1
|
Peeters WM, Gram M, Dias GJ, Vissers MCM, Hampton MB, Dickerhof N, Bekhit AE, Black MJ, Oxbøll J, Bayer S, Dickens M, Vitzel K, Sheard PW, Danielson KM, Hodges LD, Brønd JC, Bond J, Perry BG, Stoner L, Cornwall J, Rowlands DS. Changes to insulin sensitivity in glucose clearance systems and redox following dietary supplementation with a novel cysteine-rich protein: A pilot randomized controlled trial in humans with type-2 diabetes. Redox Biol 2023; 67:102918. [PMID: 37812879 PMCID: PMC10570009 DOI: 10.1016/j.redox.2023.102918] [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: 08/22/2023] [Accepted: 10/02/2023] [Indexed: 10/11/2023] Open
Abstract
We recently developed a novel keratin-derived protein (KDP) rich in cysteine, glycine, and arginine, with the potential to alter tissue redox status and insulin sensitivity. The KDP was tested in 35 human adults with type-2 diabetes mellitus (T2DM) in a 14-wk randomised controlled pilot trial comprising three 2×20 g supplemental protein/day arms: KDP-whey (KDPWHE), whey (WHEY), non-protein isocaloric control (CON), with standardised exercise. Outcomes were measured morning fasted and following insulin-stimulation (80 mU/m2/min hyperinsulinaemic-isoglycaemic clamp). With KDPWHE supplementation there was good and very-good evidence for moderate-sized increases in insulin-stimulated glucose clearance rate (GCR; 26%; 90% confidence limits, CL 2%, 49%) and skeletal-muscle microvascular blood flow (46%; 16%, 83%), respectively, and good evidence for increased insulin-stimulated sarcoplasmic GLUT4 translocation (18%; 0%, 39%) vs CON. In contrast, WHEY did not effect GCR (-2%; -25%, 21%) and attenuated HbA1c lowering (14%; 5%, 24%) vs CON. KDPWHE effects on basal glutathione in erythrocytes and skeletal muscle were unclear, but in muscle there was very-good evidence for large increases in oxidised peroxiredoxin isoform 2 (oxiPRX2) (19%; 2.2%, 35%) and good evidence for lower GPx1 concentrations (-40%; -4.3%, -63%) vs CON; insulin stimulation, however, attenuated the basal oxiPRX2 response (4%; -16%, 24%), and increased GPx1 (39%; -5%, 101%) and SOD1 (26%; -3%, 60%) protein expression. Effects of KDPWHE on oxiPRX3 and NRF2 content, phosphorylation of capillary eNOS and insulin-signalling proteins upstream of GLUT4 translocation AktSer437 and AS160Thr642 were inconclusive, but there was good evidence for increased IRSSer312 (41%; 3%, 95%), insulin-stimulated NFκB-DNA binding (46%; 3.4%, 105%), and basal PAK-1Thr423/2Thr402 phosphorylation (143%; 66%, 257%) vs WHEY. Our findings provide good evidence to suggest that dietary supplementation with a novel edible keratin protein in humans with T2DM may increase glucose clearance and modify skeletal-muscle tissue redox and insulin sensitivity within systems involving peroxiredoxins, antioxidant expression, and glucose uptake.
Collapse
Affiliation(s)
- W M Peeters
- Metabolic and Microvascular Laboratory, School of Sport, Exercise and Nutrition, Massey University, Wellington, Auckland, New Zealand; School of Biomedical, Nutritional and Sport Science, Newcastle University, United Kingdom
| | - M Gram
- Metabolic and Microvascular Laboratory, School of Sport, Exercise and Nutrition, Massey University, Wellington, Auckland, New Zealand
| | - G J Dias
- Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - M C M Vissers
- Centre for Free Radical Research, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - M B Hampton
- Centre for Free Radical Research, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - N Dickerhof
- Centre for Free Radical Research, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - A E Bekhit
- Department of Food Sciences, University of Otago, Dunedin, New Zealand
| | - M J Black
- Metabolic and Microvascular Laboratory, School of Sport, Exercise and Nutrition, Massey University, Wellington, Auckland, New Zealand
| | - J Oxbøll
- Metabolic and Microvascular Laboratory, School of Sport, Exercise and Nutrition, Massey University, Wellington, Auckland, New Zealand
| | - S Bayer
- Centre for Free Radical Research, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - M Dickens
- School of Health Sciences, Massey University, Wellington, Auckland, New Zealand
| | - K Vitzel
- School of Health Sciences, Massey University, Wellington, Auckland, New Zealand
| | - P W Sheard
- Department of Physiology, University of Otago, Dunedin, New Zealand
| | - K M Danielson
- Department of Anaesthesiology and Surgery, University of Otago, Wellington, New Zealand
| | - L D Hodges
- Metabolic and Microvascular Laboratory, School of Sport, Exercise and Nutrition, Massey University, Wellington, Auckland, New Zealand
| | - J C Brønd
- Department of Sports Science and Clinical Biomechanics, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - J Bond
- Metabolic and Microvascular Laboratory, School of Sport, Exercise and Nutrition, Massey University, Wellington, Auckland, New Zealand
| | - B G Perry
- School of Health Sciences, Massey University, Wellington, Auckland, New Zealand
| | - L Stoner
- Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, USA
| | - J Cornwall
- Centre for Early Learning in Medicine, University of Otago, Dunedin, New Zealand
| | - D S Rowlands
- Metabolic and Microvascular Laboratory, School of Sport, Exercise and Nutrition, Massey University, Wellington, Auckland, New Zealand.
