Different exercise training modalities similarly improve heart rate variability in sedentary middle-aged adults: the FIT-AGEING randomized controlled trial

Heart rate variability and autonomic nervous system imbalance: Potential biomarkers and detectable hallmarks of aging and inflammaging

The most cutting-edge issue in the research on aging is the quest for biomarkers that transcend molecular and cellular domains to encompass organismal-level implications. We recently hypothesized the role of Autonomic Nervous System (ANS) imbalance in this context. Studies on ANS functions during aging highlighted an imbalance towards heightened sympathetic nervous system (SNS) activity, instigating a proinflammatory milieu, and attenuated parasympathetic nervous system (PNS) function, which exerts anti-inflammatory effects via the cholinergic anti-inflammatory pathway (CAP) and suppression of the hypothalamic-pituitary-adrenal (HPA) axis. This scenario strongly suggests that ANS imbalance can fuel inflammaging, now recognized as one of the most relevant risk factors for age-related disease development. Recent recommendations have increasingly highlighted the need for actionable strategies to improve the quality of life for older adults by identifying biomarkers that can be easily measured, even in asymptomatic individuals. We advocate for considering ANS imbalance as a biomarker of aging and inflammaging. Measures of ANS imbalance, such as heart rate variability (HRV), are relatively affordable, non-invasive, and cost-effective, making this hallmark easily diagnosable. HRV gains renewed significance within the aging research landscape, offering a tangible link between pathophysiological perturbations and age-related health outcomes.

Heart rate variability measurement and influencing factors: Towards the standardization of methodology

Heart rate variability (HRV) is widely recognized as an effective and valuable tool for evaluating cardiac autonomic modulation. However, various factors can influence HRV before and during assessment, complicating the interpretation and comparability of results. This review outlines the different factors affecting HRV and underscores the importance of considering them to ensure consistent and reliable HRV outcomes. Key influencing factors are categorized into physiological (e.g., age, gender, genetics), lifestyle (e.g., physical activity, alcohol use, smoking, drugs, diet), environmental (e.g., time of day, temperature, noise), and methodological (e.g., body position, recording duration, and respiration) domains. Knowing these factors can help researchers and physicians gain a better understanding of HRV and improve the interpretation of their findings. Consequently, this can lead to the development of standardized methods for consistently assessing and interpreting HRV measures in clinical practice.

Comparison of Heart Rate Variability in Thai Older Adults with Hypertension, Pre-Hypertension, and Normotension

Objectives

This study aims to compare HRV variables across three cohorts: normotensive (NT), prehypertensive (pre-HT), and hypertensive (HT) and to assess the relationship between the blood pressure (BP) and HRV parameters.

Methods

Employing a cross-sectional design, 64 older participants were categorized based on the Joint National Committee's criteria into NT (n = 10), pre-HT (n = 33), and HT (n = 21) groups. Anthropometric data, lipid profiles, and HRV indices were evaluated. HRV data were obtained from the Polar V800 chest strap device using HRV Kubios software for data analysis of short-term recordings lasting 10 minutes. This analysis encompasses both time and frequency domain assessments. The time domain includes the standard deviation of NN intervals (SDNN), the root mean square of successive RR interval differences (RMSSD), and the percentage of successive RR intervals differing by over 50 ms (pNN50). The frequency domain includes low frequency (LF), high frequency (HF), and the ratio of LF-to-HF power (LF/HF). Data were statistically analyzed via one-way analysis of variance (ANOVA) and Pearson correlation.

Results

The HT group exhibited significantly lower values in SDNN, pNN50, LF power, and HF power in comparison to the NT group (P < 0.05). Moreover, the HT group had a significantly lower SDNN value compared to the pre-HT group (P < 0.05). Inverse associations were uncovered between systolic and diastolic blood pressure and SDNN, pNN50, and HF power (P < 0.05). Multiple regression further highlighted the significance of systolic and pulse pressure concerning HF power (P < 0.05).

Conclusions

HRV indices are reduced in Thai older adults with HT compared with those with NT. Monitoring HRV in older adults can provide valuable insights into autonomic function and cardiovascular disease risk.

Exercise-induced changes in plasma S-Klotho levels are associated with the obtained enhancements of heart rate variability in sedentary middle-aged adults: the FIT-AGEING study

The shed form of the Klotho protein (S-Klotho) is considered a biomarker of longevity, but it is still unknown whether the levels are related to heart rate (HR) and heart rate variability (HRV); both of them greatly influenced by the ageing process, physical fitness, exercise, and health status. This study aimed (i) to investigate the association between S-Klotho plasma levels with HR and HRV parameters and (ii) to examine the association of exercise-induced changes in S-Klotho and those obtained in HR and HRV parameters after a 12-week exercise intervention in sedentary middle-aged adults. Sixty-six sedentary middle-aged adults participated in this study (50% women; 45-65 years old). Participants were randomized into 4 groups: (a) a control group (no exercise), (b) a physical activity recommendation from the World Health Organization group, (c) a high-intensity interval training group, and (d) a high-intensity interval training group adding whole-body electromyostimulation. S-Klotho plasma levels, HR, and HRV parameters (SDNN, RMSSD, high frequency, stress score, and sympathetic/parasympathetic ratio) were measured. At baseline, S-Klotho plasma levels were not related to HR and HRV parameters. After the intervention, exercise-induced changes in S-Klotho plasma levels were positively associated with changes in SDNN (β=0.261; R2=0.102; p=0.014) and negatively related to changes in stress score and sympathetic/parasympathetic ratio (all β=-0.257; R2 ranges between 0.092 and 0.131; all p<0.020). Our study suggests that higher S-Klotho plasma levels are related to increased vagal influence and reduced sympathetic tone in the autonomic nervous system in sedentary middle-aged adults after different training programs. ClinicalTrials.gov identifier: CT03334357.

Dose-effect of exercise intervention on heart rate variability of acclimatized young male lowlanders at 3,680 m

This study investigated whether exercise could improve the reduced HRV in an environment of high altitude. A total of 97 young, healthy male lowlanders living at 3,680 m for >1 year were recruited. They were randomized into four groups, of which three performed-low-, moderate-, and high-intensity (LI, MI, HI) aerobic exercise for 4 weeks, respectively. The remaining was the control group (CG) receiving no intervention. For HI, compared to other groups, heart rate (p = 0.002) was significantly decreased, while standard deviation of RR intervals (p < 0.001), SD2 of Poincaré plot (p = 0.046) and the number of successive RR interval pairs that differ by > 50 ms divided by total number of RR (p = 0.032), were significantly increased after intervention. For MI, significantly increase of trigonometric interpolation in NN interval (p = 0.016) was observed after exercise. Further, a decrease in systolic blood pressure (SBP) after high-intensity exercise was found significantly associated with an increase in SD2 (r = - 0.428, p = 0.042). These results indicated that there was a dose effect of different intensities of aerobic exercise on the HRV of acclimatized lowlanders. Moderate and high-intensity aerobic exercise would change the status of the autonomic nervous system (ANS) and decrease the blood pressure of acclimatized lowlanders exposed to high altitude.