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  • 1.
    Abrahamsson, Erik
    et al.
    Lund University, Sweden.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    A living based on breath-hold diving in the Bajau Laut2014In: Human Evolution, ISSN 0393-9375, Vol. 29, no 1-3, p. 171-183Article in journal (Refereed)
    Abstract [en]

    Sea nomads or 'sea people,' namely the 'Bajau Laut' in the Philippines, Malaysia and Indonesia are skilled divers, and many Bajau Laut make a living from freediving. Men do most of the spearfishing, but women also dive, predominantly for gathering sea food. They start to dive at an early age and spend most days of their lives on and in the sea. Our objective was to study their diving and way of life, to reveal if modern humans have the physiological potential for making a living from breath-hold diving for fishing and gathering. Bajau Laut were visited for a total of nine months, during three periods from 2010-2013, in a combined physiological and social-Anthropological study. The diving physiology studies focused on a total of 10 male divers, whose working day diving while spearfishing was logged with time-depth loggers. One group of 5 divers were engaged in shallow (5-7 m) spearfishing with an underwater working time of 60%, when diving for 2-9 h. The other group of 5 divers went to a mean depth of 10 m and had an underwater working time of 50%, when diving for 3-9 h per day. During that time, between one and eight kilograms of coral fish, blow fish, moray eels and octopuses were caught, per diver. Seafood collected by the women included clams, crustaceans, sea weed and sea cucumbers. Life among the Bajau Laut was much like it was 25 years ago, although in some areas the fish stock is diminishing, making it necessary for the Bajau Laut to spend more time in the water to obtain the same quantity of fish. It was concluded that modern humans do possess the physiological qualities necessary for making a living from hunting-gathering via breath-hold diving.

  • 2. Andersson, J
    et al.
    Biasoletto-Tjellström, G
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Reduced pulmonary oxygen uptake during apnea in resting humans: European Underwater and Baromedical Society (EUBS) meeting Copenhagen2003Conference paper (Other academic)
  • 3. Andersson, Johan
    et al.
    Linér, Mats
    Fredsted, Anne
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Cardiovascular and respiratory responses to apneas with and without face immersion in exercising humans2004In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 96, no 3, p. 1005-1010Article in journal (Refereed)
    Abstract [en]

    The effect of the diving response on alveolar gas exchange was investigated in 15 subjects. During steady-state exercise (80 W) on a cycle ergometer, the subjects performed 40-s apneas in air and 40-s apneas with face immersion in cold (10degreesC) water. Heart rate decreased and blood pressure increased during apneas, and the responses were augmented by face immersion. Oxygen uptake from the lungs decreased during apnea in air (-22% compared with eupneic control) and was further reduced during apnea with face immersion (-25% compared with eupneic control). The plasma lactate concentration increased from control (11%) after apnea in air and even more after apnea with face immersion (20%), suggesting an increased anaerobic metabolism during apneas. The lung oxygen store was depleted more slowly during apnea with face immersion because of the augmented diving response, probably including a decrease in cardiac output. Venous oxygen stores were probably reduced by the cardiovascular responses. The turnover times of these gas stores would have been prolonged, reducing their effect on the oxygen uptake in the lungs. Thus the human diving response has an oxygen-conserving effect.

  • 4. Andersson, Johan P A
    et al.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Repeated apneas do not affect the hypercapnic ventilatory response in the short term2009In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 105, no 4, p. 569-74Article in journal (Refereed)
    Abstract [en]

    Long-term training of breath-hold diving reduces the hypercapnic ventilatory response (HCVR), an index of the CO(2) sensitivity. The aim of the present study was to elucidate whether also short-term apnea training (repeating apneas with short intervals) reduces the HCVR, thereby being one contributing factor explaining the progressively increasing breath-holding time (BHT) with repetition of apneas. Fourteen healthy volunteers performed a series of five maximal-duration apneas with face immersion and two measurements of the HCVR, using the Read rebreathing method. The BHT increased by 43% during the series of apneas (P < 0.001). However, the slope of the HCVR test was not affected by the series of apneas, being 2.52 (SD 1.27) and 2.24 (SD 1.14) l min(-1) mmHg(-1) in the control test and in the test performed within 2 min after the last apnea of the series, respectively (NS). Thus, a change in the HCVR cannot explain the observed short-term training effect on BHT.

  • 5.
    Andersson, Johan P.A.
    et al.
    Lunds universitet.
    Biasoletto-Tjellströma, Gustaf
    Schagatay, Erika K.A
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Pulmonary gas exchange is reduced by the cardiovascular diving response in resting humans2008In: Respiratory Physiology & Neurobiology, ISSN 1569-9048, E-ISSN 1878-1519, Vol. 160, no 3, p. 320-324Article in journal (Refereed)
    Abstract [en]

    The diving response reduces the pulmonary O2 uptake in exercising humans, but it has been debated whether this effect is present at rest. Therefore, respiratory and cardiovascular responses were recorded in 16 resting subjects, performing apnea in air and apnea with face immersion in cold water (10 ◦C). Duration of apneas were predetermined to be identical in both conditions (average: 145 s) and based on individual maximal capacity (average: 184 s). Compared to apnea in air, an augmented diving response was elicited by apnea with face immersion. The O2 uptake from the lungs was reduced compared to the resting eupneic control (4.6 ml min−1 kg−1), during apnea in air (3.6 ml min−1 kg−1) and even more so during apnea with face immersion (3.4 ml min−1 kg -1). We conclude that the cardiovascular djustments of the diving response reduces pulmonary gas exchange in resting humans, allowing longer apneas by preserving the lungs’ O2 store for use by vital organs.

