Heart rate variability analysis using robust period detection

Associations between saliva alpha-amylase, heart rate variability, saliva cortisol and cognitive performance in individuals at ultra high-risk for psychosis

BACKGROUND

Cognitive impairments are present in individuals at ultra-high risk (UHR) of psychosis and UHR individuals exhibit a hyperactive and dysfunctional HPA-axis. Increasing stress levels could potentially lead to cognitive impairments and no previous studies have examined the association between physiological stress biomarkers and cognition in UHR individuals. This study aims to examine the association between saliva alpha amylase (SAA), heart rate variability (HRV), saliva cortisol, and cognition in UHR individuals.

METHOD

We included 72 UHR individuals, aged 18-40, fulfilling criteria of the comprehensive assessment of at-risk mental state (CAARMS). Cognitive tests indexed the 7 core domains as stated by Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS). Physiological stress levels were observed for one day: saliva was collected at awakening, 30 min and 60 min after awakening and at bedtime. HRV was measured during sleep and before awakening. We used generalized linear model and controlled for multiple testing using false discovery rate (FDR).

RESULTS

Higher levels of SAA were significantly associated with lower cognitive performance in the domains of verbal and visual learning and memory, sustained attention, working memory and global neurocognition looking at unadjusted data. Controlling for FDR visual memory, sustained attention and global neurocognition remained significant associated with SAA. We discovered no associations between cortisol and cognition.

CONCLUSION

Visual learning and memory, sustained attention and global neurocognition remained significantly associated with SAA. This finding supports our hypothesis that an association between abnormal stress biomarkers and impaired cognition might be present in UHR individuals.

A longitudinal study on physiological stress in individuals at ultra high-risk of psychosis

INTRODUCTION

Individuals at ultra high-risk (UHR) of psychosis exhibit significantly higher stress levels than healthy controls (HC). This study investigates how physiological stress measures differ between HC and UHR individuals and how physiological stress is associated with attenuated psychotic symptoms and changes over time in UHR individuals. Additionally, it examines how the use of medication affects physiological levels of stress.

METHOD

The study included 72 UHR individuals and 36 HC. UHR were included according to the comprehensive assessment of at-risk mental state (CAARMS); a total-CAARMS score measured the attenuated psychotic symptoms and was calculated from the four psychosis subscales. HC and UHR were examined at baseline, and 47 UHR individuals were followed up after six months. Physiological stress measures were salivary cortisol, alpha-amylase (SAA) and heart-rate variability (HRV). Saliva was collected at four-time points during the day.

RESULTS

There was no significant difference regarding cortisol (awakening response) or SAA measures between HC and UHR individuals. The use of antipsychotics and antidepressants was associated with low HRV in UHR individuals. In an exploratory analysis of 19 UHR individuals, we found an association between the change in total-CAARMS (six months total-CAARMS minus baseline total CAARMS) and the change in HRV during sleep (six months HRV minus baseline HRV).

CONCLUSION

Our findings indicate that the use of antipsychotics and antidepressants could be associated with lower HRV in UHR individuals. There might be potential to investigate how HRV develops during the course of illness in UHR individuals.

Heart rate variability during sleep after two, four and seven consecutive night shifts and recovery days: a cross-over intervention study

OBJECTIVE

Recovery after shift work is an important part reducing the health problems related to shift work. Heart rate variability (HRV) is an indicator of the balance between sympathetic and parasympathetic activity in the autonomic nervous system and can be used as a measure of recovery after night shifts. The aim of the study is to investigate autonomic recovery during sleep in response to night work in a crossover intervention study.

METHODS

Seventeen male police officers working in call centres in five different police district participated in the HRV measurements. The participants were exposed to three interventions: 2 + 2: two consecutive night shifts followed by two consecutive day recovery days; 4 + 4: four consecutive night shifts followed by four consecutive recovery days; 7 + 7: seven consecutive night shifts followed by seven consecutive recovery days. On the last day with night shift and the last recovery day in each intervention the participants underwent 24 h HRV recordings. We analysed HRV during sleep. The five 5-min intervals with the lowest heart rate during each sleep period were chosen for spectral analysis of the heart interbeat interval time series. The five 5-min intervals could occur at any time during sleep.

