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Boyes NG, Mannozzi J, Rapin N, Alvarez A, Al-Hassan MH, Lessanework B, Lahti DS, Olver TD, O'Leary DS, Tomczak CR. Augmented sympathoexcitation slows postexercise heart rate recovery. J Appl Physiol (1985) 2023; 135:1300-1311. [PMID: 37883101 DOI: 10.1152/japplphysiol.00549.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/13/2023] [Accepted: 10/23/2023] [Indexed: 10/27/2023] Open
Abstract
Slow heart rate recovery following exercise may be influenced by persistent sympathoexcitation. This study examined 1) the effect of muscle metaboreflex activation (MMA) on heart rate recovery following dynamic exercise; and 2) whether the effect of MMA on heart rate recovery is reversible by reducing sympathoexcitation [baroreflex activation via phenylephrine (PE)] in canines. Twenty-two young adults completed control and MMA protocols during cycle ergometry at 110% ventilatory threshold with 5 min recovery. Heart rate recovery kinetics [tau (τ), amplitude, end-exercise, and end-recovery heart rate] and root mean square of successive differences (RMSSD) were measured. Five chronically instrumented canines completed control, MMA (50%-60% imposed reduction in hindlimb blood flow), and MMA with end-exercise PE infusion (MMA + PE) protocols during moderate exercise (6.4 km·h-1) and 3 min recovery. Heart rate recovery kinetics and MAP were measured. MAP increased during MMA versus control in canines (P < 0.001). Heart rate recovery τ was slower during MMA versus control in humans (17% slower; P = 0.011) and canines (150% slower; P = 0.002). Heart rate recovery τ was faster during MMA + PE versus MMA (40% faster; P = 0.034) and was similar to control in canines (P = 0.426). Amplitude, end-exercise, and end-recovery heart rate were similar between conditions in humans (all P ≥ 0.122) and in canines (all P ≥ 0.084). MMA decreased RMSSD in early recovery (P = 0.004). MMA-induced sympathoexcitation slows heart rate recovery and this effect is markedly attenuated with PE. Therefore, elevated sympathoexcitation via MMA impairs heart rate recovery and inhibition of this stimulus normalizes, in part, heart rate recovery.NEW & NOTEWORTHY Augmented sympathoexcitation, via muscle metaboreflex activation, functionally slows heart rate recovery in both young healthy adults and chronically instrumented canines. Furthermore, elevated sympathoexcitation corresponded with lower parasympathetic activity, as assessed by heart rate variability, during the first 3 min of recovery. Finally, sympathoinhibition, via phenylephrine infusion, normalizes heart rate recovery during muscle metaboreflex activation.
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Affiliation(s)
- Natasha G Boyes
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Joseph Mannozzi
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan, United States
| | - Nicole Rapin
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Alberto Alvarez
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan, United States
| | - Mohamed-Hussein Al-Hassan
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan, United States
| | - Beruk Lessanework
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan, United States
| | - Dana S Lahti
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - T Dylan Olver
- Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Donal S O'Leary
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan, United States
| | - Corey R Tomczak
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Notarius CF, Badrov MB, Tobushi T, Keir DA, Keys E, Floras JS. Cardiovascular reflex contributions to sympathetic inhibition during low intensity dynamic leg exercise in healthy middle-age. Physiol Rep 2023; 11:e15821. [PMID: 37701968 PMCID: PMC10498156 DOI: 10.14814/phy2.15821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 08/22/2023] [Indexed: 09/14/2023] Open
Abstract
Aging augments resting muscle sympathetic nerve activity (MSNA) and sympatho-inhibition during mild dynamic 1-leg exercise. To elucidate which reflexes elicit exercise-induced inhibition, we recruited 19 (9 men) healthy volunteers (mean age 56 ± 9 SD years), assessed their peak oxygen uptake (VO2peak ), and, on another day, measured heart rate (HR), blood pressure (BP) and MSNA (microneurography) at rest and during 1-leg cycling (2 min each at 0 load and 30%-40% VO2peak ), 3 times: (1) seated +2 min of postexercise circulatory occlusion (PECO) (elicit muscle metaboreflex); (2) supine (stimulate cardiopulmonary baroreflexes);and (3) seated, breathing 32% oxygen (suppress peripheral chemoreceptor reflex). While seated, MSNA decreased similarly during mild and moderate exercise (p < 0.001) with no increase during PECO (p = 0.44). Supine posture lowered resting MSNA (main effect p = 0.01) BP and HR. MSNA fell further (p = 0.04) along with diastolic BP and HR during mild, not moderate, supine cycling. Hyperoxia attenuated resting (main effect p = 0.01), but not exercise MSNA. In healthy middle-age, the cardiopulmonary baroreflex and arterial chemoreflex modulate resting MSNA, but contrary to previous observations in young subjects, without counter-regulatory offset by the sympatho-excitatory metaboreflex, resulting in an augmented sympatho-inhibitory response to mild dynamic leg exercise.
