Moving in extreme environments: inert gas narcosis and underwater activities
In conclusion, understanding the cause of this potentially debilitating problem is important to ensure that safe diving practices continue. (Source: Extreme Physiology and Medicine)
Source: Extreme Physiology and Medicine - February 24, 2015 Category: Physiology Source Type: research
Skeletal muscle energy metabolism in environmental hypoxia: climbing towards consensus
Abstract
Skeletal muscle undergoes metabolic remodelling in response to environmental hypoxia, yet aspects of this process remain controversial. Broadly, environmental hypoxia has been suggested to induce: (i) a loss of mitochondrial density; (ii) a substrate switch away from fatty acids and towards other substrates such as glucose, amino acids and ketone bodies; and (iii) a shift from aerobic to anaerobic metabolism. There remains a lack of a consensus in these areas, most likely as a consequence of the variations in degree and duration of hypoxic exposure, as well as the broad range of experimental pa...
Source: Extreme Physiology and Medicine - November 28, 2014 Category: Physiology Source Type: research
Acute nutritional ketosis: implications for exercise performance and metabolism
This article examines the energetic implications of ketone body utilisation with particular reference to exercise metabolism and substrate energetics. (Source: Extreme Physiology and Medicine)
Source: Extreme Physiology and Medicine - October 29, 2014 Category: Physiology Source Type: research
Are we being drowned in hydration advice? Thirsty for more?
Abstract
Hydration pertains simplistically to body water volume. Functionally, however, hydration is one aspect of fluid regulation that is far more complex, as it involves the homeostatic regulation of total body fluid volume, composition and distribution. Deliberate or pathological alteration of these regulated factors can be disabling or fatal, whereas they are impacted by exercise and by all environmental stressors (e.g. heat, immersion, gravity) both acutely and chronically. For example, dehydration during exercising and environmental heat stress reduces water volume more than electrolyte content, ...
Source: Extreme Physiology and Medicine - October 29, 2014 Category: Physiology Source Type: research
The impact of submaximal exercise during heat and/or hypoxia on the cardiovascular and monocyte HSP72 responses to subsequent (post 24 h) exercise in hypoxia
Conclusions
The prior induction of mHSP72 as a result of COM, HEAT and HYP attenuated further mHSP72 induction after HST and was indicative of conferred cellular tolerance. (Source: Extreme Physiology and Medicine)
Source: Extreme Physiology and Medicine - September 29, 2014 Category: Physiology Source Type: research
Fluid therapy in critical illness
Abstract
Major surgery and critical illnesses such as sepsis and trauma all disturb normal physiological fluid handling. Intravenous fluid therapy for resuscitation and fluid maintenance is a central part of medical care during these conditions, yet the evidence base supporting practice in this area lacks answers to a number of important questions. Recent research developments include a refinement of our knowledge of the endothelial barrier structure and function and a focus on the potential harm that may be associated with intravenous fluid therapy. Here, we briefly describe the contemporary view of fl...
Source: Extreme Physiology and Medicine - September 29, 2014 Category: Physiology Source Type: research
Excessive occupational heat exposure: a significant ergonomic challenge and health risk for current and future workers
Abstract
Occupational heat exposure threatens the health of a worker not only when heat illness occurs but also when a worker’s performance and work capacity is impaired. Occupational contexts that involve hot and humid climatic conditions, heavy physical workloads and/or protective clothing create a strenuous and potentially dangerous thermal load for a worker. There are recognized heat prevention strategies and international thermal ergonomic standards to protect the worker. However, such standards have been developed largely in temperate western settings, and their validity and relevance is questio...
Source: Extreme Physiology and Medicine - July 23, 2014 Category: Physiology Source Type: research
Career perspective: Jerome A. Dempsey
Abstract
I received most of my education in Canada, finishing at the University of Wisconsin (UW)-Madison medical school, where I have remained throughout my academic career. The research in our laboratory centered on the broad field of respiratory and cardiorespiratory physiology and pathophysiology as applied to exercise, sleep, hypoxia, and several chronic disease states. We used a team approach to our research with much emphasis given to the training of basic and clinical scientists in respiratory physiology and medicine. Our trainees provide the most important and lasting legacy to our laboratory's...
