Respiration protocols have been developed to manipulate mental states, including their use for therapeutic purposes. In this systematic review, we discuss evidence that respiration may play a fundamental role in coordinating neural activity, behavior, and emotion. The main findings are: (1) respiration affects the neural activity of a wide variety of regions in the brain; (2) respiration modulates different frequency ranges in the brain's dynamics; (3) different respiration protocols (spontaneous, hyperventilation, slow or resonance respiration) yield different neural and mental effects; and (4) the effects of respiration on the brain are related to concurrent modulation of biochemical (oxygen delivery, pH) and physiological (cerebral blood flow, heart rate variability) variables. We conclude that respiration may be an integral rhythm of the brain's neural activity. This provides an intimate connection of respiration with neuro-mental features like emotion. A respiratory-neuro-mental connection holds the promise for a brain-based therapeutic usage of respiration in mental disorders.
Humans ; Respiration ; Brain ; Hyperventilation ; Heart Rate/physiology* ; Lung

Humans ; Heart Failure/therapy* ; Kidney/physiology* ; Renal Insufficiency ; Glomerular Filtration Rate

OBJECTIVE: To investigate the association between short-term exposure to indoor total volatile organic compounds (TVOC) and nocturnal heart rate variability (HRV) among young female adults. METHODS: This panel study recruited 50 young females from one university in Beijing, China from December 2021 to April 2022. All the participants underwent two sequential visits. During each visit, real time indoor TVOC concentration was monitored using an indoor air quality detector. The real time levels of indoor temperature, relative humidity, noise, carbon dioxide and fine particulate matter were monitored using a temperature and humidity meter, a noise meter, a carbon dioxide meter and a particulate counter, respectively. HRV parameters were measured using a 12-lead Holter. Mixed-effects models were used to evaluate the association between the TVOC and HRV parameters and establish the exposure-response relationships, and two-pollutant models were applied to examine the robustness of the results. RESULTS: The mean age of the 50 female subjects was (22.5±2.3) years, and the mean body mass index was (20.4±1.9) kg/m². During this study, the median (interquartile range) of indoor TVOC concentrations was 0.069 (0.046) mg/m³, the median (interquartile range) of indoor temperature, relative humidity, carbon dioxide concentration, noise level and fine particulate matter concentration were 24.3 (2.7) ℃, 38.5% (15.0%), 0.1% (0.1%), 52.7 (5.8) dB(A) and 10.3 (21.5) μg/m³, respectively. Short-term exposure to indoor TVOC was associated with significant changes in time-domain and frequency-domain HRV parameters, and the exposure metric for most HRV parameters with the most significant changes was 1 h-moving average. Along with a 0.01 mg/m³ increment in 1 h-moving average concentration of indoor TVOC, this study observed decreases of 1.89% (95%CI: -2.28%, -1.50%) in standard deviation of all normal to normal intervals (SDNN), 1.92% (95%CI: -2.32%, -1.51%) in standard deviation of average normal to normal intervals (SDANN), 0.64% (95%CI: -1.13%, -0.14%) in percentage of adjacent NN intervals differing by more than 50 ms (pNN50), 3.52% (95%CI: -4.30%, -2.74%) in total power (TP), 5.01% (95%CI: -6.21%, -3.79%) in very low frequency (VLF) power, and 4.36% (95%CI: -5.16%, -3.55%) in low frequency (LF) power. The exposure-response curves showed that indoor TVOC was negatively correlated with SDNN, SDANN, TP, and VLF when the concentration exceeded 0.1 mg/m³. The two-pollutant models indicated that the results were generally robust after controlling indoor noise and fine particulate matter. CONCLUSION Short-term exposure to indoor TVOC was associated with significant negative changes in nocturnal HRV of young women. This study provides an important scientific basis for relevant prevention and control measures.
Humans ; Female ; Adult ; Young Adult ; Air Pollutants/analysis* ; Heart Rate/physiology* ; Volatile Organic Compounds/analysis* ; Carbon Dioxide ; Particulate Matter/adverse effects* ; Environmental Pollutants

