1
|
Cai M, Wang H, Kline G, Ding Y, Ross SE, Davis S, Mallet RT, Shi X. Habitual physical activity improves vagal cardiac modulation and carotid baroreflex function in elderly women. Exp Biol Med (Maywood) 2023; 248:991-1000. [PMID: 37092743 PMCID: PMC10525404 DOI: 10.1177/15353702231160334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 02/10/2023] [Indexed: 04/25/2023] Open
Abstract
The impact of habitual physical activity on vagal-cardiac function and baroreflex sensitivity in elderly women is poorly characterized. This study compared vagal-cardiac modulation and carotid baroreflex (CBR) function in eight physically active (67.6 ± 1.9 years; peak O2 uptake 29.1 ± 2.5 mL/min/kg) versus eight sedentary (67.3 ± 1.8 years; peak O2 uptake 18.6 ± 0.9 mL/min/kg) elderly women. Heart rate (HR) variabilities and maximal changes of HR and mean arterial pressure (MAP) elicited by 5-s pressure pulses between +40 and -80 mmHg applied to the carotid sinus were measured at rest and during carotid baroreceptor unloading effected by -15 mmHg lower-body negative pressure (LBNP). HR variability was greater in active than sedentary women in both low (0.998 ± 0.286 versus 0.255 ± 0.063 bpm2; P = 0.036) and high (0.895 ± 0.301 versus 0.156 ± 0.045 bpm2; P = 0.044) frequency domains. CBR-HR gains (bpm/mmHg) were greater (fitness factor P < 0.001) in active versus sedentary women at rest (-0.146 ± 0.014 versus -0.088 ± 0.011) and during LBNP (-0.105 ± 0.014 versus -0.065 ± 0.008). CBR-MAP gains (mmHg/mmHg) tended to be greater (fitness factor P = 0.077) in active versus sedentary women at rest (-0.132 ± 0.013 versus -0.110 ± 0.011) and during LBNP (-0.129 ± 0.015 versus -0.113 ± 0.013). However, LBNP did not potentiate CBR-MAP gains in either sedentary or active women (LBNP factor P = 0.94), and it depressed CBR-HR gains in both groups (LBNP factor P = 0.003). CBR-HR gains in the sedentary women did not differ (sex factor P = 0.65) from gains reported in age-matched sedentary men, although CBR-MAP gains tended to be greater (sex factor P = 0.109) in the men. Thus, tonic vagal modulation indicated by HR variability and dynamic vagal responses assessed by CBR-HR gain were augmented in physically active women. Enhanced vagal-cardiac function may protect against senescence-associated cardiac electrical and hemodynamic instability in elderly women.
Collapse
Affiliation(s)
- Ming Cai
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
- Shanghai University of Medicine & Health Sciences, Shanghai, 201318, China
| | - Hong Wang
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
- Shanghai University of Medicine & Health Sciences, Shanghai, 201318, China
| | - Geoffrey Kline
- Department of Internal Medicine, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Yanfeng Ding
- Department of Internal Medicine, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Sarah E Ross
- Department of Internal Medicine, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Sandra Davis
- Department of Internal Medicine, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Robert T Mallet
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107-2699, USA
| | - Xiangrong Shi
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| |
Collapse
|
2
|
Liu X, Xu D, Hall JR, Ross S, Chen S, Liu H, Mallet RT, Shi X. Enhanced cerebral perfusion during brief exposures to cyclic intermittent hypoxemia. J Appl Physiol (1985) 2017; 123:1689-1697. [DOI: 10.1152/japplphysiol.00647.