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  • 1. Andersson, J
    et al.
    Biasoletto-Tjellström, G
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Reduced pulmonary oxygen uptake during apnea in resting humans: European Underwater and Baromedical Society (EUBS) meeting Copenhagen2003Konferensbidrag (Övrigt vetenskapligt)
  • 2. Andersson, Johan
    et al.
    Linér, Mats
    Fredsted, Anne
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Cardiovascular and respiratory responses to apneas with and without face immersion in exercising humans2004Ingår i: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 96, nr 3, s. 1005-1010Artikel i tidskrift (Refereegranskat)
    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.

  • 3. Andersson, Johan P A
    et al.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Repeated apneas do not affect the hypercapnic ventilatory response in the short term2009Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 105, nr 4, s. 569-74Artikel i tidskrift (Refereegranskat)
    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.

  • 4.
    Andersson, Johan P.A.
    et al.
    Lunds universitet.
    Biasoletto-Tjellströma, Gustaf
    Schagatay, Erika K.A
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Pulmonary gas exchange is reduced by the cardiovascular diving response in resting humans2008Ingår i: Respiratory Physiology & Neurobiology, ISSN 1569-9048, E-ISSN 1878-1519, Vol. 160, nr 3, s. 320-324Artikel i tidskrift (Refereegranskat)
    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.

  • 5.
    Andersson, Johan P.A.
    et al.
    Department of Animal Physiology, Lund University.
    Linér, Mats H.
    Lund University Hospital.
    Rünow, Elisabeth
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Diving response and arterial oxygen saturation during apnea and exercise in breath-hold divers2002Ingår i: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 93, nr 3, s. 882-886Artikel i tidskrift (Refereegranskat)
    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.

  • 6. Andersson, Johan
    et al.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
    Arterial oxygen desaturation during apnea in humans.1998Ingår i: Undersea & Hyperbaric Medicine, ISSN 1066-2936, Vol. 25, nr 1, s. 21-25Artikel i tidskrift (Refereegranskat)
    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

  • 7. Andersson, Johan
    et al.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Diving response and apneic time in humans. 1998Ingår i: Undersea & Hyperbaric Medicine, ISSN 1066-2936, Vol. 25, nr 1, s. 13-19Artikel i tidskrift (Refereegranskat)
    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

  • 8. Andersson, Johan
    et al.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Effects of lung volume and involuntary breathing movements on the human diving response1997Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, Vol. 77, nr 1/2, s. 19-24Artikel i tidskrift (Refereegranskat)
    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

  • 9. Andersson, Johan
    et al.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Gislén, Anna
    Holm, Boris
    Cardiovascular responses to cold water immersions of the forearm and face, and their relationship to apnoea2000Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, Vol. 83, nr 6, s. 566-572Artikel i tidskrift (Refereegranskat)
    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

  • 10.
    Björklund, Glenn
    et al.
    Mittuniversitetet, Fakulteten för humanvetenskap, Institutionen för hälsovetenskap.
    Holmberg, Hans-Christer
    Mittuniversitetet, Fakulteten för humanvetenskap, Institutionen för hälsovetenskap.
    A comparison between elite and well trained cross-country skiers in physiological response to variations in intensity during prolonged exercise2008Ingår i: 13th Annual Congress of the European College of Sports Science, Cologne: Sportools , 2008, s. 522-Konferensbidrag (Refereegranskat)
    Abstract [en]

     

