The 2018 Global Research Expedition on Altitude-related Chronic Health (REACH) to Cerro de Pasco, Peru: An Experimental Overview

In 2016, the international research team - Global Research Expedition onAltitude-related Chronic Health (REACH) - was established and executed a high altituderesearch expedition to Nepal. The team consists of ~45 students, principal investigatorsand physicians with the common objective of conducting experiments focused on highaltitude adaptation in lowlanders, and highlanders with lifelong exposure to high altitude.In 2018, Global REACH traveled to Peru where we performed a series of experiments inthe Andean highlanders. The experimental objectives, organization and characteristics,and key cohort data from Global REACH's latest research expedition are outlined herein.Herein, fifteen major studies are described that aimed to elucidate the physiologicaldifferences in high altitude acclimatization between lowlanders (n=30) and Andean bornhighlanders with (n=22) and without (n=45) Excessive Erythrocytosis (EE). Afterbaseline testing in Kelowna, BC, Canada (344m), Global REACH travelled to Lima, Peru(~80 m), and then ascended by automobile to Cerro de Pasco, Peru (~4300m) whereexperiments were conducted over 25 days. The core studies focused on elucidating themechanism(s) governing cerebral and peripheral vascular function, cardiopulmonaryregulation, exercise performance, and autonomic control. Despite encountering seriouslogistical challenges, each of the proposed studies were completed at both sea level andhigh altitude amounting to ~780 study sessions and >3000 hrs of experimental testing.Participant demographics and data related to acid-base balance and exercise capacityare presented. The collective findings will contribute to our understanding of howlowlanders and Andean highlanders have adapted under high altitude stress

Information discernment, mis-information and pro-active scepticism

A participatory action research approach was employed to investigate school students’ information discernment capabilities. Placing school student participants at the centre of the research process enabled them to define the problem in their own words and begin to find solutions to the issue of how to choose good quality information. Findings confirmed the results of many studies - that school students adopt a cognitive default position of trust and are relatively unquestioning when using information sources for their work (in this case the Extended Project Qualification or EPQ). Results also showed that with an appropriate embedded learning and teaching intervention, which includes aspects of information and digital literacy, school students adopt a cognitive questioning state, which leads to pro-active scepticism, enhancing their information discernment and in turn enables them to make better information choices. This has implications not only for school teachers and librarians but for educational policy makers also

Mechanisms and applications of acute heat stress on vascular function

Passive heat stress shows promise as an effective strategy to reduce the risk of cardiovascular diseases (CVD) as an alternative or adjunct to exercise and/or medication. Improving function of the endothelium is one of the key targets underlying the reduction in CVD risk. Therefore, this thesis aimed to evaluate potential mechanisms of acute heat-related improvement of endothelial function and investigate the effectiveness of heat in selected clinical groups. Endothelial function was measured via the technique of flow-mediated dilation (FMD) and shear stress was estimated using duplex Doppler ultrasound imaging of large arteries. In study #1, we compared forearm vs. whole-body heating in in 12 young, healthy individuals. In addition to elevated shear stress, skin and core temperatures independently increased endothelial function. In study #2, we compared peripheral and cerebrovascular responses to whole-body heating with oral ingestion of an α-1 adrenergic antagonist (Prazosin) or placebo. Although α-1 adrenergic antagonism did not influence hyperthermia-induced reductions in cerebral blood flow or affect post-heating FMD, preliminary trends indicate a potential impact of sympathetic nervous system activity on FMD in the brachial artery. In order to test the effectiveness of passive heating in extremely sedentary individuals in study #3, we measured FMD in 15 participants with cervical spinal cord injuries (SCI) and 15 uninjured controls before and after acute leg heating. There was no change in either brachial or superficial femoral artery FMD in SCI or controls; however, systemically circulating microparticles reflective of endothelial activation were reduced by ~60% after heating in SCI but not controls These reductions in endothelial microparticles were associated with improved shear patterns. Study #4 demonstrated that FMD was not different between older adults who are habitually exposed to passive heat stress (via regular sauna use) compared to those who are not. Furthermore, an exploratory analysis suggested there was no difference in FMD in sauna users compared to non-users with coronary artery disease; these data help direct towards other mechanisms as factors underlying lower CVD risk with sauna use. Collectively, the findings within this thesis highlight thermal and hemodynamic responses to heating that acutely influence endothelial function in health and disease. These findings have implications on the design of future studies that will contribute to reducing CVD risk with aging and various disease states.Health and Social Development, Faculty of (Okanagan)Health and Exercise Sciences, School of (Okanagan)Graduat

Hourly staircase sprinting exercise “snacks” improve femoral artery shear patterns but not flow-mediated dilation or cerebrovascular regulation: A pilot study

