# The Effect of Aromatherapy on Post-Exercise Hypotension: A Pilot Study
## 4 Discussion  
Given that both aromtherapy and exercise can reduce BP, this pilot study investigated whether aromtherapy has a synergistic effect on PEH. To the best of our knowledge, this is the first study to evaluate the impact of aromtherapy on PEH. Our findings indicate that aroma oil inhalation during the post-exercise recovery phase can enhance the BP-lowering effect of exercise. Elevated BP is recognized as an independent risk factor for cardiovascular disease (CVD). Thus, preventing or reducing BP is a crucial medical objective to lower CVD-related mortality and complications in individuals with hypertension [2]. Among the strategies for the management of BP, exercise is well characterized and plays a pivotal role as a non-pharmacological approach. Previous studies have provided evidence that regular exercise can prevent or reduce resting BP, primarily through the cumulative effect of repeated transient BP reductions following acute exercise, known as PEH [6]. In our study, acute \begin{table}
\begin{tabular}{c c c} \hline \hline
**Time (min)** & **CON** & **AROMA** \\ \hline At rest & 3.0 \(\pm\) 0.4 & 2.8 \(\pm\) 0.3 \\
0 & 7.4 \(\pm\) 1.4 * & 9.1 \(\pm\) 1.7 * \\
15 & 4.7 \(\pm\) 0.6 * & 5.7 \(\pm\) 1.1 * \\
30 & 4.1 \(\pm\) 1.0 & 3.9 \(\pm\) 0.7 \\
60 & 3.4 \(\pm\) 0.4 & 2.8 \(\pm\) 0.2 \\ \hline \hline \end{tabular} CON = exposure to water vapor; AROMA = inhalation of aroma oil. * \(p\) < 0.05 compared with pre-exercise (at rest) values. There was no difference between treatments at any time point.  
\end{table} 
Table 2: Blood lactate (mmol/L) measured before and after exercise. Figure 4: Changes (post-exercise values minus pre-exercise values) in the arterial stiffness index (ASI) during the recovery period after exercise (0–120 min) (\(t\) = 14/group). CON = exposure to water vapor; AROMA = inhalation of aroma oil. Values are presented as mean \(\pm\) standard error of mean. * \(p\) < 0.05 compared with pre-exercise values (presumably 0). \(\tau\)\(p\) < 0.05 between treatments at each time point. aerobic exercise at a moderate intensity for 30 min induced PEH, which began at 20 min and persisted through 90 min of recovery, consistent with previous studies demonstrating that exercise elicits PEH. However, the magnitude and duration of PEH vary across studies, likely due to differences in exercise type, length, and intensity. In addition, factors such as the sex, age, and disease status of participants may also contribute to these variations [8; 31]. Olfactory stimuli from aromatherapy have been documented to influence cardiovascular variables. In particular, extensive research has focused on aromatherapy-induced changes in the ANS, resulting in decreased SNA and increased PNA. Moreover, aromatherapy has been demonstrated to enhance positive emotions and decrease negative emotional states, possibly via the dopaminergic reward system activation [15]. Olfactory nerves are believed to transmit information to primary olfactory regions, such as the amygdala, piriform cortex, and entorhinal cortex. In addition, olfactory input might be relayed to secondary olfactory regions, including the hippocampus, thalamus, insula, and orbitofrontal cortex [32]. Therefore, it is plausible that olfactory exposure to aromas could activate these brain regions, potentially modulating ANS activity and emotional responses [33]. Considering this, our finding that aroma inhalation augments PEH also implies that olfactory stimuli from aroma oil may modulate the ANS. Consequently, this neural change as well as dopaminergic activation via olfactory stimulation may lead to reduced vascular tone and decreased peripheral vascular resistance, ultimately amplifying the effects of exercise on PEH. This is in line with our finding that exercise-induced decreases in arterial stiffness are magnified and prolonged by aroma inhalation during the recovery phase after exercise. Unfortunately, we could not directly measure changes in SNA or PNA in this pilot study. Thus, a future investigation is warranted.