| |
Collapse
|
2
|
Perry BG, Korad S, Mündel T. Cerebrovascular and cardiovascular responses to the Valsalva manoeuvre during hyperthermia. Clin Physiol Funct Imaging 2023; 43:463-471. [PMID: 37332243 DOI: 10.1111/cpf.12843] [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: 01/17/2023] [Revised: 05/16/2023] [Accepted: 06/16/2023] [Indexed: 06/20/2023]
Abstract
BACKGROUND During hyperthermia, the perturbations in mean arterial blood pressure (MAP) produced by the Valsalva manoeuvre (VM) are more severe. However, whether these more severe VM-induced changes in MAP are translated to the cerebral circulation during hyperthermia is unclear. METHODS Healthy participants (n = 12, 1 female, mean ± SD: age 24 ± 3 years) completed a 30 mmHg (mouth pressure) VM for 15 s whilst supine during normothermia and mild hyperthermia. Hyperthermia was induced passively using a liquid conditioning garment with core temperature measured via ingested temperature sensor. Middle cerebral artery blood velocity (MCAv) and MAP were recorded continuously during and post-VM. Tieck's autoregulatory index was calculated from the VM responses, with pulsatility index, an index of pulse velocity (pulse time) and mean MCAv (MCAvmean ) also calculated. RESULTS Passive heating significantly raised core temperature from baseline (37.9 ± 0.2 vs. 37.1 ± 0.1°C at rest, p < 0.01). MAP during phases I through III of the VM was lower during hyperthermia (interaction effect p < 0.01). Although an interaction effect was observed for MCAvmean (p = 0.02), post-hoc differences indicated only phase IIa was lower during hyperthermia (55 ± 12 vs. 49.3 ± 8 cm s- 1 for normothermia and hyperthermia, respectively, p = 0.03). Pulsatility index was increased 1-min post-VM in both conditions (0.71 ± 0.11 vs. 0.76 ± 0.11 for pre- and post-VM during normothermia, respectively, p = 0.02, and 0.86 ± 0.11 vs. 0.99 ± 0.09 for hyperthermia p < 0.01), although for pulse time only main effects of time (p < 0.01), and condition (p < 0.01) were apparent. CONCLUSION These data indicate that the cerebrovascular response to the VM is largely unchanged by mild hyperthermia.
Collapse
Affiliation(s)
- Blake G Perry
- School of Health Sciences, College of Health, Massey University, Wellington, New Zealand
| | - Stephanie Korad
- School of Health Sciences, College of Health, Massey University, Wellington, New Zealand
| | - Toby Mündel
- School of Sport, Exercise and Nutrition, College of Health, Massey University, Palmerston North, New Zealand
- Department of Kinesiology, Brock University, St Catharines, Canada
| |
Collapse
|
3
|
Korad S, Mündel T, Fan JL, Perry BG. Cerebral autoregulation across the menstrual cycle in eumenorrheic women. Physiol Rep 2022; 10:e15287. [PMID: 35524340 PMCID: PMC9076937 DOI: 10.14814/phy2.15287] [Citation(s) in RCA: 3] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 04/11/2022] [Indexed: 12/20/2022] Open
Abstract
There is emerging evidence that ovarian hormones play a significant role in the lower stroke incidence observed in pre‐menopausal women compared with men. However, the role of ovarian hormones in cerebrovascular regulation remains to be elucidated. We examined the blood pressure‐cerebral blood flow relationship (cerebral autoregulation) across the menstrual cycle in eumenorrheic women (n = 12; mean ± SD: age, 31 ± 7 years). Participants completed sit‐to‐stand and Valsalva maneuvers (VM, mouth pressure of 40 mmHg for 15 s) during the early follicular (EF), late follicular (LF), and mid‐luteal (ML) menstrual cycle phases, confirmed by serum measurement of progesterone and 17β‐estradiol. Middle cerebral artery blood velocity (MCAv), arterial blood pressure and partial pressure of end‐tidal carbon dioxide were measured. Cerebral autoregulation was assessed by transfer function analysis during spontaneous blood pressure oscillations, rate of regulation (RoR) during sit‐to‐stand maneuvers, and Tieck’s autoregulatory index during VM phases II and IV (AI‐II and AI‐IV, respectively). Resting mean MCAv (MCAvmean), blood pressure, and cerebral autoregulation were unchanged across the menstrual cycle (all p > 0.12). RoR tended to be different (EF, 0.25 ± 0.06; LF; 0.19 ± 0.04; ML, 0.18 ± 0.12 sec−1; p = 0.07) and demonstrated a negative relationship with 17β‐estradiol (R2 = 0.26, p = 0.02). No changes in AI‐II (EF, 1.95 ± 1.20; LF, 1.67 ± 0.77 and ML, 1.20 ± 0.55) or AI‐IV (EF, 1.35 ± 0.21; LF, 1.27 ± 0.26 and ML, 1.20 ± 0.2) were observed (p = 0.25 and 0.37, respectively). Although, a significant interaction effect (p = 0.02) was observed for the VM MCAvmean response. These data indicate that the menstrual cycle has limited impact on cerebrovascular autoregulation, but individual differences should be considered.