Healthy males (n=10; 244 years; BMI: 242 kg/m2) completed two randomized conditions separated by ≥48 hours involving 6-8.5 hours of sitting with (“stair snacks”) and without (sedentary) hourly staircase sprint interval exercise (approx. 14-20 s each). Resting blood flow and shear rates were measured in the femoral artery, internal carotid artery, and vertebral artery (Duplex ultrasound). Flow-mediated dilation (FMD) was quantified as an index of peripheral endothelial function in the femoral artery. Neurovascular coupling (NVC; regional blood flow response to local increases in cerebral metabolism) was assessed in the posterior cerebral artery (transcranial Doppler ultrasound). Femoral artery hemodynamics were higher following the active trial with no change in the sedentary trial, including blood flow (+3223% vs. -1028%; P=0.015 and P=0.253, respectively), vascular conductance (+3227% vs. -1526%; P=0.012 and P=0.098, respectively), and mean shear rate (+178% vs. -828%; P=0.004 and P=0.310, respectively). The change in FMD was not different within or between conditions (P=0.184). Global cerebral blood flow (CBF), conductance, shear patterns, and NVC were not different within or between conditions (all P>0.05). Overall, exercise “stair snacks” improve femoral artery blood flow and shear patterns but not peripheral (e.g., FMD) or cerebral (e.g., CBF and NVC) vascular function following prolonged sitting. The study was registered at ClinicalTrials.gov (NCT03374436) Key findings: ● Breaking up 8.5 hours of sitting with hourly staircase sprinting exercise “snacks” improves resting femoral artery shear patterns but not flow-mediated dilation. ● Cerebral blood flow and neurovascular coupling were unaltered following 6 hours of sitting with and without hourly exercise breaks.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Highs and lows of hyperoxia : physiological, performance, and clinical aspects

Molecular oxygen (O2) is a vital element in human survival and plays a major role in a diverse range of biological and physiological processes. Although normobaric hyperoxia can increase arterial oxygen content CaO2, it also causes vasoconstriction and hence reduces O2 delivery in various vascular beds including the heart, skeletal muscle, and brain. Thus, a seemingly paradoxical situation exists in which the administration of oxygen may place tissues at increased risk of hypoxic stress. Nevertheless, with various degrees of effectiveness, and not without consequences, supplemental oxygen is used clinically in an attempt to correct tissue hypoxia (e.g. brain ischemia, traumatic brain injury, carbon monoxide poisoning, etc.), chronic hypoxemia (e.g. severe COPD, etc.), and to help with wound healing, necrosis, or reperfusion injuries (e.g. compromised grafts). Hyperoxia has also been used liberally by athletes in a belief that it offers performance enhancing benefits; such benefits also extend to hypoxemic patients both at rest and during rehabilitation. This review aims to provide a comprehensive overview of the effects of hyperoxia in humans from the ‘bench-to-bedside’. The first section will focus on the basic physiological principles of partial pressure of arterial O2, CaO2, barometric pressure and how these changes lead to variation in regional O2 delivery. The next section provides an overview of the evidence for and against the use of hyperoxia as an aid to enhance physical performance. The final section addresses pathophysiological concepts, clinical studies, and implications for therapy. The potential of O2 toxicity and future research directions are also considered

Distinct contributions of skin and core temperatures to flow-mediated dilation of the brachial artery following passive heating

Contains fulltext : 231165.pdf (Publisher’s version ) (Open Access

Vascular dysfunction following breath-hold diving

The pathogenesis of predominantly neurological decompression sickness (DCS) is multifactorial. In SCUBA diving, besides gas bubbles, DCS has been linked to microparticle release, impaired endothelial function, and platelet activation. This study focused on vascular damage and its potential role in the genesis of DCS in breath-hold diving. Eleven breath-hold divers participated in a field study comprising eight deep breath-hold dives with short surface periods and repetitive breath-hold dives lasting for 6 h. Endothelium-dependent vasodilation of the brachial artery, via flow-mediated dilation (FMD), and the number of microparticles (MPs) were assessed before and after each protocol. All measures were analyzed by two-way within-subject ANOVA (2 × 2 ANOVA; factors: time and protocol). Absolute FMD was reduced following both diving protocols (p < 0.001), with no interaction (p = 0.288) or main effect of protocol (p = 0.151). There was a significant difference in the total number of circulating MPs between protocols (p = 0.007), where both increased post-dive (p = 0.012). The number of CD31+/CD41– and CD66b+ MP subtypes, although different between protocols (p < 0.001), also increased by 41.0% ± 56.6% (p = 0.050) and 60.0% ± 53.2% (p = 0.045) following deep and repetitive breath-hold dives, respectively. Both deep and repetitive breath-hold diving lead to endothelial dysfunction that may play an important role in the genesis of neurological DCS.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author