Mike Stembridge
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View article: Long‐term passive heat acclimation enhances maximal oxygen consumption via haematological and cardiac adaptation in endurance runners
Long‐term passive heat acclimation enhances maximal oxygen consumption via haematological and cardiac adaptation in endurance runners Open
Long‐term heat acclimation has been shown to elevate haemoglobin mass (Hb mass ) and enhance maximal oxygen consumption (). To date, however, all evidence derives from exercise‐induced heat stress, making it unclear whether passive strateg…
View article: Elevated carotid body tonic activity contributes to ventilatory acclimatization and de‐acclimatization to high altitude at rest and during exercise
Elevated carotid body tonic activity contributes to ventilatory acclimatization and de‐acclimatization to high altitude at rest and during exercise Open
Exposure to hypoxia is associated with increased ventilation, which escalates with continued exposure. Carotid chemoreceptors play a critical role in ventilatory acclimatization to prolonged hypoxia in animals. However, the contribution of…
View article: Mechanisms of haemoglobin mass expansion following heat stress
Mechanisms of haemoglobin mass expansion following heat stress Open
Haemoglobin mass is a critical determinant of oxygen delivery to working muscle, with even modest increases enhancing maximal oxygen uptake () and endurance performance. While altitude training has long been utilised to increase haemoglobi…
View article: Ventilatory and cerebrovascular responses to exercise in lowlander children acclimatizing to high‐altitude
Ventilatory and cerebrovascular responses to exercise in lowlander children acclimatizing to high‐altitude Open
Maturational differences in chemoreception and cerebral blood flow are evident at sea‐level, yet the age‐related comparisons in cardiopulmonary and cerebrovascular responses to high‐altitude exercise are unknown. Lowland living children ( …
View article: Pulmonary arterial mechanoreceptors modulate exercise‐induced sympathetic activation in healthy humans during moderate‐intensity hypoxic exercise
Pulmonary arterial mechanoreceptors modulate exercise‐induced sympathetic activation in healthy humans during moderate‐intensity hypoxic exercise Open
Central command, muscle afferent feedback and arterial baroreceptors all contribute to sympathetic vasoconstrictor activity during moderate‐intensity dynamic exercise in humans; however, whether a causal link exists between pulmonary arter…
View article: A slow burn: Revisiting cross‐adaptation through long‐term heat acclimation
A slow burn: Revisiting cross‐adaptation through long‐term heat acclimation Open
View article: Cerebral blood flow in Andean children and adolescents living above 5,000 m
Cerebral blood flow in Andean children and adolescents living above 5,000 m Open
We have, for the first time, quantified volumetric regional and global cerebral blood flow in indigenous Andean children and adolescents living above 5,000 m in the highest city in the world. Compared with Sherpa living at moderate altitud…
View article: Intrathoracic pressure deviations attenuate left ventricular filling and stroke volume without pronounced myocardial mechanical alterations in healthy adults
Intrathoracic pressure deviations attenuate left ventricular filling and stroke volume without pronounced myocardial mechanical alterations in healthy adults Open
Incrementally more negative or positive intrathoracic pressures, relative to normal dynamic breathing, progressively attenuate left ventricular end-diastolic volume and stroke volume in healthy younger adults. Incrementally more negative o…
View article: Phosphodiesterase inhibition restores hypoxia-induced cerebrovascular dysfunction subsequent to improved systemic redox homeostasis: A randomized, double-blind, placebo-controlled crossover study
Phosphodiesterase inhibition restores hypoxia-induced cerebrovascular dysfunction subsequent to improved systemic redox homeostasis: A randomized, double-blind, placebo-controlled crossover study Open
To what extent sildenafil, a selective inhibitor of the type-5 phosphodiesterase modulates systemic redox status and cerebrovascular function during acute exposure to hypoxia remains unknown. To address this, 12 healthy males (aged 24 ± 3 …
View article: Resistance- and endurance-trained young men display comparable carotid artery strain parameters that are superior to untrained men
Resistance- and endurance-trained young men display comparable carotid artery strain parameters that are superior to untrained men Open