    Introduction: Cross-country ski racing includes continual variations in intensity due to terrain and tactics {Mygind et al 1994; Norman et al 1989). Consequently, the recovery between periods with higher intensity might affect the outcome of the race. Both blood metabolites and respiratory variables are used for standard performance evaluations for endurance athletes, although there is a lack information if respiratory variables respond similar to blood lactate and acid/base values during prolonged variable exercise. Therefore, the aims with the present study were to 1) evaluate whether respiratory variables are associated with blood lactate and acid/base variables, 2) how/if these variables might predict physical performance and 3) whether a calculated heart rate-oxygen uptake (HR-VO2) relationship is valid during variable intensity exercise. Methods: 12 cross-country skiers classified as elite (E, n=6) and formerly well-trained (FWT, n=6) performed two roller ski tests. 1) An incremental test to establish maximal oxygen uptake (VO2max), maximum heart rate (HRmax) and lactate threshold (LT). Submaximal and maximal VO2 and HR during the incremental test were used for calculating the individual HR-VO2 linear relationship and 2) a 48-min long variable intensity protocol (VIP) at alternating exercise intensities, 90% (HI90) and 70% (MI70) of VO2max. Cardio-respiratory variables and venous blood samples were continuously collected throughout the VIP. Comparisons between E and FWT were performed using a two-tailed unpaired Student’s t-test and a ANCOVA analysis was used to determine which physiological variable best could prognosticate time to exhaustion (TTE). A simple linear regression was used to establish the relationship between HR and VO2. Results: Blood lactate concentrations [La] were higher and base excess [BE] lower for FWT from the first MI70 (P<0.05). FWT had augmented RER during all HI90 and an elevated VE/VO2 during the second and third HI90 in comparison to E (P<0.05). The expected HR were higher during the MI70 exercise intensities regardless of group affiliation (P<0.05). The blood [La] response predicted time to exhaustion earlier than respiratory variables (P<0.05). Discussion: Blood lactate and acid/base fluctuations were not reflected by RER and the ventilatory equivalents. Furthermore, blood lactate is to prefer, in comparison to ventilatory variables, to study performance related recovery processes during endurance exercise with variations in intensity. The expected HR-VO2 relationship was not valid during VIP.

     

  • 11.
    Björklund, Glenn
    et al.
    Mittuniversitetet, Fakulteten för humanvetenskap, Institutionen för hälsovetenskap.
    Pettersson, Sofia
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Performance predicting factors in prolonged exhausting exercise of varying intensity2007Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 99, nr 4, s. 423-429Artikel i tidskrift (Refereegranskat)
    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

  • 12.
    de Bruijn, Robert
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Cardiovascular and hematological responses to voluntary apnea in humans2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis deals with cardiovascular and hematological responses to voluntary apnea in

    humans, with a special focus on O2 usage and storage. Humans, and many other air‐breathing

    animals, respond to apnea (breath holding) with a collection of interacting cardiovascular

    reflexes, which are collectively called the diving response. In humans, the main characteristics of

    the diving response are a reduction in heart rate (bradycardia), decreased cardiac output,

    peripheral vasoconstriction and increased arterial blood pressure. Another response during

    apnea in mammals, more recently also observed in man, is a transient increase in hemoglobin

    concentration across a series of apneas, probably due a reduction in spleen size. There may also

    be long‐term effects on erythropoiesis in the apneic diver, as suggested by high hemoglobin

    levels observed in divers. The focus of the included studies are the short transient diving

    response (I), the more slowly occurring transient hematological changes to apnea, most likely

    related to a reduction in spleen size (II), and the possible effects of repeated apnea on serum

    erythropoietin concentration (III).

    I) The aim was to study the effects of body immersion on the O2‐conserving effect of the

    human diving response. The results showed that, regardless of body immersion, apnea with face

    immersion causes a stronger cardiovascular diving response compared to during apnea alone,

    leading to a smaller reduction in arterial oxygen saturation levels. Thus the diving response is

    triggered and conserves O2 even during whole‐body immersion, which has previously only been

    observed during apnea without whole‐body immersion.

    II) The aim was to study hematological responses to voluntary repeated maximal‐duration

    apneas in divers and non‐divers. Increases in hemoglobin concentration were found across a

    series of 3 apneas in elite breath‐hold divers, elite cross‐country skiers and untrained subjects.

    However a larger increase in hemoglobin was found in divers compared to non‐divers, which

    suggests a possible training effect of their extensive apnea‐specific training. In contrast, physical

    endurance training does not appear to affect the hematological response to apnea.

    III) The aim was to study the effects of serial voluntary apnea on the serum erythropoietin

    concentration. In a comparison between elite breath‐hold divers and subjects untrained in apnea,

    divers were found to have a 5% higher resting hemoglobin concentration. An average maximum

    increase in erythropoietin of 24 % was found in untrained subjects after 15 maximal duration

    apneas, preceded by 1 min of hyperventilation. This suggests a possible erythropoietic effect of

    apnea‐induced hypoxia, which may connect the increased resting hemoglobin found in divers to

    their apnea‐specific training.

