Ultrasound Echogenicity as an Indicator of Muscle Fatigue during Functional Electrical Stimulation
Functional electrical stimulation (FES) is a potential neurorehabilitative intervention to enable functional movements in persons with neurological conditions that cause mobility impairments. However, the quick onset of muscle fatigue during FES is a significant challenge for sustaining the desired...
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MDPI AG
2022-01-01
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| Online Access: | https://www.mdpi.com/1424-8220/22/1/335 |
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| author | Qiang Zhang Ashwin Iyer Krysten Lambeth Kang Kim Nitin Sharma |
| author_facet | Qiang Zhang Ashwin Iyer Krysten Lambeth Kang Kim Nitin Sharma |
| author_sort | Qiang Zhang |
| collection | DOAJ |
| description | Functional electrical stimulation (FES) is a potential neurorehabilitative intervention to enable functional movements in persons with neurological conditions that cause mobility impairments. However, the quick onset of muscle fatigue during FES is a significant challenge for sustaining the desired functional movements for more extended periods. Therefore, a considerable interest still exists in the development of sensing techniques that reliably measure FES-induced muscle fatigue. This study proposes to use ultrasound (US) imaging-derived echogenicity signal as an indicator of FES-induced muscle fatigue. We hypothesized that the US-derived echogenicity signal is sensitive to FES-induced muscle fatigue under isometric and dynamic muscle contraction conditions. Eight non-disabled participants participated in the experiments, where FES electrodes were applied on their tibialis anterior (TA) muscles. During a fatigue protocol under either isometric and dynamic ankle dorsiflexion conditions, we synchronously collected the isometric dorsiflexion torque or dynamic dorsiflexion angle on the ankle joint, US echogenicity signals from TA muscle, and the applied stimulation intensity. The experimental results showed an exponential reduction in the US echogenicity relative change (ERC) as the fatigue progressed under the isometric (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>R</mi><mn>2</mn></msup><mo>=</mo><mn>0.891</mn><mo>±</mo><mn>0.081</mn></mrow></semantics></math></inline-formula>) and dynamic (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>R</mi><mn>2</mn></msup><mo>=</mo><mn>0.858</mn><mo>±</mo><mn>0.065</mn></mrow></semantics></math></inline-formula>) conditions. The experimental results also implied a strong linear relationship between US ERC and TA muscle fatigue benchmark (dorsiflexion torque or angle amplitude), with <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>R</mi><mn>2</mn></msup></semantics></math></inline-formula> values of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.840</mn><mo>±</mo><mn>0.054</mn></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.794</mn><mo>±</mo><mn>0.065</mn></mrow></semantics></math></inline-formula> under isometric and dynamic conditions, respectively. The findings in this study indicate that the US echogenicity signal is a computationally efficient signal that strongly represents FES-induced muscle fatigue. Its potential real-time implementation to detect fatigue can facilitate an FES closed-loop controller design that considers the FES-induced muscle fatigue. |
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| spelling | doaj.art-92dc7ec4cb054a84a3fd1b4d9b447c902023-11-23T12:20:38ZengMDPI AGSensors1424-82202022-01-0122133510.3390/s22010335Ultrasound Echogenicity as an Indicator of Muscle Fatigue during Functional Electrical StimulationQiang Zhang0Ashwin Iyer1Krysten Lambeth2Kang Kim3Nitin Sharma4UNC/NCSU Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC 27695, USAUNC/NCSU Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC 27695, USAUNC/NCSU Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC 27695, USAThe Department of Bioengineering, School of Engineering, University of Pittsburgh, Pittsburgh, PA 15260, USAUNC/NCSU Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC 27695, USAFunctional electrical stimulation (FES) is a potential neurorehabilitative intervention to enable functional movements in persons with neurological conditions that cause mobility impairments. However, the quick onset of muscle fatigue during FES is a significant challenge for sustaining the desired functional movements for more extended periods. Therefore, a considerable interest still exists in the development of sensing techniques that reliably measure FES-induced muscle fatigue. This study proposes to use ultrasound (US) imaging-derived echogenicity signal as an indicator of FES-induced muscle fatigue. We hypothesized that the US-derived echogenicity signal is sensitive to FES-induced muscle fatigue under isometric and dynamic muscle contraction conditions. Eight non-disabled participants participated in the experiments, where FES electrodes were applied on their tibialis anterior (TA) muscles. During a fatigue protocol under either isometric and dynamic ankle dorsiflexion conditions, we synchronously collected the isometric dorsiflexion torque or dynamic dorsiflexion angle on the ankle joint, US echogenicity signals from TA muscle, and the applied stimulation intensity. The experimental results showed an exponential reduction in the US echogenicity relative change (ERC) as the fatigue progressed under the isometric (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>R</mi><mn>2</mn></msup><mo>=</mo><mn>0.891</mn><mo>±</mo><mn>0.081</mn></mrow></semantics></math></inline-formula>) and dynamic (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>R</mi><mn>2</mn></msup><mo>=</mo><mn>0.858</mn><mo>±</mo><mn>0.065</mn></mrow></semantics></math></inline-formula>) conditions. The experimental results also implied a strong linear relationship between US ERC and TA muscle fatigue benchmark (dorsiflexion torque or angle amplitude), with <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>R</mi><mn>2</mn></msup></semantics></math></inline-formula> values of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.840</mn><mo>±</mo><mn>0.054</mn></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.794</mn><mo>±</mo><mn>0.065</mn></mrow></semantics></math></inline-formula> under isometric and dynamic conditions, respectively. The findings in this study indicate that the US echogenicity signal is a computationally efficient signal that strongly represents FES-induced muscle fatigue. Its potential real-time implementation to detect fatigue can facilitate an FES closed-loop controller design that considers the FES-induced muscle fatigue.https://www.mdpi.com/1424-8220/22/1/335muscle fatigueelectrical stimulationankle jointbiomechanical phenomenaultrasonographylinear models |
| spellingShingle | Qiang Zhang Ashwin Iyer Krysten Lambeth Kang Kim Nitin Sharma Ultrasound Echogenicity as an Indicator of Muscle Fatigue during Functional Electrical Stimulation Sensors muscle fatigue electrical stimulation ankle joint biomechanical phenomena ultrasonography linear models |
| title | Ultrasound Echogenicity as an Indicator of Muscle Fatigue during Functional Electrical Stimulation |
| title_full | Ultrasound Echogenicity as an Indicator of Muscle Fatigue during Functional Electrical Stimulation |
| title_fullStr | Ultrasound Echogenicity as an Indicator of Muscle Fatigue during Functional Electrical Stimulation |
| title_full_unstemmed | Ultrasound Echogenicity as an Indicator of Muscle Fatigue during Functional Electrical Stimulation |
| title_short | Ultrasound Echogenicity as an Indicator of Muscle Fatigue during Functional Electrical Stimulation |
| title_sort | ultrasound echogenicity as an indicator of muscle fatigue during functional electrical stimulation |
| topic | muscle fatigue electrical stimulation ankle joint biomechanical phenomena ultrasonography linear models |
| url | https://www.mdpi.com/1424-8220/22/1/335 |
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