Purpose Central arterial stiffness, a predictor of cardiovascular risk, attenuates with endurance-exercise in ageing populations. However, in young individuals, this effect is inconsistent and emerging evidence suggests resistance-exercise…
View article: Left ventricular trabeculation in Hominidae: divergence of the human cardiac phenotype
Left ventricular trabeculation in Hominidae: divergence of the human cardiac phenotype Open
View article: Mechanisms underpinning sympathoexcitation in hypoxia
Mechanisms underpinning sympathoexcitation in hypoxia Open
Sympathoexcitation is a hallmark of hypoxic exposure, occurring acutely, as well as persisting in acclimatised lowland populations and with generational exposure in highland native populations of the Andean and Tibetan plateaus. The mechan…
View article: Hemorheological, cardiorespiratory, and cerebrovascular effects of pentoxifylline following acclimatization to 3,800 m
Hemorheological, cardiorespiratory, and cerebrovascular effects of pentoxifylline following acclimatization to 3,800 m Open
We conducted a double-blind, placebo-controlled study on the rheological, cardiorespiratory and cerebrovascular effects of acute pentoxifylline in healthy lowlanders after 11–14 days at 3,800 m. Although red blood cell deformability was re…
View article: The influence of maturation and sex on intracranial blood velocities during exercise in children
The influence of maturation and sex on intracranial blood velocities during exercise in children Open
Cerebral blood velocity (CBv) in the anterior circulation was higher in females compared with males irrespective of maturational stage, but not in the posterior circulation. In response to exercise, females demonstrated a greater CBv compa…
View article: Regulation of haemoglobin concentration at high altitude
Regulation of haemoglobin concentration at high altitude Open
Lowlanders sojourning for more than 1 day at high altitude (HA) experience a reduction in plasma volume (PV) that increases haemoglobin concentration and thus restores arterial oxygen content. If the sojourn extends over weeks, an expansio…
View article: Adaptation of Left Ventricular Twist Mechanics in Exercise-Trained Children Is Only Evident after the Adolescent Growth Spurt
Adaptation of Left Ventricular Twist Mechanics in Exercise-Trained Children Is Only Evident after the Adolescent Growth Spurt Open
View article: Cerebral blood flow and cerebrovascular reactivity are modified by maturational stage and exercise training status during youth
Cerebral blood flow and cerebrovascular reactivity are modified by maturational stage and exercise training status during youth Open
Global cerebral blood flow (gCBF) and cerebrovascular reactivity to hypercapnia () are modulated by gonadal hormone activity, while insulin‐like growth factor 1 facilitates exercise‐mediated cerebral angiogenesis in adults. Whether critica…
View article: Neurovascular coupling and cerebrovascular hemodynamics are modified by exercise training status at different stages of maturation during youth
Neurovascular coupling and cerebrovascular hemodynamics are modified by exercise training status at different stages of maturation during youth Open
We report that the change in cerebral blood velocity during a neurovascular coupling task (NVC) is similar in pre- and postpubertal youth, regardless of exercise-training status. However, prepubertal untrained youth demonstrated a greater …
View article: Hemoglobin and cerebral hypoxic vasodilation in humans: Evidence for nitric oxide-dependent and <i>S</i>-nitrosothiol mediated signal transduction
Hemoglobin and cerebral hypoxic vasodilation in humans: Evidence for nitric oxide-dependent and <i>S</i>-nitrosothiol mediated signal transduction Open
Cerebral hypoxic vasodilation is poorly understood in humans, which undermines the development of therapeutics to optimize cerebral oxygen delivery. Across four investigations (total n = 195) we investigated the role of nitric oxide (NO) a…
View article: Adrenergic control of skeletal muscle blood flow during chronic hypoxia in healthy males
Adrenergic control of skeletal muscle blood flow during chronic hypoxia in healthy males Open
Sympathetic transduction is reduced following chronic high-altitude (HA) exposure; however, vascular α-adrenergic signaling, the primary mechanism mediating sympathetic vasoconstriction at sea level (SL), has not been examined at HA. In ni…
View article: Pulmonary vascular reactivity to supplemental oxygen in Sherpa and lowlanders during gradual ascent to high altitude
