Chronic physical activity mitigates cerebral hypoperfusion during central hypovolemia in elderly humans

Kevin Formes, Peizhen Zhang, Nancy Tierney, Frederick Schaller, Xiangrong Shi

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18 Citations (Scopus)

Abstract

This study sought to test the hypothesis that orthostasis-induced cerebral hypoperfusion would be less severe in physically active elderly humans (ACT group) than in sedentary elderly humans (SED group). The peak O2 uptake of 10 SED (67.1 ± 1.4 yr) and 9 ACT (68.0 ± 1.1 yr) volunteers was determined by a graded cycling exercise test (22.1 ± 1.2 vs 35.8 ± 1.3 ml•min-1•kg-1, P < 0.01). Baseline mean arterial pressure (MAP; tonometry) and middle cerebral arterial blood flow velocity (VMCA; transcranial Doppler) were similar between the groups (SED vs. ACT group: 91 ± 3 vs. 87 ± 3 mmHg and 54.9 ± 2.3 vs. 57.8 ± 3.2 cm/s, respectively), whereas heart rate was higher and stroke volume (bioimpedance) was smaller in the SED group than in the ACT group. Central hypovolemia during graded lower body negative pressure (LBNP) was larger (P < 0.01) in the ACT group than in the SED group. However, the slope of VMCA/LBNP was smaller (P < 0.05) in the ACT group (0.159 ± 0.016 cm/s/Torr) than in the SED group (0.211 ± 0.008 cm/s/Torr). During LBNP, the SED group had a greater augmentation of cerebral vasomotor tone (P < 0.05) and hypocapnia (P < 0.001) compared with the ACT group. Baseline MAP variability and VMCA variability were significantly smaller in the SED group than in the ACT group, i.e., 0.49 ± 0.07 vs. 1.04 ± 0.16 (mmHg)2 and 1.06 ± 0.19 vs. 4.24 ± 1.59 (cm/s)2, respectively. However, transfer function gain, coherence, and phase between MAP and VMCA signals (Welch spectral estimator) from 0.08-0.18 Hz were not different between SED (1.41 ± 0.18 cm•s-1•mmHg-1, 0.63 ± 0.06 units, and 38.03 ± 6.57° ) and ACT (1.65 ± 0.44 cm•s -1•mmHg-1, 0.56 ± 0.05 units, and 48.55 ± 11.84° ) groups. We conclude that a physically active lifestyle improves the intrinsic mechanism of cerebral autoregulation and helps mitigate cerebral hypoperfusion during central hypovolemia in healthy elderly adults.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume298
Issue number3
DOIs
StatePublished - 1 Mar 2010

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Lower Body Negative Pressure
Hypovolemia
Exercise
Cerebrovascular Circulation
Hypocapnia
Blood Flow Velocity
Manometry
Dizziness
Exercise Test
Stroke Volume
Life Style
Volunteers
Arterial Pressure
Homeostasis
Heart Rate

Keywords

  • Cerebral vasomotor tone
  • Hypocapnia
  • Lower body negative pressure
  • Transfer function gain

Cite this

@article{66ecf68cf0754a5c96cb4eb12cb21203,
title = "Chronic physical activity mitigates cerebral hypoperfusion during central hypovolemia in elderly humans",
abstract = "This study sought to test the hypothesis that orthostasis-induced cerebral hypoperfusion would be less severe in physically active elderly humans (ACT group) than in sedentary elderly humans (SED group). The peak O2 uptake of 10 SED (67.1 ± 1.4 yr) and 9 ACT (68.0 ± 1.1 yr) volunteers was determined by a graded cycling exercise test (22.1 ± 1.2 vs 35.8 ± 1.3 ml•min-1•kg-1, P < 0.01). Baseline mean arterial pressure (MAP; tonometry) and middle cerebral arterial blood flow velocity (VMCA; transcranial Doppler) were similar between the groups (SED vs. ACT group: 91 ± 3 vs. 87 ± 3 mmHg and 54.9 ± 2.3 vs. 57.8 ± 3.2 cm/s, respectively), whereas heart rate was higher and stroke volume (bioimpedance) was smaller in the SED group than in the ACT group. Central hypovolemia during graded lower body negative pressure (LBNP) was larger (P < 0.01) in the ACT group than in the SED group. However, the slope of VMCA/LBNP was smaller (P < 0.05) in the ACT group (0.159 ± 0.016 cm/s/Torr) than in the SED group (0.211 ± 0.008 cm/s/Torr). During LBNP, the SED group had a greater augmentation of cerebral vasomotor tone (P < 0.05) and hypocapnia (P < 0.001) compared with the ACT group. Baseline MAP variability and VMCA variability were significantly smaller in the SED group than in the ACT group, i.e., 0.49 ± 0.07 vs. 1.04 ± 0.16 (mmHg)2 and 1.06 ± 0.19 vs. 4.24 ± 1.59 (cm/s)2, respectively. However, transfer function gain, coherence, and phase between MAP and VMCA signals (Welch spectral estimator) from 0.08-0.18 Hz were not different between SED (1.41 ± 0.18 cm•s-1•mmHg-1, 0.63 ± 0.06 units, and 38.03 ± 6.57° ) and ACT (1.65 ± 0.44 cm•s -1•mmHg-1, 0.56 ± 0.05 units, and 48.55 ± 11.84° ) groups. We conclude that a physically active lifestyle improves the intrinsic mechanism of cerebral autoregulation and helps mitigate cerebral hypoperfusion during central hypovolemia in healthy elderly adults.",
keywords = "Cerebral vasomotor tone, Hypocapnia, Lower body negative pressure, Transfer function gain",
author = "Kevin Formes and Peizhen Zhang and Nancy Tierney and Frederick Schaller and Xiangrong Shi",
year = "2010",
month = "3",
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language = "English",
volume = "298",
journal = "American Journal of Physiology - Heart and Circulatory Physiology",
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Chronic physical activity mitigates cerebral hypoperfusion during central hypovolemia in elderly humans. / Formes, Kevin; Zhang, Peizhen; Tierney, Nancy; Schaller, Frederick; Shi, Xiangrong.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 298, No. 3, 01.03.2010.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Chronic physical activity mitigates cerebral hypoperfusion during central hypovolemia in elderly humans