    It was concluded from these studies that man responds to apnea with a series of different

    adjustments in order to limit O2 usage and increase O2 storage: The classical diving response is

    effectively restricting O2‐consumption also during full immersion, the spleen related hemoglobin

    increase occurs in both divers and non‐divers with different levels of physiological training, but

    is more prominent in divers, and finally, the observed high levels of hemoglobin concentration in

    divers may be related to enhanced erythropoiesis during dive training.

  • 13.
    de Bruijn, Robert
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Richardson, Matt
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    The function of the human diving response in the immersed diver2003Ingår i: Annual Meeting of the European Underwater and Baromedical Society, Copenhagen, Denmark, 2003Konferensbidrag (Övrigt vetenskapligt)
    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.

  • 14.
    de Bruijn, Robert
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Richardson, Matthew
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Haughey, Helena
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Björklund, Glenn
    Mittuniversitetet, Fakulteten för humanvetenskap, Institutionen för hälsovetenskap.
    Pettersson, Sofia
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    High hemoglobin levels in divers may be a result of apnea induced EPO-production2005Ingår i: FASEB JOURNAL, 2005, s. A211-A212Konferensbidrag (Refereegranskat)
    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.

  • 15.
    de Bruijn, Robert
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Richardson, Matthew
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Milling, U
    Lemon, H
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Erythropoietin production as a result of repeated apneas2004Konferensbidrag (Refereegranskat)
    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.

  • 16.
    de Bruijn, Robert
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Richardson, Matthew
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Increased erythropoietin concentration after repeated apneas in humans2008Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 102, nr 5, s. 609-613Artikel i tidskrift (Refereegranskat)
    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.

  • 17.
    de Bruijn, Robert
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Richardson, Matthew
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Oxygen-conserving effect of the diving response in the immersed human2009Ingår i: Diving and hyperbaric medicine, ISSN 1833-3516, Vol. 39, nr 4, s. 193-199Artikel i tidskrift (Refereegranskat)
    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.

  • 18.
    Engan, Harald
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Lodin-Sundström, Angelica
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Blood lactate after deep dives in 3 disciplines of competitive apnea2010Ingår i: Proceedings from the European Underwater Baromedical Society 36th Annual Meeting Istanbul, Turkey 14-18 Sept 2010, 2010Konferensbidrag (Refereegranskat)
  • 19.
    Havnes, Marianne B
    et al.
    NTNU, Trondheim Norway.
    Lodin-Sundström, Angelica
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Rasdal, Kim Vidar
    NTNU, Trondheim Norway.
    Brubakk, Alf O
    NTNU, Trondheim Norway.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Bubbles after deep breath-hold dives in competition2010Ingår i: Proceedings from the European Underwater Baromedical Society 36th Annual Meeting Istanbul, Turkey 14-18 Sept 2010, 2010Konferensbidrag (Refereegranskat)
  • 20. Holm, Boris
    et al.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Andersson, Johan
    A possible physiological role of the face as a thermosensor in an ancient water ape and in present day man1999Ingår i: Perspectives in Human Biology, Vol. 4, s. 41-46Artikel i tidskrift (Refereegranskat)
  • 21. Holm, Boris
    et al.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    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.1998Ingår i: Applied Human Science;Journal of Physiological Anthropology, ISSN 1341-3473, Vol. 17, nr 5, s. 181-187Artikel i tidskrift (Refereegranskat)
    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

