The Heart Rate Variability (HRV) Effects of Tourmaline and Terahertz Ore Material Clothing: A Randomized Double-Blind Placebo-Controlled Trial

Ore is believed to have mystical powers and health benefits. Psychological stress can affect physical and mental health, and stress can also increase an individual’s risk of various diseases, so people are looking for various solutions. Following previous research, tourmaline, and terahertz are minerals used in various fields, including health and medicine. Studies have pointed out that these two minerals benefit the human body. Therefore, two kinds of ores, tourmaline and terahertz, are finely pulverized, mixed into the printing solution for printing patterns, and then printed and attached to clothes to observe the influence on heart rate variability (HRV) when wearing ore-containing shirts. Understanding the effects on a person’s degree of relaxation and muscle sensation. There are 12 healthy adult males that participated in the experiment, the results show that after wearing tourmaline and terahertz stone powder-printed garments, the tension of the cardiac vagus nerve is increased, and the body is relaxed. The results for SDRR and RMSSD in time domain analysis, and Total (ms?), VLF (ms?), HF (ms?), and LF (nu) in frequency domain analysis have significant differences. SD1 and SD2 of nonlinear analysis have significant differences too, which have positive and significant effects on short-term or long-term sympathetic, parasympathetic, vagus nerves, healthy function, inherent self-regulation ability, and adaptation. Improvements in sexuality or resilience may be beneficial in improving fatigue.

Keywords: Stress, Autonomic nervous system, Heart rate variability (HRV), Ore shirt, Vagal Tone

Background 

Since ancient times, people believed that ore has mysterious power. Since ancient times, it has been worn and carried by authority figures in the royal family as symbols of power and decoration, and it is believed that it can benefit health. Tourmaline is commonly known as tourmaline, and the study of tourmaline has been an integral part of science and scientific exploration for centuries and continues to flourish. During the Qing Dynasty, tourmaline was a well-known piece of jewelry and was deeply loved by Empress Dowager Cixi. Terahertz ore is an artificial one made of a large amount of silicon that is said to cause vibrations of about 1 trillion hertz per second.

Tourmaline is one of the important heavy minerals in Taiwan. There are quite a lot of Tertiary and Quaternary strata in Taiwan. It is produced in the metamorphic rock distribution area and pegmatite granite on the east slope of the Central Mountain Range (Taiwan Mining Bureau, 1996, Chen Peiyuan, Lin Deging, Huang Yizhen, 2004). Tourmaline becomes charged when heated, so it is called tourmaline. Tourmaline can be made into silk and cloth containing tourmaline (Yoshio M, 2001; Ayano K., & Nobuko N., 2003), and it can be made into health articles and work with Far Infrared (FIR) as a feature (Hiromichi E, 2004) Tourmaline can emit far-infrared electromagnetic waves with a wavelength of 4-14 μm, which matches the absorption spectrum of the human body and is absorbed by human tissue, increasing the temperature and blood flow velocity of human tissue, improving microcirculation, and improving body immunity (Zhang Z, 2003 ). Far-infrared rays are biologically functional rays that specifically affect the human body, especially the activation of blood circulation and skin cells (Inoué & Kabaya, 1989; Huang Yubin, 2021). In addition, producing far-infrared rays increases arterial blood flow (Yuchi Akasaki, 2006) and peripheral blood circulation. It relieves fatigue (Suet al., 2009) and pain (Oosterveld et al., 2009), but the exact mechanism remains not thoroughly understood.

Terahertz (THz) is a vibration called “terahertz wave”. Its frequency is similar to far infrared.

Due to its unique physical properties, it has been widely used in aerospace, communication, medicine, and other fields (Sun et al., 2021). The interaction of terahertz waves with biological macromolecules has attracted more and more attention in basic research and applications in biomedicine (Sun, Zhao, & Peng, 2021). When the human body or substances are irradiated, resonance phenomena will occur, and the body temperature will rise, enhancing vitality (Zhang Jianbiao, 2021).

Psychological stress can affect physical and mental health. Stress can also increase an individual’s risk of developing various diseases. People hear about many new treatments to combat stress, such as psychopharmacology, and herbal and behavioural therapies, which promise to reduce stress levels and various health conditions (Slavich, 2016). The human body must constantly adapt to changing internal and external environments, thereby tightly regulating its internal physiological state to maintain homeostasis. In maintaining homeostasis, human bodies release hormones and switch on the autonomic nervous system (ANS, autonomic nervous system) and central nervous system, allowing us to adapt and respond to daily activities (O’Connor et al., 2021). 

