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Diving in the Arctic: Cold Water Immersion's Effects on Heart Rate Variability in Navy Divers.

https://arctichealth.org/en/permalink/ahliterature306849
Source
Front Physiol. 2019; 10:1600
Publication Type
Journal Article
Date
2019
Author
Richard V Lundell
Anne K Räisänen-Sokolowski
Tomi K Wuorimaa
Tommi Ojanen
Kai I Parkkola
Author Affiliation
Diving Medical Centre, Centre for Military Medicine, The Finnish Defence Forces, Helsinki, Finland.
Source
Front Physiol. 2019; 10:1600
Date
2019
Language
English
Publication Type
Journal Article
Abstract
Diving close to the Arctic circle means diving in cold water regardless of the time of year. The human body reacts to cold through autonomous nervous system (ANS)-mediated thermoregulatory mechanisms. Diving also induces ANS responses as a result of the diving reflex.
In order to study ANS responses during diving in Arctic water temperatures, we retrospectively analyzed repeated 5-min heart rate variability (HRV) measures and the mean body temperature from dives at regular intervals using naval diving equipment measurement tests in 0°C water. Three divers performed seven dives without physical activity (81-91 min), and two divers performed four dives with physical activity after 10 min of diving (0-10 min HRV recordings were included in the study).
Our study showed a significant increase in parasympathetic activity (PNS) at the beginning of the dives, after which PNS activity decreased significantly (measure 5-10 min). Subsequent measurements (15-20 min and onward) showed a significant increase in PNS activity over time.
Our results suggest that the first PNS responses of the human diving reflex decrease quickly. Adverse effects of PNS activity should be considered on long and cold dives. To avoid concurrent sympathetic (SNS) and PNS activity at the beginning of dives, which in turn may increase the risk of arrhythmia in cold water, we suggest a short adaptation phase before physical activity. Moreover, we suggest it is prudent to give special attention to cardiovascular risk factors during pre-dive examinations for cold water divers.
PubMed ID
32082177 View in PubMed
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Hypoxia Hangover and Flight Performance After Normobaric Hypoxia Exposure in a Hawk Simulator.

https://arctichealth.org/en/permalink/ahliterature310245
Source
Aerosp Med Hum Perform. 2019 Aug 01; 90(8):720-724
Publication Type
Journal Article
Date
Aug-01-2019
Author
Nikke Varis
Kai I Parkkola
Tuomo K Leino
Source
Aerosp Med Hum Perform. 2019 Aug 01; 90(8):720-724
Date
Aug-01-2019
Language
English
Publication Type
Journal Article
Keywords
Aerospace Medicine
Aircraft
Altitude
Finland
Humans
Hypoxia - epidemiology - etiology
Incidence
Male
Military Personnel - education - statistics & numerical data
Pilots - education - statistics & numerical data
Simulation Training
Abstract
INTRODUCTION: The incidence of hypoxia-like symptoms in military aviators is on the rise. Cases can be related to On-Board Oxygen Generating System (OBOGS) malfunction, air contamination, loss of cabin pressurization, hyperventilation, or a combination of these issues simultaneously. Normobaric hypoxia training in tactical fighter simulations has been conducted in the Finnish Air Force since 2008. This training helps aviators to recognize their individual hypoxia symptoms and refreshes hypoxia emergency procedures in a realistic cockpit.METHODS: A flight mission included three set-ups and a return to base (RTB) after the third set-up. In a tactical Hawk simulator, different concentrations of oxygen were used (8%, 7%, and 6% oxygen in nitrogen) to create normobaric hypoxia exposures. During the RTB, the flight instructor evaluated the subjects' flight performance (N = 16) in order to estimate cognitive functions after hypoxia. A control flight was evaluated before or after the flight with normobaric hypoxia exposure.RESULTS: Instrumental flight rule performance during RTB decreased significantly from 4.81 to 3.63 after normobaric hypoxia and emergency procedures. Some pilots reported fatigue, headache, memory problems, and cognitive impairment as adverse effects up to 12 h after normobaric hypoxia training.DISCUSSION: Hypoxia has a significant effect on flight performance during RTB, even 10 min after hypoxia emergency procedures. Since 100% oxygen was used as emergency oxygen, as in a real aircraft, the oxygen paradox may decrease flight performance. Hypoxia training in tactical fighter simulations provides an opportunity for pilots to also understand the effects of the "hypoxia hangover" on their flight performance.Varis N, Parkkola KI, Leino TK. Hypoxia hangover and flight performance after normobaric hypoxia exposure in a Hawk simulator. Aerosp Med Hum Perform. 2019; 90(8):720-724.
PubMed ID
31331422 View in PubMed
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