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Schagatay, Erika
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Holmström, P. K., Harman, T. S., Kalker, A., Steiner, B., Hawkins, E., Jorgensen, K. C., . . . Brutsaert, T. D. (2024). Differential splenic responses to hyperoxic breathing at high altitude in Sherpa and lowlanders. Experimental Physiology
Open this publication in new window or tab >>Differential splenic responses to hyperoxic breathing at high altitude in Sherpa and lowlanders
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2024 (English)In: Experimental Physiology, ISSN 0958-0670, E-ISSN 1469-445XArticle in journal (Refereed) Epub ahead of print
Abstract [en]

The human spleen contracts in response to stress-induced catecholamine secretion, resulting in a temporary rise in haemoglobin concentration ([Hb]). Recent findings highlighted enhanced splenic response to exercise at high altitude in Sherpa, possibly due to a blunted splenic response to hypoxia. To explore the potential blunted splenic contraction in Sherpas at high altitude, we examined changes in spleen volume during hyperoxic breathing, comparing acclimatized Sherpa with acclimatized individuals of lowland ancestry. Our study included 14 non-Sherpa (7 female) residing at altitude for a mean continuous duration of 3 months and 46 Sherpa (24 female) with an average of 4 years altitude exposure. Participants underwent a hyperoxic breathing test at altitude (4300 m; barrometric pressure = ∼430 torr; (Formula presented.) = ∼90 torr). Throughout the test, we measured spleen volume using ultrasonography and monitored oxygen saturation ((Formula presented.)). During rest, Sherpa exhibited larger spleens (226 ± 70 mL) compared to non-Sherpa (165 ± 34 mL; P < 0.001; effect size (ES) = 0.95, 95% CI: 0.3–1.6). In response to hyperoxia, non-Sherpa demonstrated 22 ± 12% increase in spleen size (35 ± 17 mL, 95% CI: 20.7–48.9; P < 0.001; ES = 1.8, 95% CI: 0.93–2.66), while spleen size remained unchanged in Sherpa (−2 ± 13 mL, 95% CI: −2.4 to 7.3; P = 0.640; ES = 0.18, 95% CI: −0.10 to 0.47). Our findings suggest that Sherpa and non-Sherpas of lowland ancestry exhibit distinct variations in spleen volume during hyperoxia at high altitude, potentially indicating two distinct splenic functions. In Sherpa, this phenomenon may signify a diminished splenic response to altitude-related hypoxia at rest, potentially contributing to enhanced splenic contractions during physical stress. Conversely, non-Sherpa experienced a transient increase in spleen size during hyperoxia, indicating an active tonic contraction, which may influence early altitude acclimatization in lowlanders by raising [Hb]. 

Place, publisher, year, edition, pages
Wiley, 2024
Keywords
acclimatization, adaptation, high altitude, hypoxia, Sherpa, spleen function
National Category
Physiology
Identifiers
urn:nbn:se:miun:diva-50264 (URN)10.1113/EP091579 (DOI)2-s2.0-85181486793 (Scopus ID)
Available from: 2024-01-16 Created: 2024-01-16 Last updated: 2024-01-16Bibliographically approved
Lindblom, H., Pernett, F., Schagatay, E. & Holmström, P. (2024). Effect of exercise intensity and apnea on splenic contraction and hemoglobin increase in well-trained cross-country skiers. European Journal of Applied Physiology
Open this publication in new window or tab >>Effect of exercise intensity and apnea on splenic contraction and hemoglobin increase in well-trained cross-country skiers
2024 (English)In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327Article in journal (Refereed) Epub ahead of print
Abstract [en]

The human spleen acts as a reservoir for red blood cells, which is mobilized into the systemic circulation during various conditions such as hypoxia and physical exertion. Cross-country (XC) skiers, renowned for their exceptional aerobic capacity, are regularly exposed to high-intensity exercise and local oxygen deficits. We investigated a putative dose-dependent relationship between splenic contraction and concomitant hemoglobin concentration ([Hb]) elevation across four exercise intensities in well-trained XC skiers. Fourteen male XC skiers voluntarily participated in a 2-day protocol, encompassing a serial apnea test and a VO2max test (day 1), followed by three submaximal exercise intensities on a roller skiing treadmill corresponding to 55, 70, and 85% of VO2max (day 2). Spleen volume was measured via ultrasonic imaging, and venous blood samples were used to determine [Hb] levels. Baseline spleen volume was similar (266(35) mL) for all conditions (NS). Notably, all conditions induced significant splenic contractions and transient [Hb] elevations. The VO2max test exhibited the most pronounced splenic contraction (35.8%, p < 0.001) and a [Hb] increase of 8.1%, while the 85% exercise intensity led to 27.1% contraction and the greatest [Hb] increase (8.3%, < 0.001) compared to baseline. The apnea test induced relatively smaller responses (splenic contraction: 20.4%, [Hb] = 3.3%, p < 0.001), akin to the response observed at the 70% exercise intensity (splenic contraction = 23%, [Hb] = 6.4%, p < 0,001) and 55% (splenic contraction = 20.0%, [Hb] = 4.8%, p < 0.001). This study shows a discernible dose-dependent relationship between splenic contraction and [Hb] increase with levels of exercise, effectively distinguishing between submaximal and maximal exercise intensity.