Collapse
Affiliation(s)
- Stephanie Korad
- School of Health Sciences, Massey University, Wellington, New Zealand.,School of Sport, Exercise and Nutrition, Massey University, Palmerston North, New Zealand
| | - Toby Mündel
- School of Sport, Exercise and Nutrition, Massey University, Palmerston North, New Zealand
| | - Jui-Lin Fan
- Department of Physiology, Faculty of Medical and Health Sciences, Manaaki Manawa, The Centre for Heart Research, University of Auckland, Auckland, New Zealand
| | - Blake G Perry
- School of Health Sciences, Massey University, Wellington, New Zealand
| |
Collapse
|
4
|
Roy MA, Labrecque L, Perry BG, Korad S, Smirl JD, Brassard P. Directional sensitivity of the cerebral pressure-flow relationship in young healthy individuals trained in endurance and resistance exercise. Exp Physiol 2022; 107:299-311. [PMID: 35213765 DOI: 10.1113/ep090159] [Citation(s) in RCA: 3] [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] [Received: 10/19/2021] [Accepted: 02/08/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does habitual exercise modality affect the directionality of the cerebral pressure-flow relationship? What is the main finding and its importance? These data suggest the hysteresis-like pattern of dynamic cerebral autoregulation appears present in long-term sedentary and endurance-trained individuals, but absent in resistance-trained individuals. This is the first study to expand knowledge on the directional sensitivity of the cerebral pressure-flow relationship to trained populations. ABSTRACT Evidence suggests the cerebrovasculature may be more efficient at dampening cerebral blood flow (CBF) variations when mean arterial pressure (MAP) transiently increases, compared to when it decreases. Despite divergent MAP and CBF responses to acute endurance and resistance training, the long-term impact of habitual exercise modality on the directionality of dynamic cerebral autoregulation (dCA) is currently unknown. Thirty-six young healthy participants [sedentary (n = 12), endurance-trained (n = 12) and resistance-trained (n = 12)] undertook a 5-min repeated squat-stand protocol at two forced MAP oscillation frequencies (0.05 Hz and 0.10 Hz). Middle cerebral artery mean blood velocity (MCAv) and MAP were continuously monitored. We calculated absolute (ΔMCAvT /ΔMAPT ) and relative (%MCAvT /%MAPT ) changes in MCAv and MAP with respect to the transition time intervals of both variables to compute a time-adjusted ratio in each MAP direction, averaged over the 5-min repeated squat-stand protocols. At 0.10 Hz repeated squat-stands, ΔMCAvT /ΔMAPT and %MCAvT /%MAPT were lower when MAP increased compared with when MAP decreased for sedentary (ΔMCAvT /ΔMAPT : p = 0.032; %MCAvT /%MAPT : p = 0.040) and endurance-trained individuals (ΔMCAvT /ΔMAPT : p = 0.012; %MCAvT /%MAPT : p = 0.007), but not in the resistance-trained (ΔMCAvT /ΔMAPT : p = 0.512; %MCAvT /%MAPT : p = 0.666). At 0.05 Hz repeated squat-stands, time-adjusted ratios were similar for all groups (all p>0.605). These findings suggest exercise training modality does influence the directionality of the cerebral pressure-flow relationship and support the presence of a hysteresis-like pattern during 0.10 Hz repeated squat-stands in sedentary and endurance-trained participants, but not in resistance-trained individuals. In future studies, assessment of elite endurance and resistance training habits may further elucidate modality-dependent discrepancies on directional dCA measurements. This article is protected by copyright. All rights reserved.
Collapse
Affiliation(s)
- Marc-Antoine Roy
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| | - Lawrence Labrecque
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| | - Blake G Perry
- School of Health Sciences, Massey University, Wellington, New Zealand.,School of Sport, Exercise and Nutrition, Massey University, Wellington, New Zealand
| | - Stephanie Korad
- School of Health Sciences, Massey University, Wellington, New Zealand.,School of Sport, Exercise and Nutrition, Massey University, Wellington, New Zealand
| | - Jonathan D Smirl
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Integrated Concussion Research Program, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.,Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada.,Concussion Research Laboratory, Faculty of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| |
Collapse
|
5
|
Perry BG, Lucas SJE. The Acute Cardiorespiratory and Cerebrovascular Response to Resistance Exercise. Sports Med Open 2021; 7:36. [PMID: 34046740 PMCID: PMC8160070 DOI: 10.1186/s40798-021-00314-w] [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] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 03/07/2021] [Indexed: 12/18/2022]
Abstract
Resistance exercise (RE) is a popular modality for the general population and athletes alike, due to the numerous benefits of regular participation. The acute response to dynamic RE is characterised by temporary and bidirectional physiological extremes, not typically seen in continuous aerobic exercise (e.g. cycling) and headlined by phasic perturbations in blood pressure that challenge cerebral blood flow (CBF) regulation. Cerebral autoregulation has been heavily scrutinised over the last decade with new data challenging the effectiveness of this intrinsic flow regulating mechanism, particularly to abrupt changes in blood pressure over the course of seconds (i.e. dynamic cerebral autoregulation), like those observed during RE. Acutely, RE can challenge CBF regulation, resulting in adverse responses (e.g. syncope). Compared with aerobic exercise, RE is relatively understudied, particularly high-intensity dynamic RE with a concurrent Valsalva manoeuvre (VM). However, the VM alone challenges CBF regulation and generates additional complexity when trying to dissociate the mechanisms underpinning the circulatory response to RE. Given the disparate circulatory response between aerobic and RE, primarily the blood pressure profiles, regulation of CBF is ostensibly different. In this review, we summarise current literature and highlight the acute physiological responses to RE, with a focus on the cerebral circulation.
Collapse
Affiliation(s)
- Blake G Perry
- School of Health Sciences, Massey University, Wellington, New Zealand.
| | - Samuel J E Lucas
- School of Sport, Exercise and Rehabilitation Sciences & Centre for Human Brain Health, College of Life and Environmental Sciences, University of Birmingham, Birmingham, UK
| |
Collapse
|
6
|
Perry BG, Mündel T. Lower body positive pressure affects systemic but not cerebral haemodynamics during incremental hyperthermia. Clin Physiol Funct Imaging 2020; 41:226-233. [PMID: 33238075 DOI: 10.1111/cpf.12682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 10/17/2020] [Accepted: 11/18/2020] [Indexed: 11/28/2022]
Abstract
Hyperthermia produces profound redistribution of blood and circulatory reflex function. We investigated the potential for lower body positive pressure (LBPP) to maintain or restore haemodynamics during graded hyperthermia. Eight healthy adults rested supine in a custom-made LBPP box, sealed distal to the iliac crest. Following 5 min of normothermic rest, 20 mmHg of LBPP was applied and repeated when core temperature (Tcore ) had increased passively by +0.5 and +1°C. Primary dependent variables included mean middle cerebral artery blood velocity (MCAvmean , transcranial Doppler), mean arterial blood pressure (MAP, finger photoplethysmography), heart rate (HR) and partial pressure of end-tidal carbon dioxide (PET CO2 ). The absolute increase in MAP during LBPP was lower at Tcore +1°C (2 ± 3 mmHg), compared with normothermia (7 ± 3 p = .01). The modest increase in MCAvmean was unchanged by Tcore (normothermia, 2 ± 3 cm/s; +0.5°C, 3 ± 3 cm/s and +1°C, 3 ± 4 cm/s, p = .74). By design, PET CO2 was unchanged in all conditions from normothermic baseline (42 ± 1, p = .81). LBPP-induced changes in HR were greater at +0.5°C (-13 ± 4 b/min) and +1°C (-12 ± 6 b/min) compared with normothermia (-3 ± 3 b/min, p = .01 and p = .01, respectively). These data indicate that despite a significant attenuation in MAP to LBPP with moderate hyperthermia, MCAvmean dynamics were unchanged among the thermal manipulations.