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Affiliation(s)
- Catherine F. Notarius
- University Health Network and Sinai Health Division of CardiologyToronto General Research InstituteTorontoOntarioCanada
- Faculty of Kinesiology and Physical EducationUniversity of TorontoTorontoOntarioCanada
| | - Mark B. Badrov
- University Health Network and Sinai Health Division of CardiologyToronto General Research InstituteTorontoOntarioCanada
| | - Tomoyuki Tobushi
- University Health Network and Sinai Health Division of CardiologyToronto General Research InstituteTorontoOntarioCanada
| | - Daniel A. Keir
- University Health Network and Sinai Health Division of CardiologyToronto General Research InstituteTorontoOntarioCanada
- School of KinesiologyThe University of Western OntarioLondonOntarioCanada
| | - Evan Keys
- University Health Network and Sinai Health Division of CardiologyToronto General Research InstituteTorontoOntarioCanada
| | - John S. Floras
- University Health Network and Sinai Health Division of CardiologyToronto General Research InstituteTorontoOntarioCanada
- Department of MedicineUniversity of TorontoTorontoOntarioCanada
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Mannozzi J, Al-Hassan MH, Kaur J, Lessanework B, Alvarez A, Massoud L, Aoun K, Spranger M, O'Leary DS. Blood flow restriction training activates the muscle metaboreflex during low-intensity sustained exercise. J Appl Physiol (1985) 2023; 135:260-270. [PMID: 37348015 PMCID: PMC10393340 DOI: 10.1152/japplphysiol.00274.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 06/09/2023] [Indexed: 06/24/2023] Open
Abstract
Blood flow restriction training (BFRT) employs partial vascular occlusion of exercising muscle and has been shown to increase muscle performance while using reduced workload and training time. Numerous studies have demonstrated that BFRT increases muscle hypertrophy, mitochondrial function, and beneficial vascular adaptations. However, changes in cardiovascular hemodynamics during the exercise protocol remain unknown, as most studies measured blood pressure before the onset and after the cessation of exercise. With reduced perfusion to the exercising muscle during BFRT, the resultant accumulation of metabolites within the ischemic muscle could potentially trigger a large reflex increase in blood pressure, termed the muscle metaboreflex. At low workloads, this pressor response occurs primarily via increases in cardiac output. However, when increases in cardiac output are limited (e.g., heart failure or during severe exercise), the reflex shifts to peripheral vasoconstriction as the primary mechanism to increase blood pressure, potentially increasing the risk of a cardiovascular event. Using our chronically instrumented conscious canine model, we utilized a 60% reduction in femoral blood pressure applied to the hindlimbs during steady-state treadmill exercise (3.2 km/h) to reproduce the ischemic environment observed during BFRT. We observed significant increases in heart rate (+19 ± 3 beats/min), stroke volume (+2.52 ± 1.2 mL), cardiac output (+1.21 ± 0.2 L/min), mean arterial pressure (+18.2 ± 2.4 mmHg), stroke work (+1.93 ± 0.2 L/mmHg), and nonischemic vascular conductance (+3.62 ± 1.7 mL/mmHg), indicating activation of the muscle metaboreflex.NEW & NOTEWORTHY Blood flow restriction training (BFRT) increases muscle mass, strength, and endurance. There has been minimal consideration of the reflex cardiovascular responses that could be elicited during BFRT sessions. We showed that during low-intensity exercise BFRT may trigger large reflex increases in blood pressure and sympathetic activity due to muscle metaboreflex activation. Thus, we urge caution when employing BFRT, especially in patients in whom exaggerated cardiovascular responses may occur that could cause sudden, adverse cardiovascular events.
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Affiliation(s)
- Joseph Mannozzi
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Mohamed-Hussein Al-Hassan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Jasdeep Kaur
- Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas, United States
| | - Beruk Lessanework
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Alberto Alvarez
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Louis Massoud
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Kamel Aoun
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Marty Spranger
- Department of Physiology, Michigan State University, East Lansing, Michigan, United States
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
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Wenner MM, Greaney JL, Matthews EL, McGinty S, Kaur J, Vongpatanasin W, Fadel PJ. Influence of Age and Estradiol on Sympathetic Nerve Activity Responses to Exercise in Women. Med Sci Sports Exerc 2022; 54:408-416. [PMID: 34711708 PMCID: PMC8847319 DOI: 10.1249/mss.0000000000002823] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Postmenopausal women (PMW) display exaggerated increases in blood pressure (BP) during exercise, yet the mechanism(s) involved remain unclear. Moreover, research on the impact of menopausal changes in estradiol on cardiovascular control during exercise are limited. Herein, we tested the hypothesis that sympathetic responses during exercise are augmented in PMWcompared with young women (YW), and estradiol administration attenuates these responses. METHODS Muscle sympathetic nerve activity (MSNA) and mean arterial pressure (MAP) were measured in 13 PMW (58 ± 1 yr) and 17 YW (22 ± 1 yr) during 2 min of isometric handgrip. Separately, MSNA and BP responses were measured during isometric handgrip in six PMW (53 ± 1 yr) before and after 1 month of transdermal estradiol (100 μg·d-1). A period of postexercise ischemia (PEI) to isolate muscle metaboreflex activation followed all handgrip bouts. RESULTS Resting MAP was similar between PMW and YW, whereas MSNA was greater in PMW (23 ± 3 vs 8 ± 1 bursts per minute; P < 0.05). During handgrip, the increases in MSNA (PMW Δ16 ± 2 vs YW Δ6 ± 1 bursts per minute; P < 0.05) and MAP (PMW Δ18 ± 2 vs YW Δ12 ± 2 mm Hg; P < 0.05) were greater in PMW and remained augmented during PEI. Estradiol administration decreased resting MAP but not MSNA in PMW. Moreover, MSNA (PMW (-E2) Δ27 ± 8 bursts per minute versus PMW (+E2) Δ12 ± 5 bursts per minute; P < 0.05) and MAP (Δ31 ± 8 mm Hg vs Δ20 ± 6 mm Hg; P < 0.05) responses during handgrip were attenuated in PMW after estradiol administration. Likewise, MAP responses during PEI were lower after estradiol. CONCLUSIONS These data suggest that PMW exhibit an exaggerated MSNA and BP response to isometric exercise, due in part to heightened metaboreflex activation. Furthermore, estradiol administration attenuated BP and MSNA responses to exercise in PMW.