  • 6.
    Andersson, Johan P.A.
    et al.
    Department of Animal Physiology, Lund University.
    Linér, Mats H.
    Lund University Hospital.
    Rünow, Elisabeth
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Diving response and arterial oxygen saturation during apnea and exercise in breath-hold divers2002In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 93, no 3, p. 882-886Article in journal (Refereed)
    Abstract [en]

    This study addressed the effects of apnea in air and apnea with face immersion in cold water (10°C) on the diving response and arterial oxygen saturation during dynamic exercise. Eight trained breath-hold divers performed steady-state exercise on a cycle ergometer at 100 W. During exercise, each subject performed 30-s apneas in air and 30-s apneas with face immersion. The heart rate and arterial oxygen saturation decreased and blood pressure increased during the apneas. Compared with apneas in air, apneas with face immersion augmented the heart rate reduction from 21 to 33% (P < 0.001) and the blood pressure increase from 34 to 42% (P < 0.05). The reduction in arterial oxygen saturation from eupneic control was 6.8% during apneas in air and 5.2% during apneas with face immersion (P < 0.05). The results indicate that augmentation of the diving response slows down the depletion of the lung oxygen store, possibly associated with a larger reduction in peripheral venous oxygen stores and increased anaerobiosis. This mechanism delays the fall in alveolar and arterial Po2 and, thereby, the development of hypoxia in vital organs. Accordingly, we conclude that the human diving response has an oxygen-conserving effect during exercise.

  • 7. Andersson, Johan
    et al.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Arterial oxygen desaturation during apnea in humans.1998In: Undersea & Hyperbaric Medicine, ISSN 1066-2936, Vol. 25, no 1, p. 21-25Article in journal (Refereed)
    Abstract [en]

    We studied the effect of the human diving response, defined as bradycardia and reduced peripheral blood flow, on arterial hemoglobin desaturation. We induced a diving response of different magnitudes by using apnea in air and apnea with face immersion. Each of21 subjects performed five apneas in air and five apneas with face immersion in 10°C water. Periods of apnea in both conditions were of the same duration in any individual subject (average: 126.4 s) and the order of air and water was equally distributed among subjects. Heart rate, skin capillary blood flow, arterial blood pressure, arterial hemoglobin oxygen saturation during apneas, and end-tidal fractions of CO2 after apneas were recorded with non-invasive methods. The bradycardia and capillary blood flow reduction during apnea in air (7.8 and 37.7% change from control, respectively) were significantly potentiated by face immersion (13.6 and 55.9%, respectively). Arterial hemoglobin desaturated more during apnea in air (2.7%) compared to during apnea with face immersion (1.4%). We conclude that the potentiation of the human diving response with face immersion in cold water leads to a smaller decrease in arterial hemoglobin saturation, which may reflect an oxygen-conserving effect

  • 8. Andersson, Johan
    et al.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Diving response and apneic time in humans. 1998In: Undersea & Hyperbaric Medicine, ISSN 1066-2936, Vol. 25, no 1, p. 13-19Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to compare apneic time with the human diving response, defined as heart rate (HR) reduction and reduced skin blood flow, in groups with varying degrees of breath-hold diving experience. Apneic time and HR reduction at apneas in air and apneas with face immersion in cold water were thus recorded in nine groups. Skin capillary blood flow was recorded in six of the groups. All subjects received the same information on maximizing apneic duration, and no information about their progress during the apneas. The longest apneas and the most pronounced cardiovascular adjustments were found in the young, trained divers. It was found that apneic time was significantly correlated to HR reduction among the nine groups (r = 0.94, P < 0.001), and to skin capillary blood flow reduction among the six groups where the parameter was measured (r = 0.82, P < 0.05). The correlation between HR reduction and skin capillary blood flow reduction was also significant (r = 0.85, P < 0.05). When the difference in HR reduction and apneic time between apneas in air and apneas with face immersion were compared in the nine groups, it was found that all groups reacted with a more pronounced HR reduction during apneas with face immersion. All groups without prior breath-hold diving experience were found to perform shorter apneas with face immersion than apneas in air, or apneas of the same duration in both conditions, which has been reported in other studies. However, in all groups with diving experience, the apneic time was prolonged during apneas with face immersion. The results of this study suggest an oxygen-conserving effect of the diving response in trained apneic divers

  • 9. Andersson, Johan
    et al.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Effects of lung volume and involuntary breathing movements on the human diving response1997In: European Journal of Applied Physiology, ISSN 1439-6319, Vol. 77, no 1/2, p. 19-24Article in journal (Refereed)
    Abstract [en]

    The effects of lung volume and involuntary breathing movements on the human diving response were studied in 17 breath-hold divers. Each subject performed maximal effort apnoeas and simulated dives by apnoea and cold water face immersion, at lung volumes of 60%, 85%, and 100% of prone vital capacity (VC). Time of apnoea, blood pressure, heart rate, skin capillary blood flow, and fractions of end-expiratory CO 2 and O 2 were measured. The length of the simulated dives was the shortest at 60% of VC, probably because at this level the build up of alveolar CO 2 was fastest. Apnoeas with face immersion at 100% of VC gave a marked drop in arterial pressure during the initial 20?s, probably due to high intrathoracic pressure mechanically reducing venous return. The diving response was most pronounced at 60% of VC. We concluded that at the two larger lung volumes both mechanical factors and input from pulmonary stretch receptors influenced the bradycardia and vasoconstriction, resulting in a non-linear relationship between the breath-hold lung volume and magnitude of the diving response in the near-VC range. Furthermore, the involuntary breathing movements that appeared during the struggle phase of the apnoeas were too small to affect the diving response

  • 10. Andersson, Johan
    et al.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Gislén, Anna
    Holm, Boris
    Cardiovascular responses to cold water immersions of the forearm and face, and their relationship to apnoea2000In: European Journal of Applied Physiology, ISSN 1439-6319, Vol. 83, no 6, p. 566-572Article in journal (Refereed)
    Abstract [en]