RESULTS

There were overall differences in HRV during sleep between days with night shifts and recovery days, primarily in parasympathetic activity. There was no difference in the lowest heart rate obtained, but the timing was different for the three interventions. The lowest heart rate after night shifts occurred 112 (SD 79) min, 174 (SD 115) min and 135 (SD 94) min after sleep onset for the 2 + 2 night shift, the 4 + 4 night shift and the 7 + 7 night shift, respectively.

CONCLUSION

Overall sleep-related autonomic recovery had higher parasympathetic modulation of cardiac rhythm on the 2 + 2 shift system compared to the 4 + 4 and 7 + 7 shift system.

The effect of spinal manipulative therapy and home stretching exercises on heart rate variability in patients with persistent or recurrent neck pain: a randomized controlled trial

BACKGROUND

Persistent or recurrent neck pain is, together with other chronic conditions, suggested to be associated with disturbances of the Autonomic Nervous System. Acute effects on the Autonomic Nervous System, commonly measured using Heart Rate Variability, have been observed with manual therapy. This study aimed to investigate the effect on Heart Rate Variability in (1) a combination of home stretching exercises and spinal manipulative therapy versus (2) home stretching exercises alone over 2 weeks in participants with persistent or recurrent neck pain.

METHODS

A randomized controlled clinical trial was carried out in five multidisciplinary primary care clinics in Stockholm from January 2019 to April 2020. The study sample consisted of 131 participants with a history of persistent or recurrent neck. All participants performed home stretching exercises daily for 2 weeks and were scheduled for four treatments during this period, with the intervention group receiving spinal manipulative therapy in addition to the home exercises. Heart Rate Variability at rest was measured at baseline, after 1 week, and after 2 weeks, with RMSSD (Root mean square of successive RR interval differences) as the primary outcome. Both groups were blinded to the other group intervention. Thus, they were aware of the purpose of the trial but not the details of the "other" intervention. The researchers collecting data were blinded to treatment allocation, as was the statistician performing data analyses. The clinicians provided treatment for participants in both groups and could not be blinded. A linear mixed-effects model with continuous variables and person-specific random intercept was used to investigate the group-time interaction using an intention to treat analysis.

RESULTS

Sixty-six participants were randomized to the intervention group and sixty-five to the control group. For RMSSD, a B coefficient of 0.4 (p value: 0.9) was found, indicating a non-significant difference in the regression slope for each time point with the control group as reference. No statistically significant differences were found between groups for any of the Heart Rate Variability indices.

CONCLUSION

Adding four treatments of spinal manipulation therapy to a 2-week program of daily stretching exercises gave no significant change in Heart Rate Variability.

TRIAL REGISTRATION

The trial was registered 03/07/2018 at ClinicalTrials.gov, registration number: NCT03576846. ( https://pubmed.ncbi.nlm.nih.gov/31606042/ ).

Changes in Humans' Autonomic Nervous System under Dynamic Lighting Environment During A Short Rest

Overloaded work and life stress often result in excessive fatigue and stresses in people, further leading to psychological burden and physiological disease. In this case, good rest is important in busy life. Good rest could result in good quality of life and work efficiency. In order to assist people in getting into deep rest to obtain a restorative state after fatigue, a dynamic lighting system with low-frequency change for assisting users in effective relaxation is proposed in this study. Heart rate variability analysis is used for discussing the change in the autonomic nervous system of the subjects under dynamic lighting environment, and a self-report questionnaire is applied to understand the subjects' psychological feeling. The research results indicate that the subjects significantly showed enhancement in the activities of parasympathetic nervous system within 25 minutes in the dynamic lighting process, in comparison with the steady lighting system. The questionnaire survey results also reveal that the subjects receive higher quality of rest, after the dynamic and low-illuminance lighting stimuli, with good feeling.

