Autonomic Nervous Function During Whole-Body Cold Exposure Before and After Cold Acclimation

Mäkinen, Tero; Mäntysaari, Matti; Pääkkönen, Tiina; Jokelainen, Jari; Palinkas, Lawrence A.; Hassi, Juhani; Leppäluoto, Juhani; Tahvanainen, Kari U. O.; Rintamäki, Hannu

doi:10.3357/asem.2235.2008

Cited by 94 publications

(75 citation statements)

References 26 publications

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“…These authors reported that the increases in BP and heart rate during isometric HG were not different in warm (25°C) and cold (10°C) ambient environmental conditions (32). The results of the present investigation are similar, as the increases in BP during HG were not different during combined cold stress in young adults.…”

Section: Discussionsupporting

confidence: 80%

“…To our knowledge, only one previous study has examined cardiovascular function during combined isometric exercise and whole body cold exposure in young adults (32). These authors reported that the increases in BP and heart rate during isometric HG were not different in warm (25°C) and cold (10°C) ambient environmental conditions (32).…”

Section: Discussionmentioning

confidence: 99%

“…Studies of both young and older subjects exercising in cold environments are surprisingly limited. In young adults, the increases in BP and heart rate during isometric HG were not different in warm (25°C) and cold (10°C) environmental conditions (32). However, this study (32) was not designed to examine the mechanistic role of the sympathetic nervous system in mediating these responses nor to our knowledge have any studies examined the MSNA and BP responses to combined cold stress and exercise in healthy older adults.…”

mentioning

confidence: 97%

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Muscle sympathetic nerve activity during cold stress and isometric exercise in healthy older adults

Greaney

Stanhewicz

Kenney

et al. 2014

Journal of Applied Physiology

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Greaney JL, Stanhewicz AE, Kenney WL, Alexander LM. Muscle sympathetic nerve activity during cold stress and isometric exercise in healthy older adults. J Appl Physiol 117: 648 -657, 2014. First published August 7, 2014 doi:10.1152/japplphysiol.00516.2014.-Cardiovascular mortality increases in cold weather in older adults, and physical activity may impart even greater cardiovascular risk than cold exposure alone. Human aging is associated with exaggerated pressor responses to whole body cooling; however, the sympathetic response to cold stress alone and in combination with isometric exercise is unknown. We hypothesized that cold stress would 1) increase muscle sympathetic nerve activity (MSNA) and 2) augment the MSNA response to isometric handgrip in older adults. Whole body cooling (water-perfused suit) was conducted in 11 young (23 Ϯ 1 yr) and 12 healthy older adults (60 Ϯ 2 yr). Blood pressure (BP; Finometer) and MSNA (microneurography) were measured throughout cooling and during isometric handgrip at 30% maximal voluntary contraction performed at a mean skin temperature (T sk) of 34 and 30.5°C. MSNA was greater in older adults at T sk ϭ 34.0°C and throughout cooling (P Ͻ 0.05). MSNA increased during cooling in older, but not young, adults (young: ⌬0 Ϯ 1 vs. older: ⌬8 Ϯ 1 bursts/min; P Ͻ 0.05). The cooling-induced increase in BP was greater in older adults (P Ͻ 0.05). During handgrip, the increases in MSNA and BP were not different between conditions in either young (⌬14 Ϯ 2 T sk 34°C vs. ⌬12 Ϯ 3 Tsk 30.5°C bursts/min; ⌬20 Ϯ 3 Tsk 34°C vs. ⌬19 Ϯ 3 Tsk 30.5°C mmHg; both P Ͼ 0.05) or older adults (⌬12 Ϯ 1 Tsk 34°C vs. ⌬8 Ϯ 1 Tsk 30.5°C bursts/min; ⌬18 Ϯ 3 Tsk 34°C vs. ⌬17 Ϯ 2 Tsk 30.5°C mmHg; both P Ͼ 0.05). In summary, MSNA increased during cold stress in older, but not young, adults. Furthermore, concomitant cold stress did not alter the sympathetic responses to isometric exercise in either age group, suggesting preserved sympathetic responsiveness during exercise in the cold in healthy aging. blood pressure; aging; handgrip; whole body cooling AGING IS A PRIMARY RISK FACTOR for cardiovascular disease, the leading cause of death in the United States (18). Furthermore, cardiovascular-related morbidity and mortality increase at low ambient temperatures, especially in older adults (5,38,44,50,63). The acute systemic physiological responses to cold exposure include peripheral and visceral vasoconstriction, elevated plasma norepinephrine, and increased blood pressure (BP) (9,52,62). Therefore, alterations in the acute responses to cold may contribute to the clinical relation between cold temperatures and increased cardiovascular-related mortality in primary aging. Perturbations that further challenge systemic physiological function during cold exposure, such as static or dynamic exercise, may result in increased sympathetic activation and excessive increases in BP, imparting even greater risk for an acute cardiovascular event in older adults. As such, understanding age-related changes in the acute sympathetic and...