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Affiliation(s)
- Megan M. Wenner
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE
| | - Jody L. Greaney
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX
| | - Evan L. Matthews
- Department of Exercise Science and Physical Education, Montclair State University, Montclair, NJ
| | - Shane McGinty
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE
| | - Jasdeep Kaur
- Department of Kinesiology and Health Education, University of Texas at Austin, Austin, TX
| | | | - Paul J. Fadel
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX
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Hasegawa D, Hori A, Okamura Y, Baba R, Suijo K, Mizuno M, Sugawara J, Kitatsuji K, Ogata H, Toda K, Hotta N. Aging exaggerates blood pressure response to ischemic rhythmic handgrip exercise in humans. Physiol Rep 2021; 9:e15125. [PMID: 34817113 PMCID: PMC8611780 DOI: 10.14814/phy2.15125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 11/02/2021] [Accepted: 11/02/2021] [Indexed: 12/23/2022] Open
Abstract
Ischemic skeletal muscle conditions are known to augment exercise-induced increases in blood pressure (BP). Aging is also a factor that enhances the pressor response to exercise. However, the effects of aging on the BP response to ischemic exercise remain unclear. We, therefore, tested the hypothesis that aging enhances the BP response to rhythmic handgrip (RHG) exercise during postexercise muscle ischemia (PEMI). We divided the normotensive participants without cardiovascular diseases into three age groups: young (n = 26; age, 18-28 years), middle-aged (n = 23; age, 35-59 years), and older adults (n = 23; age, 60-80 years). The participants performed RHG exercise with minimal effort for 1 min after rest with and without PEMI, which was induced by inflating a cuff on the upper arm just before the isometric handgrip exercise ended; the intensity was 30% of maximal voluntary contraction force. Under PEMI, the increase in diastolic BP (DBP) from rest to RHG exercise in the older adult group (Δ13 ± 2 mmHg) was significantly higher than that in the young (Δ5 ± 2 mmHg) and middle-aged groups (Δ6 ± 1 mmHg), despite there being no significant difference between the groups in the DBP response from rest to RHG exercise without PEMI. Importantly, based on multiple regression analysis, age remained a significant independent determinant of both the SBP and DBP responses to RHG exercise during PEMI (p < 0.01). These findings indicate that aging enhances the pressor response to ischemic rhythmic exercise.
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Affiliation(s)
- Daisuke Hasegawa
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- Nagoya Heisei College of Nursing and Medical CareNagoyaJapan
| | - Amane Hori
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- Japan Society for the Promotion of ScienceTokyoJapan
| | - Yukiko Okamura
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
| | - Reizo Baba
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
| | - Kenichi Suijo
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
| | - Masaki Mizuno
- Department of Applied Clinical ResearchUniversity of Texas Southwestern Medical CenterDallasTexasUSA
| | - Jun Sugawara
- Human Informatics and Interaction Research InstituteNational Institute of Advanced Industrial Science and TechnologyTsukubaJapan
| | - Koji Kitatsuji
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
| | - Hisayoshi Ogata
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
| | - Kaoru Toda
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
| | - Norio Hotta
- Graduate School of Life and Health SciencesChubu UniversityKasugaiJapan
- College of Life and Health SciencesChubu UniversityKasugaiJapan
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Okamoto Y, Amano T. Effects of sex and menstrual cycle on sweating during isometric handgrip exercise and postexercise forearm occlusion. Exp Physiol 2021; 106:1508-1523. [PMID: 33899281 DOI: 10.1113/ep089464] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 04/20/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Do sex and menstrual cycle modulate sweating during isometric handgrip exercise and muscle metaboreceptor stimulation? What is the main finding and its importance? Sex modulates sweating during isometric handgrip exercise, as indicated by the lower sweat output per gland in women than in men, but not during muscle metaboreceptor stimulation. Sweat output per gland during isometric handgrip exercise and muscle metaboreceptor stimulation were lower in the mid-luteal phase than in the early follicular phase in women. Cholinergic sweat gland sensitivity might explain, in part, the individual variation of the response. Our results provide new insights regarding sex- and menstrual cycle-related modulation of the sweating response. ABSTRACT We investigated whether sex and menstrual cycle could modulate sweating during isometric handgrip (IH) exercise and muscle metaboreceptor stimulation. Twelve young, healthy women in the early follicular (EF) and mid-luteal (ML) phases and 14 men underwent two experimental sessions consisting of a 1.5 min IH exercise at 25 and 50% of maximal voluntary contraction (MVC) in a hot environment (35°C, relative humidity 50%) followed by 2 min forearm occlusion to stimulate muscle metaboreceptors. Sweat rates, the number of activated sweat glands and the sweat output per gland (SGO) on the forearm and chest were assessed. Pilocarpine-induced sweating was also assessed via transdermal iontophoresis to compare the responses with those of IH exercise and muscle metaboreceptor stimulation, based on correlation analysis. Sweat rates on the forearm and chest during IH exercise and muscle metaboreceptor stimulation did not differ between men and women in either menstrual cycle phase (all P ≥ 0.144). However, women in both phases showed lower SGO on the forearm and/or chest compared with men during IH exercise at 50% of MVC, with no differences in muscle metaboreceptor stimulation. Women in the ML phase had a lower forearm sweat rate during IH exercise at 50% of MVC (P = 0.015) and SGO during exercise and muscle metaboreceptor stimulation (main effect, both P ≤ 0.003) compared with those in the EF phase. Overall, sweat rate and SGO during IH exercise and muscle metaboreceptor stimulation were correlated with pilocarpine-induced responses (all P ≤ 0.064, r ≥ 0.303). We showed that sex and menstrual cycle modulate sudomotor activity during IH exercise and/or muscle metaboreceptor stimulation. Cholinergic sweat gland sensitivity might explain, in part, the individual variation of the response.