AU - Formes, Kevin

AU - Zhang, Peizhen

AU - Tierney, Nancy

AU - Schaller, Frederick

AU - Shi, Xiangrong

PY - 2010/3/1

Y1 - 2010/3/1

N2 - This study sought to test the hypothesis that orthostasis-induced cerebral hypoperfusion would be less severe in physically active elderly humans (ACT group) than in sedentary elderly humans (SED group). The peak O2 uptake of 10 SED (67.1 ± 1.4 yr) and 9 ACT (68.0 ± 1.1 yr) volunteers was determined by a graded cycling exercise test (22.1 ± 1.2 vs 35.8 ± 1.3 ml•min-1•kg-1, P < 0.01). Baseline mean arterial pressure (MAP; tonometry) and middle cerebral arterial blood flow velocity (VMCA; transcranial Doppler) were similar between the groups (SED vs. ACT group: 91 ± 3 vs. 87 ± 3 mmHg and 54.9 ± 2.3 vs. 57.8 ± 3.2 cm/s, respectively), whereas heart rate was higher and stroke volume (bioimpedance) was smaller in the SED group than in the ACT group. Central hypovolemia during graded lower body negative pressure (LBNP) was larger (P < 0.01) in the ACT group than in the SED group. However, the slope of VMCA/LBNP was smaller (P < 0.05) in the ACT group (0.159 ± 0.016 cm/s/Torr) than in the SED group (0.211 ± 0.008 cm/s/Torr). During LBNP, the SED group had a greater augmentation of cerebral vasomotor tone (P < 0.05) and hypocapnia (P < 0.001) compared with the ACT group. Baseline MAP variability and VMCA variability were significantly smaller in the SED group than in the ACT group, i.e., 0.49 ± 0.07 vs. 1.04 ± 0.16 (mmHg)2 and 1.06 ± 0.19 vs. 4.24 ± 1.59 (cm/s)2, respectively. However, transfer function gain, coherence, and phase between MAP and VMCA signals (Welch spectral estimator) from 0.08-0.18 Hz were not different between SED (1.41 ± 0.18 cm•s-1•mmHg-1, 0.63 ± 0.06 units, and 38.03 ± 6.57° ) and ACT (1.65 ± 0.44 cm•s -1•mmHg-1, 0.56 ± 0.05 units, and 48.55 ± 11.84° ) groups. We conclude that a physically active lifestyle improves the intrinsic mechanism of cerebral autoregulation and helps mitigate cerebral hypoperfusion during central hypovolemia in healthy elderly adults.

AB - This study sought to test the hypothesis that orthostasis-induced cerebral hypoperfusion would be less severe in physically active elderly humans (ACT group) than in sedentary elderly humans (SED group). The peak O2 uptake of 10 SED (67.1 ± 1.4 yr) and 9 ACT (68.0 ± 1.1 yr) volunteers was determined by a graded cycling exercise test (22.1 ± 1.2 vs 35.8 ± 1.3 ml•min-1•kg-1, P < 0.01). Baseline mean arterial pressure (MAP; tonometry) and middle cerebral arterial blood flow velocity (VMCA; transcranial Doppler) were similar between the groups (SED vs. ACT group: 91 ± 3 vs. 87 ± 3 mmHg and 54.9 ± 2.3 vs. 57.8 ± 3.2 cm/s, respectively), whereas heart rate was higher and stroke volume (bioimpedance) was smaller in the SED group than in the ACT group. Central hypovolemia during graded lower body negative pressure (LBNP) was larger (P < 0.01) in the ACT group than in the SED group. However, the slope of VMCA/LBNP was smaller (P < 0.05) in the ACT group (0.159 ± 0.016 cm/s/Torr) than in the SED group (0.211 ± 0.008 cm/s/Torr). During LBNP, the SED group had a greater augmentation of cerebral vasomotor tone (P < 0.05) and hypocapnia (P < 0.001) compared with the ACT group. Baseline MAP variability and VMCA variability were significantly smaller in the SED group than in the ACT group, i.e., 0.49 ± 0.07 vs. 1.04 ± 0.16 (mmHg)2 and 1.06 ± 0.19 vs. 4.24 ± 1.59 (cm/s)2, respectively. However, transfer function gain, coherence, and phase between MAP and VMCA signals (Welch spectral estimator) from 0.08-0.18 Hz were not different between SED (1.41 ± 0.18 cm•s-1•mmHg-1, 0.63 ± 0.06 units, and 38.03 ± 6.57° ) and ACT (1.65 ± 0.44 cm•s -1•mmHg-1, 0.56 ± 0.05 units, and 48.55 ± 11.84° ) groups. We conclude that a physically active lifestyle improves the intrinsic mechanism of cerebral autoregulation and helps mitigate cerebral hypoperfusion during central hypovolemia in healthy elderly adults.

KW - Cerebral vasomotor tone

KW - Hypocapnia

KW - Lower body negative pressure

KW - Transfer function gain

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U2 - 10.1152/ajpheart.00662.2009

DO - 10.1152/ajpheart.00662.2009

M3 - Article

VL - 298

JO - American Journal of Physiology - Heart and Circulatory Physiology

JF - American Journal of Physiology - Heart and Circulatory Physiology

SN - 0363-6135

IS - 3

ER -