    Apnoea as well as cold stimulation of the face or the extremities elicits marked cardiovascular reflexes in humans. The purpose of this study was to investigate whether forearm immersion in cold water has any effect on the cardiovascular responses to face immersion and apnoea. We recorded cardiovascular responses to cold-water immersions of the forearm and face in 19 (part I) and 23 subjects (part II). The experimental protocol was divided in two parts, each part containing four tests: I1, forearm immersion during eupnoea; I2, face immersion during eupnoea; I3, forearm and face immersion during eupnoea; I4, face immersion during apnoea; II1, apnoea without immersion; II2, forearm immersion during apnoea; II3, face immersion during apnoea; and II4, forearm and face immersion during apnoea. The water temperature was 9–11 °C. Cold-water immersion of either the forearm or face was enough to elicit the most pronounced thermoregulatory vasoconstriction during both eupnoea and apnoea. During eupnoea, heart rate responses to forearm immersion (3% increase) and face immersion (9% decrease) were additive during concurrent stimulation (3% decrease). During apnoea, the heart rate responses were not affected by the forearm immersion. The oxygen-conserving diving response seems to dominate over thermoregulatory responses in the threat of asphyxia. During breathing, however, the diving response serves no purpose and does not set thermoregulatory adjustments aside

  • 11.
    Bakker, Emily
    et al.
    Norwegian Univ Sci & Technol, Dept Circulat & Med Imaging, Fac Med, KG Jebsen Ctr Exercise Med, N-7006 Trondheim, Norway..
    Engan, Harald
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. ;LHL Hlth, LHL Klinikkene Raros, Roros, Norway..
    Patrician, Alexander
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Karlsen, Trine
    Norwegian Univ Sci & Technol, Dept Circulat & Med Imaging, Fac Med, KG Jebsen Ctr Exercise Med, N-7006 Trondheim, Norway.;St Olavs Univ Hosp, Trondheim, Norway..
    Wisloff, Ulrik
    Norwegian Univ Sci & Technol, Dept Circulat & Med Imaging, Fac Med, KG Jebsen Ctr Exercise Med, N-7006 Trondheim, Norway..
    Gaustad, Svein Erik
    Norwegian Univ Sci & Technol, Dept Circulat & Med Imaging, Fac Med, KG Jebsen Ctr Exercise Med, N-7006 Trondheim, Norway..
    Acute dietary nitrate supplementation improves arterial endothelial function at high altitude: A double-blinded randomized controlled cross over study2015In: Nitric oxide, ISSN 1089-8603, E-ISSN 1089-8611, Vol. 50, p. 58-64Article in journal (Refereed)
    Abstract [en]

    Introduction: Dietary nitrate (NO3-) supplementation serves as an exogenous source of nitrite (NO3-) and nitric oxide (NO) through the NO3- NO3- NO pathway, and may improve vascular functions during normoxia. The effects of NO3- supplementation in healthy lowlanders during hypobaric hypoxia are unknown. Purpose: Determine the effect of acute oral NO3- supplementation via beetroot juice (BJ) on endothelial function (flow mediated dilation; FMD) in lowlanders at 3700 m. Methods: FMD was measured using ultrasound and Doppler in the brachial artery of 11 healthy subjects (4 females, age 25 +/- 5 yrs; height 1.8 +/- 0.1 m, weight 72 +/- 10 kg) sojourning to high altitude. In a randomized, double-blinded crossover study design, FMD was measured 3 h after drinking BJ (5.0 mmol NO3-) and placebo (PL; 0.003 mmol No-3(-)) supplementation at 3700 m, with a 24-h wash out period between tests. FMD was also measured without any BJ supplementation pre-trek at 1370 m, after 5 days at 4200 m and upon return to 1370 m after 4 weeks of altitude exposure (above 2500 m). The altitude exposure was interrupted by a decent to lower altitude where subjects spent two nights at 1370 m before returning to altitude again. Results: Ten subjects completed the NO3- supplementation. FMD (mean +/- SD) pre-trek value was 6.53 +/- 2.32% at 1370 m. At 3700 m FMD was reduced to 3.84 +/- 1.31% (p < 0.01) after PL supplementation but was normalized after receiving BJ (5.77 +/- 1.14% (p = 1.00). Eight of the subjects completed the interrupted 4-week altitude stay, and their FMD was lower at 4200 m (FMD 3.04 +/- 2.22%) and at post-altitude exposure to 1370 m (FMD 3.91 +/- 2.58%) compared to pre-trek FMD at 1370 m. Conclusion: Acute dietary NO3- supplementation may abolish altitude-induced reduction in endothelial function, and can serve as a dietary strategy to ensure peripheral vascular function in lowland subjects entering high altitude environments. (C) 2015 Elsevier Inc. All rights reserved.

  • 12.
    Bakker, Emily
    et al.
    Norwegian Univ Sci & Technol, N-7034 Trondheim, Norway.
    Engan, Harald
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Patrician, Alexander
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Karlsen, Trine
    Norwegian Univ Sci & Technol, N-7034 Trondheim, Norway.
    Wisloff, Ulrik
    Norwegian Univ Sci & Technol, N-7034 Trondheim, Norway.
    Gaustad, Svein Erik
    Norwegian Univ Sci & Technol, N-7034 Trondheim, Norway.
    Effects Of Dietary Nitrate Supplementation On Endothelial Function At High Altitude2014In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 46, no 5, p. 424-424Article in journal (Other academic)
  • 13. Björkhagen, M
    et al.
    Björkhagen, A
    Engan, Harald
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Role of group dynamics and leadership in the development of acute mountain sickness2014Conference paper (Refereed)
  • 14.
    Björklund, Glenn
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Pettersson, Sofia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Performance predicting factors in prolonged exhausting exercise of varying intensity2007In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 99, no 4, p. 423-429Article in journal (Refereed)
    Abstract [en]

