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Shoemaker LN, Wilson LC, Lucas SJE, Machado L, Walker RJ, Cotter JD. Indomethacin markedly blunts cerebral perfusion and reactivity, with little cognitive consequence in healthy young and older adults. J Physiol 2020; 599:1097-1113. [DOI: 10.1113/jp280118] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 11/05/2020] [Indexed: 12/11/2022] Open
Affiliation(s)
- L. N. Shoemaker
- School of Physical Education, Sport and Exercise Sciences University of Otago Dunedin New Zealand
| | - L. C. Wilson
- Department of Medicine Otago Medical School ‐ Dunedin Campus University of Otago Dunedin New Zealand
| | - S. 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
- Centre for Human Brain Health University of Birmingham Birmingham UK
| | - L. Machado
- Department of Psychology University of Otago Dunedin New Zealand
| | - R. J. Walker
- Department of Medicine Otago Medical School ‐ Dunedin Campus University of Otago Dunedin New Zealand
| | - J. D. Cotter
- School of Physical Education, Sport and Exercise Sciences University of Otago Dunedin New Zealand
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Affiliation(s)
- K E Joyce
- Birmingham Medical Research Expeditionary Society, University of Birmingham, Birmingham, United Kingdom
| | - S J E Lucas
- Birmingham Medical Research Expeditionary Society, University of Birmingham, Birmingham, United Kingdom
| | - A R Bradwell
- Birmingham Medical Research Expeditionary Society, University of Birmingham, Birmingham, United Kingdom
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Paquette M, Le Blanc O, Lucas SJE, Thibault G, Bailey DM, Brassard P. Effects of submaximal and supramaximal interval training on determinants of endurance performance in endurance athletes. Scand J Med Sci Sports 2016; 27:318-326. [DOI: 10.1111/sms.12660] [Citation(s) in RCA: 16] [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] [Accepted: 01/19/2016] [Indexed: 12/21/2022]
Affiliation(s)
- M. Paquette
- Department of Kinesiology; Faculty of Medicine; Université Laval; Québec QC Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec; Québec QC Canada
| | - O. Le Blanc
- Department of Kinesiology; Faculty of Medicine; Université Laval; Québec QC Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec; Québec QC Canada
| | - S. J. E. Lucas
- School of Sport, Exercise and Rehabilitation Sciences; University of Birmingham; Birmingham UK
- Department of Physiology; University of Otago; Dunedin New Zealand
| | - G. Thibault
- Department of Kinesiology; Faculty of Medicine; Université Laval; Québec QC Canada
| | - D. M. Bailey
- Neurovascular Research, Laboratory, Faculty of Life Sciences and Education; University of South Wales; South Wales UK
- Sondes Moléculaires en Biologie; Laboratoire Chimie Provence UMR 6264 CNRS; Université de Provence Marseille; Marseille France
| | - P. Brassard
- Department of Kinesiology; Faculty of Medicine; Université Laval; Québec QC Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec; Québec QC Canada
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Bradford CD, Lucas SJE, Gerrard DF, Cotter JD. Swimming in warm water is ineffective in heat acclimation and is non-ergogenic for swimmers. Scand J Med Sci Sports 2016; 25 Suppl 1:277-86. [PMID: 25943679 DOI: 10.1111/sms.12351] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2014] [Indexed: 11/28/2022]
Abstract
Heat acclimation (HA) in air confers adaptations that improve exercise capabilities in hot and possibly temperate air. Swimmers may benefit from HA, yet immersion may constrain adaptation. Therefore, we examined whether warm-water swimming constitutes effective HA. In a randomized-crossover study, eight male swimmers swam 60 min/day on 7 days in 33 °C (HA) or 28 °C (CON) water. They performed 20-min distance trials before and after each regime: in 33 °C water (Warm); 28 °C water (Temperate); and cycling in 29 °C air (Terrestrial) following standardized exercise. Rectal temperature (Tre ) rose ∼ 1 °C in HA sessions, and sweat loss averaged 1.4 L/h. After accounting for CON, HA did not confer any clear expansion of plasma volume [1.9% (95% CI: 7.7)], reduction in heart rate during standardized cycling exercise [1 b/min (9)], reduction in Tre during rest [+0.1 °C (0.1)] or exercise, or change in sudomotor function. Only perceived temperature and discomfort tended to improve. Performance was clearly not improved for Warm [+0.3% (1.8)] or Temperate [+0.3% (1.9)], was unclear for Terrestrial [+0.4% (17.7)], and was unrelated to changes in resting plasma volume (r < 0.3). In conclusion, short-term HA using swimming in 33 °C water confers little adaptation and is not ergogenic for warm or temperate conditions.