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Affiliation(s)
- Yumi Okamoto
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
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7
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Skow RJ, Steele AR, Fraser GM, Davenport MH, Steinback CD. The sympathetic muscle metaboreflex is not different in the third trimester in normotensive pregnant women. J Appl Physiol (1985) 2020; 130:640-650. [PMID: 33270512 DOI: 10.1152/japplphysiol.00728.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Isometric handgrip (IHG) is used to assess sympathetic nervous system responses to exercise and may be useful at predicting hypertension in both pregnant and nonpregnant populations. We previously observed altered sympathetic nervous system control of blood pressure in late pregnancy. Therefore, we measured muscle sympathetic nerve activity (MSNA) and blood pressure during muscle metaboreflex activation (IHG) in normotensive pregnant women in the third trimester compared with in healthy nonpregnant women. Further, 19 pregnant (32 ± 3 wk gestation) and 14 nonpregnant women were matched for age, non/prepregnant body mass index (BMI), and parity. MSNA (microneurography), heart rate (ECG), and arterial blood pressure (Finometer) were continuously recorded during 10 min of rest, and then during 2 min of IHG at 30% of maximal voluntary contraction, and 2 min of postexercise circulatory occlusion (PECO). Baseline sympathetic nerve activity (SNA) was elevated in pregnant (41 ± 11 bursts/min) compared with nonpregnant women (27 ± 9 bursts/min; P = 0.005); however, the sympathetic baroreflex gain and neurovascular transduction were not different between groups (P = 0.62 and P = 0.32, respectively). During IHG and PECO, there were no significant differences in the pressor responses (ΔMAP) between groups, (P = 0.25, main effect of group) nor was the sympathetic response different between groups (interaction effect: P = 0.16, 0.25, and 0.27 for burst frequency, burst incidence, and total SNA, respectively). These data suggest that pregnant women who have maintained sympathetic baroreflex and neurovascular transduction also have similar sympathetic and pressor responses during exercise.NEW & NOTEWORTHY We compared sympathetic nervous system activation by muscle metaboreflex between pregnant women in the third trimester and nonpregnant women. We show that the sympathetic nerve activity and associated pressor responses to isometric handgrip and post-exercise circulatory occlusion are not different between third-trimester pregnant and nonpregnant women. These data suggest that unlike other reflexes (e.g., cold pressor test or head-up tilt), metaboreflex control is maintained in pregnant women.
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Affiliation(s)
- Rachel J Skow
- Program for Pregnancy and Postpartum Health, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Andrew R Steele
- Program for Pregnancy and Postpartum Health, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Graham M Fraser
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Margie H Davenport
- Program for Pregnancy and Postpartum Health, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Craig D Steinback
- Program for Pregnancy and Postpartum Health, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
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Fadel PJ. Editorial to accompany exchange of views: Role of exercise pressor reflex in control of ventilation during exercise. Exp Physiol 2020; 105:2258-2259. [PMID: 33217087 DOI: 10.1113/ep089124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 10/30/2020] [Indexed: 11/08/2022]
Affiliation(s)
- Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX, USA
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Incognito AV, Nardone M, Teixeira AL, Lee JB, Kathia MM, Millar PJ. Muscle sympathetic single-unit response patterns during progressive muscle metaboreflex activation in young healthy adults. J Neurophysiol 2020; 124:682-690. [PMID: 32727266 DOI: 10.1152/jn.00305.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Muscle sympathetic single units can respond differentially to stress, but whether these responses are linked to the degree of sympathoexcitation is unclear. Fifty-three muscle sympathetic single units (microneurography) were recorded in 17 participants (8 women; 24 ± 3 yr). Five 40-s bouts of 10% static handgrip were performed during a 10-min forearm ischemia to progressively increase metabolite accumulation. Each static handgrip was separated by a 75-s ischemic rest [postexercise circulatory occlusion (PECO)] to assess the isolated action of the muscle metaboreflex. During each set of PECO, individual single units were classified as activated, nonresponsive, or inhibited if the spike frequency was above, within, or below the baseline variability, respectively. From sets 1-5 of PECO, the proportion of single units with activated (34, 45, 68, 87, and 89%), nonresponsive (43, 44, 23, 7, and 9%), or inhibited (23, 11, 9, 6, and 2%) responses changed (P < 0.001) as total muscle sympathoexcitation increased. A total of 51/53 (96%) single units were activated in at least one set of PECO, 16 (31%) initially inhibited before activation. This response pattern delayed the activation onset compared with noninhibited units (set 3 ± 1 vs. 2 ± 1, P < 0.001). Once activated, the spike-frequency rate of rise was similar (8.5 ± 6.5 vs. 7.1 ± 6.0 spikes/min per set, P = 0.48). Muscle sympathetic single-unit firing demonstrated differential control during muscle metaboreflex activation. Single units that were initially inhibited during progressive metaboreflex activation were capable of being activated in later sets. These findings reveal that single-unit activity is influenced by convergent neural inputs (i.e., both inhibitory and excitatory), which yield heterogenous single-unit activation thresholds.NEW & NOTEWORTHY Muscle sympathetic single units respond differentially to sympathoexcitatory stress such that single units can increase firing to contribute to the sympathoexcitatory response or can be nonresponsive or even inhibited. We observed a subgroup of single units that can respond bidirectionally, being first inhibited before activated by progressive increases in forearm muscle metaboreflex activation. These results suggest convergent neural inputs (i.e., inhibitory and excitatory), which yield heterogenous muscle sympathetic single-unit activation thresholds.