    Several endurance sports, e.g. road cycling, have a varying intensity profile during competition. At present, few laboratory tests take this intensity profile into consideration. Thus, the purpose of this study was to examine the prognostic value of heart rate (HR), lactate (La−1), potassium (K+), and respiratory exchange ratio (RER) performance at an exhausting cycling exercise with varying intensity. Eight national level cyclists performed two cycle tests each on a cycle ergometer: (1) a incremental test to establish VO2max, maximum power (W max), and lactate threshold (VO2LT), and (2) a variable intensity protocol (VIP). Exercise intensity for the VIP was based upon the VO2max obtained during the incremental test. The VIP consisted of six high intense (HI) workloads at 90% of VO2max for 3 min each, interspersed by five middle intense (MI) workloads at 70% of VO2max for 6 min each. VO2 and HR were continuously measured throughout the tests. Venous blood samples were taken before, during, and after the test. Increases in HR, La-, K+, and RER were observed when workload changed from MI to HI workload (P < 0.05). Potassium and RER decreased after transition from HI to MI workloads (P < 0.05). There was a negative correlation between time to exhaustion and decrease in La- concentration during the first MI (r = −0.714; P = 0.047). Furthermore, time to exhaustion correlated with VO2LT calculated from the ramp test (r = 0.738; P = 0.037). Our results suggest that the magnitude of decrease of La−1 between the first HI workload and the consecutive MI workload could predict performance during prolonged exercise with variable intensity

  • 15.
    de Bruijn, Robert
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Richardson, Matt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    The function of the human diving response in the immersed diver2003In: Annual Meeting of the European Underwater and Baromedical Society, Copenhagen, Denmark, 2003Conference paper (Other scientific)
    Abstract [en]

    Background: Much previous research has used apneic face immersion as a model for studying the diving response and its oxygen-conserving effect, however there are few direct comparisons to apneic face immersion with the body immersed. Therefore, it is not settled if the oxygen conserving effect revealed in the dry-body model persists in the immersed diver. In this study we compared the diving response and its effect on arterial oxygen saturation between apnea in horizontal dry-body and immersed-body conditions. Methods: Twelve individually determined near-maximal apneas of the same duration were completed by 17 healthy untrained subjects at rest. Three apneas in each of four categories were performed: dry-body apnea (DA), dry-body, face-immersion apnea (DFIA), immersed-body apnea (IA), and immersed-body, face-immersion apnea (IFIA), in a weighted order. For the face and body immersions, mean water temperature (± SD) was 23.1 ±0.12oC and mean air temperature was 23.3 ±0.32oC. Heart rate and arterial haemoglobin saturation were recorded non-invasively with a pulse oximeter. Results: The diving response was similar for both the dry-body and the immersed body-categories. In all 4 categories the heart rate was reduced. The heart rate reduction in DFIA and IFIA categories was more pronounced than in the DA and IA categories. Heart rate reduction during DA and DFIA was 10% (±1.6) and 18% (±2.8) respectively (P<0.01), while heart rate reduction during IA and IFIA was 9% (±2.6) and 18% (±3.1) respectively (P<0.01). In both the DFIA and IFIA categories there was less desaturation compared to the DA and IA categories (DA vs. DFIA P<0.001, IA vs. IFIA P<0.05). Conclusion: Face immersion enhances the apneic diving response both in the dry- and immersed-body conditions, and is associated with a less pronounced arterial oxygen desaturation. We conclude that the immersed diver may benefit from an oxygen conserving diving response. This study also shows that the dry-body model can be useful for studying the diving response.

  • 16.
    de Bruijn, Robert
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Richardson, Matthew
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Haughey, Helena
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Björklund, Glenn
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Pettersson, Sofia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    High hemoglobin levels in divers may be a result of apnea induced EPO-production2005In: FASEB JOURNAL, 2005, p. A211-A212Conference paper (Refereed)
    Abstract [en]

    Oxygen storage capacity is important for apneic duration and affects performance in endurance sports. We studied if hemoglobin concentration (Hb) was different in divers compared to endurance athletes and untrained subjects and if any differences could be connected to training-induced erythropoietin (EPO) -production. We first compared Hb in 3 groups of subjects: 13 elite apneic divers (35±4 years), 13 elite cross-country skiers (20±1 years) and 23 untrained subjects (29±1 years) with similar weight and height. After 20 min of horizontal rest blood samples were drawn and analysed for Hb using standard methods. In a second experiment, we compared EPO levels before and after a series of 15 maximal apneas in air in 9 previously untrained volunteers (302 years). Apneas were spaced by 2 minutes, the last minute with hyperventilation to produce durations long enough to induce hypoxia. Values were also compared to the EPO levels of a control day without apneas. The apneic divers had higher Hb than untrained subjects (P<0.05) and skiers (P<0.01). After apnea training in untrained subjects EPO levels increased in all subjects, with a mean peak value after 3 h, where the increase was 135 % of the pre apnea value (P<0.05). No increase was observed during the same time period of the control day. We concluded that higher Hb levels in apneic divers may be a result of enhanced EPO-production due to the apnea training.

  • 17.
    de Bruijn, Robert
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Richardson, Matthew
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Haughey, Helena
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Björklund, Glenn
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Hemoglobin levels in elite divers, elite skiers and untrained humans2004Conference paper (Other academic)
  • 18.
    de Bruijn, Robert
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Richardson, Matthew
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Milling, U
    Lemon, H
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Erythropoietin production as a result of repeated apneas2004Conference paper (Refereed)
    Abstract [en]