Cardiorespiratory fitness, occupational aerobic workload and age: workplace measurements among blue-collar workers

BACKGROUND

The knowledge, from laboratory studies dating back to the 1950s on the importance of the association between cardiorespiratory fitness and aerobic workload for workers health, is fundamental for promoting sustainable healthy employability among ageing blue-collar workers today. However, the association between cardiorespiratory fitness and aerobic workload has not yet been documented during daily work, and we do not know if it applies to the normal work of blue-collar workers in different age groups. We aim to investigate the association between cardiorespiratory fitness and aerobic workload among blue-collar workers using measurements of 24-h heart rate collected over consecutive working days.

METHODS

We analyzed baseline cardiorespiratory fitness, assessed using a sub-maximal cycle ergometer test, and 1-4 days of 24-h heart rate measurement from 497 blue-collar workers participating in the DPHACTO study. We investigated the association between cardiorespiratory fitness and aerobic workload defined as the average percentage of heart rate reserve (%HRR), maximum %HRR and the duration time spent at a high HRR (> 30%) during working hours. The association was assessed using multivariate linear regression models adjusted for age, sex, self-rated health, shift-work, prescription medication and occupation, as well as for different age strata.

RESULTS

Higher cardiorespiratory fitness was significantly associated with decreased mean %HRR -0.32 [95% CI -0.39 to -0.25], maximum %HRR -0.35 [95% CI -0.45 to -0.25] and time spent at  ≥ 30% HRR; -1.8% [95% CI -2.2 to -1.5%]. These associations were evident across age groups, with slightly stronger associations for workers aged 46-51 (total range 18-68).

CONCLUSIONS

Higher cardiorespiratory fitness was associated with the decreased aerobic workload during normal work across all age groups and levels of work intensity. Our findings highlight the importance of cardiorespiratory fitness when considering the workload and its relevance in the promotion of healthy sustainable employment.

The DPhacto cohort: An overview of technically measured physical activity at work and leisure in blue-collar sectors for practitioners and researchers

For improved prevention of health issues among blue-collar workers, there is a need for an overview of the physical activity at work and leisure using technical long-term measurements in blue-collar sectors investigation of differences between the sectors. Thus, the objective of this paper was to provide an overview and investigate differences in physical activities and body postures at work and leisure among blue-collar sectors. The Dphacto cohort consists of 1087 workers from manufacturing, transportation and cleaning sectors (901 blue-collar and 186 white-collar workers) in Denmark. Eligible workers provided physical activity and heart rate measurements over several days with follow-up on health-related outcomes by self-report and registers. Considerable differences in sitting, standing, time on feet (walking, shuffling and standing combined) and forward bending of the back were found between work and leisure, and between the sectors. This overview of physical activity at work and leisure can be useful for better prevention of work-related health issues among blue-collar workers.

Objectively Measured Sitting and Standing in Workers: Cross-Sectional Relationship with Autonomic Cardiac Modulation

Excessive sitting and standing are proposed risk factors for cardiovascular diseases (CVDs), possibly due to autonomic imbalance. This study examines the association of objectively measured sitting and standing with nocturnal autonomic cardiac modulation. The cross-sectional study examined 490 blue-collar workers in three Danish occupational sectors. Sitting and standing during work and leisure were assessed during 1⁻5 days using accelerometers. Heart rate (HR) and heart rate variability (HRV) were obtained during nocturnal sleep as markers of resting autonomic modulation. The associations of sitting and standing still (h/day) with HR and HRV were assessed with linear regression models, adjusted for age, gender, body mass index, smoking, and physical activity. More sitting time during leisure was associated with elevated HR (p = 0.02), and showed a trend towards reduced HRV. More standing time at work was associated with lower HR (p = 0.02), and with increased parasympathetic indices of HRV (root mean squared successive differences of R-R intervals p = 0.05; high-frequency power p = 0.07). These findings, while cross-sectional and restricted to blue-collar workers, suggest that sitting at leisure is detrimental to autonomic cardiac modulation, but standing at work is beneficial. However, the small effect size is likely insufficient to mitigate the previously shown detrimental effects of prolonged standing on CVD.