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Affiliation(s)
- Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jordan B Lee
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Muhammad M Kathia
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.,Toronto General Research Institute, Toronto, Ontario, Canada
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Hotta N, Hori A, Okamura Y, Baba R, Watanabe H, Sugawara J, Vongpatanasin W, Wang J, Kim HK, Ishizawa R, Iwamoto GA, Mitchell JH, Smith SA, Mizuno M. Insulin resistance is associated with an exaggerated blood pressure response to ischemic rhythmic handgrip exercise in nondiabetic older adults. J Appl Physiol (1985) 2020; 129:144-151. [PMID: 32584663 DOI: 10.1152/japplphysiol.00247.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Patients with type 2 diabetes display an exaggerated pressor response to exercise. However, evidence supporting the association between the magnitude of the pressor response to exercise and insulin resistance-related factors including hemoglobin A1c (HbA1c) or homeostatic model assessment of insulin resistance (HOMA-IR) in nondiabetic subjects has remained sparse and inconclusive. Thus we investigated the relationship between cardiovascular responses to exercise and insulin resistance-related factors in nondiabetic healthy men (n = 23) and women (n = 22) above 60 yr old. We measured heart rate (HR) and blood pressure (BP) responses during: isometric handgrip (IHG) exercise of 30% maximal voluntary contraction, a period of skeletal muscle ischemia (SMI) induced by tourniqueting the arm after IHG, and rhythmic dynamic handgrip (DHG) exercise during SMI. Greater diastolic BP (DBP) responses to DHG with SMI was associated with male sex (r = 0.44, P = 0.02) and higher HbA1c (r = 0.33, P = 0.03), heart-ankle pulse wave velocity (haPWV) (r = 0.45, P < 0.01), and resting systolic BP (SBP) (r = 0.36, P = 0.02). HbA1c persisted as a significant determinant explaining the variance in the DBP response to DHG with SMI in multivariate models despite adjustment for sex, haPWV, and resting SBP. It was also determined that the DBP response to DHG with SMI in a group in which HOMA-IR was abnormal (Δ33 ± 3 mmHg) was significantly higher than that of groups in which HOMA-IR was at intermediate (Δ20 ± 4 mmHg) and normal (Δ23 ± 2 mmHg) levels. These data suggest that even in nondiabetic older adults, insulin resistance is related to an exaggerated pressor response to exercise especially when performed under ischemic conditions.NEW & NOTEWORTHY The diastolic blood pressure response to rhythmic dynamic handgrip exercise under ischemic conditions was demonstrated to be correlated with insulin resistance-related factors in nondiabetic older adults. This finding provides important insight to the prescription of exercise in this particular patient population as the blood pressure response to exercise, especially under ischemic conditions, could be exaggerated to nonsafe levels.
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Affiliation(s)
- Norio Hotta
- College of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Amane Hori
- Graduate School of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Yukiko Okamura
- College of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Reizo Baba
- College of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Hidehiro Watanabe
- Department of Rehabilitation, Tokai Memorial Hospital, Kasugai, Japan
| | - Jun Sugawara
- Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
| | - Wanpen Vongpatanasin
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jijia Wang
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Han-Kyul Kim
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Rie Ishizawa
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Gary A Iwamoto
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jere H Mitchell
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Scott A Smith
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Masaki Mizuno
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
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11
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Notarius CF, Millar PJ, Keir DA, Murai H, Haruki N, O'Donnell E, Marzolini S, Oh P, Floras JS. Training heart failure patients with reduced ejection fraction attenuates muscle sympathetic nerve activation during mild dynamic exercise. Am J Physiol Regul Integr Comp Physiol 2019; 317:R503-R512. [PMID: 31365304 DOI: 10.1152/ajpregu.00104.2019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Muscle sympathetic nerve activity (MSNA) decreases during low-intensity dynamic one-leg exercise in healthy subjects but increases in patients with heart failure with reduced ejection fraction (HFrEF). We hypothesized that increased peak oxygen uptake (V̇o2peak) after aerobic training would be accompanied by less sympathoexcitation during both mild and moderate one-leg dynamic cycling, an attenuated muscle metaboreflex, and greater skin vasodilation. We studied 27 stable, treated HFrEF patients (6 women; mean age: 65 ± 2 SE yr; mean left ventricular ejection fraction: 30 ± 1%) and 18 healthy age-matched volunteers (6 women; mean age: 57 ± 2 yr). We assessed V̇o2peak (open-circuit spirometry) and the skin microcirculatory response to reactive hyperemia (laser flowmetry). Fibular MSNA (microneurography) was recorded before and during one-leg cycling (2 min unloaded and 2 min at 50% of V̇o2peak) and, to assess the muscle metaboreflex, during posthandgrip ischemia (PHGI). HFrEF patients were evaluated before and after 6 mo of exercise-based cardiac rehabilitation. Pretraining V̇o2peak and skin vasodilatation were lower (P < 0.001) and resting MSNA higher (P = 0.01) in HFrEF than control subjects. Training improved V̇o2peak (+3.0 ± 1.0 mL·kg-1·min-1; P < 0.001) and cutaneous vasodilation and diminished resting MSNA (-6.0 ± 2.0, P = 0.01) plus exercise MSNA during unloaded (-4.0 ± 2.5, P = 0.04) but not loaded cycling (-1.0 ± 4.0 bursts/min, P = 0.34) and MSNA during PHGI (P < 0.05). In HFrEF patients, exercise training lowers MSNA at rest, desensitizes the sympathoexcitatory metaboreflex, and diminishes MSNA elicited by mild but not moderate cycling. Training-induced downregulation of resting MSNA and attenuated reflex sympathetic excitation may improve exercise capacity and survival.