    Background: It has been known for decades that high altitude hypoxia will lead to increased erythropoiesis. Hypoxia in mainly the kidney results in an increased production of erythropoietin (EPO) stimulating erythropoiesis. High altitude natives display a higher haemoglobin concentration than sea level residents, which in turn increase their haemoglobin concentration as part of the adaptation to altitude. Another group of humans exposed to hypoxia is apneic divers, which may endure transient acute hypoxia, spaced by periods of normal breathing. We recently found higher haemoglobin levels in elite apneic divers, compared to groups of elite skiers and untrained subjects, suggesting that apnea training may induce erythropoiesis in humans. It is well known that diving mammals display high haemoglobin concentrations, and the beneficial effects are obvious: A larger oxygen store before diving prolongs the aerobic dive limit, and a higher haemoglobin concentration may speed up recovery after apneas and act as a buffer against acidosis during the dive. Although our group comparisons reveal a higher haemoglobin concentration in divers, it cannot be determined whether this is a training effect or genetically determined i.e. if individuals with higher concentrations of haemoglobin are more prone to take up apneic diving. Methods: To investigate if apnea training can induce EPO production, 5 previously untrained volunteers (3 men and 2 women, mean ageSD 28 5.5 years) performed 15 maximal apneas in a horizontal position in air. The apneas were grouped in 3 series of 5 apneas and spaced by 2 minutes of which 1 minute was spent slightly hyperventilating, to produce apneas sufficiently long to induce hypoxia. Series were spaced by 10 minutes resting periods. To determine EPO levels, venous blood samples were taken before apneas and directly after the last apnea series, followed by samples 1, 2, 3 and 5 hours after the apneas. Results: Mean baseline EPO before the apneas was 10.2 U/L. In all subjects EPO levels increased during the 5 hours period after the apneas. The time for EPO-peak values were different among individuals. The mean peak value occurred after 3 h, where the mean increase was 12 % of the pre apnea reference value. Conclusion: The results suggest that apnea induced intermittent hypoxia could lead to increased erythropoiesis. The evaluation of these findings in a larger group of subjects, including measurements of the individual circadian variations in EPO production, is in progress.

  • 19.
    de Bruijn, Robert
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Richardson, Matthew
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Increased erythropoietin concentration after repeated apneas in humans2008In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 102, no 5, p. 609-613Article in journal (Refereed)
    Abstract [en]

    Hypoxia-induced increases in red blood cell production have been found in both altitudeadapted populations and acclimatized lowlanders. This process is mediated by erythropoietin (EPO) released mainly by the hypoxic kidney. We have previously observed high hemoglobin concentrations in elite breath-hold divers and our aim was to investigate whether apnea-induced hypoxia could increase EPO concentration. Ten healthy volunteers performed 15 voluntary maximal duration apneas, divided into three seriesof five apneas, each series separated by 10 min of rest. Apneas within series were separated by 2 min and preceded by 1 min of hyperventilation to increase apnea duration and arterial oxygen desaturation. When EPO concentration after serial apneas was compared to baseline values, an average maximum increase of 24% was found (P<0.01). No changes in EPO concentration were observed during a control day without apnea, eliminating possible effects of a diurnal rhythm or blood loss. We therefore conclude that serial apneas increase circulating EPO concentration in humans.

  • 20.
    de Bruijn, Robert
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Richardson, Matthew
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Oxygen-conserving effect of the diving response in the immersed human2009In: Diving and hyperbaric medicine, ISSN 1833-3516, Vol. 39, no 4, p. 193-199Article in journal (Refereed)
    Abstract [en]

    Research involving the human diving response has often simulated diving by apneic face immersion. However, no comparisons of cardiovascular responses and their oxygen- conserving function have been made between simulated diving and apneic face immersion when the body is constantly immersed as during diving. We compared the diving response and its effects on arterial oxygen saturation during apneas in horizontal dry body and immersed body positions. Both air and water temperatures were 23ºC. Twelve near-maximal apneas of the same duration were completed by 17 subjects. Four series of 3 apneas each were conducted: dry body apnea (DA), dry body, face-immersion apnea (DFIA), immersed body apnea (IA), and immersed body, face-immersion apnea (IFIA). Heart rate, skin capillary blood flow, arterial blood pressure, arterial hemoglobin saturation, lung volume and end-tidal PACO2 and PAO2 were recorded non-invasively and responses during apneas were compared among series. Cardiovascular responses showed similar patterns in all series. Face immersion led to a greater reduction in heart rate during apnea, regardless of body immersion. Both DFIA and DA resulted in a transient skin vasoconstriction, more pronounced during DFIA (p<0.001). During body immersion skin vasoconstriction was constant, and neither IA nor IFIA reduced blood flow further. Less arterial desaturation occurred after both FIA series, suggesting an oxygen-conserving effect of the more powerful diving response associated with face immersion in both body positions. We conclude that a similar oxygen-conserving diving response is triggered by apnea and face immersion during full-body immersion in cool water, as in the dry body model.

  • 21.
    Engan, Harald
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Bakker, Emily
    Norwegian Univ Sci & Technol, Trondheim, Norway..
    Patrician, Alexander
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Gaustad, SE
    Norwegian Univ Sci & Technol, Trondheim, Norway..
    Karlsen, T
    Norwegian Univ Sci & Technol, Trondheim, Norway..
    Wisløff, U
    Norwegian Univ Sci & Technol, Trondheim, Norway..
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Reductions in endothelial function during altitude exposure2014Conference paper (Refereed)
  • 22.
    Engan, Harald K.
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Jones, Andrew M.
    Univ Exeter, Coll Life & Environm Sci, Exeter, Devon, England.
    Ehrenberg, Fanny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Acute dietary nitrate supplementation improves dry static apnea performance2012In: Respiratory Physiology & Neurobiology, ISSN 1569-9048, E-ISSN 1878-1519, Vol. 182, no 2-3, p. 53-59Article in journal (Refereed)
    Abstract [en]

    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.

  • 23.
    Engan, Harald K.
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Comparison of two methods potentially reducing metabolism during apnea2015Conference paper (Refereed)
  • 24.
    Engan, Harald K.
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering. LHL Health Röros, Norwegian Heart and Lung Patient Organization, Oslo, Norway.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Fanny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    The effect of climbing mount everest on spleen contraction and increase in hemoglobin concentration during breath holding and exercise2014In: High Altitude Medicine & Biology, ISSN 1527-0297, E-ISSN 1557-8682, Vol. 15, no 1, p. 52-57Article in journal (Refereed)
    Abstract [en]

    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.