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cerebral vasodilation and increased cerebral oxygen extraction help maintain cerebral oxygen uptake in the face of hypoxemia. This study examined cerebrovascular responses to intermittent hypoxemia in eight healthy men breathing 10% O2 for 5 cycles, each 6 min, interspersed with 4 min of room air breathing. Hypoxia exposures raised heart rate ( P < 0.01) without altering arterial pressure, and increased ventilation ( P < 0.01) by expanding tidal volume. Arterial oxygen saturation ([Formula: see text]) and cerebral tissue oxygenation ([Formula: see text]) fell ( P < 0.01) less appreciably in the first bout (from 97.0 ± 0.3% and 72.8 ± 1.6% to 75.5 ± 0.9% and 54.5 ± 0.9%, respectively) than the fifth bout (from 94.9 ± 0.4% and 70.8 ± 1.0% to 66.7 ± 2.3% and 49.2 ± 1.5%, respectively). Flow velocity in the middle cerebral artery ( VMCA) and cerebrovascular conductance increased in a sigmoid fashion with decreases in [Formula: see text] and [Formula: see text]. These stimulus-response curves shifted leftward and upward from the first to the fifth hypoxia bouts; thus, the centering points fell from 79.2 ± 1.4 to 74.6 ± 1.1% ( P = 0.01) and from 59.8 ± 1.0 to 56.6 ± 0.3% ( P = 0.002), and the minimum VMCA increased from 54.0 ± 0.5 to 57.2 ± 0.5 cm/s ( P = 0.0001) and from 53.9 ± 0.5 to 57.1 ± 0.3 cm/s ( P = 0.0001) for the [Formula: see text]- VMCA and [Formula: see text]- VMCA curves, respectively. Cerebral oxygen extraction increased from prehypoxia 0.22 ± 0.01 to 0.25 ± 0.02 in minute 6 of the first hypoxia bout, and remained elevated between 0.25 ± 0.01 and 0.27 ± 0.01 throughout the fifth hypoxia bout. These results demonstrate that cerebral vasodilation combined with enhanced cerebral oxygen extraction fully compensated for decreased oxygen content during acute, cyclic hypoxemia. NEW & NOTEWORTHY Five bouts of 6-min intermittent hypoxia (IH) exposures to 10% O2 progressively reduce arterial oxygen saturation ([Formula: see text]) to 67% without causing discomfort or distress. Cerebrovascular responses to hypoxemia are dynamically reset over the course of a single IH session, such that threshold and saturation for cerebral vasodilations occurred at lower [Formula: see text] and cerebral tissue oxygenation ([Formula: see text]) during the fifth vs. first hypoxia bouts. Cerebral oxygen extraction is augmented during acute hypoxemia, which compensates for decreased arterial O2 content.
Collapse
Affiliation(s)
- Xiaoli Liu
- Institute of Cardiovascular & Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas
- Department of Physical Therapy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Diqun Xu
- Institute of Cardiovascular & Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas
| | - James R. Hall
- Hubei University for Nationalities, Enshi, Hubei, China
| | - Sarah Ross
- Hubei University for Nationalities, Enshi, Hubei, China
| | - Shande Chen
- Hubei University for Nationalities, Enshi, Hubei, China
- Institute of Healthy Aging, University of North Texas Health Science Center, Fort Worth, Texas
| | - Howe Liu
- Department of Biostatistics, University of North Texas Health Science Center, Fort Worth, Texas
| | - Robert T. Mallet
- Institute of Cardiovascular & Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas
| | - Xiangrong Shi
- Institute of Cardiovascular & Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas
- Institute of Healthy Aging, University of North Texas Health Science Center, Fort Worth, Texas
| |
Collapse
|
3
|
Xu D, Wang H, Chen S, Ross S, Liu H, Olivencia-Yurvati A, Raven PB, Shi X. Aerobic Exercise Training Improves Orthostatic Tolerance in Aging Humans. Med Sci Sports Exerc 2017; 49:728-735. [PMID: 27824693 DOI: 10.1249/mss.0000000000001153] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE This study was designed to test the hypothesis that aerobic exercise training of the elderly will increase aerobic fitness without compromising orthostatic tolerance (OT). METHODS Eight healthy sedentary volunteers (67.0 ± 1.7 yr old, four women) participated in 1 yr of endurance exercise training (stationary bicycle and/or treadmill) program at the individuals' 65%-75% of HRpeak. Peak O2 uptake (V˙O2peak) and HRpeak were determined by a maximal exercise stress test using a bicycle ergometer. Carotid baroreceptor reflex (CBR) control of HR and mean arterial pressure (MAP) were assessed by a neck pressure-neck suction