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- Engan, Harald K., et al.
(författare)
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Acute dietary nitrate supplementation improves dry static apnea performance
- 2012
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Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 182:2-3, s. 53-59
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Tidskriftsartikel (refereegranskat)abstract
- Acute dietary nitrate (NO3-) supplementation has been reported to lower resting blood pressure, reduce the oxygen (O-2) cost of sub-maximal exercise, and improve exercise tolerance. Given the proposed effects of NO3- on tissue oxygenation and metabolic rate, it is possible that NO3- supplementation might enhance the duration of resting apnea. If so, this might have important applications both in medicine and sport. We investigated the effects of acute NO3- supplementation on pre-apnea blood pressure, apneic duration, and the heart rate (HR) and arterial O-2 saturation (SaO(2)) responses to sub-maximal and maximal apneas in twelve well-trained apnea divers. Subjects were assigned in a randomized, double blind, crossover design to receive 70 ml of beetroot juice (BR; containing similar to 5.0 mmol of nitrate) and placebo juice (PL; similar to 0.003 mmol of nitrate) treatments. At 2.5 h post-ingestion, the subjects completed a series of two 2-min (sub-maximal) static apneas separated by 3 min of rest, followed by a maximal effort apnea. Relative to PL, BR reduced resting mean arterial pressure by 2% (PL: 86 +/- 7 vs. BR: 84 +/- 6 mmHg; P = 0.04). The mean nadir for SaO(2) after the two sub-maximal apneas was 97.2 +/- 1.6% in PL and 98.5 +/- 0.9% in BR (P = 0.03) while the reduction in HR from baseline was not significantly different between PL and BR. Importantly, BR increased maximal apneic duration by 11% (PL: 250 +/- 58 vs. BR: 278 +/- 64 s; P = 0.04). In the longer maximal apneas in BR, the magnitude of the reductions in HR and SaO(2) were greater than in PL (P <= 0.05). The results suggest that acute dietary NO3- supplementation may increase apneic duration by reducing metabolic costs. (c) 2012 Elsevier B.V. All rights reserved.
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- Engan, Harald K, et al.
(författare)
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Are web-based questionnaires accepted in patients attending rehabilitation?
- 2016
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Ingår i: Disability and Rehabilitation. - : Informa UK Limited. - 0963-8288 .- 1464-5165. ; 38:24-26, s. 2406-2412
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The aim of the present paper was to study preferences for web based self-administered questionnaires (web SAQs) vs. paper-based self-administered questionnaires (paper SAQs) and to evaluate the feasibility of using web SAQs in patients referred to cardiac, lung, occupational and cancer rehabilitation programs. Methods: The patients were approached by mail and given the choice to answer the compulsory SAQs either on paper or on a web-based platform. Results: Hundred and twenty seven out of 183 eligible patients (69.3%) were willing to participate and 126 completed the study. Web SAQs were preferred by 77.7%, and these patients were significantly younger, more often cohabiting and tended to have higher level of education than paper SAQ users. Mean number of data missing per patient was less among the web SAQ users than the paper SAQ users (0.55 vs. 2.15, p <0.001). Costs related to human resources were estimated to be 60% lower with web SAQs compared to paper SAQs. Conclusions: Web SAQs were well accepted among the patients scheduled for rehabilitation, led to less missing data and considerable cost savings related to human resources. Patients referred to rehabilitation should be offered the choice to complete self-administered questionnaires on internet platforms when internet access is common and available.
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| 6. |
- Engan, Harald K., et al.
(författare)
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The effect of climbing mount everest on spleen contraction and increase in hemoglobin concentration during breath holding and exercise
- 2014
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Ingår i: High Altitude Medicine & Biology. - : Mary Ann Liebert Inc. - 1527-0297 .- 1557-8682. ; 15:1, s. 52-57
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Tidskriftsartikel (refereegranskat)abstract
- Release of stored red blood cells resulting from spleen contraction improves human performance in various hypoxic situations. This study determined spleen volume resulting from two contraction-evoking stimuli: breath holding and exercise before and after altitude acclimatization during a Mount Everest ascent (8848m). Eight climbers performed the following protocol before and after the climb: 5min ambient air respiration at 1370m during rest, 20min oxygen respiration, 20min ambient air respiration at 1370m, three maximal-effort breath holds spaced by 2min, 10min ambient air respiration, 5min of cycling at 100 W, and finally 10min ambient air respiration. We measured spleen volume by ultrasound and capillary hemoglobin (HB) concentration after each exposure, and heart rate (HR) and arterial oxygen saturation (Sao2) continuously. Mean (SD) baseline spleen volume was unchanged at 213 (101) mL before and 206 (52) mL after the climb. Before the climb, spleen volume was reduced to 184 (83) mL after three breath holds, and after the climb three breath holds resulted in a spleen volume of 132 (26) mL (p=0.032). After exercise, the preclimb spleen volume was 186 (89) mL vs. 112 (389) mL) after the climb (p=0.003). Breath hold duration and cardiovascular responses were unchanged after the climb. We concluded that spleen contraction may be enhanced by altitude acclimatization, probably reflecting both the acclimatization to chronic hypoxic exposure and acute hypoxia during physical work. © Copyright 2014, Mary Ann Liebert, Inc. 2014.
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| 7. |
- Holmström, Pontus
(författare)
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Protective Responses to Freediving Reveal High-Altitude Tolerance
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- High-altitude mountaineers - just as freedivers - are exposed to hypoxia. During freediving, the diving response leads to reduced oxygen consumption, and splenic contraction increases circulating hemoglobin concentration (Hb), which enhances freediving performance. It is unknown whether these responses relate with altitude-induced responses and what role the spleen has at high-altitude. My thesis aimed to explore whether associations exist between these apnea-induced responses and tolerance to high-altitude. In five studies, I investigated the diving response and splenic contraction during apnea in a range of groups, including recreational trekkers, elite climbers, indigenous Sherpa (living high and living low) and endurance athletes, at low-altitude and at high-altitude. My primary finding was striking: the diving response and splenic size were associated with tolerance to high-altitude; lowlanders with a strong diving response and large spleen showed less symptoms of acute mountain sickness at high-altitude. I also found that groups often exposed to high-altitude have larger spleens compared with groups who reside at sea-level. Interestingly, the Sherpa living high had larger spleens compared with Sherpa living low. Another important finding was that the spleen is reduced in size by ~14% per 1000 m of ascent in lowlanders, which was associated with enhanced baseline Hb. I also found that endurance athletes, who are dependent on efficient oxygen delivery, have larger spleens compared with untrained individuals. I conclude, that a strong diving response and a large spleen may be characteristics of high-altitude tolerant lowlanders, and could possibly be used to predict high-altitude sensitivity. Studies 1-4 suggest that a large spleen is a favourable trait in several groups to tolerate high-altitude hypoxia, likely by its ability to regulate circulating Hb. Sherpa had larger spleens compared with lowlanders, indicating that genetic factors influence splenic size, while the finding that Sherpa living high had larger spleens than Sherpa living low indicate that splenic size also is influenced by environmental exposure. Study 4 revealed a tonic splenic contraction in lowlanders at high-altitude, suggesting that the Hb regulating function may be important before EPO-induced red cell increase occurs, thereby aiding individual acclimatization.
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