  • 25.
    Engan, Harald
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Blood lactate after deep dives in 3 disciplines of competitive apnea2010In: Proceedings from the European Underwater Baromedical Society 36th Annual Meeting Istanbul, Turkey 14-18 Sept 2010, 2010Conference paper (Refereed)
  • 26.
    Engan, Harald
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Fanny
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Enhanced blood boosting spleen contraction after climbing Mt Everest2014Conference paper (Refereed)
  • 27.
    Engan, Harald
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Mattiason, S
    Norwegian Univ Sci & Technol, Trondheim, Norway..
    Bakker, Emily
    Norwegian Univ Sci & Technol, Trondheim, Norway..
    Patrician, Alexander
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Effect of dietary nitrate supplementation on blood pressure in native lowlanders at altitude2014Conference paper (Refereed)
  • 28.
    Engan, Harald
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering. Norwegian Heart & Lung Patient Org, LHL Klinikkene Roros, Roros, Norway.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    "Spleen Contraction and Hemoconcentration" Regarding the Review "Hemoconcentration and Hemostasis During Acute Stress: Interacting and Independent Effects" by Austin et al. 20112015In: Annals of Behavioral Medicine, ISSN 0883-6612, E-ISSN 1532-4796, Vol. 49, no 4, p. 634-635Article in journal (Refereed)
  • 29.
    Engan, Harald
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering. Department of Human Movement Science, Faculty of Social Sciences and Technology Management, NTNU, Trondheim, Norway.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Richardson, Matt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Beekvelt, Mireille
    Department of Human Movement Science, Faculty of Social Sciences and Technology Management, NTNU, Trondheim, Norway.
    Effects of two weeks of daily apnea training on diving response, spleen contraction, and erythropoiesis in novel subjects.2013In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 23, no 3, p. 340-348Article in journal (Refereed)
    Abstract [en]

    Three potentially protective responses to hypoxia have been reported to be enhanced in divers: (1) the diving response, (2) the blood-boosting spleen contraction, and (3) a long-term enhancement of hemoglobin concentration (Hb). Longitudinal studies, however, have been lacking except concerning the diving response. Ten untrained subjects followed a 2-week training program with 10 maximal effort apneas per day, with pre- and posttraining measurements during three maximal duration apneas, and an additional post-training series when the apneic duration was kept identical to that before training. Cardiorespiratory parameters and venous blood samples were collected across tests, and spleen diameters were measured via ultrasound imaging. Maximal apneic duration increased by 44 s (P < 0.05). Diving bradycardia developed 3 s earlier and was more pronounced after training (P < 0.05). Spleen contraction during apneas was similar during all tests. The arterial hemoglobin desaturation (SaO(2)) nadir after apnea was 84% pretraining and 89% after the duration-mimicked apneas post-training (P < 0.05), while it was 72% (P < 0.05) after maximal apneas post-training. Baseline Hb remained unchanged after training, but reticulocyte count increased by 15% (P < 0.05). We concluded that the attenuated SaO(2) decrease during mimic apneas was due mainly to the earlier and more pronounced diving bradycardia, as no enhancement of spleen contraction or Hb had occurred. Increased reticulocyte count suggests augmented erythropoiesis.

  • 30.
    Fahlman, Andreas
    et al.
    Department of Life Sciences Texas A&M- Corpus Christi 6300 Ocean Dr Unit 5892.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Man's place among the diving mammals2014In: Human Evolution, ISSN 0393-9375, Vol. 29, no 1-3, p. 47-66Article in journal (Refereed)
  • 31. Fernández, FA
    et al.
    Patrician, Alexander
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Predicting static and dynamic apnea performance in elite divers using a 2-minute static apnea test2015Conference paper (Refereed)
  • 32.
    Havnes, Marianne B
    et al.
    NTNU, Trondheim Norway.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Rasdal, Kim Vidar
    NTNU, Trondheim Norway.
    Brubakk, Alf O
    NTNU, Trondheim Norway.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Bubbles after deep breath-hold dives in competition2010In: Proceedings from the European Underwater Baromedical Society 36th Annual Meeting Istanbul, Turkey 14-18 Sept 2010, 2010Conference paper (Refereed)
  • 33. Holm, Boris
    et al.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Andersson, Johan
    A possible physiological role of the face as a thermosensor in an ancient water ape and in present day man1999In: Perspectives in Human Biology, Vol. 4, p. 41-46Article in journal (Refereed)
  • 34. Holm, Boris
    et al.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Kobayashi, Toshio
    Masuda, Atsuko
    Ohdaira, Tetsuro
    Honda, Yoshiyuki
    Cardiovascular Change in Elderly Male Breath-hold Divers (Ama) and their Socio-economical Background at Chikura in Japan.1998In: Applied Human Science;Journal of Physiological Anthropology, ISSN 1341-3473, Vol. 17, no 5, p. 181-187Article in journal (Refereed)
    Abstract [en]

    The Ama have existed for more than 2000 years in Japan and Korea. They have been diving for seaweed and molluscs. Their traditional way of fishing, with goggles or a mask, but without a wetsuit, is still practised as a result of laws against overfishing. We investigated cardiovascular diving responses, expressed as heart rate (HR) reduction, peripheral vasoconstriction indicated by skin blood flow (SkBF) and mean arterial blood pressure (MAP) during breath-hold face immersion in a group of eight elderly male Ama at Chikura, Japan. Their data were compared to those from three other groups: a) elderly non-divers; b) young divers and c) young non-divers. Our previous studies have shown that young divers show a more pronounced bradycardia than young non-divers. The present study of elderly Ama and elderly non-divers was performed to investigate if this difference persists in old age. We found that, in spite of many years of diving experience, HR reduction of the elderly professional divers observed during face immersion did not differ from that of elderly non-divers, but it was much less pronounced than in the two younger groups. We conclude that even if a well-developed diving response at young age has been reduced to the level of non-divers, the Ama are still able to continue their work of diving in old age. Ama that has been a traditionally female occupation, is mostly practised by men at Chikura today. No young have been recruited for this profession. Therefore, the present Ama are senior and the traditional breath-hold diving will probably cease to exist in the near future. The probable reasons for these changes are discussed

