## 2 Materials and Methods  
Ethics Approval. The current study was conducted in accordance with the ethics and standards set forth by the Declaration of Helsinki 2013 and was approved by the Institutional Review Board of the University of South Alabama (IRB# 22-333/2087315-2) on 31 August 2023. However, this study was not registered in a public database. Prior to the initiation of any experimental protocol, all participants gave written signed consent and completed a health history document. Experimental Design. Participants reported to the Integrative Laboratory of Exercise and Applied Physiology (iLEAP) to complete paperwork and then were led to the body composition laboratory for recording of anthropometrics and body composition. The same single researcher then led participants to the body composition laboratory for recording of anthropometrics and body composition. Once these characteristics were measured, the participants were instructed to quietly lay still in the supine position on a padded patient table within the iLEAP. Their dominant arm was abducted 90\({}^{\circ}\) and supported at heart level by a foam base on a height-adjustable table. Ultrasonography was used to evaluate the brachial artery and forearm ATT of the abducted limb. A blood pressure cuff was attached to the non-dominant arm to measure mean arterial pressure (MAP) and heart rate (HR) with a patient monitor (Datascope Passport 2 Patient Monitor, Mindray DS USA, Inc., Mahwah, NJ, USA). After measures were collected with the ultrasound device, a mercury in-silastic strain-gauge (based on forearm circumference size), NIRS device, and pneumatic cuffs were attached to the dominant arm for the simultaneous recording of FBF and muscle oxygenation parameters (i.e., O\({}_{2}\)Hb) at rest and in response to transient ischemia (Figure 1). That is, the NIRS device and a strain-gauge were both attached to the same forearm and simultaneously collected data during VOP resting and RH assessments. These simultaneously collected values were then analyzed to determine match/correlation. Protocols associated with this experimental design are described below, and this concluded the visit. Human Participants. Thirty-three young (19-31 years old), healthy adults were recruited for this single-visit investigation. Data from two participants were not properly recorded due to NIRS device signal interruptions. Subsequently, an evaluation of potential influential outliers was performed, which utilized Cook's D versus studentized residuals (SREDIS) plots. These plots were visually inspected under the specific evaluation criteria of a Cook's D \(>\) 1.5 and SREDIS \(>\)\(\pm\)2. This identified two influential outliers. Thus, a total of four participants were removed from all further statistical analyses. The characteristics of this final sample (n = 29) are presented in Table 1 (male = 15, female = 14). These characteristics included a surrogate measure of physical activity, step count. This value was self-reported by each participant as a seven-day average calculated by participant-owned smart devices (e.g., Apple Watch, Garmin, or Apple iPhone). Further, all participants were classified as being recreationally active as defined by the World Health Organization activity guidelines, which included completing a minimum of 150-300 min of moderate-intensity activity or 75-150 min of vigorous-intensity activity per week, and/or muscle-strengthening activities two or more days a week [33]. The participants were instructed to continue their typical dietary, hydration, and medication habits while abstaining from exercise for at least 48 h before arriving to their experimental visit. Although no attempts were made to control for the menstrual cycle, four female participants reported the use of pharmaceutical contraceptives.