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Aoki M, Yamazaki Y, Otsuka J, Okamoto Y, Takada S, Shirai N, Fujimoto T, Ochi G, Yamashiro K, Sato D, Amano T. Influence of Heat Exposure on Motor Control Performance and Learning as Well as Physiological Responses to Visuomotor Accuracy Tracking Task. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:12328. [PMID: 36231630 PMCID: PMC9566463 DOI: 10.3390/ijerph191912328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 09/21/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
This study aimed to determine whether heat exposure attenuates motor control performance and learning, and blunts cardiovascular and thermoregulatory responses to visuomotor accuracy tracking (VAT) tasks. Twenty-nine healthy young adults (22 males) were divided into two groups performing VAT tasks (5 trials × 10 blocks) in thermoneutral (NEUT: 25 °C, 45% RH, n = 14) and hot (HOT: 35 °C, 45% RH, n = 15) environments (acquisition phase). One block of the VAT task was repeated at 1, 2, and 4 h after the acquisition phase (retention phase). Heat exposure elevated skin temperature to ~3 °C with a marginally increased core body temperature. VAT performance (error distance of curve tracking) was more attenuated overall in HOT than in NEUT in the acquisition phase without improvement in magnitude alteration. Heat exposure did not affect VAT performance in the retention phase. The mean arterial blood pressure and heart rate, but not for sweating and cutaneous vascular responses to VAT acquisition trials, were more attenuated in HOT than in NEUT without any retention phase alternations. We conclude that skin temperature elevation exacerbates motor control performance and blunts cardiovascular response during the motor skill acquisition period. However, these alternations are not sustainable thereafter.
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Affiliation(s)
- Mao Aoki
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata 950-2181, Japan
| | - Yudai Yamazaki
- Laboratory of Exercise Biochemistry and Neuroendocrinology, Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City 305-8574, Japan
- Japan Society for the Promotion of Science, Tokyo 102-0083, Japan
| | - Junto Otsuka
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata 950-2181, Japan
| | - Yumi Okamoto
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata 950-2181, Japan
| | - Shota Takada
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata 950-2181, Japan
| | - Nobu Shirai
- Department of Psychology, College of Contemporary Psychology, Rikkyo University, Saitama 352-8558, Japan
| | - Tomomi Fujimoto
- Institute for Human Movement and Medical Sciences, Department of Health and Sports, Niigata University of Health and Welfare, Niigata 950-3198, Japan
| | - Genta Ochi
- Institute for Human Movement and Medical Sciences, Department of Health and Sports, Niigata University of Health and Welfare, Niigata 950-3198, Japan
| | - Koya Yamashiro
- Institute for Human Movement and Medical Sciences, Department of Health and Sports, Niigata University of Health and Welfare, Niigata 950-3198, Japan
| | - Daisuke Sato
- Institute for Human Movement and Medical Sciences, Department of Health and Sports, Niigata University of Health and Welfare, Niigata 950-3198, Japan
| | - Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata 950-2181, Japan
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Sex differences in blood pressure regulation during the isometric exercise under heated environment. Blood Press Monit 2021; 27:55-62. [PMID: 34569989 DOI: 10.1097/mbp.0000000000000566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In the absence of heat stress, females increase blood pressure (BP) during isometric handgrip exercise due to cardiac output more than total peripheral resistance (TPR) compared to men. Although heat stress seems to blunt BP responses at rest and during handgrip, possible sex differences remained unknown. We hypothesized that BP responses during handgrip under a heated environment (HOT) will be different between men and women. Eight healthy men (29 ± 6 years) and eight women (26 ± 4 years) participated in this study. The experimental protocol was separated into two environmental conditions: HOT (~ 36 °C) and thermoneutral (TC; ~ 24 °C). In both conditions, participants rested for 30 min and performed the handgrip for 3 min. BP, heart rate (HR) stroke volume and cardiac output were continuously recorded, and TPR was calculated (TPR = mean blood pressure (MBP)/cardiac output). HOT reduced BP and TPR at baseline and during handgrip in females as compared to TC, while males showed similar responses in both thermal conditions. HR was higher under HOT in both groups. Cardiac output and stroke volume were not different under HOT compared to TC for females. In males, cardiac output increased at the last minute of handgrip under HOT through augmented HR, because stroke volume was unchanged. In conclusion, the main effect of HOT was to shift downwards BP and total peripheral resistance at rest and during isometric exercise in females. In males, the combination of handgrip and HOT increased cardiac output by augmented HR, whereas BP presented similar responses between thermal conditions during handgrip.