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Affiliation(s)
- C D Bradford
- School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
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Smith KJ, MacLeod D, Willie CK, Lewis NCS, Hoiland RL, Ikeda K, Tymko MM, Donnelly J, Day TA, MacLeod N, Lucas SJE, Ainslie PN. Influence of high altitude on cerebral blood flow and fuel utilization during exercise and recovery. J Physiol 2014; 592:5507-27. [PMID: 25362150 DOI: 10.1113/jphysiol.2014.281212] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We examined the hypotheses that: (1) during incremental exercise and recovery following 4-6 days at high altitude (HA) global cerebral blood flow (gCBF) increases to preserve cerebral oxygen delivery (CDO2) in excess of that required by an increasing cerebral metabolic rate of oxygen ( CM RO2); (2) the trans-cerebral exchange of oxygen vs. carbohydrates (OCI; carbohydrates = glucose + ½lactate) would be similar during exercise and recovery at HA and sea level (SL). Global CBF, intra-cranial arterial blood velocities, extra-cranial blood flows, and arterial-jugular venous substrate differences were measured during progressive steady-state exercise (20, 40, 60, 80, 100% maximum workload (Wmax)) and through 30 min of recovery. Measurements (n = 8) were made at SL and following partial acclimatization to 5050 m. At HA, absolute Wmax was reduced by ∼50%. During submaximal exercise workloads (20-60% Wmax), despite an elevated absolute gCBF (∼20%, P < 0.05) the relative increases in gCBF were not different at HA and SL. In contrast, gCBF was elevated at HA compared with SL during 80 and 100% Wmax and recovery. Notwithstanding a maintained CDO2 and elevated absolute CM RO2 at HA compared with SL, the relative increase in CM RO2 was similar during 20-80% Wmax but half that of the SL response (i.e. 17 vs. 27%; P < 0.05 vs. SL) at 100% Wmax. The OCI was reduced at HA compared with SL during 20, 40, and 60% Wmax but comparable at 80 and 100% Wmax. At HA, OCI returned almost immediately to baseline values during recovery, whereas at SL it remained below baseline. In conclusion, the elevations in gCBF during exercise and recovery at HA serve to maintain CDO2. Despite adequate CDO2 at HA the brain appears to increase non-oxidative metabolism during exercise and recovery.
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Affiliation(s)
- K J Smith
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - D MacLeod
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - C K Willie
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - N C S Lewis
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - R L Hoiland
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - K Ikeda
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - M M Tymko
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - J Donnelly
- University of Otago, Dunedin, New Zealand University Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - T A Day
- Department of Biology, Mount Royal Univeristy, Calgary, AB, Canada
| | - N MacLeod
- Carolina Friends School, Durham, NC, USA
| | - S J E Lucas
- University of Otago, Dunedin, New Zealand University of Birmingham, Birmingham, UK
| | - P N Ainslie
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
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Faull OK, Cotter JD, Lucas SJE. Cerebrovascular responses during rowing: Do circadian rhythms explain morning and afternoon performance differences? Scand J Med Sci Sports 2014; 25:467-75. [DOI: 10.1111/sms.12273] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/21/2014] [Indexed: 11/29/2022]
Affiliation(s)
- O. K. Faull
- School of Physical Education, Sport and Exercise Sciences; University of Otago; Dunedin New Zealand
- Nuffield Department of Clinical Neuroscience; University of Oxford; Oxford UK
| | - J. D. Cotter
- School of Physical Education, Sport and Exercise Sciences; University of Otago; Dunedin New Zealand
| | - S. J. E. Lucas
- Department of Physiology; University of Otago; Dunedin New Zealand
- School of Sport, Exercise & Rehabilitation Sciences; College of Life and Environmental Sciences; University of Birmingham; Birmingham UK