Collapse
Affiliation(s)
- Blake G Perry
- School of Health Sciences, Massey University, Wellington, New Zealand.,School of Sport, Exercise and Nutrition, Massey University, Palmerston North, New Zealand
| | - Toby Mündel
- School of Sport, Exercise and Nutrition, Massey University, Palmerston North, New Zealand
| |
Collapse
|
7
|
Kung SM, Suksreephaisan TK, Perry BG, Palmer BR, Page RA. The Effects of Anticipation and Visual and Sensory Performance on Concussion Risk in Sport: A Review. Sports Med Open 2020; 6:54. [PMID: 33196878 PMCID: PMC7669979 DOI: 10.1186/s40798-020-00283-6] [Citation(s) in RCA: 4] [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] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 11/01/2020] [Indexed: 12/24/2022]
Abstract
Sports-related concussions pose a significant public health concern, and preventative measures are needed to help reduce risk in sport. Vision training could be a suitable prevention strategy for sports-related concussion to help improve athletes’ abilities to scan the visual field for oncoming objects or opponents and thus anticipate head impacts. By accurately anticipating impacts, athletes can prepare for impact or attempt to avoid the collision altogether. The purpose of this review is to explore the relationships between anticipation, visual and sensorimotor performance and head accelerations, as well as to examine the efficacy of vision training programmes in reducing concussion risk in sport. Anticipation of head impacts has been shown to help reduce linear and rotational head accelerations, particularly for mild-to-moderate severity head impacts, but less so for severe head impacts. There is conflicting evidence regarding the influences visual and sensorimotor performance and oculomotor behaviour have on concussion risk. However, preliminary research indicates vision training may help reduce concussion rates in collegiate American Football players. Therefore, this promising area of research warrants further investigation, particularly the role of anticipation and visual and sensory performance on reducing concussion risk in non-helmeted contact sports.
Collapse
Affiliation(s)
- Stacey M Kung
- School of Sport, Exercise & Nutrition, Massey University, Wellington, New Zealand
| | | | - Blake G Perry
- School of Health Sciences, Massey University, Wellington, New Zealand
| | - Barry R Palmer
- School of Health Sciences, Massey University, Wellington, New Zealand
| | - Rachel A Page
- School of Health Sciences, Massey University, Wellington, New Zealand.
| |
Collapse
|
8
|
Barnes MJ, Perry BG, Hurst RD, Lomiwes D. Anthocyanin-Rich New Zealand Blackcurrant Extract Supports the Maintenance of Forearm Blood-Flow During Prolonged Sedentary Sitting. Front Nutr 2020; 7:74. [PMID: 32537457 PMCID: PMC7267005 DOI: 10.3389/fnut.2020.00074] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 04/30/2020] [Indexed: 12/22/2022] Open
Abstract
Objectives: We examined the acute effects of anthocyanin-rich New Zealand blackcurrant extract and a placebo on hemodynamics during 120 min of sedentary sitting in healthy males. Additionally, we investigated whether changes in resting hemodynamics altered repeated isometric hand-grip exercise performance and post exercise forearm blood flow (FBF). Methods: Ten healthy males completed two trials during which they ingested either blackcurrant extract (1.87 mg total anthocyanins/kg bodyweight) or placebo powder. Heart rate, blood pressure and forearm blood flow were measured, and venous blood was sampled, prior to and 30, 60, 90 and 120 min-post ingestion. Participants remained seated for the duration of each trial. At 120 min post-ingestion participants completed as many repetitions of isometric hand-grip contractions as possible. Results: Heart rate, blood pressure and mean arterial pressure changed over time (all p < 0.001) but did not differ between treatments. A treatment x time interaction for FBF (p = 0.025) and forearm vascular resistance (FVR) (p = 0.002) was found. No difference in the number of isometric hand-grip contractions was observed between treatments (p = 0.68) nor was there any treatment x time interaction in post-exercise FBF (p = 0.997). Plasma endothelin-1 (p = 0.023) and nitrate (p = 0.047) changed over time but did not differ between treatments (both p > 0.1). Plasma nitrite did not change over time (p = 0.732) or differ between treatments (p = 0.373). Conclusion: This study demonstrated that acute ingestion of a single dose of blackcurrant extract maintained FBF and FVR during an extended period of sitting; however, this did not influence exercise performance during hand-grip exercise.
