1. Date of download: 6/21/2016 Copyright © 2016 SPIE. All rights reserved. (a) Experimental setup: (1) diffuse correlation spectroscopy (DCS)/near-infrared spectroscopy (NIRS) hybrid equipment received analog position input from the dynamometer to gate data collection during exercise. (2) Optical probe [depicted uncovered in (b)] sited over medial gastrocnemius at the location of the muscle belly. (3) Occlusion cuff secured above the thigh for inducing venous and arterial occlusions (VO and AO) for calibration. (4) The strain gauge and control computer run independently and concurrently during both calibration and exercise protocols. (5) The dynamometer was used to control exercise workload and frequency via setting 30% maximal voluntary isometric contraction (MVIC) resistance and passive return to rest. A visual metronome was used to regulate subject timing. Figure Legend: From: Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise J. Biomed. Opt. 2015;20(12):125006. doi:10.1117/1.JBO.20.12.125006

2. Date of download: 6/21/2016 Copyright © 2016 SPIE. All rights reserved. Protocol layout for (a) venous and arterial calibrations and (b) 30% MVIC plantar flexion exercise. The diagram summarizes the duration and timing for each procedure. The black dotted box signifies the period in which the gating algorithm was active to reduce muscle motion artifacts. Figure Legend: From: Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise J. Biomed. Opt. 2015;20(12):125006. doi:10.1117/1.JBO.20.12.125006

3. Date of download: 6/21/2016 Copyright © 2016 SPIE. All rights reserved. Illustrative subject (subject 4) hemodynamic and strain gauge data during calibration protocols; descending order (a) to (f): [Hb], [HbO2], total hemoglobin concentration (THC), blood oxygen saturation (StO2), relative changes in blood flow (rBF), and strain gauge venous plethysmography (SGVP). Raw rBF data were filtered with second-order Butterworth low-pass filter (cut-off frequency: 0.033 Hz) to reduce high-frequency noises. Hemodynamic trends indicated successful VO and AO. Figure Legend: From: Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise J. Biomed. Opt. 2015;20(12):125006. doi:10.1117/1.JBO.20.12.125006

4. Date of download: 6/21/2016 Copyright © 2016 SPIE. All rights reserved. Zoomed-in view of the illustrative subject (subject 4) calibration occlusion responses. (a) The optical THC slope during VO was used to calculate arterial inflow (baseline BF). A MATLAB® polyfit function was used to determine the slope. (b) The SGVP slope during VO was used to calculate baseline limb BF. Simultaneous time registries indicated both methods to determine BF are sensitive to VO. (c) The hemoglobin concentration change slope ([HbO2]−[Hb]) during AO was used to determine baseline oxygen consumption rate (V˙O2). Optical data showed initial increases as the pressure cuff reached VO pressure and then AO pressure. One-minute AO is sufficient to calculate V˙O2, whereas 3-min AO was used to confirm hyperemic response and verify occlusion integrity. Figure Legend: From: Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise J. Biomed. Opt. 2015;20(12):125006. doi:10.1117/1.JBO.20.12.125006

5. Date of download: 6/21/2016 Copyright © 2016 SPIE. All rights reserved. Linear regression of BF values measured by NIRS and SGVP. A correlation of R2=0.51 was obtained, indicating a sound correlation between the two measurements despite high degrees of intrasubject variation. BF measured by SGVP is generally higher than NIRS measurements, as has been noted by many previous studies. Figure Legend: From: Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise J. Biomed. Opt. 2015;20(12):125006. doi:10.1117/1.JBO.20.12.125006

6. Date of download: 6/21/2016 Copyright © 2016 SPIE. All rights reserved. Group mean (n=10) hemodynamic and metabolic profiles of gastrocnemius muscle during exercise; descending order (a) to (h): [Hb], [HbO2], THC, StO2, BF, V˙O2, heart rate, and mean arterial pressure (MAP). For MAP, subject 1 is excluded because of poor data quality. Group means were calculated after aligning each subject’s time series with the beginning and end of the exercise period. BF time series of each subject were filtered with a second-order Butterworth low-pass filter (cut-off frequency: 0.033 Hz) to reduce the high-frequency noises before calculating group mean. The three marks in each panel denote the beginning and end of the exercise, as well as the VO applied immediately after exercise for the SGVP BF calibration. Responses to exercise were rapid and immediately observable from all measurements. BF values immediately after exercise (5.13±0.32/100 ml/min) measured by SGVP (data are not shown in the figure) were much greater than those (1.05±0.17/100 ml/min) measured by DCS. Figure Legend: From: Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise J. Biomed. Opt. 2015;20(12):125006. doi:10.1117/1.JBO.20.12.125006