# The Effect of Aromatherapy on Post-Exercise Hypotension: A Pilot Study
## 2 Materials and Methods
### Experimental Protocol  
This study employed a randomized crossover design. The participants visited the laboratory twice, with a one-week wash-out interval between the visits. This washout period was chosen based on the short-acting nature, rapid clearance of essential oil constituents, and precedents in a previous crossover study [19], which was complemented by a trial using a shorter washout interval (2 days) while assuming no carryover effects [20]. It was also considered with a study showing that physiological responses to acute exercise return to baseline within 24-72 h in healthy individuals [21]. The individuals were instructed to fast overnight but were allowed to drink water before each visit. The participants were also instructed to avoid excessive physical activity, alcohol, nicotine, and caffeine for 24 h before each laboratory visit. To ensure laboratory standardization, the room temperature and humidity were maintained at 20-25 \({}^{\circ}\)C and 40-60%, respectively.  
The experimental procedure is illustrated in Figure 1. Briefly, upon arrival at the laboratory at 10:00 a.m., anthropometric measurements were obtained using a digital height- and weight-measuring machine (DS-103M, Dong-Sahn JENIX Co., Seoul, Republic of Korea). The body composition was determined using bioelectrical impedance analysis (Inbody 720, Biospace Co., Seoul, Republic of Korea), which is widely used to estimate body fat percentage, fat mass, and fat-free mass [22]. After baseline resting HR, BP, blood lactate (BL), and arterial stiffness index (ASI) measurements, the participants rested on a medical couch for 10 min. Subsequently, the participants performed 30 min of treadmill running at a 0% incline, which included a 5-min warm-up followed by 25 min of main exercise at 60-65% of their age-predicted maximal HRs. The HR during exercise was monitored using a sensor (Polar H10, Polar, Kempele, Finland). After exercise, the participants were seated immediately and remained at rest on a medical couch in the laboratory for 120 min with food and drink restrictions. The participants inhaled either aroma oil or water vapor at 5, 35, 65, and 95 min following exercise. This timing and frequency were determined based on previous studies that investigated the effects of exposure to external physiological stimulation on PEH [23; 24].  
The BP, HR, and ASI were assessed at 0, 10, 20, 30, 60, 90, and 120 min, with BL concentrations measured at 0, 15, 30, and 60 min after exercise. The HR and BP were measured in the left arm using a digital BP machine (HBP-1320, Omron, Kyoto, Japan). Measurements were acquired twice at 1-min intervals, and the average of the two readings was used for analysis. The BL levels were assessed using a small amount of blood collected from the fingertips of the right hand using a lactate analyzer (Lactate Pro 2, Kyoto, Japan).  
The ASI was measured in the left arm using the second derivative of the photoplethysmogram (SDPTG) via photoplethysmography (uBioClip v70, Biosense Creative Co., Seoul, Republic of Korea) as previously described [24]. Briefly, a sensor was noninvasively placed on the tip of the index finger to record the pulse wave in a capillary vessel for 1 min. SDPTG  
Figure 1: The experimental procedure. HR = heart rate; BP = blood pressure; BL = blood lactate; ASI = arterial stiffness index; THR = target HR; AT = aroma therapy.  
facilitates the analysis of wave indices, including the b/a ratio, which can be utilized to identify increased arterial stiffness [25]. All measurements were performed by the same investigator (S.P.).