Collapse
Affiliation(s)
- Matthew J Barnes
- School of Sport, Exercise and Nutrition, Massey University, Palmerston North, New Zealand
| | - Blake G Perry
- School of Health Sciences, Massey University, Wellington, New Zealand
| | - Roger D Hurst
- The New Zealand Institute for Plant and Food Research Ltd, Palmerston North, New Zealand
| | - Dominic Lomiwes
- The New Zealand Institute for Plant and Food Research Ltd, Palmerston North, New Zealand
| |
Collapse
|
9
|
Perry BG, Cotter JD, Korad S, Lark S, Labrecque L, Brassard P, Paquette M, Le Blanc O, Lucas SJE. Implications of habitual endurance and resistance exercise for dynamic cerebral autoregulation. Exp Physiol 2019; 104:1780-1789. [DOI: 10.1113/ep087675] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 09/23/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Blake G. Perry
- School of Health SciencesMassey University Wellington New Zealand
- School of Sport, Exercise and NutritionMassey University Wellington New Zealand
| | - James D. Cotter
- School of Physical EducationSport and Exercise SciencesUniversity of Otago Dunedin New Zealand
| | - Stephanie Korad
- School of Sport, Exercise and NutritionMassey University Wellington New Zealand
| | - Sally Lark
- School of Sport, Exercise and NutritionMassey University Wellington New Zealand
| | - Lawrence Labrecque
- Department of KinesiologyFaculty of MedicineLaval University Quebec Canada
- Research center of the Institut universitaire de cardiologie et de pneumologie de Québec Quebec Canada
| | - Patrice Brassard
- Department of KinesiologyFaculty of MedicineLaval University Quebec Canada
- Research center of the Institut universitaire de cardiologie et de pneumologie de Québec Quebec Canada
| | - Myriam Paquette
- Department of KinesiologyFaculty of MedicineLaval University Quebec Canada
- Research center of the Institut universitaire de cardiologie et de pneumologie de Québec Quebec Canada
| | - Olivier Le Blanc
- Department of KinesiologyFaculty of MedicineLaval University Quebec Canada
- Research center of the Institut universitaire de cardiologie et de pneumologie de Québec Quebec Canada
| | - Samuel J. E. Lucas
- Department of PhysiologyUniversity of Otago Dunedin New Zealand
- School of Sport, Exercise and Rehabilitation Sciences & Centre for Human Brain HealthUniversity of Birmingham Birmingham UK
| |
Collapse
|
10
|
Lei T, Cotter JD, Schlader ZJ, Stannard SR, Perry BG, Barnes MJ, Mündel T. On exercise thermoregulation in females: interaction of endogenous and exogenous ovarian hormones. J Physiol 2019; 597:71-88. [PMID: 30320879 PMCID: PMC6312528 DOI: 10.1113/jp276233] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [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: 03/28/2018] [Accepted: 10/01/2018] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS One in two female athletes chronically take a combined, monophasic oral contraceptive pill (OCP). Previous thermoregulatory investigations proposed that an endogenous rhythm of the menstrual cycle still occurs with OCP usage. Forthcoming large international sporting events will expose female athletes to hot environments differing in their thermal profile, yet few data exist on how trained women will respond from both a thermoregulatory and performance stand-point. In the present study, we have demonstrated that a small endogenous rhythm of the menstrual cycle still affects Tcore and also that chronic OCP use attenuates the sweating response, whereas behavioural thermoregulation is maintained. Furthermore, humid heat affects both performance and thermoregulatory responses to a greater extent than OCP usage and the menstrual cycle does. ABSTRACT We studied thermoregulatory responses of ten well-trained ( V ̇ O 2 max , 57 ± 7 mL min-1 kg-1 ) women taking a combined, monophasic oral contraceptive pill (OCP) (≥12 months) during exercise in dry and humid heat, across their active OCP cycle. They completed four trials, each of resting and cycling at fixed intensities (125 and 150 W), aiming to assess autonomic regulation, and then a self-paced intensity (30-min work trial) to assess behavioural regulation. Trials were conducted in quasi-follicular (qF) and quasi-luteal (qL) phases in dry (DRY) and humid (HUM) heat matched for wet bulb globe temperature (WBGT) (27°C). During rest and exercise at 125 W, rectal temperature was 0.15°C higher in qL than qF (P = 0.05) independent of environment (P = 0.17). The onset threshold and thermosensitivity of local sweat rate and forearm blood flow relative to mean body temperature was unaffected by the OCP cycle (both P > 0.30). Exercise performance did not differ between quasi-phases (qF: 268 ± 31 kJ, qL: 263 ± 26 kJ, P = 0.31) but was 5 ± 7% higher during DRY than during HUM (273 ± 29 kJ, 258 ± 28 kJ; P = 0.03). Compared to matched eumenorrhoeic athletes, chronic OCP use impaired the sweating onset threshold and thermosensitivity (both P < 0.01). In well-trained, OCP-using women exercising in the heat: (i) a performance-thermoregulatory trade-off occurred that required behavioural adjustment; (ii) humidity impaired performance as a result of reduced evaporative power despite matched WBGT; and (iii) the sudomotor but not behavioural thermoregulatory responses were impaired compared to matched eumenorrhoeic athletes.
Collapse
Affiliation(s)
- Tze‐Huan Lei
- School of Sport, Exercise and NutritionMassey UniversityPalmerston NorthNew Zealand
| | - James D. Cotter
- School of Physical Education, Sport and Exercise SciencesUniversity of OtagoDunedinNew Zealand
| | - Zachary J. Schlader
- Center for Research and Education in Special EnvironmentsDepartment of Exercise and Nutrition SciencesUniversity at BuffaloBuffaloNYUSA
| | - Stephen R. Stannard
- School of Sport, Exercise and NutritionMassey UniversityPalmerston NorthNew Zealand
| | - Blake G. Perry
- School of Sport, Exercise and NutritionMassey UniversityPalmerston NorthNew Zealand
| | - Matthew J. Barnes
- School of Sport, Exercise and NutritionMassey UniversityPalmerston NorthNew Zealand
| | - Toby Mündel
- School of Sport, Exercise and NutritionMassey UniversityPalmerston NorthNew Zealand
| |
Collapse
|
11
|
Barnes MJ, Fraser J, Coley K, Perry BG. Is Postexercise Blood Flow Restriction a Viable Alternative to Other Resistance Exercise Protocols? Res Q Exerc Sport 2018; 89:504-510. [PMID: 30239290 DOI: 10.1080/02701367.2018.1510170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
PURPOSE The purpose of this study was to identify whether post-resistance exercise (REx) blood flow restriction (BFR) can elicit a similar acute training stimulus to that offered by either heavy REx or traditional low-load BFR REx. METHOD Ten men completed trials with 30% one-repetition maximum (1RM) for 5 sets of 15 repetitions without BFR (30%), with BFR during exercise (30% RD), and with postexercise BFR (30% RP) and at 75% 1RM for 3 sets of 10 repetitions. Lactate and cortisol were measured before and up to 60 min after exercise. Thigh circumference, ratings of perceived exertion (RPE), and pain were measured before and after exercise. Surface electromyography was measured during exercise. RESULTS All conditions had a large effect (effect size [ES] > 0.8) on lactate, with the largest effects observed with the 75% condition; no differences were observed between the 30% conditions. All conditions had a moderate effect (ES > 0.25 ≤ 0.4) on increasing thigh circumference. This effect was maintained (ES = 0.35) with the application of BFR after REx (30% RP). Change in RPE, from the first to last set, was significantly greater with 30% RD compared with other conditions (all p < .05). Electromyography amplitude was higher and percentage change was greater for the 75% condition compared with the other conditions (both p < .05). CONCLUSIONS The application of BFR immediately post-REx altered several of the responses associated with REx that is aimed at inducing muscular hypertrophy. Additionally, these changes occurred with less pain and perceived exertion suggesting that this form of REx may offer an alternative, tolerable method of REx.