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Rathod SB, Sorte SR, Patel S. The Effect of High Temperature on Cardiovascular Autonomic Function Tests in Steel Plant Furnace Worker. Indian J Occup Environ Med 2021; 25:67-71. [PMID: 34421240 PMCID: PMC8341409 DOI: 10.4103/ijoem.ijoem_193_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 06/20/2020] [Accepted: 07/28/2020] [Indexed: 11/07/2022] Open
Abstract
Background: The high temperature in the working environment could be one of the risk factors for cardiovascular diseases in steel plant workers. The excessive high temperature at the working place leads to altered autonomic activity and is related to more cardiovascular risk. Aims and Objectives: The effect of high temperature on cardiovascular autonomic function tests in steel plant furnace worker. Material and Method: This was a case-control study for which 50 steel plant furnace workers and 50 controls were selected. The cardiovascular sympathetic function status in worker and control were analyzed by three tests: (i) Blood pressure (BP) response to sustained isometric handgrip test, (ii) BP response to the cold pressor test, and (iii) BP response to standing from a supine position (orthostasis). Statistical analysis was done by using an independent t-test. Results: Diastolic BP (DBP) response to sustained isometric handgrip and systolic BP (SBP) and DBP response to the cold pressor test showed that the increase BP in workers were more than controls but the difference was not statistically significant (P > 0.05). SBP response to standing from the supine position showed statistically significant (P < 0.001) greater fall in steel plant workers. Conclusion: The sympathetic autonomic dysfunction was seen in steel furnace workers in response to environmental stressor–excessive heat.
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Affiliation(s)
- Sachin B Rathod
- Department of Physiology, Shri Shankaracharya Institute of Medical Sciences, Bhilai, Chattishgarh, India
| | - Smita R Sorte
- Department of Physiology, AIIMS, Nagpur, Maharashtra, India
| | - Sandeep Patel
- Shri Shankaracharya Institute of Medical Sciences, Bhilai, Chattishgarh, India
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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] [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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Stens NA, Hisdal J, Bakke EF, Kaur N, Sharma A, Stranden E, Thijssen DHJ, Høiseth LØ. Factors mediating the pressor response to isometric muscle contraction: An experimental study in healthy volunteers during lower body negative pressure. PLoS One 2020; 15:e0243627. [PMID: 33296410 PMCID: PMC7725372 DOI: 10.1371/journal.pone.0243627] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/24/2020] [Indexed: 12/20/2022] Open
Abstract
Whilst both cardiac output (CO) and total peripheral resistance (TPR) determine mean arterial blood pressure (MAP), their relative importance in the pressor response to isometric exercise remains unclear. This study aimed to elucidate the relative importance of these two different factors by examining pressor responses during cardiopulmonary unloading leading to step-wise reductions in CO. Hemodynamics were investigated in 11 healthy individuals before, during and after two-minute isometric exercise during lower body negative pressure (LBNP; -20mmHg and -40mmHg). The blood pressure response to isometric exercise was similar during normal and reduced preload, despite a step-wise reduction in CO during LBNP (-20mmHg and -40mmHg). During -20mmHg LBNP, the decreased stroke volume, and consequently CO, was counteracted by an increased TPR, while heart rate (HR) was unaffected. HR was increased during -40 mmHg LBNP, although insufficient to maintain CO; the drop in CO was perfectly compensated by an increased TPR to maintain MAP. Likewise, transient application of LBNP (-20mmHg and -40mmHg) resulted in a short transient drop in MAP, caused by a decrease in CO, which was compensated by an increase in TPR. This study suggests that, in case of reductions of CO, changes in TPR are primarily responsible for maintaining the pressor response during isometric exercise. This highlights the relative importance of TPR compared to CO in mediating the pressor response during isometric exercise.