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Affiliation(s)
- Catherine F Notarius
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Philip J Millar
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada.,Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, Canada
| | - Daniel A Keir
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Hisayoshi Murai
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Nobuhiko Haruki
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Emma O'Donnell
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada.,School of Sport, Exercise, and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Susan Marzolini
- Cardiovascular Prevention and Rehabilitation Program, Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada
| | - Paul Oh
- Cardiovascular Prevention and Rehabilitation Program, Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada
| | - John S Floras
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
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12
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Kaur J, Barbosa TC, Fadel PJ. Metaboreceptor polymorphisms: do genes determine your blood pressure response to exercise? J Physiol 2018; 596:5069-5070. [PMID: 30211439 DOI: 10.1113/jp276971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Jasdeep Kaur
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX, USA
| | - Thales C Barbosa
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX, USA
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX, USA
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13
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Incognito AV, Doherty CJ, Lee JB, Burns MJ, Millar PJ. Interindividual variability in muscle sympathetic responses to static handgrip in young men: evidence for sympathetic responder types? Am J Physiol Regul Integr Comp Physiol 2017; 314:R114-R121. [PMID: 29070505 DOI: 10.1152/ajpregu.00266.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Negative and positive muscle sympathetic nerve activity (MSNA) responders have been observed during mental stress. We hypothesized that similar MSNA response patterns could be identified during the first minute of static handgrip and contribute to the interindividual variability throughout exercise. Supine measurements of multiunit MSNA (microneurography) and continuous blood pressure (Finometer) were recorded in 29 young healthy men during the first (HG1) and second (HG2) minute of static handgrip (30% maximal voluntary contraction) and subsequent postexercise circulatory occlusion (PECO). Responders were identified on the basis of differences from the typical error of baseline total MSNA: 7 negative, 12 positive, and 10 nonresponse patterns. Positive responders demonstrated larger total MSNA responses during HG1 ( P < 0.01) and HG2 ( P < 0.0001); however, the increases in blood pressure throughout handgrip exercise were similar between all groups, as were the changes in heart rate, stroke volume, cardiac output, total vascular conductance, and respiration (all P > 0.05). Comparing negative and positive responders, total MSNA responses were similar during PECO ( P = 0.17) but opposite from HG2 to PECO (∆40 ± 46 vs. ∆-21 ± 62%, P = 0.04). Negative responders also had a shorter time-to-peak diastolic blood pressure during HG1 (20 ± 20 vs. 44 ± 14 s, P < 0.001). Total MSNA responses during HG1 were associated with responses to PECO ( r = 0.39, P < 0.05), the change from HG2 to PECO ( r = -0.49, P < 0.01), and diastolic blood pressure time to peak ( r = 0.50, P < 0.01). Overall, MSNA response patterns during the first minute of static handgrip contribute to interindividual variability and appear to be influenced by differences in central command, muscle metaboreflex activation, and rate of loading of the arterial baroreflex.
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Affiliation(s)
- Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Connor J Doherty
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Jordan B Lee
- Department of Kinesiology, University of Guelph-Humber , Toronto, Ontario , Canada
| | - Matthew J Burns
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada.,Toronto General Research Institute , Toronto, Ontario , Canada
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14
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Spranger MD, Krishnan AC, Levy PD, O'Leary DS, Smith SA. Blood flow restriction training and the exercise pressor reflex: a call for concern. Am J Physiol Heart Circ Physiol 2015; 309:H1440-52. [PMID: 26342064 PMCID: PMC7002872 DOI: 10.1152/ajpheart.00208.2015] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 08/31/2015] [Indexed: 02/07/2023]
Abstract
Blood flow restriction (BFR) training (also known as Kaatsu training) is an increasingly common practice employed during resistance exercise by athletes attempting to enhance skeletal muscle mass and strength. During BFR training, blood flow to the exercising muscle is mechanically restricted by placing flexible pressurizing cuffs around the active limb proximal to the working muscle. This maneuver results in the accumulation of metabolites (e.g., protons and lactic acid) in the muscle interstitium that increase muscle force and promote muscle growth. Therefore, the premise of BFR training is to simulate and receive the benefits of high-intensity resistance exercise while merely performing low-intensity resistance exercise. This technique has also been purported to provide health benefits to the elderly, individuals recovering from joint injuries, and patients undergoing cardiac rehabilitation. Since the seminal work of Alam and Smirk in the 1930s, it has been well established that reductions in blood flow to exercising muscle engage the exercise pressor reflex (EPR), a reflex that significantly contributes to the autonomic cardiovascular response to exercise. However, the EPR and its likely contribution to the BFR-mediated cardiovascular response to exercise is glaringly missing from the scientific literature. Inasmuch as the EPR has been shown to generate exaggerated increases in sympathetic nerve activity in disease states such as hypertension (HTN), heart failure (HF), and peripheral artery disease (PAD), concerns are raised that BFR training can be used safely for the rehabilitation of patients with cardiovascular disease, as has been suggested. Abnormal BFR-induced and EPR-mediated cardiovascular complications generated during exercise could precipitate adverse cardiovascular or cerebrovascular events (e.g., cardiac arrhythmia, myocardial infarction, stroke and sudden cardiac death). Moreover, although altered EPR function in HTN, HF, and PAD underlies our concern for the widespread implementation of BFR, use of this training mechanism may also have negative consequences in the absence of disease. That is, even normal, healthy individuals performing resistance training exercise with BFR are potentially at increased risk for deleterious cardiovascular events. This review provides a brief yet detailed overview of the mechanisms underlying the autonomic cardiovascular response to exercise with BFR. A more complete understanding of the consequences of BFR training is needed before this technique is passively explored by the layman athlete or prescribed by a health care professional.