Collapse
|
12
|
Barnes MJ, Perry BG, Hurst RD, Lomiwes D. Effects Of Blackcurrant Extract On Peripheral Blood Flow And Muscular Endurance. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000538374.17437.0b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
13
|
Abstract
Real-world cycling performance depends not only on exercise capacities, but also on efficiently traversing the bicycle through the terrain. The aim of this study was to determine if it was possible to quantify the braking done by a cyclist in the field. One cyclist performed 408 braking trials (348 on a flat road; 60 on a flat dirt path) over 5 days on a bicycle fitted with brake torque and angular velocity sensors to measure brake power. Based on Newtonian physics, the sum of brake work, aerodynamic drag and rolling resistance was compared with the change in kinetic energy in each braking event. Strong linear relationships between the total energy removed from the bicycle-rider system through braking and the change in kinetic energy were observed on the tar-sealed road (r2 = 0.989; p < 0.0001) and the dirt path (r2 = 0.952; p < 0.0001). T-tests revealed no difference between the total energy removed and the change in kinetic energy on the road (p = 0.715) or dirt (p = 0.128). This study highlights that brake torque and angular velocity sensors are valid for calculating brake power on the disc brakes of a bicycle in field conditions. Such a device may be useful for investigating cyclists' ability to traverse through various terrains.
Collapse
Affiliation(s)
- Matthew C Miller
- a School of Sport & Exercise , Massey University , Palmerston North , New Zealand
| | - Philip W Fink
- a School of Sport & Exercise , Massey University , Palmerston North , New Zealand
| | | | - Blake G Perry
- a School of Sport & Exercise , Massey University , Palmerston North , New Zealand
| | - Stephen R Stannard
- a School of Sport & Exercise , Massey University , Palmerston North , New Zealand
| |
Collapse
|
14
|
Lei T, Stannard SR, Perry BG, Schlader ZJ, Cotter JD, Mündel T. Influence of menstrual phase and arid vs. humid heat stress on autonomic and behavioural thermoregulation during exercise in trained but unacclimated women. J Physiol 2017; 595:2823-2837. [PMID: 27900769 PMCID: PMC5407968 DOI: 10.1113/jp273176] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [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: 07/29/2016] [Accepted: 11/10/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Despite an attenuated fluctuation in ovarian hormone concentrations in well-trained women, one in two of such women believe their menstrual cycle negatively impacts training and performance. Forthcoming large international events will expose female athletes to hot environments, and studies evaluating aerobic exercise performance in such environments across the menstrual cycle are sparse, with mixed findings. We have identified that autonomic heat loss responses at rest and during fixed-intensity exercise in well-trained women are not affected by menstrual cycle phase, but differ between dry and humid heat. Furthermore, exercise performance is not different across the menstrual cycle, yet is lower in humid heat, in conjunction with reduced evaporative cooling. Menstrual cycle phase does not appear to affect exercise performance in the heat in well-trained women, but humidity impairs performance, probably due to reduced evaporative power. ABSTRACT We studied thermoregulatory responses of ten well-trained [V̇O2 max , 57 (7) ml min-1 kg-1 ] eumenorrheic women exercising in dry and humid heat, across their menstrual cycle. They completed four trials, each of resting and cycling at fixed intensities (125 and 150 W), to assess autonomic regulation, then self-paced intensity (30 min work trial), to assess behavioural regulation. Trials were in early-follicular (EF) and mid-luteal (ML) phases in dry (DRY) and humid (HUM) heat matched for wet bulb globe temperature (WBGT, 27°C). During rest and fixed-intensity exercise, rectal temperature was ∼0.2°C higher in ML than EF (P < 0.01) independent of environment (P = 0.66). Mean skin temperature did not differ between menstrual phases (P ≥ 0.13) but was higher in DRY than HUM (P < 0.01). Local sweat rate and/or forearm blood flow differed as a function of menstrual phase and environment (interaction: P ≤ 0.01). Exercise performance did not differ between phases [EF: 257 (37), ML: 255 (43) kJ, P = 0.62], but was 7 (9)% higher in DRY than HUM [263 (39), 248 (40) kJ; P < 0.01] in conjunction with equivalent autonomic regulation and thermal strain but higher evaporative cooling [16 (6) W m2 ; P < 0.01]. In well-trained women exercising in the heat: (1) menstrual phase did not affect performance, (2) humidity impaired performance due to reduced evaporative cooling despite matched WBGT and (3) behavioural responses nullified thermodynamic and autonomic differences associated with menstrual phase and dry vs. humid heat.