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Affiliation(s)
- Niels A. Stens
- Department of Physiology, Research Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Vascular Surgery, Division of Cardiovascular and Pulmonary Diseases, Section of Vascular Investigations, Oslo University Hospital, Oslo, Norway
| | - Jonny Hisdal
- Department of Vascular Surgery, Division of Cardiovascular and Pulmonary Diseases, Section of Vascular Investigations, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Espen F. Bakke
- Institute of Aviation Medicine, Norwegian Armed Forces Medical Service, Oslo, Norway
| | - Narinder Kaur
- Department of Vascular Surgery, Division of Cardiovascular and Pulmonary Diseases, Section of Vascular Investigations, Oslo University Hospital, Oslo, Norway
- Dermatology Center Telemark, Porsgrunn, Norway
| | - Archana Sharma
- Department of Endocrinology, Oslo University Hospital, Oslo, Norway
- Department of Anesthesiology, Oslo University Hospital, Oslo, Norway
| | - Einar Stranden
- Department of Vascular Surgery, Division of Cardiovascular and Pulmonary Diseases, Section of Vascular Investigations, Oslo University Hospital, Oslo, Norway
| | - Dick H. J. Thijssen
- Department of Physiology, Research Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Lars Øivind Høiseth
- Department of Anesthesiology, Oslo University Hospital, Oslo, Norway
- * E-mail:
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Akerman AP, Lucas SJE, Katare R, Cotter JD. Heat and Dehydration Additively Enhance Cardiovascular Outcomes following Orthostatically-Stressful Calisthenics Exercise. Front Physiol 2017; 8:756. [PMID: 29062280 PMCID: PMC5640974 DOI: 10.3389/fphys.2017.00756] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 09/19/2017] [Indexed: 02/04/2023] Open
Abstract
Exercise and exogenous heat each stimulate multiple adaptations, but their roles are not well delineated, and that of the related stressor, dehydration, is largely unknown. While severe and prolonged hypohydration potentially “silences” the long-term heat acclimated phenotype, mild and transient dehydration may enhance cardiovascular and fluid-regulatory adaptations. We tested the hypothesis that exogenous heat stress and dehydration additively potentiate acute (24 h) cardiovascular and hematological outcomes following exercise. In a randomized crossover study, 10 physically-active volunteers (mean ± SD: 173 ± 11 cm; 72.1 ± 11.5 kg; 24 ± 3 year; 6 females) completed three trials of 90-min orthostatically-stressful calisthenics, in: (i) temperate conditions (22°C, 50% rh, no airflow; CON); (ii) heat (40°C, 60% rh) whilst euhydrated (HEAT), and (iii) heat with dehydration (no fluid ~16 h before and during exercise; HEAT+DEHY). Using linear mixed effects model analyses, core temperature (TCORE) rose 0.7°C more in HEAT than CON (95% CL: [0.5, 0.9]; p < 0.001), and another 0.4°C in HEAT+DEHY ([0.2, 0.5]; p < 0.001, vs. HEAT). Skin temperature also rose 1.2°C more in HEAT than CON ([0.6, 1.8]; p < 0.001), and similarly to HEAT+DEHY (p = 0.922 vs. HEAT). Peak heart rate was 40 b·min−1 higher in HEAT than in CON ([28, 51]; p < 0.001), and another 15 b·min−1 higher in HEAT+DEHY ([3, 27]; p = 0.011, vs. HEAT). Mean arterial pressure at 24-h recovery was not consistently below baseline after CON or HEAT (p ≥ 0.452), but was reduced 4 ± 1 mm Hg after HEAT+DEHY ([0, 8]; p = 0.020 vs. baseline). Plasma volume at 24 h after exercise increased in all trials; the 7% increase in HEAT was not reliably more than in CON (5%; p = 0.335), but was an additional 4% larger after HEAT+DEHY ([1, 8]; p = 0.005 vs. HEAT). Pooled-trial correlational analysis showed the rise in TCORE predicted the hypotension (r = −0.4) and plasma volume expansion (r = 0.6) at 24 h, with more hypotension reflecting more plasma expansion (r = −0.5). In conclusion, transient dehydration with heat potentiates short-term (24-h) hematological (hypervolemic) and cardiovascular (hypotensive) outcomes following calisthenics.