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Affiliation(s)
- Marty D Spranger
- Department of Physiology, Michigan State University, East Lansing, Michigan; Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan;
| | - Abhinav C Krishnan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Phillip D Levy
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Department of Emergency Medicine, Wayne State University School of Medicine, Detroit, Michigan
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Scott A Smith
- Department of Health Care Sciences, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
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15
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Ichinose M, Ichinose-Kuwahara T, Kondo N, Nishiyasu T. Increasing blood flow to exercising muscle attenuates systemic cardiovascular responses during dynamic exercise in humans. Am J Physiol Regul Integr Comp Physiol 2015; 309:R1234-42. [PMID: 26377556 DOI: 10.1152/ajpregu.00063.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 09/09/2015] [Indexed: 11/22/2022]
Abstract
Reducing blood flow to working muscles during dynamic exercise causes metabolites to accumulate within the active muscles and evokes systemic pressor responses. Whether a similar cardiovascular response is elicited with normal blood flow to exercising muscles during dynamic exercise remains unknown, however. To address that issue, we tested whether cardiovascular responses are affected by increases in blood flow to active muscles. Thirteen healthy subjects performed dynamic plantarflexion exercise for 12 min at 20%, 40%, and 60% of peak workload (EX20, EX40, and EX60) with their lower thigh enclosed in a negative pressure box. Under control conditions, the box pressure was the same as the ambient air pressure. Under negative pressure conditions, beginning 3 min after the start of the exercise, the box pressure was decreased by 20, 45, and then 70 mmHg in stepwise fashion with 3-min step durations. During EX20, the negative pressure had no effect on blood flow or the cardiovascular responses measured. However, application of negative pressure increased blood flow to the exercising leg during EX40 and EX60. This increase in blood flow had no significant effect on systemic cardiovascular responses during EX40, but it markedly attenuated the pressor responses otherwise seen during EX60. These results demonstrate that during mild exercise, normal blood flow to exercising muscle is not a factor eliciting cardiovascular responses, whereas it elicits an important pressor effect during moderate exercise. This suggests blood flow to exercising muscle is a major determinant of cardiovascular responses during dynamic exercise at higher than moderate intensity.
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Affiliation(s)
- Masashi Ichinose
- Human Integrative Physiology Laboratory, School of Business Administration, Meiji University, Tokyo, Japan;
| | - Tomoko Ichinose-Kuwahara
- Human Integrative Physiology Laboratory, School of Business Administration, Meiji University, Tokyo, Japan; Laboratory for Human Performance Research, Osaka International University, Osaka, Japan
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Faculty of Human Development, Kobe University, Kobe, Japan; and
| | - Takeshi Nishiyasu
- Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
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16
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Delliaux S, Ichinose M, Watanabe K, Fujii N, Nishiyasu T. Cardiovascular responses to forearm muscle metaboreflex activation during hypercapnia in humans. Am J Physiol Regul Integr Comp Physiol 2015; 309:R43-50. [PMID: 25904685 DOI: 10.1152/ajpregu.00402.2014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 04/16/2015] [Indexed: 12/27/2022]
Abstract
We characterized the cardiovascular responses to forearm muscle metaboreflex activation during hypercapnia. Ten healthy males participated under three experimental conditions: 1) hypercapnia (HCA, PetCO2 : +10 mmHg, by inhalation of a CO2-enriched gas mixture); 2) muscle metaboreflex activation (MMA, by 5 min of local circulatory occlusion after 1 min of 50% maximum voluntary contraction isometric handgrip under normocapnia); and 3) HCA+MMA. We measured mean arterial pressure (MAP), heart rate (HR), and cardiac output (CO); calculated stroke volume (SV), and total peripheral resistance (TPR); and evaluated myocardial oxygen consumption (MV̇o2) and cardiac work (CW) noninvasively. MAP increased in the three experimental conditions but HCA+MMA led to the highest MAP, CO, and HR. Moreover, HCA+MMA increased SV and was associated with the highest MV̇o2 and CW. HCA and MMA exhibited inhibitory interactions with MAP, HR, TPR, MV̇o2, and CW, increases of which were smaller during HCA+MMA than the sum of the increases during HCA and MMA alone (MAP: +28 ± 2 vs. +34 ± 2 mmHg, P < 0.001; HR: +15 ± 2 vs. +22 ± 3 bpm, P < 0.01; TPR: +1.1 ± 1.4 vs. +3.0 ± 1.5 mmHg·l·min(-1), P < 0.05; MV̇o2: +50.25 ± 4.74 vs. +59.48 ± 5.37 mmHg·min(-1)·10(-2), P < 0.01; CW: +59.10 ± 7.52 vs. +63.67 ± 7.71 ml mmHg·min(-1)·10(-4), P < 0.05). Oppositely, HCA and MMA interactions were linearly additive for CO (+2.3 ± 0.4 l/min) and SV (+13 ± 4 ml). We showed that muscle metaboreflex and hypercapnia interact in healthy humans, reducing vasoconstriction but enhancing SV.
