This study adopted a randomized controlled design to examine the psychological and physiological outcomes of interventions among pilots with hypertension. Participants were allocated into different groups through computer-generated randomization, and the procedures included recruitment, intervention, and follow-up assessments. The overall procedure is illustrated in Figure 1.

120 male participants with hypertension were recruited from pilot medical examination. Participants were recruited for this study if they met the following criteria: (1) Met the specified range of the 2018 Chinese Hypertension Prevention and Treatment Guidelines, where hypertension is defined as a systolic blood pressure ≥ 140 mm Hg and/or a diastolic blood pressure ≥ 90 mm Hg (1 mm Hg = 0.133 kPa) (Li-Sheng, 2019); (2) had no organic damage such as retinal lesions or electrocardiographic abnormalities; (3) had no history of hypertension or syncope; (4) had no family history of hypertension; (5) had no history of anemia, hyperthyroidism, adrenal cortical adenoma, or other diseases affecting the cardiovascular system.

As a control, 120 healthy male participants were recruited during the pilot medical examination. The studies involving human participants were reviewed and approved by the Medical Ethics Committee of The Air Force Hospital from Eastern Theater of the People’s Liberation Army (PLA).

Anxiety was assessed using the Self-Rating Anxiety Scale, a 20-item measure in which items 5, 7, 10, and 13 are reverse-scored (Zung, 1971). A 4-point Likert scale was used, with 1 indicating “never” and 4 signifying “most or all of the time.” Higher scores reflected elevated levels of anxiety in individuals. The Cronbach’s αα in this study was 0.82.

Perceived stress was measured with Chinese Perceived Stress Scale, a 14-item measure in which items 4, 5, 6, 7, 9, 10, 12, and 13 are reverse-scored (Cohen et al., 1983; Yang and Huang, 2003). A 6-point Likert scale was used, with 1 being “never” and 6 being “always.” A higher total score indicates a higher perceived stress and a greater sense of uncontrollability. Cronbach’s α in this study was 0.78.

Blood pressure was measured using the Omron HEM-907XL, with the following standardized procedures: the measurements were taken three times, with a one-min interval between each measurement to ensure accuracy. The appropriate cuff size (22–32 cm) was selected based on the participant’s arm circumference. Participants were instructed to remain seated in a relaxed position, with their feet flat on the floor and their back supported. A resting period of at least five minutes was allowed before measurements were taken to ensure a stable baseline reading.

The pass rate refers to the probability that blood pressure meets the selection criteria for Air Force pilot recruitment.

The single intervention group took part in relaxation training sessions lasting about 30 min. These sessions included guided techniques to promote physical and mental relaxation, such as controlled breathing exercises, progressive muscle relaxation and visualization methods to reduce stress and tension.

The combined intervention group received a more comprehensive approach. Participants first underwent a recognized intervention based on cognitive behavioral therapy (CBT). This phase involved structured activities that focused on identifying and challenging negative thought patterns, promoting adaptive coping strategies, and developing emotional regulation skills. This was followed by approximately 30 min of relaxation training, like the single intervention group. This sequential approach aimed to combine the cognitive benefits of CBT with the physiological and emotional relaxation benefits of the training to achieve more substantial and lasting effects on stress and blood pressure reduction. Both interventions were delivered under the guidance of trained professionals in a quiet and comfortable environment to maximize participants’ concentration and effectiveness.

Additionally, the Control group received no intervention.

Before the start of the study, all 240 participants signed the informed consent form. Participants in the hypertension group were randomly assigned to their respective groups using the website https://www.randomizer.org/. The entire study was conducted at a dedicated medical examination center. Data were collected by three medical staff members responsible for aviation medical examinations, who were blinded to the study purpose. To ensure consistency, each participant’s psychological and blood pressure data were collected by the same assessor.

During the first blood pressure measurement, participants rested in the waiting room for 5 min prior to measurement, which was usually conducted between 8:00 and 10:00 a.m. In the afternoon, between 2:00 and 3:00 p.m., participants returned according to their assigned groups to receive either a single psychological intervention (approximately 30 min) or a combined psychological intervention (approximately 50 min), while the control group did not receive any intervention. At around 4:30 p.m., all groups rested in the waiting room for 5 min before the second blood pressure measurement.

SPSS 26.0 was used to compare the differences in anxiety, perceived stress, systolic blood pressure (SBP) and diastolic blood pressure (DBP) between the BBG and NCG. Additionally, Pearson correlation coefficients were calculated to examine the relationships between anxiety, perceived stress, SBP and DBP within each group. A two-way repeated measures analysis of variance was conducted to determine whether the interventions significantly affected anxiety, SBP, and DBP. A chi-square test was used to assess whether the pass rates between the three groups were significantly different.

The studies involving human participants were reviewed and approved by the Medical Ethics Committee of The Air Force Hospital from Eastern Theater of the People’s Liberation Army (PLA). All participants provided written informed consent prior to participation.

