The Effect of Sex on Heart Rate Variability at High Altitude

Boos, Christopher J.; Vincent, Emma; Mellor, Adrian; O’Hara, John; Newman, Caroline; Cruttenden, Richard; Scott, Phylip; Cooke, M. P.; Matu, Jamie; Woods, David R.

doi:10.1249/mss.0000000000001384

Cited by 31 publications

(45 citation statements)

References 26 publications

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“…Boos et al (2016) recently investigated various cardiopulmonary responses to acute normobaric hypoxia (simulated 4800 m) and did not detect any sex differences. In contrast, the same authors report differences between sexes with regard to HR variability indices when acutely exposed to various altitudes, which, however, were not predictive for AMS development (Boos et al, 2017). In line with our findings, similar resting (and exercising) cardiorespiratory responses to acute hypoxia have been reported in young and older subjects of a large cohort (Lhuissier et al, 2012;Richalet et al, 2012;Richalet and Lhuissier 2015).…”

Section: Discussionsupporting

confidence: 88%

“…Reduced BG values at high altitude are hard to interpret since they do not represent fasting values but may at least partly be explained by enhanced carbohydrate oxidation during the short-term high-altitude exposure (Goto et al, 2015). The lack of differences between sexes, at least regarding cardiovascular and ventilatory responses to acute exposure to high altitude or hypoxia, is consistent with earlier and recent studies as well (Muza et al, 2001;Boos et al, 2016Boos et al, , 2017. For instance, Muza et al (2001) demonstrated a nearly identical time course of ventilatory acclimatization in female lowlanders who rapidly ascended to 4300 m compared with reports of male lowlanders.…”

Section: Discussionsupporting

confidence: 78%

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Physiological Responses in Humans Acutely Exposed to High Altitude (3480 m): Minute Ventilation and Oxygenation Are Predictive for the Development of Acute Mountain Sickness

Burtscher

Philadelphy²,

Gatterer

et al. 2019

High Altitude Medicine & Biology

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Physiological responses in humans acutely exposed to high altitude (3480 m): Minute ventilation and oxygenation are predictive for the development of acute mountain sickness. High Alt Med Biol. 20:192-197, 2019.-The importance of arterial oxygen saturation for the prediction of acute mountain sickness (AMS) is still a matter of debate. Reasons for discrepancies may result from varying laboratory or field conditions and their interactions. Thus, we analyzed data from our prior high-altitude studies, including participants of a broad range of age of both sexes (20 males and 20 females, aged between 20 and 67 years) under strictly standardized conditions of pre-exposure and acute exposure to real high altitude (3480 m). A set of resting cardiovascular, respiratory, hematological, and metabolic variables were recorded at high altitude (Testa Grigia, Plateau Rosa, 3480 m; Swiss-Italian boarder) after performing pretests at low altitude (Innsbruck, 600 m, Austria). Our analyses indicate that (1) smaller changes in resting minute ventilation (VE) and a larger decrease of peripheral oxygen saturation (SpO 2) during the first 3 hours of acute exposure to high altitude were independent predictors for subsequent development of AMS (90% correct prediction), (2) there are no differences of responses between sexes, and (3) there is no association of responses with age. Considering the independent effects of both responses (VE and SpO 2) may be of clinical/practical relevance. Moreover, the presented data derived from a broad age range of both sexes might be of interest for comparative purposes.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionsupporting

confidence: 78%

Physiological Responses in Humans Acutely Exposed to High Altitude (3480 m): Minute Ventilation and Oxygenation Are Predictive for the Development of Acute Mountain Sickness

Burtscher

Philadelphy²,

Gatterer

et al. 2019

High Altitude Medicine & Biology

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“…The influence of HA on the changes in cardiac inter-beat intervals (IBI), known as heart rate variability (HRV), has been an area of significant recent research interest (Huang et al, 2010; Karinen et al, 2012; Boos et al, 2016a, 2017b; Mellor et al, 2017). This attention relates, in part, to the fact many of the factors that are known to affect HRV (e.g., fatigue, stress, insomnia, hypoxia, and cold) are predominant at HA (West, 2006; Kemp et al, 2012; Kiviniemi et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…There is evidence to suggest that HA exposure is associated with significant changes in HRV compared with sea-level/low altitude (Huang et al, 2010; Karinen et al, 2012; Boos et al, 2016a, 2017b; Mellor et al, 2017). However, the majority of the published data relate to short-term HRV recordings (1–5 min) obtained conducted in hypoxic chambers during ‘simulated’ rather than genuine terrestrial HA (Vigo et al, 2010; Prabhakaran and Tripathi, 2011; Mairer et al, 2013; Zhang et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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High Altitude Affects Nocturnal Non-linear Heart Rate Variability: PATCH-HA Study

Boos

Bye²,

Sevier

et al. 2018

Front. Physiol.

