaukee, WI, United StatesDepartment of Clinical and Experimental Sciences, Università degli studi di Brescia, Brescia, ItalyDepartment of Bioengineering, Imperial College London, London, United KingdomDepartment of Physical Therapy, Marquette University, Milwaukee, WI, United StatesIntegrative Neural Engineering and Rehabilitation Laboratory, Department of Biomedical Engineering, Marquette University, Milwaukee, WI, United StatesCardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United StatesIntegrative Neural Engineering and Rehabilitation Laboratory, Department of Biomedical Engineering, Marquette University, Milwaukee, WI, United StatesDepartment of Physical Therapy, Marquette University, Milwaukee, WI, United StatesWe quantified the relationship between the change in post-contraction blood flow with motor unit firing rates and metrics of fatigue during intermittent, sub-maximal fatiguing contractions of the knee extensor muscles after stroke. Ten chronic stroke survivors (>1-year post-stroke) and nine controls participated. Throughout fatiguing contractions, the discharge timings of individual motor units were identified by decomposition of high-density surface EMG signals. After five consecutive contractions, a blood flow measurement through the femoral artery was obtained using an ultrasound machine and probe designed for vascular measurements. There was a greater increase of motor unit firing rates from the beginning of the fatigue protocol to the end of the fatigue protocol for the control group compared to the stroke group (14.97 ± 3.78% vs. 1.99 ± 11.90%, p = 0.023). While blood flow increased with fatigue for both groups (p = 0.003), the magnitude of post-contraction blood flow was significantly greater for the control group compared to the stroke group (p = 0.004). We found that despite the lower magnitude of muscle perfusion through the femoral artery in the stroke group, blood flow has a greater impact on peripheral fatigue for the control group; however, we observed a significant correlation between change in blood flow and motor unit firing rate modulation (r2 = 0.654, p = 0.004) during fatigue in the stroke group and not the control group (r2 = 0.024, p < 0.768). Taken together, this data showed a disruption between motor unit firing rates and post-contraction blood flow in the stroke group, suggesting that there may be a disruption to common inputs to both the reticular system and the corticospinal tract. This study provides novel insights in the relationship between the hyperemic response to exercise and motor unit firing behavior for post-stroke force production and may provide new approaches for recovery by improving both blood flow and muscle activation simultaneously.https://www.frontiersin.org/article/10.3389/fphys.2019.00545/fullstrokeblood flowmotor unitfatigueEMG |
| spellingShingle | Spencer Murphy Matthew Durand Francesco Negro Dario Farina Sandra Hunter Brian Schmit David Gutterman Allison Hyngstrom Allison Hyngstrom The Relationship Between Blood Flow and Motor Unit Firing Rates in Response to Fatiguing Exercise Post-stroke Frontiers in Physiology stroke blood flow motor unit fatigue EMG |
| title | The Relationship Between Blood Flow and Motor Unit Firing Rates in Response to Fatiguing Exercise Post-stroke |
| title_full | The Relationship Between Blood Flow and Motor Unit Firing Rates in Response to Fatiguing Exercise Post-stroke |
| title_fullStr | The Relationship Between Blood Flow and Motor Unit Firing Rates in Response to Fatiguing Exercise Post-stroke |
| title_full_unstemmed | The Relationship Between Blood Flow and Motor Unit Firing Rates in Response to Fatiguing Exercise Post-stroke |
| title_short | The Relationship Between Blood Flow and Motor Unit Firing Rates in Response to Fatiguing Exercise Post-stroke |
| title_sort | relationship between blood flow and motor unit firing rates in response to fatiguing exercise post stroke |
| topic | stroke blood flow motor unit fatigue EMG |
| url | https://www.frontiersin.org/article/10.3389/fphys.2019.00545/full |
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