The association between multisite musculoskeletal pain and cardiac autonomic modulation during work, leisure and sleep - a cross-sectional study

Background

The prevention and rehabilitation of multisite musculoskeletal pain would benefit from studies aiming to understand its underlying mechanism. Autonomic imbalance is a suggested mechanism for multisite pain, but hardly been studied during normal daily living. Therefore, the aim of the study is to investigate the association between multisite musculoskeletal pain and cardiac autonomic modulation during work, leisure and sleep.

Methods

This study is based on data from the “Danish Physical activity cohort with objective measurements” among 568 blue-collar workers. Pain intensity scales were dichotomized according to the median of each scale, and the number of pain sites was calculated. No site was regarded as the pain-free, one site was considered as single-site musculoskeletal pain and pain in two or more sites was regarded as multisite musculoskeletal pain. Heart rate variability (HRV) was measured by an electrocardiogram system (ActiHeart) and physical activity using accelerometers (Actigraph). Crude and adjusted linear mixed models were applied to investigate the association between groups and cardiac autonomic regulation during work, leisure and sleep.

Results

There was no significant difference between groups and no significant interaction between groups and domains in the crude or adjusted models for any HRV index. Significant differences between domains were found in the crude and adjusted model for all indices, except SDNN; sleep time showed higher values than leisure and work time, except for LF and LF/HF, which were higher during work.

Conclusion

This cross-sectional study showed that multisite musculoskeletal pain is not associated with imbalanced cardiac autonomic regulation during work, leisure and sleep time.

Electronic supplementary material

The online version of this article (10.1186/s12891-018-2312-3) contains supplementary material, which is available to authorized users.

Different autonomic responses to occupational and leisure time physical activities among blue-collar workers

Purpose

The differential effect of occupational and leisure time physical activity on cardiovascular health is termed the physical activity health paradox. Cardiac autonomic modulation could bring insights about the underlying mechanism behind this differential effect. The aim was to compare heart rate variability (HRV) during different activities (sitting, standing and moving) at work and leisure among blue-collar workers.

Methods

One hundred thirty-eight workers from the NOMAD cohort were included. Data from physical activity and HRV were obtained for 3–4 days using tri-axial accelerometers (Actigraph GT3X+) and a heart rate monitor (Actiheart). HRV indices were determined during sitting, standing and moving both at work and leisure. Linear mixed-models with two fixed factors (activities and domains) were applied to investigate differences in HRV indices adjusting for individual and occupational factors.

Results

The results showed significant effects of domain (p < 0.01), physical activity type (p < 0.01) and interaction between domain and activity type (p < 0.01) on HRV indices. Mean heart rate (IBI) and parasympathetic measures of HRV (RMSSD and HF) were lower for sitting (p < 0.01) and higher for moving (p < 0.01) during work compared with leisure, while no difference between domains was found for standing (p > 0.05). Sympathovagal balance (LF/HF) was higher during work for sitting and moving (p < 0.01), but showed no difference for standing (p = 0.62).

Conclusions

Differences in cardiac autonomic modulation between work and leisure were found, indicating sympathetic predominance during work and parasympathetic predominance during leisure for sitting. Autonomic responses can be part of the mechanism that explains the differential effect of occupational and leisure time physical activity on health.

On the health paradox of occupational and leisure-time physical activity using objective measurements: Effects on autonomic imbalance

OBJECTIVE

Leisure-time physical activity (LTPA) has considerable benefits for cardiovascular health and longevity, while occupational physical activity (OPA) is associated with an elevated cardiovascular risk. This "health paradox" may be explained by different effects on the autonomic nervous system from OPA and LTPA. Thus, we aimed to investigate whether objectively measured OPA and LTPA are differentially associated with autonomic regulation among workers.

METHODS

The study comprised 514 blue-collar workers from the Danish cohort DPHACTO. Physical activity (i.e. walking, climbing stairs, running and cycling) was assessed objectively using accelerometers worn on the thigh, hip and trunk over multiple working days. During this period, a heart rate monitor was used to sample heart period intervals from the ECG signal. Heart rate and heart rate variability (HRV) indices were analyzed during nocturnal sleep as markers of autonomic regulation. Multiple regression analysis was used to determine the main effects of OPA and LTPA and their interaction on heart rate and HRV, adjusting for multiple confounders.