Stress Response: Broadly speaking, when we experience stress, two systems are activated. The Sympathetic-adrenal-medullary (SAM system is the first and easiest to activate. The second is the hypothalamic-pituitary-adrenal (HPA, Hypothalamic-pituitary-adrenal) axis. In good health, these systems are usually in a state of homeostasis, dominated by the PNS (Parasympathetic nervous system), which can become unbalanced under stressful conditions, where it is chronically activated, causing excessive wear and tear on physiological systems. Numerous studies have shown an association between ANS imbalances and adverse health outcomes (Thayer & Lane, 2007; Thayer et al., 2010)

Comparisons of heart rate variability in past studies have shown that a comparison of cloth woven with tourmaline and cloth without tourmaline showed that wearing cloth made of Tourmaline powder has far infrared effects that increased body temperature and relaxation effects. ECG (electrocardiogram) found that the parasympathetic nervous system became dominant after wearing it (Yoshio Machi, 2001). Research on betting also shows that parasympathetic nerves are dominant (Hiromachi, E. and Yukihiro, K. 2004).

Therefore this study compares the effects of these two minerals on human HRV with and without wearing them and observes the changes and effects.

Purpose

Following previous research findings, tourmaline and terahertz are two minerals used in various fields including health medicine. Studies have pointed out that these two minerals benefit the human body. Therefore, in this study these two minerals (tourmaline and terahertz) were finely powdered, mixed into the printing and dying solution, and printed on the shirt together to observe the effect of heart rate variability when wearing the shirt.

Research Methods

(1)Research Object

This research project was approved by the Ethical Experimental Committee (Nippon Yakuro No. 3-18)  and was recruited publicly at Nippon Pharmaceutical University. 12 healthy men aged 26 to 62 participated in this research after full explanation and written consent.

(2)Research Materials

The test item used this time is: wearing a shirt with two kinds of ores,  each weighing 1.15 G and 325 mesh,  mixed with tourmaline and terahertz at a ratio of one to one in the printing and dying solution for printing the pattern, and a shirt that does not contain ore in the dying solution that prints the same pattern and looks the same in color and shape see figures 1 and 2. Crossover randomized double-blind ore free,  and ore-containing tests were performed.

1. Spectral Characteristics of Tourmaline

Tourmaline is a columnar structure formed by cyclic triangular silicate. Tourmaline can produce the phenomenon of electron migration so that it can release far infrared rays with a wavelength range of 3 to 1,000 micrometers. (Chen Junliang, Chen Zuicheng, Gui Tianai, Liao Jianhong, Chen Baizhou, 2010).

2. Spectral characteristics of terahertz stone (THz)

 Terahertz frequencies (THz) lie between the far infrared, infrared IR, and microwave regions. The terahertz region generally includes frequencies ranging from 0.1 to 10 terahertz, where one terahertz equals 10 12 Hertz the range corresponds to a wavelength λ (30-300 micrometers).   

(3)Test Content

Random Grouping of Test Subjects: Twelve males were randomly divided into two groups, one group without ore and one group with ore. Each test subject wore the clothes for one hour, continuously for one week, and continuously for two weeks. There were three data collection points in total, with each point tested twice. The tests were conducted after a week of not wearing the clothes from this experiment (Figure 1, 2). To minimize the influence of gender and age differences on heart rate variability, only males of similar age were included in this study.

Heart Rate Variability Analysis: All participants underwent electrocardiogram (ECG) monitoring and recording. The ECG recordings were then analyzed using methods accepted by the European Society of Cardiology. Time-domain analysis included evaluation of SDRR (standard deviation of RR intervals) and RMSSD (root mean square of successive R interval differences), as well as frequency-domain analysis including LF (low-frequency band), HF (high-frequency band), LF/HF (low-to-high-frequency ratio), ULF (ultra-low frequency), and VLF (very low frequency). Nonlinear indices such as SD1 and SD2 were also measured.

HRV Measurement Definition: Heart rate variability was recorded for 5 minutes while participants in each group sat quietly with their eyes open. The recordings were conducted in the Sports Pharmacy Laboratory of Nihon Pharmaceutical University.