  • 35.
    Johansson, Hampus
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Engan, Harald K.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Melin, Maja
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Patrician, Alexander
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    No effect of dietary nitrate on the human diving response in dry and wet apneas2015Conference paper (Refereed)
  • 36.
    Johansson, O
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Patrician, Alexander
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Wisniewski, Sarah
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Spirometry during ascent to altitude and its correlation to acute mountain sickness2014Conference paper (Refereed)
    Abstract [en]

    Easily measurable variables capable of predicting altitude sickness, before symptom onset, would be beneficial for those requiring slower ascent or even medical attention. Unfortunately few such reliable factors exist. Our objective was to test respiratory function during ascent in the Nepali Himalaya, to see if any correlations with altitude sickness, expressed by Lake Louis scores, could be identified. Eleven healthy subjects (six male and five female, mean(SD) age 26(9.3) years) travelled from 1370m to 4200m, and spent 9 days at or above this altitude. Variables of lung function, including vital capacity, forced expiratory volume over one second (FEV1) and peak expiratory flow were measured using a portable spirometer every-other morning before breakfast in the standing position. Subjects also completed the Lake Louis self-assessment questionnaire daily. Mean(SD) vital capacity and FEV1 decreased from 5.3(1.4) L and 4.5(0.9) L at 1370m to 4.8(1.4) L and 4.2(1.0) L at 4200m, respectively (p<0.05), but did not correlate to Lake Louis scores. Mean(SD) peak expiratory flow was 9.4(2.3) L/s at 1370m and did not change during ascent. However once at 4200m it increased from 9.2(2.7) L/s to 9.6(2.4) L/s following the stay at altitude (p<0.05). Interestingly, an absolute change in peak expiratory flow at 4200m compared to 1370m, showed a high correlation to Lake Louis scores at 3700m and 4200m (r= -0.971; p<0.001). We conclude that peak expiratory flow values were closely related to signs of altitude sickness, and should be explored further for determining their predictive value.

  • 37.
    Johansson, Orio
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Lung-packing and stretching increases vital capacity in recreational freedivers2012In: The European respiratory journal. Supplement, ISSN 0904-1850, Vol. 40, no Supplement 56, p. 149s-Article in journal (Refereed)
  • 38.
    Johansson, Orio
    et al.
    Lund University, Sweden.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Sara Campbell, World Champion in Deep Diving After 9 Months of Training – How Is This Possible?2014In: Human Evolution, ISSN 0393-9375, Vol. 29, no 1-3, p. 67-73Article in journal (Refereed)
  • 39.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Björklund, Glenn
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Pettersson, Sofia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Performance predicting factors during prolonged non-steady state cycling2006In: Book of Abstracts of the 11th Annual Congress of the European College of Sport Science in Lausanne, Switzerland from 5-8 July 2006, 2006Conference paper (Refereed)
  • 40. Lodin-Sundström, Angelica
    et al.
    Engan, H
    Richarson, Matt
    Schagatay, Erika
    Oxygen conservation by the diving response improved after 2 weeks of apnea training2009In: 14th Annual Congress of the ECSS in Oslo, Norway 24-27 June 2009, 2009Conference paper (Refereed)
  • 41.
    Lodin-Sundström, Angelica
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Engan, Harald K.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Mechanisms underlying spleen contraction during apneic diving2015Conference paper (Refereed)
  • 42.
    Lodin-Sundström, Angelica
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Engan, Harald
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Schagatay, Fanny
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Effects of warm-up on static apnea performance2010In: Proceedings from the European Underwater Baromedical Society 36th Annual Meeting Istanbul, Turkey 14-18 Sept 2010, 2010Conference paper (Refereed)
  • 43.
    Lodin-Sundström, Angelica
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Lunde, Alexander
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Palm, Oscar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Nilsson, Simon
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Swedish Winter Sports Research Centre, Östersund, Sweden..
    Blood boosting by spleen contraction during exercise at different altitudes.2014Conference paper (Refereed)
    Abstract [en]

    Spleen contraction with release of erythrocytes improves human performance in hypoxic situations. Hypoxia and exercise are known to separately trigger the response. We studied the response to exercise at different altitudes during a two week ascent to 4200m. Eleven healthy lowlanders (five women; mean±SD age 26±3 years) did a modified Harvard step test at 1370, 3700 and 4200m altitude after 10 min rest. Spleen volume was measured via ultrasonic imaging and capillary hemoglobin (Hb) with Hemocue before and after tests. Mean(±SD) baseline spleen volume at 1370m was 250(±9)ml, after exercise it had been reduced to 207(±10)ml (P<0.01). At 3700m, baseline spleen volume was 230(±9)ml, after exercise 173(±10)ml (P<0.01). At 4200m baseline was 211(±10)ml, after exercise 158(±13)ml (P<0.05). Baseline Hb increased by altitude from 137.8(±3.8)g/L at 1370m, to 141.2(±2.3)g/L at 3700m and 151.4(±2.3)g/L at 4200m (P<0.01). At all locations Hb had increased after exercise; at 1370m by 7.2%, at 3700m by 6.2% and at 4200m by 3.2%. This suggests the spleen was already somewhat contracted during rest at higher altitudes, which was reflected by the progressively higher baseline Hb. Exercise initiated spleen contraction of similar magnitude at all altitudes, and post exercise values were progressively smaller with altitude. Hb was also elevated at all exercise tests, but not directly reflecting the spleen volume reductions, possibly due to differences in peak times. This study suggests that baseline spleen volume is affected by altitude which elevates Hb and that contraction after exercise results in further Hb elevation.