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Ainslie PN, Lucas SJE, Fan JL, Thomas KN, Cotter JD, Tzeng YC, Burgess KR. Influence of sympathoexcitation at high altitude on cerebrovascular function and ventilatory control in humans. J Appl Physiol (1985) 2012; 113:1058-67. [PMID: 22837165 DOI: 10.1152/japplphysiol.00463.2012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We sought to determine the influence of sympathoexcitation on dynamic cerebral autoregulation (CA), cerebrovascular reactivity, and ventilatory control in humans at high altitude (HA). At sea level (SL) and following 3-10 days at HA (5,050 m), we measured arterial blood gases, ventilation, arterial pressure, and middle cerebral blood velocity (MCAv) before and after combined α- and β-adrenergic blockade. Dynamic CA was quantified using transfer function analysis. Cerebrovascular reactivity was assessed using hypocapnia and hyperoxic hypercapnia. Ventilatory control was assessed from the hypercapnia and during isocapnic hypoxia. Arterial Pco(2) and ventilation and its control were unaltered following blockade at both SL and HA. At HA, mean arterial pressure (MAP) was elevated (P < 0.01 vs. SL), but MCAv remained unchanged. Blockade reduced MAP more at HA than at SL (26 vs. 15%, P = 0.048). At HA, gain and coherence in the very-low-frequency (VLF) range (0.02-0.07 Hz) increased, and phase lead was reduced (all P < 0.05 vs. SL). Following blockade at SL, coherence was unchanged, whereas VLF phase lead was reduced (-40 ± 23%; P < 0.01). In contrast, blockade at HA reduced low-frequency coherence (-26 ± 20%; P = 0.01 vs. baseline) and elevated VLF phase lead (by 177 ± 238%; P < 0.01 vs. baseline), fully restoring these parameters back to SL values. Irrespective of this elevation in VLF gain at HA (P < 0.01), blockade increased it comparably at SL and HA (∼43-68%; P < 0.01). Despite elevations in MCAv reactivity to hypercapnia at HA, blockade reduced (P < 0.05) it comparably at SL and HA, effects we attributed to the hypotension and/or abolition of the hypercapnic-induced increase in MAP. With the exception of dynamic CA, we provide evidence of a redundant role of sympathetic nerve activity as a direct mechanism underlying changes in cerebrovascular reactivity and ventilatory control following partial acclimatization to HA. These findings have implications for our understanding of CBF function in the context of pathologies associated with sympathoexcitation and hypoxemia.
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Affiliation(s)
- P N Ainslie
- Dept. of Human Kinetics, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada.
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Lewis NCS, Atkinson G, Lucas SJE, Grant EJM, Jones H, Tzeng YC, Horsman H, Ainslie PN. Diurnal variation in time to presyncope and associated circulatory changes during a controlled orthostatic challenge. Am J Physiol Regul Integr Comp Physiol 2010; 299:R55-61. [DOI: 10.1152/ajpregu.00030.2010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epidemiological data indicate that the risk of neurally mediated syncope is substantially higher in the morning. Syncope is precipitated by cerebral hypoperfusion, yet no chronobiological experiment has been undertaken to examine whether the major circulatory factors, which influence perfusion, show diurnal variation during a controlled orthostatic challenge. Therefore, we examined the diurnal variation in orthostatic tolerance and circulatory function measured at baseline and at presyncope. In a repeated-measures experiment, conducted at 0600 and 1600, 17 normotensive volunteers, aged 26 ± 4 yr (mean ± SD), rested supine at baseline and then underwent a 60° head-up tilt with 5-min incremental stages of lower body negative pressure until standardized symptoms of presyncope were apparent. Pretest hydration status was similar at both times of day. Continuous beat-to-beat measurements of cerebral blood flow velocity, blood pressure, heart rate, stroke volume, cardiac output, and end-tidal Pco2 were obtained. At baseline, mean cerebral blood flow velocity was 9 ± 2 cm/s (15%) lower in the morning than the afternoon ( P < 0.0001). The mean time to presyncope was shorter in the morning than in the afternoon (27.2 ± 10.5 min vs. 33.1 ± 7.9 min; 95% CI: 0.4 to 11.4 min, P = 0.01). All measurements made at presyncope did not show diurnal variation ( P > 0.05), but the changes over time (from baseline to presyncope time) in arterial blood pressure, estimated peripheral vascular resistance, and α-index baroreflex sensitivity were greater during the morning tests ( P < 0.05). These data indicate that tolerance to an incremental orthostatic challenge is markedly reduced in the morning due to diurnal variations in the time-based decline in blood pressure and the initial cerebral blood flow velocity “reserve” rather than the circulatory status at eventual presyncope. Such information may be used to help identify individuals who are particularly prone to orthostatic intolerance in the morning.