  • 22. Lodin-Sundström, Angelica
    et al.
    Engan, H
    Richarson, Matt
    Schagatay, Erika
    Oxygen conservation by the diving response improved after 2 weeks of apnea training2009Ingår i: 14th Annual Congress of the ECSS in Oslo, Norway 24-27 June 2009, 2009Konferensbidrag (Refereegranskat)
  • 23.
    Lodin-Sundström, Angelica
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Engan, Harald
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Schagatay, Fanny
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Effects of warm-up on static apnea performance2010Ingår i: Proceedings from the European Underwater Baromedical Society 36th Annual Meeting Istanbul, Turkey 14-18 Sept 2010, 2010Konferensbidrag (Refereegranskat)
  • 24.
    Lodin-Sundström, Angelica
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Richardson, Matt
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Biphasic spleen contraction during apnea in divers suggests chemoreceptor input2009Ingår i: Abstract EUBS Aberdeen, UK, 25-28 Aug, 2009., 2009Konferensbidrag (Refereegranskat)
  • 25.
    Lodin-Sundström, Angelica
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Richardson, Matt
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Spleen contraction and erythrocyte release in elite apnea divers during submaximal and maximal effort apneas2009Ingår i: 14th Annual Congress of the ECSS in Oslo, Norway 24-27 June 2009, 2009Konferensbidrag (Refereegranskat)
  • 26.
    Lodin-Sundström, Angelica
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Spleen contraction develops progressively across long apneas: Meeting abstract2009Ingår i: Journal of Physiological Sciences, Suppl 1, 2009, Tokyo: Springer, 2009, s. 504-504Konferensbidrag (Refereegranskat)
  • 27.
    Lodin-Sundström, Angelica
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Spleen contraction during 20 min normobaric hypoxia and 2 min apnea in humans2010Ingår i: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 81, nr 6, s. 545-549Artikel i tidskrift (Refereegranskat)
    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.

  • 28. Richardson, M
    et al.
    de Bruijn, Robert
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Haughey, Helena
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Andersson, J
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    The incidence of hematocrit increase during apnea in non divers: European Underwater and Baromedical Society (EUBS) meeting Copenhagen, Denmark2003Konferensbidrag (Övrigt vetenskapligt)
  • 29.
    Richardson, Matt
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    de Bruijn, Robert
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Hypoxia augments apnea-induced increase in hematocrit and hemoglobin concentration2009Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 105, nr 1, s. 63-68Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Increased hemoglobin concentration (Hb) and hematocrit (Hct) attributable to spleen contraction raises blood gas storage capacity during apnea, but the mechanisms that trigger this response have not been clarified. We focused on the role of hypoxia in triggering these Hb and Hct elevations. After horizontal rest for 20 min, 10 volunteers performed 3 maximal apneas spaced by 2 min, each preceded by a deep inspiration of air. The series was repeated using the same apneic durations but after 1 min of 100% oxygen breathing and oxygen inspiration prior to apneas. Mean apneic durations were 150s, 171s, and 214s for apneas 1, 2, and 3, respectively. Relative to pre-apnea values, the mean post-apneic arterial oxygen saturation nadir was 84.7% after air and 98% after oxygen. A more pronounced elevation of both Hb and Hct occurred during the air trial: after apnea 1 with air, mean Hb had increased by 1.5% (P<0.01), but no clear increase was found after the first apnea in with oxygen. After the third apnea with air Hb had increased by 3.0% (P<0.01), and with oxygen by 2.0% (P<0.01). After the first apnea with air Hct had increased by 1.9% (P<0.01) and after 3 apneas by 3.0% (P<0.01), but Hct did not change significantly in the oxygen trial. In both trials, Hb and Hct were at pre-apneic levels 10 min after apneas. Diving bradycardia during apnea was the same in both trials. We concluded that hypoxia is essential in inducing spleen-related Hb and Hct increase during apnea.