protocol. Each subject's maximal gain (Gmax), or sensitivity, of the CBR function curves were derived from fitting their reflex HR and MAP responses to the corresponding neck pressure-neck suction stimuli using a logistic function curve. The subjects' OT was assessed using lower-body negative pressure (LBNP) graded to -50 mm Hg; the sum of the product of LBNP intensity and time (mm Hg·min) was calculated as the cumulative stress index. RESULTS Training increased V˙O2peak (before vs after: 22.8 ± 0.92 vs 27.9 ± 1.33 mL·min·kg, P < 0.01) and HRpeak (154 ± 4 vs 159 ± 3 bpm, P < 0.02) and decreased resting HR (65 ± 5 vs 59 ± 5 bpm, P < 0.02) and MAP (99 ± 2 vs 87 ± 2 mm Hg, P < 0.05). CBR stimulus-response curves identified a leftward shift with an increase in CBR-HR Gmax (from -0.13 ± 0.02 to -0.27 ± 0.04 bpm·mm Hg, P = 0.01). Cumulative stress index was increased from 767 ± 68 mm Hg·min pretraining to 946 ± 44 mm Hg·min posttraining (P < 0.05). CONCLUSION Aerobic exercise training improved the aerobic fitness and OT in elderly subjects. An improved OT is likely associated with an enhanced CBR function that has been reset to better maintain cerebral perfusion and cerebral tissue oxygenation during LBNP.
Collapse
Affiliation(s)
- Diqun Xu
- 1Institute of Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, TX; 2Minnan Normal University, Fujian Province, CHINA; 3Department of Physical Therapy, University of North Texas Health Science Center, Fort Worth, TX; 4Shanghai University of Medicine and Health Sciences, Shanghai, CHINA; 5Department of Biostatistics and Epidemiology, University of North Texas Health Science Center, Fort Worth, TX; 6Center for Alzheimer's and Neurodegenerative Disease Research, University of North Texas Health Science Center, Fort Worth, TX; and 7Center for Geriatrics, Institute for Healthy Aging, University of North Texas Health Science Center, Fort Worth, TX
| | | | | | | | | | | | | | | |
Collapse
|
4
|
Lucas RAI, Ainslie PN, Morrison SA, Cotter JD. Compression leggings modestly affect cardiovascular but not cerebrovascular responses to heat and orthostatic stress in young and older adults. AGE (DORDRECHT, NETHERLANDS) 2012; 34:439-49. [PMID: 21526339 PMCID: PMC3312639 DOI: 10.1007/s11357-011-9250-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 04/10/2011] [Indexed: 05/17/2023]
Abstract
We tested the hypothesis that wearing commercially available compression leggings would attenuate postural reductions in mean arterial blood pressure (MAP) and cerebral perfusion during heat stress, particularly in older adults. Six older (70 years ± 4) and six younger (29 years ± 4) males were heated (esophageal temperature raised 0.5°C) in a water-perfused suit whilst wearing compression or control leggings (>1 week apart, randomized order). Blood flow velocity in the middle cerebral artery (MCAv), blood pressure (photoplethysmography), total peripheral resistance (TPR; ModelFlow) and the partial pressure of end-tidal carbon dioxide were measured continuously before and during 3-min standing in each thermal state. When supine, compression leggings did not change any cardiorespiratory variables in either age group or thermal condition (P > 0.05). Upon standing, wearing compression leggings delayed (~15%; P = 0.044) the maximal drop (nadir) in MAP irrespective of age or thermal condition. During the last minute of standing, wearing compression leggings in normothermia increased TPR (+16%) in older participants but dropped TPR (-8%) in younger participants (P = 0.004 compression × age group). When standing and heated, wearing compression leggings lowered TPR in older and younger participants (~43%; P < 0.01) without changing MAP or MCAv (P > 0.05). In older adults, when standing, compression leggings maintained MAP by elevating TPR. In contrast, under combined heat and orthostatic stress, wearing compression leggings dropped TPR in both older and younger adults, though MAP and MCAv were maintained.