Pulmonary vascular reactivity to supplemental oxygen in Sherpa and lowlanders during gradual ascent to high altitude Open
Prolonged alveolar hypoxia leads to pulmonary vascular remodelling. We examined the time course at altitude, over which hypoxic pulmonary vasoconstriction goes from being acutely reversible to potentially irreversible. Study subjects were …
View article: Cardiopulmonary and cerebrovascular acclimatization in children and adults at 3800 m
Cardiopulmonary and cerebrovascular acclimatization in children and adults at 3800 m Open
Maturational differences exist in cardiopulmonary and cerebrovascular function at sea‐level, but the impact of maturation on acclimatization responses to high altitude is unknown. Ten children (9.8 ± 2.5 years) and 10 adults (34.7 ± 7.1 ye…
View article: Cerebral O<sub>2</sub> and CO<sub>2</sub> transport in isovolumic haemodilution: Compensation of cerebral delivery of O<sub>2</sub> and maintenance of cerebrovascular reactivity to CO<sub>2</sub>
Cerebral O<sub>2</sub> and CO<sub>2</sub> transport in isovolumic haemodilution: Compensation of cerebral delivery of O<sub>2</sub> and maintenance of cerebrovascular reactivity to CO<sub>2</sub> Open
This study investigated the influence of acute reductions in arterial O 2 content (CaO 2 ) via isovolumic haemodilution on global cerebral blood flow (gCBF) and cerebrovascular CO 2 reactivity (CVR) in 11 healthy males (age; 28 ± 7 years: …
View article: A change of heart: Mechanisms of cardiac adaptation to acute and chronic hypoxia
A change of heart: Mechanisms of cardiac adaptation to acute and chronic hypoxia Open
Over the last 100 years, high‐altitude researchers have amassed a comprehensive understanding of the global cardiac responses to acute, prolonged and lifelong hypoxia. When lowlanders are exposed to hypoxia, the drop in arterial oxygen con…
View article: Dynamic onset response of the internal carotid artery to hypercapnia is blunted in children compared with adults
Dynamic onset response of the internal carotid artery to hypercapnia is blunted in children compared with adults Open
Intracranial blood velocity reactivity to a steady-state hypercapnic stimulus has been shown to be similar in children and adults, but the onset response to hypercapnia is slower in the child. Given the vasodilatory effect of hypercapnia o…
View article: Body mass and growth rates in captive chimpanzees (<i>Pan troglodytes</i>) cared for in African wildlife sanctuaries, zoological institutions, and research facilities
Body mass and growth rates in captive chimpanzees (<i>Pan troglodytes</i>) cared for in African wildlife sanctuaries, zoological institutions, and research facilities Open
Captive chimpanzees ( Pan troglodytes ) mature earlier in body mass and have a greater growth rate compared to wild individuals. However, relatively little is known about how growth parameters compare between chimpanzees living in differen…
View article: Reply from D. R. Perkins and Mike Stembridge
Reply from D. R. Perkins and Mike Stembridge Open
View article: Kids With Altitude: Acute Mountain Sickness and Changes in Body Mass and Total Body Water in Children Travelling to 3800 m
Kids With Altitude: Acute Mountain Sickness and Changes in Body Mass and Total Body Water in Children Travelling to 3800 m Open
Introduction We explored the incidence of acute mountain sickness (AMS) and extravascular lung water (ELW) in children in relation to changes in body composition and peripheral blood oxygenation (S p O 2 ) during 1 week of acclimatization …
View article: Co-Production at Work: The Process of Breaking Up Sitting Time to Improve Cardiovascular Health. A Pilot Study
Co-Production at Work: The Process of Breaking Up Sitting Time to Improve Cardiovascular Health. A Pilot Study Open
Prolonged sitting negatively affects several cardiovascular disease biomarkers. Current workplace physical activity interventions to reduce sitting result in inconsistent uptake and adherence rates. Co-production attempts to improve the tr…
View article: The influence of hemoconcentration on hypoxic pulmonary vasoconstriction in acute, prolonged, and lifelong hypoxemia
The influence of hemoconcentration on hypoxic pulmonary vasoconstriction in acute, prolonged, and lifelong hypoxemia Open
Red blood cell concentration influences the pulmonary vasculature via direct frictional force and vasoactive signaling, but whether the magnitude of the response is modified with duration of exposure is not known. By assessing the pulmonar…