  • 30.
    Richardson, Matt
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Lodin, Angelica
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Engan, Harald
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Hypercapnia moderates hemoglobin increases during apneaManuskript (Övrigt vetenskapligt)
  • 31.
    Richardson, Matt
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Lodin, Angelica
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Reimers, J
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Short-term effects of normobaric hypoxia on the human spleen2008Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 104, nr 2, s. 395-399Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spleen contraction resulting in an increase in circulating erythrocytes has been shown to occur during apnea. This effect, however, has not previously been studied during normobaric hypoxia whilst breathing. After 20 min of horizontal rest and normoxic breathing, five subjects underwent 20-min of normobaric hypoxic breathing (12.8% oxygen) followed by 10 min of normoxic breathing. Ultrasound measurements of spleen volume and samples for venous hemoglobin concentration (Hb) and hematocrit (Hct) were taken simultaneously at short intervals from 20 min before until 10 min after the hypoxic period. Heart rate, arterial oxygen saturation (SaO2) and respiration rate were recorded continuously. During hypoxia, a reduction in SaO2 by 34% (P < 0.01) was accompanied by an 18% reduction in spleen volume and a 2.1% increase in both Hb and Hct (P < 0.05). Heart rate increased 28% above baseline (P < 0.05). Within 3 min after hypoxia SaO2 had returned to pre-hypoxic levels, and spleen volume, Hb and Hct had all returned to pre-hypoxic levels within 10 min. Respiratory rate remained stable throughout the protocol. This study of short-term exposure to eupneic normobaric hypoxia suggests that hypoxia plays a key role in triggering spleen contraction and subsequent release of stored erythrocytes in humans. This response could be beneficial during early altitude acclimatization.

  • 32.
    Richardson, Matt
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Lodin-Sundström, Angelica
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Spleen contraction in accessory spleens during apnea in elite divers2009Ingår i: Abstract EUBS Aberdeen, UK, 25-28 Aug, 2009, 2009Konferensbidrag (Refereegranskat)
  • 33.
    Richardson, Matt X.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Hematological changes arising from spleen contraction during apnea and altitude in humans2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 34.
    Richardson, Matthew
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Cheung, S
    Connolly, J
    Streimer, C
    White, M
    Event-related potential amplitude and latency changes of the P300 wave in response to whole-body cooling.Manuskript (Övrigt vetenskapligt)
    Abstract [en]

    Cold exposure can result in core body temperature reductions and subsequent physiological and psychological effects. While the physiological effects of core temperature cooling have been well documented, a precise method of quantification of cognitive performance during cold stress is yet to be established. We investigated the effects of a 1oC drop in rectal temperature in male subjects at two different exposure temperatures (5oC and 12oC circulated water in a liquid-cooled garment) on the P300 event-related potential waveform during a dual modality (auditory and visual) continuous performance task. Changes in waveform amplitude and latency suggested modification of task engagement or perceived difficulty, and speed of processing, respectively. Decreases in amplitude occurred in both 5oC and 12oC conditions, and increases in latency occurred in the 5oC condition compared to control subjects. It was suggested that cognitive performance suffered in terms of task engagement as rectal temperature decreased, with speed of processing slowed in the 5oC condition. The further use of event-related potential recordings in future thermal studies is discussed.

  • 35.
    Richardson, Matthew
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    de Bruijn, Robert
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Holmberg, Hans-Christer
    Mittuniversitetet, Fakulteten för humanvetenskap, Institutionen för hälsovetenskap.
    Björklund, Glenn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Haughey, Helena
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Increase of hemoglobin concentration after maximal apneas in divers, skiers and untrained humans2005Ingår i: Canadian Journal of Applied Physiology, ISSN 1066-7814, Vol. 30, nr 3, s. 276-281Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Apnea is physiologically stressful and can within a short time frame pose a threat to survival. To sustain prolonged apnea, oxygen use should be minimized and its storage maximized. Two mechanisms known to have this effect are the cardiovascular diving response, directing the available oxygen selectively to the heart and brain, and spleen contraction increasing the circulating erythrocyte volume and thereby gas storage capacity. Spleen contraction is also observed after maximal exercise, and is thought to enhance aerobic performance. While the cardiovascular diving response is known to be more pronounced after apnea training, spleen contraction has not been studied in conjunction with apnea training or other types of training. The aim of the present investigation is to study the hematological responses to apnea performed during rest by elite apneic divers, by elite cross-country skiers and by untrained subjects. After 20 min of rest, subjects performed 3 maximal apneas spaced by 2 min normal breathing intervals. Blood samples were drawn before, directly after, and 10 min after the apnea series and hemoglobin concentration was measured. All groups responded to maximal apneas with an increase in hemoglobin concentration, which had disappeared after 10 min of recovery. The increase in hemoglobin concentration was more pronounced in the apneic divers (4g/L) than in skiers (3g/L) and untrained subjects (2g/L; P < 0.05). All groups prolonged their apneic times through the series, but the increase was most evident for the divers versus both the skiers (P < 0.05) and untrained subjects (P < 0.01). The results suggest that these responses could be more pronounced as a result of apnea training.