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Affiliation(s)
- N. C. S. Lewis
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - G. Atkinson
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - S. J. E. Lucas
- Department of Physiology and
- School of Physical Education, University of Otago, Dunedin, New Zealand
| | | | - H. Jones
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - Y. C. Tzeng
- Physiological Rhythms Unit, Department of Surgery and Anaesthesia, University of Otago, Wellington, New Zealand; and
| | - H. Horsman
- Physiological Rhythms Unit, Department of Surgery and Anaesthesia, University of Otago, Wellington, New Zealand; and
| | - P. N. Ainslie
- Department of Human Kinetics, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, Canada
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Abstract
Emerging evidence has suggested that with minimal prerequisite training, slow deep breathing around 0.10 Hz can acutely enhance cardiovagal baroreflex sensitivity (BRS) in humans. Such reports have led to the speculation that behavioral interventions designed to reduce breathing frequency may serve a therapeutic role in ameliorating depressed baroreflex function in conditions such as chronic heart failure, essential hypertension, and obstructive airway disease. This study sought to test the hypothesis that slow controlled breathing acutely enhances cardiovagal baroreflex function in young healthy volunteers. Distinct from earlier studies, however, baroreflex function was examined ( n = 30) using the classical pharmacological modified Oxford method, which enabled the assessment of cardiovagal BRS through experimentally driven baroreceptor stimulation across a wide range of blood pressures. For a comparison against existing evidence, spontaneous cardiovagal BRS was also assessed using the α-index and sequence method. Compared with fast breathing (0.25 Hz), slow breathing (0.10 Hz) was associated with an increase in the α-index (8.1 ± 14 ms/mmHg, P < 0.01) and spontaneous up-sequence BRS (10 ± 11 ms/mmHg, P < 0.01). In contrast, BRS derived from spontaneous down sequences and the modified Oxford method were unaltered by slow breathing. The lack of change in BRS derived from the modified Oxford method challenges the concept that slow breathing acutely augments arterial baroreflex function in otherwise healthy humans. Our results also provide further evidence that spontaneous BRS may not reflect the BRS determined by experimentally driven baroreceptor stimulation.
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Geertsema L, Lucas SJE, Cotter JD, Hock B, McKenzie J, Fernyhough LJ. The cardiovascular risk factor, soluble CD40 ligand (CD154), but not soluble CD40 is lowered by ultra-endurance exercise in athletes. Br J Sports Med 2008; 45:42-5. [DOI: 10.1136/bjsm.2008.051896] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Helge JW, Rehrer NJ, Pilegaard H, Manning P, Lucas SJE, Gerrard DF, Cotter JD. Increased fat oxidation and regulation of metabolic genes with ultraendurance exercise. Acta Physiol (Oxf) 2007; 191:77-86. [PMID: 17488246 DOI: 10.1111/j.1748-1716.2007.01709.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
AIM Regular endurance exercise stimulates muscle metabolic capacity, but effects of very prolonged endurance exercise are largely unknown. This study examined muscle substrate availability and utilization during prolonged endurance exercise, and associated metabolic genes. METHODS Data were obtained from 11 competitors of a 4- to 5-day, almost continuous ultraendurance race (seven males, four females; age: 36 +/- 11 years; cycling Vo(2peak): males 57.4 +/- 5.9, females 48.1 +/- 4.0 mL kg(-1) min(-1)). Before and after the race muscle biopsies were obtained from vastus lateralis, respiratory gases were sampled during cycling at 25 and 50% peak aerobic power output, venous samples were obtained, and fat mass was estimated by bioimpedance under standardized conditions. RESULTS After the race fat mass was decreased by 1.6 +/- 0.4 kg (11%; P < 0.01). Respiratory exchange ratio at the 25 and 50% workloads decreased (P < 0.01) from 0.83 +/- 0.06 and 0.93 +/- 0.03 before, to 0.71 +/- 0.01 and 0.85 +/- 0.02, respectively, after the race. Plasma fatty acids were 3.5 times higher (from 298 +/- 74 to 1407 +/- 118 micromol L(-1); P < 0.01). Muscle glycogen content fell 50% (from 554 +/- 28 to 270 +/- 25 nmol kg(-1) d.w.; n = 7, P < 0.01), whereas the decline in muscle triacylglycerol (from 32 +/- 5 to 22 +/- 3 mmol kg(-1) d.w.; P = 0.14) was not statistically significant. After the race, muscle mRNA content of lipoprotein lipase and glycogen synthase increased (P < 0.05) 3.9- and 1.7-fold, respectively, while forkhead homolog in rhabdomyosarcoma, pyruvate dehydrogenase kinase 4 and vascular endothelial growth factor mRNA tended (P < 0.10) to be higher, whereas muscle peroxisome proliferator-activated receptor gamma co-activator-1beta mRNA tended to be lower (P = 0.06). CONCLUSION Very prolonged exercise markedly increases plasma fatty acid availability and fat utilization during exercise. Exercise-induced regulation of genes encoding proteins involved in fatty acid recruitment and oxidation may contribute to these changes.
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Affiliation(s)
- J W Helge
- Department of Biomedical Sciences, Copenhagen Muscle Research Centre, University of Copenhagen, Copenhagen, Denmark.
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