Collapse
Affiliation(s)
- Tze‐Huan Lei
- School of Sport and ExerciseMassey UniversityPalmerston NorthNew Zealand
| | | | - Blake G. Perry
- School of Sport and ExerciseMassey UniversityPalmerston NorthNew Zealand
| | - Zachary J. Schlader
- Department of Exercise and Nutrition SciencesUniversity at BuffaloBuffaloNYUSA
| | - James D. Cotter
- School of Physical EducationSport and Exercise SciencesUniversity of OtagoDunedinNew Zealand
| | - Toby Mündel
- School of Sport and ExerciseMassey UniversityPalmerston NorthNew Zealand
| |
Collapse
|
15
|
Perry BG, Pritchard HJ, Barnes MJ. Cerebrovascular, cardiovascular and strength responses to acute ammonia inhalation. Eur J Appl Physiol 2015; 116:583-92. [DOI: 10.1007/s00421-015-3313-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 12/10/2015] [Indexed: 10/22/2022]
|
16
|
Perry BG, Bear TLK, Lucas SJE, Mündel T. Mild dehydration modifies the cerebrovascular response to the cold pressor test. Exp Physiol 2015; 101:135-42. [DOI: 10.1113/ep085449] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 09/11/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Blake G. Perry
- School of Sport and Exercise; Massey University; Palmerston North New Zealand
| | - Tracey L. K. Bear
- School of Sport and Exercise; Massey University; Palmerston North New Zealand
- School of Psychology; Massey University; Palmerston North New Zealand
| | - Samuel J. E. Lucas
- Department of Physiology; University of Otago; Dunedin New Zealand
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences; University of Birmingham; UK
| | - Toby Mündel
- School of Sport and Exercise; Massey University; Palmerston North New Zealand
| |
Collapse
|
17
|
Mündel T, Perry BG, Ainslie PN, Thomas KN, Sikken ELG, Cotter JD, Lucas SJE. Postexercise orthostatic intolerance: influence of exercise intensity. Exp Physiol 2015; 100:915-25. [DOI: 10.1113/ep085143] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 05/29/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Toby Mündel
- School of Sport and Exercise; Massey University; Palmerston North New Zealand
| | - Blake G. Perry
- School of Sport and Exercise; Massey University; Palmerston North New Zealand
| | - Philip N. Ainslie
- Centre for Heart, Lung and Vascular Health; School of Health and Exercise Sciences, University of British Columbia; Okanagan British Columbia Canada
- Department of Physiology; University of Otago; Dunedin New Zealand
| | - Kate N. Thomas
- School of Physical Education, Sport and Exercise Sciences; University of Otago; Dunedin New Zealand
- Department of Surgical Sciences; University of Otago; Dunedin New Zealand
| | - Elisabeth L. G. Sikken
- Department of Physiology; University of Otago; Dunedin New Zealand
- Department of Physiology; Radboud University Nijmegen Medical Centre; The Netherlands
| | - James D. Cotter
- School of Physical Education, Sport and Exercise Sciences; University of Otago; Dunedin New Zealand
| | - Samuel J. E. Lucas
- Department of Physiology; University of Otago; Dunedin New Zealand
- School of Sport, Exercise and Rehabilitation Sciences; College of Life and Environmental Sciences, University of Birmingham; UK
| |
Collapse
|
18
|
Abstract
The Valsalva maneuver (VM) produces large and abrupt changes in mean arterial pressure (MAP) that challenge cerebral blood flow and oxygenation. We examined the effect of VM intensity on middle cerebral artery blood velocity (MCAv) and cortical oxygenation responses during (phases I–III) and following (phase IV) a VM. Healthy participants (n = 20 mean ± SD: 27 ± 7 years) completed 30 and 90% of their maximal VM mouth pressure for 10 s (order randomized) whilst standing. Beat-to-beat MCAv, cerebral oxygenation (NIRS) and MAP across the different phases of the VM are reported as the difference from standing baseline. There were significant interaction (phase * intensity) effects for MCAv, total oxygenation index (TOI) and MAP (all P < 0.01). MCAv decreased during phases II and III (P < 0.01), with the greatest decrease during phase III (−5 ± 8 and −19 ± 15 cm·s−1 for 30 and 90% VM, respectively). This pattern was also evident in TOI (phase III: −1 ± 1 and −5 ± 4%, both P < 0.05). Phase IV increased MCAv (22 ± 15 and 34 ± 23 cm·s−1), MAP (15 ± 14 and 24 ± 17 mm Hg) and TOI (5 ± 6 and 7 ± 5%) relative to baseline (all P < 0.05). Cerebral autoregulation, indexed, as the %MCAv/%MAP ratio, showed a phase effect only (P < 0.001), with the least regulation during phase IV (2.4 ± 3.0 and 3.2 ± 2.9). These data illustrate that an intense VM profoundly affects cerebral hemodynamics, with a reactive hyperemia occurring during phase IV following modest ischemia during phases II and III.
Collapse
Affiliation(s)
- Blake G Perry
- School of Sport and Exercise, Massey University Palmerston North, New Zealand
| | - James D Cotter
- School of Physical Education, Sport and Exercise Sciences, University of Otago Dunedin, New Zealand
| | - Gaizka Mejuto
- Laboratory of Sport Performance Analysis, Sport and Physical Education Department, Faculty of Sport Sciences, University of the Basque Country Vitoria-Gasteiz, Spain
| | - Toby Mündel
- School of Sport and Exercise, Massey University Palmerston North, New Zealand
| | - Samuel J E Lucas
- Department of Physiology, University of Otago Dunedin, New Zealand ; School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham Birmingham, UK
| |
Collapse
|
19
|
Abstract
Hypercapnia impairs cerebrovascular control during rapid changes in blood pressure (BP); however, data concerning the effect of hypercapnia on steady state, nonpharmacological increases in BP is scarce. We recruited fifteen healthy volunteers (mean ± SD: age, 28 ± 6 years; body mass, 77 ± 12 kg) to assess the effect of hypercapnia on cerebrovascular control during steady-state elevations in mean arterial BP (MAP), induced via lower body positive pressure (LBPP). Following 20 min of supine rest, participants completed 5 min of eucapnic 20 and 40 mm Hg LBPP (order randomized) followed by 5 min of hypercapnia (5% CO2 in air) with and without LBPP (order randomized), and each stage was separated by ≥5 min to allow for recovery. Middle cerebral artery blood velocity (MCAv), BP, partial pressure of end-tidal carbon dioxide (PETCO2) and heart rate were recorded and presented as the change from the preceding baseline. No difference in MCAv was apparent between eupcapnic baseline and LBPPs (grouped mean 65 ± 11 cm·s(-1), all P > 0.05), despite the increased MAP with LBPP (Δ6 ± 5 and Δ8 ± 3 mm Hg for 20 and 40 mm Hg, respectively, both P < 0.001 vs. baseline). Conversely, MCAv during the hypercapnic +40 mm Hg stage (Δ31 ± 13 cm·s(-1)) was greater than hypercapnia alone (Δ25 ± 11 cm·s(-1), P = 0.026), due to an increased MAP (Δ14 ± 7 mm Hg, P < 0.001 vs. hypercapnia alone and P = 0.026 vs. hypercapnia +20 mm Hg). As cardiac output and PETCO2 were similar across all hypercapnic stages (all P > 0.05), our findings indicate that hypercapnia impairs static autoregulation, such that higher blood pressures are translated into the cerebral circulation.