(3)Data Collection and Analysis

The electrocardiographic data was collected using the PowerLab system physiological recorder, and the LabChart Pro7.0 software was used for ECG recording. HRV v2.0 was used for heart rate variability analysis, following the standards for HRV measurement, physiological interpretation, and clinical use established by the European Society of Cardiology (ESC) and the North American Society of Heart and Electrophysiology (NASPE) working group in 1996 (Heart Rate Variability, 1996). 

Time-domain analysis involved calculations of mean NIN interval (average RR], SDNN (standard deviation of NN intervals), SDRR (standard deviation of R intervals), and RMSSD (root mean square of successive R interval differences). Frequency-domain analysis included VLF (ms2), VLF%, LF (ms2), LF%, LF (nu), HF (ms2), HF%, HF (nu), LF/HF, as well as SD1 and SD2 as nonlinear indices (Laborde et al., 2017). Statistical analysis was conducted using two independent sample t-tests to determine if there were any significant differences in the indicators between the two groups, with a significance level set at a < 0.05.

Results

In this study, 12 males, averaging 53 +/- 12 years old, wore shirts containing ore powder for more than 23 hours a day, except for when bathing and changing clothes, for 14 consecutive days. The analysis aimed to detect various indicators of heart rate variability representing the autonomic nervous system, comparing shirts with and without ore powder.

(1) Time domain analysis (Table 1)

Average RR: The small change in the interval between consecutive heartbeats (milliseconds).

The average value of the group without ore is 914.85 ‡ 93.53 ms, and the average value of the group with ore is 923.58 ‡ 124.98 ms.

SDRR: Standard deviation of all R-R intervals, the cyclic component leading to heart rate variability, with an average of 39.73 ‡ 8.82 ms for the group without ore and 44.31 # 12.22 ms for the group with ore.

RMSSD: Mean root square of the continuous difference, representing the vagus nerve. The average value for the group without ore is 31.49 ‡ 9.39 ms, and for the group with ore is 36.25 ‡ 12.7 ms on average.

pRR50: The percentage of continuous normal sinus RRvf intervals exceeding 50 milliseconds, representing the vagus nerve. The average value of the group without ore is 11.32 ‡ 8.66%, and the average value of the group with ore is 14.89 ‡ 13.3%

(2) Frequency domain analysis (Table 1)

VLF: Very low frequency, long-term, thermoregulatory, and hormonal regulatory mechanisms.

The average VLF (ms?) of the group without ore was 569.05 ‡ 336.37 ms?, and the average VLF % was 41.89 ‡ 13.81%. The average VLF (ms) of the group with ore was 748.38 ‡ 566.97 ms?, and the average VLF % was 41.4 ‡ 16.38%.

LF: Low frequency, sympathetic and vagal activity, baroreflex activity. The average LF (ms2) of the group without ore was 409.24 = 219.59 ms?, the average LF % was 29.4 * 10.1%, and the average LF (nu) was 50.31 * 11.22 nu. The average LF (ms2) of the group with ore was 455.92 + 273.71 ms. The average LF % was 26.3 = 11.2%, and the average LF (nu) was 45.45 * 15.69 nu.

HF: High frequency, vagus nerve. The average HF (ms) of the group without ore was 376.88 ‡ 177.83 ms2, the average HF % was 28.4 ‡ 9.07%, and the average HF (nu) was 48.92 ‡ 11.23 nu.

The average HF (ms?) of the group with ore was 519.44 ‡ 302.16 ms?, the average HF % was 30 ‡ 11.7%, and the average HF (nu) was 52.11 ‡ 13.44 nu.

LF/HF: Low frequency/high-frequency ratio, a mixture of sympathetic and vagal activity. The average LE/HF of the group without ore is 1.12 * 0. 0.48, and the average LF/H of the ore-containing group is 1.034 0.58.

 

3. Nonlinear index (Table 1)

(1) SD1: Describes rapid and frequent changes in heart rate variability. The average SD1 time of the group without ore is 22.3‡ 6.65 ms, and the average time of the group with ore is 25.74 9 ms in SD1.

(2) SD2: Describes long-term changes in heart rate variability. The average SD2 value of the group without ore is 51.4 ‡11.3 ms, and that of the group containing ore is 56.74 ‡16.7 ms in SD2.

 

 

 

Discussion 

‘Since ancient times, people have been fascinated by gemstones and held positive and magical beliefs about their effects. Gemstones are known to have different impacts on the human body. The use of stones as tools dates to the Stone Age. With the advancement of science and technology, various types of stones are cut and processed to become usable materials or products. In Taiwan, tourmaline is an important mineral used in healthcare products to improve human health, along with artificial terahertz stone. Previous studies have shown that tourmaline can enhance human body function and promote health (Ezumi, 2004; Kimura, 2004). Recently, there has been increasing attention worldwide to the use of natural minerals, such as far infrared rays and negative ions, for health improvement (Zhan Jie, 2006).