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Background: High altitude (HA) exposure can lead to changes in resting heart rate variability (HRV), which may be linked to acute mountain sickness (AMS) development. Compared with traditional HRV measures, non-linear HRV appears to offer incremental and prognostic data, yet its utility and relationship to AMS have been barely examined at HA. This study sought to examine this relationship at terrestrial HA.Methods: Sixteen healthy British military servicemen were studied at baseline (800 m, first night) and over eight consecutive nights, at a sleeping altitude of up to 3600 m. A disposable cardiac patch monitor was used, to record the nocturnal cardiac inter-beat interval data, over 1 h (0200–0300 h), for offline HRV assessment. Non-linear HRV measures included Sample entropy (SampEn), the short (α1, 4–12 beats) and long-term (α2, 13–64 beats) detrend fluctuation analysis slope and the correlation dimension (D2). The maximal rating of perceived exertion (RPE), during daily exercise, was assessed using the Borg 6–20 RPE scale.Results: All subjects completed the HA exposure. The average age of included subjects was 31.4 ± 8.1 years. HA led to a significant fall in SpO2 and increase in heart rate, LLS and RPE. There were no significant changes in the ECG-derived respiratory rate or in any of the time domain measures of HRV during sleep. The only notable changes in frequency domain measures of HRV were an increase in LF and fall in HFnu power at the highest altitude. Conversely, SampEn, SD1/SD2 and D2 all fell, whereas α1 and α2 increased (p < 0.05). RPE inversely correlated with SD1/SD2 (r = -0.31; p = 0.002), SampEn (r = -0.22; p = 0.03), HFnu (r = -0.27; p = 0.007) and positively correlated with LF (r = 0.24; p = 0.02), LF/HF (r = 0.24; p = 0.02), α1 (r = 0.32; p = 0.002) and α2 (r = 0.21; p = 0.04). AMS occurred in 7/16 subjects (43.8%) and was very mild in 85.7% of cases. HRV failed to predict AMS.Conclusion: Non-linear HRV is more sensitive to the effects of HA than time and frequency domain indices. HA leads to a compensatory decrease in nocturnal HRV and complexity, which is influenced by the RPE measured at the end of the previous day. HRV failed to predict AMS development.

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Duration at high altitude influences the onset of arrhythmogenesis during apnea

et al. 2021

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Purpose Autonomic control of the heart is balanced by sympathetic and parasympathetic inputs. Excitation of both sympathetic and parasympathetic systems occurs concurrently during certain perturbations such as hypoxia, which stimulate carotid chemoreflex to drive ventilation. It is well established that the chemoreflex becomes sensitized throughout hypoxic exposure; however, whether progressive sensitization alters cardiac autonomic activity remains unknown. We sought to determine the duration of hypoxic exposure at high altitude necessary to unmask cardiac arrhythmias during instances of voluntary apnea. Methods Measurements of steady-state chemoreflex drive (SS-CD), continuous electrocardiogram (ECG) and SpO 2 (pulse oximetry) were collected in 22 participants on 1 day at low altitude (1045 m) and over eight consecutive days at high-altitude (3800 m). SS-CD was quantified as ventilation (L/min) over stimulus index (P ET CO 2 /SpO 2 ). Results Bradycardia during apnea was greater at high altitude compared to low altitude for all days (p < 0.001). Cardiac arrhythmias occurred during apnea each day but became most prevalent (> 50%) following Day 5 at high altitude. Changes in saturation during apnea and apnea duration did not affect the magnitude of bradycardia during apnea (ANCOVA; saturation, p = 0.15 and apnea duration, p = 0.988). Interestingly, the magnitude of bradycardia was correlated with the incidence of arrhythmia per day (r = 0.8; p = 0.004). Conclusion Our findings suggest that persistent hypoxia gradually increases vagal tone with time, indicated by augmented bradycardia during apnea and progressively increased the incidence of arrhythmia at high altitude.

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The Effect of Sex on Heart Rate Variability at High Altitude

Abstract: Increasing HA leads to a reduction in HRV. Significant differences between men and women emerge at HA. HRV was not predictive of AMS.

Cited by 31 publications

References 26 publications

Physiological Responses in Humans Acutely Exposed to High Altitude (3480 m): Minute Ventilation and Oxygenation Are Predictive for the Development of Acute Mountain Sickness

Physiological Responses in Humans Acutely Exposed to High Altitude (3480 m): Minute Ventilation and Oxygenation Are Predictive for the Development of Acute Mountain Sickness

High Altitude Affects Nocturnal Non-linear Heart Rate Variability: PATCH-HA Study

Duration at high altitude influences the onset of arrhythmogenesis during apnea

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