Collapse
Affiliation(s)
- Blake G Perry
- School of Sport and Exercise, Massey University, Palmerston North, New Zealand
| | - Samuel J E Lucas
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, UK Department of Physiology, University of Otago, Dunedin, New Zealand School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
| | - Kate N Thomas
- School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand Department of Surgical Sciences, University of Otago, Dunedin, New Zealand
| | - Darryl J Cochrane
- School of Sport and Exercise, Massey University, Palmerston North, New Zealand
| | - Toby Mündel
- School of Sport and Exercise, Massey University, Palmerston North, New Zealand
| |
Collapse
|
20
|
Perry BG, Mündel T, Cochrane DJ, Cotter JD, Lucas SJE. The cerebrovascular response to graded Valsalva maneuvers while standing. Physiol Rep 2014; 2:e00233. [PMID: 24744902 PMCID: PMC3966248 DOI: 10.1002/phy2.233] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 01/20/2014] [Accepted: 01/21/2014] [Indexed: 12/02/2022] Open
Abstract
The Valsalva maneuver (VM) produces large and abrupt increases in mean arterial pressure (MAP) at the onset of strain (Phase I), however, hypotension, sufficient to induce syncope, occurs upon VM release (phase III). We examined the effect of VM intensity and duration on middle cerebral artery blood velocity (MCAv) responses. Healthy men (n =10; mean ± SD: 26 ± 4 years) completed 30%, 60%, and 90% of their maximal VM mouth pressure, for 5 and 10 sec (order randomized) while standing. Beat‐to‐beat MCAv and MAP during phase I (peak), at nadir (phase III), and recovery are reported as the change from standing baseline. During phase I, MCAv rose 15 ± 6 cm·s−1 (P <0.001), which was not reliably different between intensities (P =0.11), despite graded increases in MAP (P <0.001; e.g., +12 ± 9 mmHg vs. +35 ± 14 for 5 sec 30% and 90% VM, respectively). During Phase III, the MCAv response was duration‐ (P = 0.045) and intensity dependent (P < 0.001), with the largest decrease observed following the 90% VM (e.g., −19 ± 13 and −15 ± 11 cm·s−1 for 5 and 10 sec VM, respectively) with a concomitant decrease in MAP (P <0.001, −23 ± 11 and −23 ± 9 mmHg). This asymmetric response may be attributable to the differential modulators of MCAv throughout the VM. The mechanical effects of the elevated intrathoracic pressure during phase I may restrain increases in cerebral perfusion via related increases in intracranial pressure; however, during phase III the decrease in MCAv arises from an abrupt hypotension, the extent of which is dependent upon both the duration and intensity of the VM. More intense Valsalva maneuvers when standing are associated with an increase blood pressure response during Phase I of the maneuver although this is not accompanied by changes in cerebral blood flow. However, following the maneuver (phase III) more intense straining is associated with a greater decrease in both blood pressure and cerebral blood flow and in some instances is sufficient to induce syncope.
Collapse
Affiliation(s)
- Blake G Perry
- School of Sport and Exercise, Massey University, Palmerston North, New Zealand
| | - Toby Mündel
- School of Sport and Exercise, Massey University, Palmerston North, New Zealand
| | - Darryl J Cochrane
- School of Sport and Exercise, Massey University, Palmerston North, New Zealand
| | - James D Cotter
- School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
| | - Samuel J E Lucas
- School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand ; Department of Physiology, University of Otago, Dunedin, New Zealand ; School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| |
Collapse
|
21
|
Perry BG, Schlader ZJ, Raman A, Cochrane DJ, Lucas SJE, Mündel T. Middle cerebral artery blood flow velocity in response to lower body positive pressure. Clin Physiol Funct Imaging 2013; 33:483-8. [PMID: 23701382 DOI: 10.1111/cpf.12046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [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: 02/03/2013] [Accepted: 04/09/2013] [Indexed: 11/28/2022]
Abstract
Lower body positive pressure (LBPP) has been used in the treatment of haemorrhagic shock and in offsetting g-force induced fluid shifts. However, the middle cerebral artery blood flow velocity (MCAv) response to supine LBPP is unknown. Fifteen healthy volunteers (mean ± SD: age, 26 ± 5 year; body mass, 79 ± 10 kg; height, 174 ± 9 cm) completed 5 minutes of 20 and 40 mm Hg LBPP, in a randomized order, separated by 5 minutes rest (baseline). Beat-to-beat MCAv and blood pressure, partial pressure of end-tidal carbon dioxide (PET CO2 ) and heart rate were recorded and presented as the change from the preceding baseline. All measures were similar between baseline periods (all P>0·30). Mean arterial pressure (MAP) increased by 7 ± 6 (8 ± 7%) and 13 ± 7 mm Hg (19 ± 11%) from baseline during 20 and 40 mm Hg (P<0·01), respectively. The greater MAP increase at 40 mm Hg (P<0·01 versus 20 mm Hg) was mediated via a greater increase in total peripheral resistance (P<0·01), with heart rate, cardiac output (Model flow) and PET CO2 remaining unchanged (all P>0·05) throughout. MCAv increased from baseline by 3 ± 4 cm s(-1) (5 ± 5%) during 20 mm Hg (P = 0·003), whilst no change (P = 0·18) was observed during 40 mm Hg. Our results indicate a divergent response, in that 20 mm Hg LBPP-induced modest increases in both MCAv and MAP, yet no change in MCAv was observed at the higher LBPP of 40 mm Hg despite a further increase in MAP.
Collapse
Affiliation(s)
- Blake G Perry
- School of Sport and Exercise, Massey University, Palmerston North, New Zealand
| | | | | | | | | | | |
Collapse
|