Heart rate variability (HRV) is an indicator of neurocardiac function, reflecting the complex and nonlinear interactions between the heart and the brain, as well as the dynamic processes of the autonomic nervous system (ANS) (Shaffer & Ginsberg, 2017). Healthy heart oscillations exhibit variability and nonlinearity, allowing for quick responses to uncertain and changing environments (Frank Beckers, 2006). Studies have also indicated a link between high heart rate (HIR) and low vagal-mediated HRV, which may indicate poor health outcomes (Thayer & Lane, 2007; Thayer et al., 2010). Therefore, we propose methods to investigate the changes in HRV parameters, including IF, IF/HF ratio, SDNN, RMSSD, pNN50, and SD1, as indicators of sympathetic and parasympathetic nervous system activity in response to stress. Studies have suggested that stress leads to an increase in sympathetic nervous system activity, reflected by higher LF and LF/HF ratios, and a decrease in parasympathetic nervous system activity, reflected by reduced SDNN, RMSSD, pNN50, and SD1. These changes are often reversed during relaxation (Hammoud et al., 2018).”

In the time-domain analysis of the overall HRV, the average RMSSD of the clothing containing tourmaline and terahertz increased significantly, as indicated by the T-test offspring. The study proposed that RMSSD reflected vagal tone, which showed increased vagal tone after wearing mineral-containing clothing. A higher vagal tone indicates the body can relax more quickly after stress. However, higher HRV is not always better, as previous studies have suggested that HRV levels in an organism reflect healthy function, inherent self-regulation, fitness, or resilience. The European Society of Cardiology uses RMSSD, LF/HF (low frequency/high frequency) ratio, and other indicators for short-term assessment of HRV for an overall assessment of HRV.

In the frequency domain analysis, the average value of LF/HIF becomes smaller, indicating increased parasympathetic activity. There were no significant differences in VLF (very low frequency), LF (low frequency), and HF (high frequency) between the ore-containing group and the control group. This reflects long-term regulatory mechanisms, thermoregulatory and hormonal mechanisms, sympathetic and vagal activity, and a mixture of baroreflex activity and vagus nerve activity, consistent with previous studies on tourmaline products showing similar effects on body temperature elevation and relaxation. IF power has been suggested to indicate baroreflex function. Although there were no significant differences in the average value of LF/HF, there were significant differences in SD1 and SD2, with the average value becoming smaller, indicating a tendency towards balanced sympathetic and parasympathetic activity, which has benefits for both parasympathetic stimulations. This supports the suggestion that HRV levels reflect healthy function, inherent self-regulation, adaptability, or resilience. For nonlinear index analysis, it is usually used as a supplement to HRV, and SD1 and SD2 showed statistically significant differences, indicating short-term and long-term changes in heart rate variability after wearing mineral clothing. Poincare plots, which illustrate quantitative and qualitative patterns of individual HRV in oval shapes, can be considered indicators of vagal activity and reduced cardiac vagal control associated with physiological and psychological tension and stress, showing a beneficial effect on HRV homeostasis.

Research limitations: This study only focused on comparing wearing and not wearing mineral clothing and did not test fatigue and post-exercise. However, after interviews with the subjects, they described feeling muscle relaxation when wearing mineral clothing, especially in the muscles of the shoulders. It will be confirmed in future studies.

Conclusions and Suggestions:

This study found that shirts containing tourmaline and terahertz stone powder positively benefit the human body. Psychological stress can affect physical and mental health, and imbalances can arise under stressful conditions, leading to increased risks of various diseases due to chronic activation. This study suggests that using tourmaline and artificial terahertz stones to make healthcare products may improve human health. HRV provides valuable information about the body’s physiological state. The heart rate variability results in this study show that wearing mineral clothing containing tourmaline and terahertz stone increases RMSSD and SD1 and changes the average value of LF/HF, indicating a balanced HRV. These indicators suggest that improving self-regulation ability, adaptability, and resilience may be beneficial for reducing fatigue and stress in modern people’s lives and work. In addition to traditional medicine, exercise, and nutritional therapy, this study proposes a possible method for improvement in the face of the current social phenomenon of stress.

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