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

Jody L Greaney; Anna E Stanhewicz; W Larry Kenney; Lacy M Alexander

doi:10.1152/japplphysiol.00516.2014

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

Journal article

Open access

Peer reviewed

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

Jody L Greaney, Anna E Stanhewicz, W Larry Kenney and Lacy M Alexander

Journal of applied physiology (1985), Vol.117(6), pp.648-657

09/15/2014

DOI: 10.1152/japplphysiol.00516.2014

PMCID: PMC4157163

PMID: 25103970

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Abstract

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 ± 1 yr) and 12 healthy older adults (60 ± 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 (Tsk) of 34 and 30.5°C. MSNA was greater in older adults at Tsk = 34.0°C and throughout cooling (P < 0.05). MSNA increased during cooling in older, but not young, adults (young: Δ0 ± 1 vs. older: Δ8 ± 1 bursts/min; P < 0.05). The cooling-induced increase in BP was greater in older adults (P < 0.05). During handgrip, the increases in MSNA and BP were not different between conditions in either young (Δ14 ± 2 Tsk 34°C vs. Δ12 ± 3 Tsk 30.5°C bursts/min; Δ20 ± 3 Tsk 34°C vs. Δ19 ± 3 Tsk 30.5°C mmHg; both P > 0.05) or older adults (Δ12 ± 1 Tsk 34°C vs. Δ8 ± 1 Tsk 30.5°C bursts/min; Δ18 ± 3 Tsk 34°C vs. Δ17 ± 2 Tsk 30.5°C mmHg; both P > 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.

Aged

Aging - physiology

Baroreflex - physiology

Blood Pressure - physiology

Cold Temperature - adverse effects

Exercise - physiology

Female

Hand Strength - physiology

Humans

Male

Middle Aged

Muscle, Skeletal - innervation

Muscle, Skeletal - physiology

Stress, Physiological - physiology

Sympathetic Nervous System - physiology

Young Adult

Details

Title: Subtitle: Muscle sympathetic nerve activity during cold stress and isometric exercise in healthy older adults
Creators: Jody L Greaney - Pennsylvania State University
Anna E Stanhewicz - Pennsylvania State University
W Larry Kenney - Pennsylvania State University
Lacy M Alexander - Pennsylvania State University
Resource Type: Journal article
Publication Details: Journal of applied physiology (1985), Vol.117(6), pp.648-657
DOI: 10.1152/japplphysiol.00516.2014
PMID: 25103970
PMCID: PMC4157163
NLM abbreviation: J Appl Physiol (1985)
ISSN: 8750-7587
eISSN: 1522-1601
Grant note: HL-120471-01 / NHLBI NIH HHS F32 HL120471 / NHLBI NIH HHS AG-007004-23 / NIA NIH HHS HL-093-238-04 / NHLBI NIH HHS R01 HL093238 / NHLBI NIH HHS
Language: English
Date published: 09/15/2014
Academic Unit: Fraternal Order of Eagles Diabetes Research Center; Health, Sport, and Human Physiology ; Internal Medicine
Record Identifier: 9984259640402771

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