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Affiliation(s)
- Ashley P Akerman
- School of Physical Education, Sport and Exercise Sciences, Division of Sciences, University of Otago, Dunedin, New Zealand.,Department of Physiology, Division of Health Sciences, University of Otago, Dunedin, New Zealand
| | - Samuel J E Lucas
- Department of Physiology, Division of Health Sciences, University of Otago, Dunedin, New Zealand.,School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Rajesh Katare
- Department of Physiology, Division of Health Sciences, University of Otago, Dunedin, New Zealand
| | - James D Cotter
- School of Physical Education, Sport and Exercise Sciences, Division of Sciences, University of Otago, Dunedin, New Zealand
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Peçanha T, Forjaz CLM, Low DA. Additive effects of heating and exercise on baroreflex control of heart rate in healthy males. J Appl Physiol (1985) 2017; 123:1555-1562. [PMID: 28860171 DOI: 10.1152/japplphysiol.00502.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study assessed the additive effects of passive heating and exercise on cardiac baroreflex sensitivity (cBRS) and heart rate variability (HRV). Twelve healthy young men (25 ± 1 yr, 23.8 ± 0.5 kg/m2) randomly underwent two experimental sessions: heat stress (HS; whole body heat stress using a tube-lined suit to increase core temperature by ~1°C) and normothermia (NT). Each session was composed of a preintervention rest (REST1); HS or NT interventions; postintervention rest (REST2); and 14 min of cycling exercise [7 min at 40%HRreserve (EX1) and 7 min at 60%HRreserve (EX2)]. Heart rate and finger blood pressure were continuously recorded. cBRS was assessed using the sequence (cBRSSEQ) and transfer function (cBRSTF) methods. HRV was assessed using the indexes standard deviation of RR intervals (SDNN) and root mean square of successive RR intervals (RMSSD). cBRS and HRV were not different between sessions during EX1 and EX2 (i.e., matched heart rate conditions: EX1 = 116 ± 3 vs. 114 ± 3 and EX2 = 143 ± 4 vs. 142 ± 3 beats/min but different workloads: EX1 = 50 ± 9 vs. 114 ± 8 and EX2 = 106 ± 10 vs. 165 ± 8 W; for HS and NT, respectively; P < 0.01). However, when comparing EX1 of NT with EX2 of HS (i.e., matched workload conditions but with different heart rates), cBRS and HRV were significantly reduced in HS (cBRSSEQ = 1.6 ± 0.3 vs. 0.6 ± 0.1 ms/mmHg, P < 0.01; SDNN = 2.3 ± 0.1 vs. 1.3 ± 0.2 ms, P < 0.01). In conclusion, in conditions matched by HR, the addition of heat stress to exercise does not affect cBRS and HRV. Alternatively, in workload-matched conditions, the addition of heat to exercise results in reduced cBRS and HRV compared with exercise in normothermia. NEW & NOTEWORTHY The present study assessed cardiac baroreflex sensitivity during the combination of heat and exercise stresses. This is the first study to show that prior whole body passive heating reduces cardiac baroreflex sensitivity and autonomic modulation of heart rate during exercise. These findings contribute to the better understanding of the role of thermoregulation on cardiovascular regulation during exercise.