  • 36.
    Richardson, Matthew
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    de Bruijn, Robert
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Pettersson, Sofia
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Reimers, J.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    CORRELATION BETWEEN SPLEEN SIZE AND HEMATOCRIT DURING APNEA IN HUMANS2006Ingår i: Proceedings of the Undersea and Hyperbaric Medical Society/Divers Alert Network 2006 June 20-21 Workshop. Durham, NC, 2006Konferensbidrag (Övrigt vetenskapligt)
  • 37.
    Richardson, Matthew
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    de Bruijn, Robert
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Hypoxia - A trigger for spleen contraction?2005Ingår i: EUBS 2005, 2005Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Several mechanisms involving oxygen conservation or increased blood gas storage capacity serve to facilitate prolonged diving in mammals. Two such mechanisms present in humans are the cardiovascular �diving response� and the blood boosting spleen contraction. Repeated diving may elicit these adaptive responses by similar or different mechanisms. Increased hematocrit (Hct) attributable to spleen contraction raises blood gas storage capacity during human apneic diving or simulated diving, but the underlying mechanisms have not been clarified. The time course for development of the Hct response is slower than for the cardiovascular diving response: The development of spleen contraction is progressive across 3 serial apneas, and recovery takes 8-9 minutes. Also, while the diving response is initiated by apnea and fortified by facial chilling, the stimulus eliciting Hct increase is related to apnea alone. Thus apnea itself or its consequences appear to be the main stimulus. In this study we focused on the role of hypoxia in triggering spleen induced elevations in Hct. After horizontal rest for 20 min, nine volunteers performed 3 maximal apneas spaced by 2 min of rest, preceeded by an inspiration of normal air. The series was repeated at a different day using the same apneic durations but after 60 s of 100% oxygen breathing and oxygen inspiration prior to apneas. Relative to pre-apnea values, the post apneic arterial oxygen saturation nadir averaged 84% after the air trial and 99% after the oxygen trial. The Hct rose in both protocols, but with about twice the magnitude after apneas with air. A relative increase of 2.7% was found after three apneas with air (p<0.01), and 1.4% increase after three apneas with oxygen (p<0.05). Values returned to pre-apneic levels within 10 minutes. We conclude that hypoxia may be an important modifying factor influencing the magnitude of hematocrit increase during apnea.

  • 38.
    Richardson, Matthew
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Altitude attenuates apnea-induced increase in haemoglobin concentration2007Ingår i: International Conference on Environmental Ergonomics, 2007Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    INTRODUCTION During apnea at sea-level, a contraction of the spleen is found in humans (Hurford et al 1990) causing a transient increase in hemoglobin concentration (Hb) and hematocrit (Schagatay et al 2001). The development of these increases is progressive across 3 serial apneas, typically resulting in Hb increases of 2% (Richardson et al, 2003), and recovery to pre-apneic values within 8-9 minutes (Schagatay et al 2005). The spleen contraction-associated Hb increase is in part triggered by the hypoxia occurring during apnea (Richardson et al 2005). The Hb increase leads to increased blood gas storage capacity which facilitates prolonged apnea in humans and may be responsible for the known prolongation of serial apneas (Schagatay et al 2001). At altitude, we suggest that the chronic hypoxia could induce splenic contraction during eupnea in humans, as previously observed in mice (Cook and Alafi 1956). Our aim was to reveal whether spleen related Hb increase occurs during eupneic altitude exposure in humans, thereby abolishing the Hb increase normally seen during apnea.