Source: Extreme Physiology and Medicine - July 7, 2014 Category: Physiology Source Type: research
Moving in extreme environments: open water swimming in cold and warm water
Abstract
Open water swimming (OWS), either ‘wild’ such as river swimming or competitive, is a fast growing pastime as well as a part of events such as triathlons. Little evidence is available on which to base high and low water temperature limits. Also, due to factors such as acclimatisation, which disassociates thermal sensation and comfort from thermal state, individuals cannot be left to monitor their own physical condition during swims. Deaths have occurred during OWS; these have been due to not only thermal responses but also cardiac problems. This paper, which is part of a series on ‘Moving ...
Source: Extreme Physiology and Medicine - June 11, 2014 Category: Physiology Source Type: research
Moving in extreme environments: what’s extreme and who decides?
Abstract
Humans work, rest and play in immensely varied extreme environments. The term ‘extreme’ typically refers to insufficiency or excess of one or more stressors, such as thermal energy or gravity. Individuals’ behavioural and physiological capacity to endure and enjoy such environments varies immensely. Adverse effects of acute exposure to these environments are readily identifiable (e.g. heat stroke or bone fracture), whereas adverse effects of chronic exposure (e.g. stress fractures or osteoporosis) may be as important but much less discernable. Modern societies have increasingly sought to ...
Source: Extreme Physiology and Medicine - June 11, 2014 Category: Physiology Source Type: research
Mitochondria at the extremes: pioneers, protectorates, protagonists
Abstract
The engulfment of a proto-mitochondrion by a primitive unicellular organism gave rise to the first eukaryotic cell, and ever since, mitochondrial function has been a vital aspect of eukaryotic life. Under conditions of physiological stress, the mitochondrion is far from a passive bystander, instead playing a key role in signalling pathways and the cellular responses they elicit. In this thematic series of Extreme Physiology & Medicine, the role of the mitochondrion in the response to physiological stress will be considered anew, through research articles, reviews, viewpoints and methodology...
Source: Extreme Physiology and Medicine - May 12, 2014 Category: Physiology Source Type: research
The +Gz recovery of consciousness curve
Conclusions
Mean recovery time from +Gz-induced unconsciousness is dependent on the deceleration profile's offset rate from the point of loss of consciousness. This relationship is described by a curve plotting offset rate and time for recovery of consciousness. This curve predicts when conscious function should return following exposure to +Gz stress sufficient to cause unconsciousness. The maximum +Gz level of the recovery exposure profile was found to be inadequate for predicting variations in the time for recovery of consciousness. (Source: Extreme Physiology and Medicine)
Source: Extreme Physiology and Medicine - May 2, 2014 Category: Physiology Source Type: research
Cycling performance decrement is greater in hypobaric versus normobaric hypoxia
Conclusion
Cycling time trial performance is impaired to a greater degree in HH versus NH at the same ambient PO2 equivalent to 4,300 m despite similar cardiorespiratory responses. (Source: Extreme Physiology and Medicine)
Source: Extreme Physiology and Medicine - April 28, 2014 Category: Physiology Source Type: research
Frostbite: a practical approach to hospital management
Abstract
Frostbite presentation to hospital is relatively infrequent, and the optimal management of the more severely injured patient requires a multidisciplinary integration of specialist care. Clinicians with an interest in wilderness medicine/freezing cold injury have the awareness of specific potential interventions but may lack the skill or experience to implement the knowledge. The on-call specialist clinician (vascular, general surgery, orthopaedic, plastic surgeon or interventional radiologist), who is likely to receive these patients, may have the skill and knowledge to administer potentially l...
Source: Extreme Physiology and Medicine - April 22, 2014 Category: Physiology Source Type: research
High altitude pulmonary edema (HAPE) in a Himalayan trekker: a case report
Conclusion
The case report highlights numerous points:
1) Many high altitude trekkers have invested significant time, money and physical efforts in in their ventures and are determined to ascend despite early warning and illnesses. 2) Despite no history of altitude illnesses in previous altitude exposure,inter-current illness (in this case a nonspecific respiratory tract infection) may contribute to the development of high altitude pulmonary edema. 3) Continuing ascent using other transport means, whilst suffering from symptoms of high altitude illness, worsens the condition and ...
Source: Extreme Physiology and Medicine - March 17, 2014 Category: Physiology Source Type: research