Objective: To evaluate the consistency on the determination of target heart rate by simple calculation method based on resting heart rate and by anaerobic threshold method in cardiopulmonary exercise test (CPET) for patients with coronary artery disease after percutaneous coronary intervention (PCI). Methods: This study was a diagnostic test. Patients with coronary artery disease who underwent the first PCI in the Department of Cardiology of Peking University People's Hospital from October 2011 to April 2021 were enrolled. Patients were further divided into subgroups according to gender, age (<60 years group and ≥60 years group), with or without myocardial infarction history (myocardial infarction group and angina pectoris group) and whether β blockers were applied. The general clinical data of patients, resting heart rate (RHR) and anaerobic threshold heart rate in CPET were collected through the electronic medical record system. The simple target rate (RHR plus 20 or 30 bpm) and the target rate calculated by anaerobic threshold (anaerobic threshold heart rate minus 10 bpm) were both calculated in each patient. Consistency test of target heart rate derived by above the two methods was shown by intra-class correlation (ICC) and Bland-Altman plots. Results: A total of 439 patients were included, age was (56.2±8.8) years, body mass index was (25.77±2.34) kg/m², there were 382 males (87.0%). The target heart rate determined by anaerobic threshold method was (90.0±11.8)bpm, and the simple target heart rate determined by RHR plus 20 bpm was (91.0±8.4)bpm. There was no significant difference on the target heart rate derived from the two calculation methods (P=0.091). The simple target heart rate determined by RHR plus 30 bpm was (101.0±8.4)bpm, which was significant higher than that determined by anaerobic threshold method (P<0.001). In the following analysis, RHR plus 20 bpm was defined as the simple target heart rate. The ICC value of target heart rate determined by anaerobic threshold and resting rate plus 20 bpm was 0.529(95%CI 0.458-0.593, P<0.001). Bland-Altman plots analysis showed that the ratio of the simple target heart rate and the target heart rate determined by anaerobic threshold method was 1.03±0.11 and the 95% limits of agreement (LOA) were 0.812-1.245. In the subgroup of patients aged<60 years (n=247), the ICC value was 0.492, the ratio by Bland-Altman plots analysis was 1.02±0.11 and LOA was 0.814-1.234; in the subgroup of patients aged ≥60 years (n=192), the ICC value was 0.566, the ratio by Bland-Altman plots analysis was 1.03±0.11 and LOA was 0.810-1.260. In male subgroup(n=382), the ICC value was 0.540, the ratio by Bland-Altman plots analysis was 1.03±0.11 and LOA was 0.813-1.246; in female subgroup(n=57), the ICC value was 0.445, the ratio by Bland-Altman plots analysis was 1.03±0.11 and LOA was 0.810-1.240.In myocardial infarction subgroup (n=186), the ICC value was 0.568, the ratio by Bland-Altman plots analysis was 1.02±0.11 and LOA was 0.810-1.227; in angina pectoris subgroup (n=253), the ICC value was 0.495, the ratio by Bland-Altman plots analysis was 1.04±0.11 and LOA was 0.813-1.260. In the subgroup of patients with β blockers (n=353), the ICC value was 0.520, the ratio by Bland-Altman plots analysis was 1.03±0.11 and LOA was 0.810-1.252; in the subgroup of patients without β blockers (n=86), the ICC value was 0.570, the ratio by Bland-Altman plots analysis was 1.02±0.10 and LOA was 0.821-1.219. Conclusions: The simple target heart rate determined by RHR plus 20 bpm is consistent with the target heart rate determined by anaerobic threshold in patients with coronary artery disease after PCI. But the simple target heart rate determined by RHR plus 20 bpm can't replace the target heart rate determined by anaerobic threshold in this patient cohort.
Adrenergic beta-Antagonists ; Anaerobic Threshold ; Angina Pectoris ; Coronary Artery Disease ; Female ; Heart Rate/physiology* ; Humans ; Male ; Myocardial Infarction ; Percutaneous Coronary Intervention

Photoplethysmography (PPG) is a non-invasive technique to measure heart rate at a lower cost, and it has been recently widely used in smart wearable devices. However, as PPG is easily affected by noises under high-intensity movement, the measured heart rate in sports has low precision. To tackle the problem, this paper proposed a heart rate extraction algorithm based on self-adaptive heart rate separation model. The algorithm firstly preprocessed acceleration and PPG signals, from which cadence and heart rate history were extracted respectively. A self-adaptive model was made based on the connection between the extracted information and current heart rate, and to output possible domain of the heart rate accordingly. The algorithm proposed in this article removed the interference from strong noises by narrowing the domain of real heart rate. From experimental results on the PPG dataset used in 2015 IEEE Signal Processing Cup, the average absolute error on 12 training sets was 1.12 beat per minute (bpm) (Pearson correlation coefficient: 0.996; consistency error: -0.184 bpm). The average absolute error on 10 testing sets was 3.19 bpm (Pearson correlation coefficient: 0.990; consistency error: 1.327 bpm). From experimental results, the algorithm proposed in this paper can effectively extract heart rate information under noises and has the potential to be put in usage in smart wearable devices.
Algorithms ; Heart Rate/physiology* ; Photoplethysmography/methods* ; Signal Processing, Computer-Assisted ; Wearable Electronic Devices