  • 39.
    Richardson, Matthew
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    de Bruijn, Robert
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Haughey, Helena
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Hematological response pattern associated with maximal-duration apnea series in untrained subjects: Annual Meeting of the European Underwater and Baromedical Society, Copenhagen, Denmark.2003Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Background: In addition to the human cardiovascular ‘diving response’, i.e., bradycardia and peripheral vasoconstriction during apnea, recent studies have shown that spleen contraction also occurs during repeated apneas. This latter response may serve to expel erythrocytes into the circulation to promote gas transportation. However, prospective changes in blood parameters after repeated apneas have yet to be systematically described. As is the case with diving response parameters, some individuals may have stronger haematological changes from performing apneic series than others. These variations need to be considered in future studies of the function of the spleen and blood components during apnea. The present study was aimed to describe the haematological response pattern associated with repeated maximal apneas in healthy non-divers. Methods: After 20 min of rest, 46 healthy untrained subjects of both sexes performed three maximal apneas, spaced by two minutes rest and normal breathing. Blood samples were taken before, within 1 minute after, and 10 minutes after the apneic series and analyzed for changes in haemoglobin (Hb) concentration and hematocrit (Hct). Results: Pre-apnea Hb concentration (mean±SE) was normally distributed (147.1±1.6 g/L). An increase of 2.1±0.3% in the Hb value was seen immediately post-series, followed by a decrease from this value of 1.8±0.3% at 10 minutes post-series. Pre-apnea hematocrit (41.2±0.6 percent) showed a similar increase immediately post-series of 3.2±0.8% followed by a decrease of 1.6±0.4% from this value at 10 minutes post-series. Classifying subjects as strong responders (above 75th percentile) and weak responders (below 25th percentile) resulted in mean increases in Hb and Hct above pre-apneic values of 4.7±0.4% and 7.1±2.1%, respectively for strong responders, and -0.5±0.4 and 0.5±0.6, respectively for weak responders. Conclusion: Significant increases in Hb and Hct values occur immediately after a maximal apneic series, followed by a return towards baseline values after 10 minutes. These increases may be due to the spleen contraction as demonstrated in previous research. Furthermore, some subjects appear to respond more strongly than others, and pre-screening for these types of responders may be judicious in future testing. The mechanism(s) underlying the strength of these haematological responses warrants further investigation.

  • 40.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Deaths from breath-hold diving Reply - Increased reporting improves safety2009Ingår i: Diving and Hyperbaric Medicine, ISSN 1833-3516, Vol. 39, nr 3, s. 179-179Artikel i tidskrift (Övrigt vetenskapligt)
  • 41.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Diving response and spleen contraction – two ways of shifting to a diving mode. : Tunisian Federation of Diving (FAST), Bizerte, Tunisia2003Konferensbidrag (Övrigt vetenskapligt)
  • 42.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Effects of water and ambient air temperatures on human diving bradycardia.1996Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, Vol. 73, nr 1/2, s. 1-6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Upon apnoeic face immersion, humans develop a diving response resembling that found in diving mammals. There have been contradictory reports regarding the influence of water temperature on the magnitude of the resulting bradycardia. This study examined the influence of both water and ambient air temperatures on human diving bradycardia. A group of 23 volunteers performed three series of apnoeic episodes after 60-min exposure to air at temperatures of 10, 20 or 30°C. Oral and skin temperatures were measured during this exposure and during the subsequent test on 5 subjects. At 20°C air temperature oral and skin temperatures were measured on 10 subjects. Heart rate (HR) was recorded for the 23 subjects during apnoea in air and apnoea with the face immersed in water of 10, 20 or 30°C, at each air temperature. We found that both air and water temperatures had significant effects on immersion bradycardia, but in opposite directions. Face immersion in cold water after exposure to a high ambient air temperature induced the most pronounced bradycardia. We further observed that exposure to different ambient air temperatures resulted in different patterns of HR response to water temperature. The range in which the response was positively correlated to water temperature differed at 30°C ambient air from that at 10 and 20°C ambient air. We concluded from these studies that human bradycardia resulting from apnoeic face immersion is inversely proportional to water temperature within a range which is determined by the ambient air temperature. Thus, the interval in which the response to cold stimulation varies with temperature, would appear to be determined by the ambient temperature before stimulation

  • 43.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Human sexual dimorphism1991Ingår i: The Aquatic Ape: Fact or Fiction: the first scientific evaluation of a controversial theory of human evolution, London: Souvenir Press , 1991, s. 299-305Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract

  • 44.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Is the human diving response an adaptation to diving? 1996Ingår i: Bulletin de Medecine Subaquatique et Hyperbare, ISSN 1248-2846, nr 6, s. 109-122Artikel i tidskrift (Övrigt vetenskapligt)
  • 45.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Review: Predicting performance in competitive apnea diving. Part II: dynamic apnea2010Ingår i: Diving and hyperbaric medicine, ISSN 1833-3516, Vol. 40, nr 1, s. 11-22Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Part I of this series of articles identified the main physiological factors defining the limits of static apnea, while this paper reviews the factors involved when physical work is added in the dynamic distance disciplines, performed in shallow water in a swimming pool. Little scientific work has been done concerning the prerequisites and limitations of swimming with or without fins whilst breath-holding to extreme limits. Apneic duration influences all competitive apnea disciplines, and can be prolonged by any means that increase gas storage or tolerance to asphyxia, or reduce metabolic rate, as reviewed in the first article. For horizontal underwater distance swimming, the main challenge is to restrict metabolism despite the work, and to direct blood flow only to areas where demand is greatest, to allow sustained function. Here, work economy, local tissue energy and oxygen stores and the anaerobic capacity of the muscles are key components. Improvements in swimming techniques and, especially in swimming with fins, equipment have already contributed to enhanced performance and may do so further. High lactate levels observed after dynamic competition dives suggest a high anaerobic component, and muscle hypoxia could ultimately limit muscle work and swimming distance. However, the frequency of syncope, especially in swimming without fins, suggests that cerebral oxygenation may often be compromised before this occurs. In these pool disciplines, safety is high and the dive can be interrupted by the competitor or safety diver within seconds. The safety routines in place during pool competitions are described.

  • 46.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling.
    Review: Predicting performance in competive apnoea diving, part I: static apnoea2009Ingår i: Diving and Hyperbaric Medicine, ISSN 1833-3516, Vol. 39, nr 2, s. 88-99Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Ever since the first deep diving competitions were organized, there has been debate about when the ultimate limits of human apnoeic performance will be reached, and which factors will determine these limits. Divers have thus far surpassed all former predictions by physiologists in depth and time. The common factor for all competitive apnoea disciplines is apnoeic duration, which can be prolonged by any means that increase total gas storage or tolerance to asphyxia, or reduce metabolic rate. These main factors can be broken down further into several physiological or psychophysiological factors, which are identified in this review. Like in other sports, the main aim in competitive apnoea is to extend human performance beyond the known limits. While a beginner may extend apnoeic duration by getting closer to his or her personal limit, the elite diver can only extend the duration further by pushing the individual physiological limit further by training. In order to achieve this, it is essential to identify the performance predicting factors of apnoea sports and which factors can be affected by training, work that has only just begun. This is the first of two papers reviewing the main factors predicting performance in competitive apnoea diving, which focuses on static apnoea, while the following paper will review dynamic distance and depth disciplines. Great improvements have been made in all diving disciplines in recent years and the 10-minute barrier in resting 'static apnoea' has been broached. Despite this, current training methods and the strategies employed suggest that duration can be prolonged still further, and divers themselves suggest the ultimate limit will be 15 minutes, which appears physiologically possible, for example, with further development of techniques to reduce metabolic rate.

  • 47.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Spleen function related to apneic diving in humans2003Ingår i: Revue Francaise de Plongé, nr 3, s. 43-46Artikel i tidskrift (Refereegranskat)
  • 48.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    The human diving response - effects of temperature and training.1996Doktorsavhandling, monografi (Övrigt vetenskapligt)
  • 49.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    The second crisis1991Ingår i: The aquatic ape: Fact or fiction?, 1991, s. 296-299Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Schagatay E, (1991) In: "The aquatic ape: Fact or fiction?", M Roede, J Wind, J Patrick, V Reynolds (eds) Souvenir Press, London, p 296-299.

  • 50.
    Schagatay, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    The significance of the human diving reflex1991Ingår i: The Aquatic Ape: Fact or Fiction: the first scientific evaluation of a controversial theory of human evolution, London: Souvenir Press , 1991, s. 247-254Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Schagatay E (1991) The significance of the human diving reflex.

12 1 - 50 av 70
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