Northwestern University Feinberg School of Medicine

Physical Therapy & Human Movement Sciences

Neuromuscular Biomechanics Laboratory

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The primary research focus of this laboratory is to determine the underlying mechanisms that contribute to impaired movement in individuals with neurological impairments such as stroke, cerebral palsy or spinal cord injury. Using a variety of techniques such as ultrasound imaging, magnetic resonance imaging, modeling, histochemistry, electromyography and gait analysis, we can begin to elucidate the complex nature of altered movement. Specifically, we are interested in changes in musculoskeletal architecture, muscle material properties and composition, as well as recruitment patterns of different motor unit types. Knowing the influence of these changes on impaired movement will form the basis for proposing clinical tools used to aid in diagnosing and assessment and for developing novel interventions for rehabilitation.

Areas of Research

Quantifying changes in musculoskeletal properties in individuals with neurological impairments

The primary objective of this study is to quantify changes in musculoskeletal architecture, composition and material properties in individuals with neurological impairments. Using B-mode ultrasound, we can make measurements of musculoskeletal architecture (moment arm fascicle length, thickness, pennation angle) and muscle composition by quantifying the echogenicity. Using shear wave ultrasound elastography, we can measure the speed of shear wave propagation through the muscle which is related to stiffness. We can then relate these changes in musculoskeletal properties to muscle function and severity of impairment through measurements of gait, muscle strength and clinical tests.

Quantifying altered recruitment patterns of different motor unit types

Using wavelet analysis, a technique for time-frequency decomposition, accompanied with principal component analysis, we can track the recruitment patterns of different motor unit types such as slow and fast motor units from surface electromyography in individuals with neurological impairments. There is evidence that fiber type composition changes occur due to stroke, cerebral palsy and spinal cord injury and since slow and fast fibers can have different properties, altered recruitment patterns may result in impaired muscle contraction during tasks such as walking.

Principal Investigator

Collaborating Faculty