Altitude ; Exercise/physiology* ; Heart Rate/physiology* ; Humans ; Lung ; Respiration

Objective: To investigate the correlation between heart rate index (HRI), systolic blood pressure(SBP) peak-to-SBPrest ratio (SBPR) and peak oxygen consumption (peakVO₂) in patients with chronic heart failure (CHF), and discuss the possibility of using HRI and SBPR collected during exercise to assess the exercise tolerance of CHF patients in the absence of gas analysis. Methods: In this cross-sectional study, a total of 547 patients with CHF who underwent cardiopulmonary exercise test(CPET) in Tongji Hospital Heart Rehabilitation Center Affiliated to Tongji University from March 2007 to December 2018 were collected retrospectively, focusing on their clinical data including age, gender, type of heart failure,BMI as well as data collected during their CPETs, such as peakVO₂, HRI and SBPR. Spearman univariate correlation analysis was used for statistical analysis, to unveil the correlations between peakVO₂ and those parameters, and multiple linear regression analysis was also conducted. Results: A total of 547 CHF patients conducting CPET were included in this research, of which 447 were male, at age of 63(56, 69). Univariate analysis indicates that HRI, SBPR and peakVO₂ showed significant positive correlation (r=0.323, 0.263, respectively, all P<0.001); Age and peak VO₂ showed significant negative correlation(r=-0.207, P<0.001); Male patients showed peakVO₂ higher than female(r=-0.229, P<0.001); PeakVO₂ of heart failure with reduced ejection fraction(HFrEF) was lower than heart failure with mid-range ejection fraction(HFmrEF)and heart failure with preserved ejection fraction(HFpEF) (r=0.181, P<0.001). Body mass index (BMI) had no significant correlation with peakVO₂ (P>0.05). Multivariate linear regression analysis showed that the HRI, SBPR were positively correlated with peakVO₂(t=7.68, 5.08, respectively, all P<0.05), while age and BMI showed negative correlation with peakVO₂(t=-5.43, -0.31, respectively, all P<0.05). PeakVO₂ of male was higher than female(t=-6.03, P<0.05), and peakVO₂ of HFrEF was lower than those of HFmrEF and HFpEF(t=3.17, 4.48, respectively, all P<0.05). A linear equation (F=33.52, adjusted R²=0.29) could be constructed: peakVO₂=10.65(male) or 8.53(female)+4.26HRI+3.31SBPR-0.07age-0.13BMI+0(HFrEF) or 1.05 (HFmrEF) or 1.62(HFpEF). Conclusion: HRI and SBPR are positively correlated with peakVO₂. In the absence of gas analysis, it is possible to apply HRI and SBPR during exercise to predict exercise tolerance in patients with CHF.
Chronic Disease ; Cross-Sectional Studies ; Female ; Heart Failure ; Heart Rate ; Humans ; Male ; Oxygen Consumption/physiology* ; Prognosis ; Retrospective Studies ; Stroke Volume/physiology*

Objective: To explore the effect of emotional optimization of workplace employees in immersive virtual natural environment. Methods: In July 2020, 15 subjects were selected to complete two groups of treadmill walking training experiments in virtual natural environment and daily environment respectively. At the same time, the subjects' skin electrical (EDA) , pulse frequency (Pf) , respiratory frequency (Rf) physiological data and Self-Assessment Manikin (SAM) data before and after walking were collected; the mean value of three dimensions of SAM and the emotion difference before and after the experiment were calculated. The differences of physiological indexes and subjective mood changes of subjects were tested by paired sample t-test. Results: Compared with the daily environment, the ΔEDA, ΔPf and ΔRf of the subjects in the virtual natural environment were all decreased , and the differences were statistically significant (P<0.05). There were statistically significant differences in pleasure and arousal between subjects before and after using the virtual natural environment (P <0.05). Compared with the daily environment, the Δpleasure degree of subjects using the virtual natural environment increased, and the Δarousal degree and Δdominance degree decreased, and the differences were statistically significant (P <0.05). Conclusion: Walking in virtual natural environment can help subjects improve their mood, relax and improve the regulation ability of autonomic nervous system.
Arousal ; Emotions/physiology* ; Heart Rate ; Humans ; Virtual Reality ; Workplace