Table 1 revealed no significant differences between the BBG and NCG in terms of anxiety and perceived stress (both p > 0.05). However, a substantial difference was observed between the groups regarding systolic blood pressure (SBP) and diastolic blood pressure (DBP), with the BBG group showing significantly higher values than the NCG group (t = 20.61, p < 0.001, t = 10.73, p < 0.001). This result demonstrates that the grouping is effective.

Table 2 showed a significant correlation positive correlation between anxiety and perceived stress (r = 0.47, p < 0.001) within BBG; however, no significant correlation was found between SBP and DBP. Anxiety showed marginally significant correlation with both SBP and DBP (r = 0.13, p = 0.20; r = 0.15, p = 0.13). Additionally, perceived stress showed a significant correlation with both SBP and DBP (r = 0.20, r = 0.20, both p < 0.05). Similarly, within the NCG group detected a significant positive correlation between anxiety and perceived stress (r = 0.47, p < 0.001) and between SBP and DBP (r = 0.48, p < 0.001).

The further analysis of the blood pressure and anxiety changes in the high-pressure group revealed a significant negative correlation between the change in blood pressure and the change in anxiety.

The results are presented in Figure 2 and Table 3, the results of two-way repeated measures ANOVA revealed a significant main effect of time on anxiety level was significant, anxiety levels in post-intervention (M = 23.84, SD = 0.61) were significantly higher than pre-intervention (M = 21.16, SD = 0.46), F(1,99)=23.37,p<0.001,ηp2=0.19. A Tukey-adjusted simple effects analysis was conducted to examine changes in anxiety levels from pre-test to post-test across the three groups. In the control group, scores significantly increased from 20.26 (pre-test) to 22.87 (post-test), with a least-squares (LS) mean difference of −2.61, 95% CI [4.60,0.63], t₍₉₉₎ = 3.70, adjusted p < 0.05. The single intervention group also showed a significant increase, from 21.95 to 25.13, LS mean difference = −3.18, 95% CI [4.92,1.43], t₍₉₉₎ 5.11, adjusted p < 0.001. Similarly, the combined intervention group exhibited a significant increase from 21.26 to 23.52, LS mean difference = −2.26, 95% CI [4.24,0.28], t₍₉₉₎ = 3.20, adjusted p < 0.05.

The results of two-way repeated measures ANOVA showed that the main effect of time on SBP was significant, SBP in post-intervention (M = 143.24, SD = 1.28) were significantly lower than pre-intervention (M = 146.67, SD = 0.67), F(1,99)=7.08,p<0.01,ηp2=0.07. A Tukey-adjusted simple effects analysis was conducted to examine changes in SBP from pre-test to post-test within each group. In the control group, there was no significant change in SBP (LS mean difference = −0.19, 95% CI [4.79, 4.41]), t₍₉₉₎ = 0.12, adjusted p < 0.93. Similarly, the single intervention group showed no significant difference in SBP between pre-test and post-test (LS mean difference = 1.60, 95% CI [2.45, 5.65]), t₍₉₉₎ = 1.11, adjusted p < 0.43. However, the combined intervention group demonstrated a significant reduction in SBP, with levels decreasing from 145.2 to 136.3 (LS mean difference = 8.87, 95% CI [4.27, 13.47]), t₍₉₉₎ = 5.41, adjusted p < 0.001.

The results of two-way repeated measures ANOVA indicated a main effect of time on DBP was significant, DBP in post-intervention (M = 86.86, SD = 0.79) were significantly lower than pre-intervention (M = 88.67, SD = 0.68), F(1,99)=5.56,p<0.05,ηp2=0.05. A Tukey-adjusted simple effects analysis was conducted to examine changes in DBP from pre-test to post-test within each group. In the control group, there was no significant change in DBP (LS mean difference = −1.23, 95% CI [−3.96, 1.51]), t₉₉ = 1.26, adjusted p = 0.38. The single intervention group showed a significant reduction in DBP between pre-test and post-test (LS mean difference = 2.48, 95% CI [0.07, 4.88]), t₉₉ = 2.89, adjusted p < 0.05. Similarly, the combined intervention group demonstrated a significant decrease in DBP, with levels decreasing from 87.23 to 83.06 (LS mean difference = 4.16, 95% CI [1.43, 6.90]), t₉₉ = 4.27, adjusted p < 0.01.

As shown in Table 4, a chi-square test was conducted to assess the differences in the pass rates across three groups: the control group, the single-intervention group, and the combined-intervention group. The results, summarized in Table 4, revealed significant differences in the pass rates among the three groups, χ²(2) = 15.12, p = 0.001. Specifically, the pass rates in both the single-intervention group (57.5%) and combined-intervention group (74.2%) were significantly higher than those in the control group (25.8%). However, no significant difference was observed between the single-intervention group and the combined-intervention group.

