Occlusion calibrations and gating techniques have been recently applied by our laboratory for continuous and absolute diffuse optical measurements of foreann muscle hemodynamics during handgrip exercises. The translation of these techniques from the foreann 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 poncentrations, blood oxygen ~aturation, and relative changes in blood flow (rBF) and oxygen consumption rate (rV02) . We calibrated rBF and rV02 profiles with absolute baseline values of BF and V02 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.

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Published in Journal of Biomedical Optics, v. 20, no. 12, article 125006, p. 1-10.

Brad Henry, Mingjun Zhao, Yu Shang, Timothy Uhl, D. Travis Thomas, Eleftherios S. Xenos, Sibu P. Saha, and Guoqiang Vu, " Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise," Journal of Biomedical Optics, 20(12), 125006, (2015).

Copyright 2015 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

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We thank the National Institutes of Health for support from R2 1-AG034279 and R21-AG046762.