RESULTS

Statistically significant interaction was found between OPA and LTPA on heart rate (adjusted p<0.0001) and HRV indices in time (rMSSD, adjusted p = 0.004) and frequency-domains (HF, adjusted p = 0.022; LF, adjusted p = 0.033). The beneficial effect of LTPA on nocturnal heart rate and HRV clearly diminished with higher levels of OPA, and high levels of both OPA and LTPA had a detrimental effect.

CONCLUSION

We found contrasting associations for objectively measured OPA and LTPA with heart rate and HRV during sleep. Differential effects of OPA and LTPA on autonomic regulation may contribute to the physical activity health paradox.

Effects of stroke on changes in heart rate variability during hemodialysis

Background

Stroke and low heart rate variability (HRV) are both associated with an unfavorable prognosis in hemodialysis patients. The relationship between stroke and changes in HRV during hemodialysis remains unclear.

Methods

This study measured differences between predialysis and postdialysis HRV (△HRV) in 182 maintenance hemodialysis patients, including 30 patients with stroke, to assess changes in HRV during hemodialysis, and also to compare results to 114 healthy controls.

Results

All predialysis HRV measurements had no differences between stroke patients and those without stroke, but were lower than healthy controls. Postdialysis very low frequency (VLF) (P < 0.001), low frequency (LF) (P = 0.001), total power (TP) (P < 0.001) and the LF/high frequency (HF) ratio (P < 0.001) increased significantly relative to predialysis values in patients without stroke, whereas postdialysis HRV did not increase in stroke patients. After multivariate adjustment, dialysis vintage was negatively associated with △VLF (β = -0.698, P = 0.046), △LF (β = -0.931, P = 0.009), and △TP (β = -0.887, P = 0.012) in patients without stroke. Serum intact parathyroid hormone (β = -0.707, P = 0.019) was negatively associated with △LF. Total cholesterol (β = -0.008, P = 0.001) and high sensitivity C-reactive protein (β = -0.474, P = 0.012) were inversely correlated with the △LF/HF ratio in patients without stroke.

Conclusion

HRV in hemodialysis patients is lower than in the general population. Increase in △HRV was observed in hemodialysis patients without stroke but not in stroke patients. This result suggests suppressed autonomic nervous reactions against volume unloading during hemodialysis, which might contribute to unfavorable outcomes in hemodialysis patients but even more so in those with prior stroke. Nephrologists should notice the importance of △HRV especially in high-risk patients.

Prolonged Sitting is Associated with Attenuated Heart Rate Variability during Sleep in Blue-Collar Workers

Prolonged sitting is associated with increased risk for cardiovascular diseases and mortality. However, research into the physiological determinants underlying this relationship is still in its infancy. The aim of the study was to determine the extent to which occupational and leisure-time sitting are associated with nocturnal heart rate variability (HRV) in blue-collar workers. The study included 138 blue-collar workers (mean age 45.5 (SD 9.4) years). Sitting-time was measured objectively for four days using tri-axial accelerometers (Actigraph GT3X+) worn on the thigh and trunk. During the same period, a heart rate monitor (Actiheart) was used to sample R-R intervals from the electrocardiogram. Time and frequency domain indices of HRV were only derived during nighttime sleep, and used as markers of cardiac autonomic modulation. Regression analyses with multiple adjustments (age, gender, body mass index, smoking, job-seniority, physical work-load, influence at work, and moderate-to-vigorous physical activity) were used to investigate the association between sitting time and nocturnal HRV. We found that occupational sitting-time was negatively associated (p < 0.05) with time and frequency domain HRV indices. Sitting-time explained up to 6% of the variance in HRV, independent of the covariates. Leisure-time sitting was not significantly associated with any HRV indices (p > 0.05). In conclusion, objectively measured occupational sitting-time was associated with reduced nocturnal HRV in blue-collar workers. This indicates an attenuated cardiac autonomic regulation with increasing sitting-time at work regardless of moderate-to-vigorous physical activity. The implications of this association for cardiovascular disease risk warrant further investigation via long-term prospective studies and intervention studies.