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Affiliation(s)
- Tiago Peçanha
- Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of Sao Paulo , Sao Paulo , Brazil
| | - Cláudia L M Forjaz
- Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of Sao Paulo , Sao Paulo , Brazil
| | - David A Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University , Liverpool , United Kingdom
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Cui J, Blaha C, Sinoway LI. Whole body heat stress attenuates the pressure response to muscle metaboreceptor stimulation in humans. J Appl Physiol (1985) 2016; 121:1178-1186. [PMID: 27763873 DOI: 10.1152/japplphysiol.00212.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 10/04/2016] [Accepted: 10/04/2016] [Indexed: 01/20/2023] Open
Abstract
The effects of whole body heat stress on sympathetic and cardiovascular responses to stimulation of muscle metaboreceptors and mechanoreceptors remains unclear. We examined the muscle sympathetic nerve activity (MSNA), blood pressure, and heart rate in 14 young healthy subjects during fatiguing isometric handgrip exercise, postexercise circulatory occlusion (PECO), and passive muscle stretch during PECO. The protocol was performed under normothermic and whole body heat stress (increase internal temperature ~0.6°C via a heating suit) conditions. Heat stress increased the resting MSNA and heart rate. Heat stress did not alter the mean blood pressure (MAP), heart rate, and MSNA responses (i.e., changes) to fatiguing exercise. During PECO, whole body heat stress accentuated the heart rate response [change (Δ) of 5.8 ± 1.5 to Δ10.0 ± 2.1 beats/min, P = 0.03], did not alter the MSNA response (Δ16.4 ± 2.8 to Δ17.3 ± 3.8 bursts/min, P = 0.74), and lowered the MAP response (Δ20 ± 2 to Δ12 ± 1 mmHg, P < 0.001). Under normothermic conditions, passive stretch during PECO evoked significant increases in MAP and MSNA (both P < 0.001). Of note, heat stress prevented the MAP and MSNA responses to stretch during PECO (both P > 0.05). These data suggest that whole body heat stress attenuates the pressor response due to metaboreceptor stimulation, and the sympathetic nerve response due to mechanoreceptor stimulation.
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Affiliation(s)
- Jian Cui
- Penn State Health, Penn State Heart and Vascular Institute, Hershey, Pennsylvania
| | - Cheryl Blaha
- Penn State Health, Penn State Heart and Vascular Institute, Hershey, Pennsylvania
| | - Lawrence I Sinoway
- Penn State Health, Penn State Heart and Vascular Institute, Hershey, Pennsylvania
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Paull G, Dervis S, McGinn R, Haqani B, Flouris AD, Kondo N, Kenny GP. Muscle metaboreceptors modulate postexercise sweating, but not cutaneous blood flow, independent of baroreceptor loading status. Am J Physiol Regul Integr Comp Physiol 2015; 309:R1415-24. [PMID: 26377560 DOI: 10.1152/ajpregu.00287.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/04/2015] [Indexed: 11/22/2022]
Abstract
We examined whether sustained changes in baroreceptor loading status during prolonged postexercise recovery can alter the metaboreceptors' influence on heat loss. Thirteen young males performed a 1-min isometric handgrip exercise (IHG) at 60% maximal voluntary contraction followed by 2 min of forearm ischemia (to activate metaboreceptors) before and 15, 30, 45, and 60 min after a 15-min intense treadmill running exercise (>90% maximal heart rate) in the heat (35°C). This was repeated on three separate days with continuous lower body positive (LBPP, +40 mmHg), negative (LBNP, -20 mmHg), or no pressure (Control) from 13- to 65-min postexercise. Sweat rate (ventilated capsule; forearm, chest, upper back) and cutaneous vascular conductance (CVC; forearm, upper back) were measured. Relative to pre-IHG levels, sweating at all sites increased during IHG and remained elevated during ischemia at baseline and similarly at 30, 45, and 60 min postexercise (site average sweat rate increase during ischemia: Control, 0.13 ± 0.02; LBPP, 0.12 ± 0.02; LBNP, 0.15 ± 0.02 mg·min(-1)·cm(-2); all P < 0.01), but not at 15 min (all P > 0.10). LBPP and LBNP did not modulate the pattern of sweating to IHG and ischemia (all P > 0.05). At 15-min postexercise, forearm CVC was reduced from pre-IHG levels during both IHG and ischemia under LBNP only (ischemia: 3.9 ± 0.8% CVCmax; P < 0.02). Therefore, we show metaboreceptors increase postexercise sweating in the middle to late stages of recovery (30-60 min), independent of baroreceptor loading status and similarly between skin sites. In contrast, metaboreflex modulation of forearm but not upper back CVC occurs only in the early stages of recovery (15 min) and is dependent upon baroreceptor unloading.
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Affiliation(s)
- Gabrielle Paull
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Sheila Dervis
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Ryan McGinn
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Baies Haqani
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Andreas D Flouris
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada; FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece; and
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada;
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