Objective: To analyze the characteristics of heart rate variability (HRV) in patients with vestibular migraine (VM) and to explore its possible mechanism. Methods: Forty-eight patients with VM [17 males and 31 females, age (36.2±9.2) years], 44 patients with migraine [15 males and 29 females, age (34.4±9.0) years], and 30 patients with health check-ups during the same period [12 males and 18 females, age (34.6±6.5) years old] were selected as study subjects. Ambulatory ECG monitoring was performed in all subjects, and the HRV characteristics of each group were analyzed from both daytime and nighttime time phases. Time domain parameters were analyzed: standard deviation of normal to normal (SDNN), root mean square of successive differences (RMSSD), and percentage of normal to normal intervals differing by more than 50 ms (pNN50). The parameters in the frequency domain were analyzed: high frequency power (HF), low frequency power (LF), and the ratio of low frequency to high frequency power (LF/HF). Statistical analysis of the data was performed using SPSS 26.0 software. Results: At night, RMSSD (F=6.694) and HF (F=9.434) were lower in the VM and migraine groups compared to the control group, while LF/HF (F=16.049) and LF (F=9.434) were elevated compared to the control group, with statistically significant differences (P<0.05 or P<0.01), while LF was significantly elevated in the VM group compared to the migraine group, with a statistically significant (P<0.05). On the daytime measurements, mainly LF was elevated in the vestibular migraine group compared with the control group, while RMSSD was decreased compared with the control group, with statistically significant differences (P<0.05). Conclusion: Autonomic dysfunction characterized by sympathetic hyperfunction and vagal hypofunction is present in VM patients and is more pronounced at night. In addition, the degree of autonomic dysfunction may be more pronounced in VM patients than in migraine patients.
Adult ; Female ; Heart Rate/physiology* ; Humans ; Male ; Middle Aged ; Migraine Disorders ; Vertigo

OBJECTIVE: To observe the effect of transcutaneous auricular vagus nerve stimulation (taVNS) on the sleep quality and nocturnal heart rate variability (HRV) in patients with primary insomnia. METHODS: Twenty-one patients with primary insomnia were included. Using SDZ-ⅡB electric acupuncture apparatus, Xin (CO₁₅) and Shen (CO₁₀) were stimulated with disperse-dense wave, 4 Hz/ 20 Hz in frequency, (0.2±30%) ms of pulse width and tolerable intensity. Electric stimulation was given once every morning and evening of a day, 30 min each time, for 4 weeks totally. Before and after treatment, the score of Pittsburgh sleep quality index (PSQI), objective sleep structure (total sleep time [TST], sleep latency [SL], wake after sleep onset [WASO], sleep efficiency [SE], the percentages of non-rapid eye movement period 1, 2, 3, and the percentage of rapid eye movement period to TST [N1%, N2%, N3%, REM%] ) and nocturnal HRV (high frequency [HF], low frequency [LF], the ratio of LF to HF [LF/HF], standard deviation for the normal RR intervals [SDNN], squared root of the mean sum of squares of differences between adjacent intervals RR [RMSSD], the percentage of adjacent RR intervals with differences larger than 50 ms in the entire recording [PNN50%], the mean of sinus RR intervals [NNMean] ) were compared in the patients separately. RESULTS: After treatment, the score of each item and the total score of PSQI and SL were all reduced as compared with those before treatment (P<0.01, P<0.001); SE, N3%, LF, HF, LF/HF, SDNN, NNMean and RMSSD were all increased compared with those before treatment (P<0.001, P<0.01). CONCLUSION The taVNS improves the sleep quality and objective sleep structure in patients with primary insomnia, which is probably related to the regulation of autonomic nervous functions.
Heart Rate/physiology* ; Humans ; Sleep/physiology* ; Sleep Initiation and Maintenance Disorders/therapy* ; Vagus Nerve ; Vagus Nerve Stimulation