title: Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise.
abstract: Occlusion calibrations and gating techniques have been recently applied by our laboratory for continuous and absolute diffuse optical measurements of forearm muscle hemodynamics during handgrip exercises. The translation of these techniques from the forearm to the lower limb is the goal of this study as various diseases preferentially affect muscles in the lower extremity. This study adapted a hybrid near-infrared spectroscopy and diffuse correlation spectroscopy system with a gating algorithm to continuously quantify hemodynamic responses of medial gastrocnemius during plantar flexion exercises in 10 healthy subjects. The outcomes from optical measurement include oxy-, deoxy-, and total hemoglobin concentrations, blood oxygen saturation, and relative changes in blood flow (rBF) and oxygen consumption rate (rV̇O2). We calibrated rBF and rV̇O2 profiles with absolute baseline values of BF and V̇O2 obtained by venous and arterial occlusions, respectively. Results from this investigation were comparable to values from similar studies. Additionally, significant correlation was observed between resting local muscle BF measured by the optical technique and whole limb BF measured concurrently by a strain gauge venous plethysmography. The extensive hemodynamic and metabolic profiles during exercise will allow for future comparison studies to investigate the diagnostic value of hybrid technologies in muscles affected by disease.
authors.affiliation: University of Kentucky, College of Engineering, Department of Biomedical Engineering, 143 Graham Avenue, Lexington, Kentucky 40506-0108, United States.
authors.forename: Brad
authors.initials: B
authors.lastname: Henry
authors.affiliation: University of Kentucky, College of Engineering, Department of Biomedical Engineering, 143 Graham Avenue, Lexington, Kentucky 40506-0108, United States.
authors.forename: Mingjun
authors.initials: M
authors.lastname: Zhao
authors.affiliation: University of Kentucky, College of Engineering, Department of Biomedical Engineering, 143 Graham Avenue, Lexington, Kentucky 40506-0108, United States.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shang
authors.affiliation: University of Kentucky, College of Health Sciences, Department of Rehabilitation Science, 900 S Limestone Street, Lexington, Kentucky 40536-0200, United States.
authors.forename: Timothy
authors.initials: T
authors.lastname: Uhl
authors.affiliation: University of Kentucky, College of Health Sciences, Department of Clinical Sciences, 900 S Limestone Street, Lexington, Kentucky 40536-0200, United States.
authors.forename: D Travis
authors.initials: DT
authors.lastname: Thomas
authors.affiliation: University of Kentucky, College of Medicine, Department of Surgery, 900 S Limestone Street, Lexington, Kentucky 40536-0200, United States.
authors.forename: Eleftherios S
authors.initials: ES
authors.lastname: Xenos
authors.affiliation: University of Kentucky, College of Medicine, Department of Surgery, 900 S Limestone Street, Lexington, Kentucky 40536-0200, United States.
authors.forename: Sibu P
authors.initials: SP
authors.lastname: Saha
authors.affiliation: University of Kentucky, College of Engineering, Department of Biomedical Engineering, 143 Graham Avenue, Lexington, Kentucky 40506-0108, United States.
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Yu
mesh_terms: D000328:Adult; D000465:Algorithms; D001783:Blood Flow Velocity; D002138:Calibration; D015444:Exercise; D005260:Female; D064368:Healthy Volunteers; D006439:Hemodynamics; D006454:Hemoglobins / Q000737:chemistry; D006801:Humans; D007537:Isometric Contraction; D035002:Lower Extremity / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D055095:Optics and Photonics / Q000379:methods*; D010100:Oxygen / Q000737:chemistry; D010101:Oxygen Consumption
chemical_list: D006454:Hemoglobins; D010100:Oxygen