Collapse
|
5
|
Coverdale NS, O'Leary DD, Faught BE, Chirico D, Hay J, Cairney J. Baroreflex sensitivity is reduced in adolescents with probable developmental coordination disorder. RESEARCH IN DEVELOPMENTAL DISABILITIES 2012; 33:251-257. [PMID: 22093671 DOI: 10.1016/j.ridd.2011.09.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 09/12/2011] [Indexed: 05/31/2023]
Abstract
Developmental coordination disorder (DCD) is a neurodevelopmental condition characterized by poor motor skills leading to a significant impairment in activities of daily living. Compared to typically developing children, those with DCD are less fit and physically active, and have increased body fat. This is an important consequence as both sedentary lifestyle and obesity are risk factors for cardiovascular disease. One indicator of cardiovascular health is baroreflex sensitivity (BRS), which is a measure of short term blood pressure (BP) regulation and is partly accomplished through changes in heart rate. Diminished BRS is predictive of future cardiovascular morbidity and mortality. The purpose of this study was to compare BRS in typically developing (TD) adolescents with probable DCD (pDCD) or suspect pDCD (spDCD) adolescents (13-14 years of age). Percentile scores on the Movement Assessment Battery for Children, 2nd edition, assessed at two time points were averaged and used to classify participants into the following groups: pDCD ≤ 5th percentile, spDCD > 5th percentile and ≤16th percentile and TD>16th percentile. Following 15 min of supine rest, 5 min of continuous beat-by-beat blood pressure (Finapres) and R-R interval were recorded (standard ECG). Spectral indices were computed using Fast Fourier Transform with transfer function analysis used to compute BRS in the low frequency region (0.04-0.15 Hz). BRS was compared between groups with an ANOVA and post hoc Bonferroni correction. BRS was reduced in the pDCD compared to the TD groups. In multivariate regression analyses predicting BRS, when pDCD and spDCD were entered as the only variables, pDCD was found to be a significant predictor of BRS (b=-6.74, p=0.016). However, when sex, VO(2) peak, and percent body fat (PBF) were entered as covariates, pDCD was no longer a predictor, while PBF approached significance (-0.32, p=0.056). Therefore, in this sample, BRS was reduced in adolescents with pDCD principally due to increased PBF.
Collapse
Affiliation(s)
- Nicole S Coverdale
- Department of Community Health Sciences, Brock University, St Catharines, ON, Canada
| | | | | | | | | | | |
Collapse
|
6
|
|
7
|
Formes K, Zhang P, Tierney N, Schaller F, Shi X. Chronic physical activity mitigates cerebral hypoperfusion during central hypovolemia in elderly humans. Am J Physiol Heart Circ Physiol 2009; 298:H1029-37. [PMID: 20044443 DOI: 10.1152/ajpheart.00662.2009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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 O(2) 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 (V(MCA); 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 V(MCA)/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 V(MCA) 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 V(MCA) 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 degrees ) and ACT (1.65 +/- 0.44 cm.s(-1).mmHg(-1), 0.56 +/- 0.05 units, and 48.55 +/- 11.84 degrees ) 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.
Collapse
Affiliation(s)
- Kevin Formes
- Dept. of Integrative Physiology, Univ. of North Texas Health Science Center, Fort Worth, 76107, USA
| | | | | | | | | |
Collapse
|
8
|
Cold face test in persons with spinal cord injury: age versus inactivity. Clin Auton Res 2009; 19:221-9. [DOI: 10.1007/s10286-009-0009-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Accepted: 03/13/2009] [Indexed: 12/21/2022]
|