  • 44.
    Lodin-Sundström, Angelica
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Richardson, Matt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Biphasic spleen contraction during apnea in divers suggests chemoreceptor input2009In: Abstract EUBS Aberdeen, UK, 25-28 Aug, 2009., 2009Conference paper (Refereed)
  • 45.
    Lodin-Sundström, Angelica
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Richardson, Matt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Spleen contraction and erythrocyte release in elite apnea divers during submaximal and maximal effort apneas2009In: 14th Annual Congress of the ECSS in Oslo, Norway 24-27 June 2009, 2009Conference paper (Refereed)
  • 46.
    Lodin-Sundström, Angelica
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Spleen contraction develops progressively across long apneas: Meeting abstract2009In: Journal of Physiological Sciences, Suppl 1, 2009, Tokyo: Springer, 2009, p. 504-504Conference paper (Refereed)
  • 47.
    Lodin-Sundström, Angelica
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Spleen contraction during 20 min normobaric hypoxia and 2 min apnea in humans2010In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 81, no 6, p. 545-549Article in journal (Refereed)
    Abstract [en]

    Introduction: Spleen contraction occurs in humans during exercise, apnea, and simulated altitude, resulting in ejection of stored red blood cells into circulation. The mechanisms responsible for initiating the contraction are not fully known: hypoxia is likely involved, but other, unknown factors may also contribute. To reveal the initiating factors, we studied its occurrence in two different situations involving similar reductions in arterial oxygen saturation (SaO2). We hypothesized that similar spleen responses would result if the level of hypoxia is the main factor involved. Methods: Five female and four male healthy volunteers performed two different trials on separate days: 1)20 min of normobaric hypoxic breathing (14.2% oxygen); and II) 2 min of apnea after a deep inspiration of air. Both trials started and ended with 10 min of sitting eupneic rest. Spleen diameter was intermittently measured via ultrasonic imaging in three dimensions to calculate volume. S aO2 and heart rate (HR) were recorded continuously with a pulse oximeter. Results: Exposures resulted in similar nadir SaO 2: 87% after normobaric hypoxia and 89% after apnea. During normobaric hypoxia, spleen volume was reduced by 16% and during apnea by 34%. HR increased by 7% during normobaric hypoxia, but fell by 25% during apnea. Discussion: Both normobaric hypoxia and apnea induced spleen contraction, but despite similar levels of SaO2 apnea evoked a significantly stronger response, possibly due to hypercapnia, faster desaturation, ortheapneic stimulus in itself. Spleen contraction may facilitate adaptation to altitude and to apneic diving by elevating blood gas storage capacity.

  • 48.
    Lodin-Sundström, Angelica
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Söderberg, Daniel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Ekstam, Marcus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Swedish Winter Sports Research Centre, Östersund, Sweden..
    Exercise at simulated altitude enhances spleen contraction2014Conference paper (Refereed)
  • 49.
    Melin, Maja
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Johansson, Hampus
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Patrician, Alexander
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Engan, Harald K.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    The effect of dietary nitrate on spleen contraction and Hb increase during apnea2015Conference paper (Refereed)
  • 50.
    Patrician, Alexander
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Engan, Harald K.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Norwegian Heart & Lung Patient Org, LHL Klinikkene Roros, Oslo, Norway.
    Lundsten, David
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Grote, Ludger
    Sahlgrens Univ Hosp, Sleep Disorders Ctr, Pulm Med, Gothenburg.
    Vigetun-Haughey, Helena
    Capio St Gorans Hosp, Dept Clin Physiol, Stockholm.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    The Effect of Dietary Nitrate on Nocturnal Sleep-Disordered Breathing and Arterial Oxygen Desaturation at High Altitude2018In: High Altitude Medicine & Biology, ISSN 1527-0297, E-ISSN 1557-8682, Vol. 19, no 1, p. 21-27Article in journal (Refereed)
    Abstract [en]

    Patrician, Alexander, Harald Engan, David Lundsten, Ludger Grote, Helena Vigetun-Haughey, and Erika Schagatay. The effect of dietary nitrate on nocturnal sleep-disordered breathing and arterial oxygen desaturation at high altitude. High Alt Med Biol 00:000-000, 2017.Sleep-disordered breathing and fluctuations in arterial oxygen saturation (SaO(2)) are common during sleep among lowlanders ascending to high altitude. Dietary nitrate (NO3-) supplementation has been shown to lower the O-2 consumption in various conditions. Our objective was to investigate whether dietary NO3- could reduce sleep-disordered breathing and SaO(2) desaturation during sleep at altitude. Cardiorespiratory responses during sleep were measured in 10 healthy lowlanders at 330m and then again in the Himalayas at 3700-4900m. Each subject received two 70mL shots of either beetroot juice (BR; approximate to 5.0mmol NO3- per shot) or placebo (PL: approximate to 0.003mmol NO3- per shot) in a single-blinded, weighted order over two consecutive nights at altitude. At 2.5-4.5 hours into sleep at altitude, BR increased the SaO(2) desaturation drop (4.2 [0.1]% with PL vs. 5.3 [0.4]% with BR; p=0.024) and decreased the SaO(2) desaturation duration (14.1 [0.9] seconds with PL to 11.1 [0.9] seconds with BR; p=0.0.041). There was a reduction in breaths with flow limitation (p=0.025), but no changes in Apnea-Hypopnea Index (AHI), mean and minimum SaO(2). The study suggests BR supplementation does not improve AHI or oxygenation, but may increase fluctuations in arterial O-2 saturation during sleep at altitude in native lowlanders.

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