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Affiliation(s)
- Stephane Delliaux
- Aix-Marseille University, MD, DS-ACI, UMR 2, Marseille, France; APHM, Hôpital Nord, Pôle cardiovasculaire et thoracique, Laboratoire de Physiologie Respiratoire-Explorations à l'Exercice, Marseille, France; Assistance Publique, Hôpitaux de Marseille, Hôpital Nord, Pôle cardiovasculaire et thoracique, Laboratoire de Physiologie Respiratoire-Explorations à l'Exercice, Marseille, France; Laboratory of Physiology-Circulation, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan; and Japan Society for the Promotion of Science, Tokyo, Japan
| | - Masashi Ichinose
- School of Business and Administration, Meiji University, Tokyo, Japan; Laboratory of Physiology-Circulation, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan; and
| | - Kazuhito Watanabe
- Laboratory of Physiology-Circulation, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan; and
| | - Naoto Fujii
- Laboratory of Physiology-Circulation, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan; and Japan Society for the Promotion of Science, Tokyo, Japan
| | - Takeshi Nishiyasu
- Laboratory of Physiology-Circulation, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan; and
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17
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Schuler B, Rieger G, Gubser M, Arras M, Gianella M, Vogel O, Jirkof P, Cesarovic N, Klohs J, Jakob P, Brock M, Gorr TA, Baum O, Hoppeler H, Samillan-Soto V, Gassmann M, Fischer JA, Born W, Vogel J. Endogenous α-calcitonin-gene-related peptide promotes exercise-induced, physiological heart hypertrophy in mice. Acta Physiol (Oxf) 2014; 211:107-21. [PMID: 24479375 DOI: 10.1111/apha.12244] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 10/10/2013] [Accepted: 01/24/2014] [Indexed: 11/29/2022]
Abstract
AIM It is unknown how the heart distinguishes various overloads, such as exercise or hypertension, causing either physiological or pathological hypertrophy. We hypothesize that alpha-calcitonin-gene-related peptide (αCGRP), known to be released from contracting skeletal muscles, is key at this remodelling. METHODS The hypertrophic effect of αCGRP was measured in vitro (cultured cardiac myocytes) and in vivo (magnetic resonance imaging) in mice. Exercise performance was assessed by determination of maximum oxygen consumption and time to exhaustion. Cardiac phenotype was defined by transcriptional analysis, cardiac histology and morphometry. Finally, we measured spontaneous activity, body fat content, blood volume, haemoglobin mass and skeletal muscle capillarization and fibre composition. RESULTS While αCGRP exposure yielded larger cultured cardiac myocytes, exercise-induced heart hypertrophy was completely abrogated by treatment with the peptide antagonist CGRP(8-37). Exercise performance was attenuated in αCGRP(-/-) mice or CGRP(8-37) treated wild-type mice but improved in animals with higher density of cardiac CGRP receptors (CLR-tg). Spontaneous activity, body fat content, blood volume, haemoglobin mass, muscle capillarization and fibre composition were unaffected, whereas heart index and ventricular myocyte volume were reduced in αCGRP(-/-) mice and elevated in CLR-tg. Transcriptional changes seen in αCGRP(-/-) (but not CLR-tg) hearts resembled maladaptive cardiac phenotype. CONCLUSIONS Alpha-calcitonin-gene-related peptide released by skeletal muscles during exercise is a hitherto unrecognized effector directing the strained heart into physiological instead of pathological adaptation. Thus, αCGRP agonists might be beneficial in heart failure patients.
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Affiliation(s)
- B. Schuler
- Institute of Veterinary Physiology; Vetsuisse Faculty University of Zürich; Zürich Switzerland
- Department of Physiology, Anatomy and Genetics; University of Oxford; Oxford UK
| | - G. Rieger
- Institute of Anatomy; University of Bern; Bern Switzerland
| | - M. Gubser
- Institute of Anatomy; University of Bern; Bern Switzerland
| | - M. Arras
- Division of Surgical Research; University Hospital Zürich; Zürich Switzerland
| | - M. Gianella
- Institute of Veterinary Physiology; Vetsuisse Faculty University of Zürich; Zürich Switzerland
| | - O. Vogel
- Institute of Veterinary Physiology; Vetsuisse Faculty University of Zürich; Zürich Switzerland
| | - P. Jirkof
- Division of Surgical Research; University Hospital Zürich; Zürich Switzerland
| | - N. Cesarovic
- Division of Surgical Research; University Hospital Zürich; Zürich Switzerland
| | - J. Klohs
- Institute for Biomedical Engineering; University of Zurich and Swiss Federal Institute of Technology; Zürich (ETHZ); Zürich Switzerland
| | - P. Jakob
- Institute of Physiology and Cardiovascular Research; University of Zürich; Zürich Switzerland
| | - M. Brock
- Division of Pulmonology; University Hospital Zürich; Zürich Switzerland
- Zürich Center for Integrative Human Physiology (ZIHP); Zürich Switzerland
| | - T. A. Gorr
- Institute of Veterinary Physiology; Vetsuisse Faculty University of Zürich; Zürich Switzerland
- Clinic IV; Division of Pediatric Hematology and Oncology; University Medical Center; Freiburg Germany
| | - O. Baum
- Institute of Anatomy; University of Bern; Bern Switzerland
| | - H. Hoppeler
- Institute of Anatomy; University of Bern; Bern Switzerland
| | - V. Samillan-Soto
- Institute of Veterinary Physiology; Vetsuisse Faculty University of Zürich; Zürich Switzerland
- Physiology Department; Medical School; Universidad Alas Peruanas; Lima Peru
| | - M. Gassmann
- Institute of Veterinary Physiology; Vetsuisse Faculty University of Zürich; Zürich Switzerland
- Zürich Center for Integrative Human Physiology (ZIHP); Zürich Switzerland
- Universidad Peruana Cayetano Heredia (UPCH); Lima Peru
| | - J. A. Fischer
- Former Research Laboratory for Calcium Metabolism; Orthopedic University Hospital Zürich; Zürich Switzerland
| | - W. Born
- Former Research Laboratory for Calcium Metabolism; Orthopedic University Hospital Zürich; Zürich Switzerland
| | - J. Vogel
- Institute of Veterinary Physiology; Vetsuisse Faculty University of Zürich; Zürich Switzerland
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