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 97%

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Muscle sympathetic nerve activity during cold stress and isometric exercise in healthy older adults

Greaney

Stanhewicz

Kenney

et al. 2014

Journal of Applied Physiology

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“…Furthermore, although the effect on PRV of cooling varies with the duration of the temperature change, it is thought that cold exposure modulates short-term variability (i.e., HF, RMSSD, and SD1) more than long-term variability (LF, SDNN, and SD2). 8 This indicates that cold exposure modulates SNS-PSNS balance by causing a shift toward increased PSNS activity. Previous studies comparing PRV derived from PPG and ECG under optimal rest conditions did not report significant differences in PRV assessment.…”

Section: Sympathetic and Parasympathetic Autonomous Nervous System Comentioning

confidence: 99%

“…[5][6][7] Under resting conditions, recordings derived from PPG and ECG demonstrate a high degree of correlation (∼r > 0.93). 7,8 However, PRV PPG also has disadvantages. While sufficient accuracy can be obtained when subjects are under optimal resting conditions, PRV PPG has been reported to be vulnerable to motion artifacts, 6 physical exercise, 5 or mental stressors, 7 making it considerably less accurate compared to ECG.…”

Section: Introductionmentioning

confidence: 99%

Short-term pulse rate variability is better characterized by functional near-infrared spectroscopy than by photoplethysmography

2016

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Pulse rate variability (PRV) can be extracted from functional near-infrared spectroscopy (fNIRS) (PRV(NIRS)) and photoplethysmography (PPG) (PRV(PPG)) signals. The present study compared the accuracy of simultaneously acquired PRV(NIRS) and PRV(PPG), and evaluated their different characterizations of the sympathetic (SNS) and parasympathetic (PSNS) autonomous nervous system activity. Ten healthy subjects were recorded during resting-state (RS) and respiratory challenges in two temperature conditions, i.e., room temperature (23°C) and cold temperature (4°C). PRV(NIRS) was recorded based on fNIRS measurement on the head, whereas PRV(PPG) was determined based on PPG measured at the finger. Accuracy between PRV(NIRS) and PRV(PPG), as assessed by cross-covariance and cross-sample entropy, demonstrated a high degree of correlation (r > 0.9), which was significantly reduced by respiration and cold temperature. Characterization of SNS and PSNS using frequency-domain, time-domain, and nonlinear methods showed that PRV(NIRS) provided significantly better information on increasing PSNS activity in response to respiration and cold temperature than PRV(PPG). The findings show that PRV(NIRS) may outperform PRV(PPG) under conditions in which respiration and temperature changes are present, and may, therefore, be advantageous in research and clinical settings, especially if characterization of the autonomous nervous system is desired. Abstract. Pulse rate variability (PRV) can be extracted from functional near-infrared spectroscopy (fNIRS) (PRV NIRS ) and photoplethysmography (PPG) (PRV PPG ) signals. The present study compared the accuracy of simultaneously acquired PRV NIRS and PRV PPG , and evaluated their different characterizations of the sympathetic (SNS) and parasympathetic (PSNS) autonomous nervous system activity. Ten healthy subjects were recorded during resting-state (RS) and respiratory challenges in two temperature conditions, i.e., room temperature (23°C) and cold temperature (4°C). PRV NIRS was recorded based on fNIRS measurement on the head, whereas PRV PPG was determined based on PPG measured at the finger. Accuracy between PRV NIRS and PRV PPG , as assessed by cross-covariance and cross-sample entropy, demonstrated a high degree of correlation (r > 0.9), which was significantly reduced by respiration and cold temperature. Characterization of SNS and PSNS using frequency-domain, time-domain, and nonlinear methods showed that PRV NIRS provided significantly better information on increasing PSNS activity in response to respiration and cold temperature than PRV PPG . The findings show that PRV NIRS may outperform PRV PPG under conditions in which respiration and temperature changes are present, and may, therefore, be advantageous in research and clinical settings, especially if characterization of the autonomous nervous system is desired.

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Temperature‐Dependent Relationship of Autophagy and Apoptotic Signaling During Cold‐Water Immersion in Young and Older Males

King,

McCormick,

Kenny

2023

Advanced Biology

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Autophagy is a crucial cytoprotective mechanism preventing the accumulation of cellular damage, especially during external stimuli such as cold exposure. Older adults poorly tolerate cold exposure and age‐related impairments in autophagy may contribute to the associated reductions in cold tolerance. The purpose of this investigation is to evaluate the effect of different intensities of in vivo cold‐water immersion and in vitro cold exposure on autophagic and apoptotic signaling in young and older males. Peripheral blood mononuclear cells (PBMCs) are isolated at baseline, end‐cold exposure, and after 3 h of thermoneutral recovery. Additionally, PBMCs are treated with rapamycin and bafilomycin prior to in vitro cold exposure equivalent to in vivo core temperatures (35–37 °C). Proteins associated with autophagy, apoptosis, the heat shock response, and inflammation are analyzed via Western blotting. Moderate cold stress (0.5 °C decrease in core temperature) increased autophagic and heat shock protein activity while high cold stress (1.0 °C decrease in core temperature) augmented apoptosis in young males. In older males, minimal autophagic activation during both cold‐water exposures are associated with increased apoptotic and inflammatory proteins. Although in vitro cold exposure confirmed age‐related dysfunction in autophagy, rapamycin‐induced stimulation of autophagic proteins underlie the potential to reverse age‐related vulnerability to cold exposure.

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Autonomic Nervous Function During Whole-Body Cold Exposure Before and After Cold Acclimation

Cited by 94 publications

References 26 publications

Muscle sympathetic nerve activity during cold stress and isometric exercise in healthy older adults

Muscle sympathetic nerve activity during cold stress and isometric exercise in healthy older adults

Short-term pulse rate variability is better characterized by functional near-infrared spectroscopy than by photoplethysmography

Temperature‐Dependent Relationship of Autophagy and Apoptotic Signaling During Cold‐Water Immersion in Young and Older Males

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