The findings revealed that in the BBG group, perceived stress was significantly positively correlated with blood pressure, and anxiety showed a marginally significant positive association, whereas no such patterns were observed in the NCG group. This is partially consistent with the results of some previous studies (Forte et al., 2022; Gavrilova and Zawadzki, 2023). One possible explanation for this phenomenon is heightened hypothalamic-pituitary-adrenal (HPA) axis activation in individuals with hypertension, likely due to their prolonged near-hypertensive state, which increases their susceptibility to stress and anxiety (Johnson, 2019; Qi et al., 2023). Therefore, the BBG group may show a correlation between psychological factors and blood pressure, while the NCG group does not. Another possible explanation is that hypertension is often comorbid with trait or chronic anxiety (Rosas et al., 2021, 2024). Concurrently, individuals with higher levels of trait anxiety are more likely to show high state anxiety and stress (Weger and Sandi, 2018; Saviola et al., 2020). As the participants in the NCG group had normal blood pressure, their trait anxiety levels might generally be lower, resulting in weaker associations with state anxiety and perceived stress levels. This could help explain the absence of significant relationships between blood pressure and anxiety or stress levels within this group. Furthermore, additional potential psychological factors, such as emotional regulation ability and personality traits, or physiological mechanisms, including vascular elasticity and heart rate variability (HRV), may also act as influence factors between normotensive and prehypertensive groups (Piotrowska-Półrolnik et al., 2019; Chapuis-de-Andrade et al., 2021; Yugar et al., 2023; Kim, 2023). These differences warrant further investigation.

Post-intervention results indicated that both relaxation training alone and its combination with cognitive intervention significantly reduced blood pressure compared to the control group, with the combined intervention demonstrating the most pronounced effect. Furthermore, intervention groups showed a significantly higher rate of achieving target blood pressure levels. These findings support previous research showing that psychological interventions can help manage blood pressure (Huang et al., 2023; Chen et al., 2024). Possible mechanisms underlying these effects can be explained by the BERN framework, an operational model within mind-body medicine (MBM) that encompasses four multimodal intervention strategies: Behavior, Exercise, Relaxation, and Nutrition (Esch and Stefano, 2022). Based on this framework, psychological interventions including relaxation training may reduce blood pressure through two main mechanisms. First, relaxation training modulates the autonomic nervous system by enhancing parasympathetic activity and reducing sympathetic arousal, thereby lowering heart rate, decreasing vascular resistance, and inducing a self-regulated relaxation response. Second, it activates the central nervous system’s rewards and motivation circuits, engaging self-regulation processes and neurobiological signaling pathways, including the release of key messengers such as nitric oxide (NO) and dopamine, which further reduce stress responses and promote cardiovascular relaxation. This study found that the combination of relaxation training and cognitive intervention yielded the most effective results in blood pressure management, providing empirical support for future interventions. Future research could further explore and compare the effectiveness of other interventions, such as forest bathing, mindfulness, and the combination of relaxation training and cognitive intervention, in their impact on blood pressure (Lee et al., 2020; Peterfalvi et al., 2021).

It is noteworthy that participants’ anxiety levels increased after the intervention, which is contrary to the findings of previous research studies (Wells et al., 2021; White et al., 2022). There are several possible explanations for this phenomenon. Firstly, it is possible that the intervention may have altered participants’ cognitive and expressive perceptions of anxiety, leading to a more sensitive and accurate self-report of anxiety, rather than a true increase in anxiety (Van Der Gucht et al., 2019). Secondly, Participants’ awareness that failure to achieve the required blood pressure standard in a single test could result in disqualification from the selection process may have increased their stress levels, leading to increased anxiety. Despite elevated anxiety levels, participants exhibited a decrease in blood pressure, suggesting that psychological interventions may not rely solely on anxiety reduction to impact blood pressure (Mann, 2012). Indeed, some studies have suggested that relaxation training could directly regulate physiological responses, such as reducing sympathetic nervous system activity and improving cardiovascular function (Barnes et al., 2001; Rusinova et al., 2024). This would therefore influence blood pressure independently of psychological stress or anxiety relief (Ketelhut et al., 2023). It is worth noting that there is a small difference in the level of anxiety increase between different intervention methods, indicating that differences in intervention methods may affect changes in anxiety levels. Although the overall anxiety level increased, the anxiety level of subjects who received relaxation training combined with cognitive intervention increased less than that of subjects who only received relaxation training. Some previous studies have also suggested that relaxation training and interventions combined with cognitive measures are effective in reducing anxiety (Smits et al., 2008; Montero-Marin et al., 2019; Roper et al., 2024). Based on previous studies, this study concluded that compared with single relaxation training combined with cognitive psychological intervention, it is more effective in lowering blood pressure and relieving anxiety.