Place, publisher, year, edition, pages
Springer Nature, 2024
Keywords
Spleen, Cross-country skiing, Endurance exercise, Oxygen-carrying capacity, Sports performance
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-50891 (URN)10.1007/s00421-024-05428-z (DOI)001172245500001 ()38393417 (PubMedID)
Available from: 2024-03-15 Created: 2024-03-15 Last updated: 2024-03-15
Rixen, M., Weickmann, J., Gebauer, R. A., Weidenbach, M., Markel, F., Michaelis, A., . . . Paech, C. (2024). First Real-Life Data on the Diving Response in Healthy Children. Pediatric Cardiology, 45(2), 314-322
Open this publication in new window or tab >>First Real-Life Data on the Diving Response in Healthy Children
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2024 (English)In: Pediatric Cardiology, ISSN 0172-0643, E-ISSN 1432-1971, Vol. 45, no 2, p. 314-322Article in journal (Refereed) Published
Abstract [en]

Swimming and diving are popular recreational activities, representing an effective option in maintaining and improving cardiovascular fitness in healthy people. To date, only little is known about the cardiovascular adaption to submersion in children. This study was conducted to improve an understanding thereof. We used a stepwise apnea protocol with apnea at rest, apnea with facial immersion, and at last apnea during whole body submersion. Continuous measurement of heart rate, oxygen saturation, and peripheral resistance index was done. Physiologic data and analysis of influencing factors on heart rate, oxygen saturation, and peripheral vascular tone response are reported. The current study presents the first data of physiologic diving response in children. Data showed that facial or whole body submersion leads to a major drop in heart rate, and increase of peripheral resistance, while the oxygen saturation seems to be unaffected by static apnea in most children, with apnea times of up to 75 s without change in oxygen saturation. 

Place, publisher, year, edition, pages
Springer Nature, 2024
Keywords
Bradycardia, Children, Dive reflex, Diving, Pediatrics, Swimming
National Category
Physiology
Identifiers
urn:nbn:se:miun:diva-50260 (URN)10.1007/s00246-023-03370-z (DOI)2-s2.0-85181508361 (Scopus ID)
Available from: 2024-01-16 Created: 2024-01-16 Last updated: 2024-01-29Bibliographically approved
Mulder, E., Längle, L., Pernett, F., Bouten, J., Sieber, A. & Schagatay, E. (2023). Case Studies in Physiology: Is blackout in breath-hold diving related to cardiac arrhythmias?. Journal of applied physiology, 134(4), 951-956
Open this publication in new window or tab >>Case Studies in Physiology: Is blackout in breath-hold diving related to cardiac arrhythmias?
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2023 (English)In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 134, no 4, p. 951-956Article in journal (Refereed) Published
Abstract [en]

Syncope or "blackout" (BO) in breath-hold diving (freediving) is generally considered to be caused by hypoxia. However, it has been suggested that cardiac arrhythmias affecting the pumping effectivity could contribute to BO. BO is fairly common in competitive freediving, where athletes aim for maximal performance. We recorded heart rate (HR) during a static apnea (STA) competition, to reveal if arrhythmias occur. Four male freedivers with STA personal best (PB) of 349 ± 43 s, volunteered during national championships, where they performed STA floating face down in a shallow indoor pool. A non-coded Polar T31 chest strap recorded R-R intervals and a water- and pressure-proof pulse oximeter arterial oxygen saturation. Three divers produced STA near their PB without problems, whereas one diver ended with BO at 5 min 17s, which was 12 s beyond his PB. He was immediately brought up by safety divers and resumed breathing within 10 s. All divers attained similar lowest diving HR (47 ± 4 beats/min), but HR recordings displayed a different pattern for the diver ending with BO. After a short tachycardia, the three successful divers developed bradycardia, which became more pronounced during the second half of the apnea. The fourth diver developed pronounced bradycardia earlier, and at 2.5 min into the apnea, HR started alternating between approximately 50 and 140 beats/min, until the diver lost consciousness. At resumed breathing, HR returned to baseline. Nadir oxygen saturation was similar for all divers. We speculate that arrhythmia could have contributed to BO, by lowering stroke volume leading to a systolic blood pressure drop, affecting brain perfusion.NEW & NOTEWORTHY Heart rate during prolonged breath-holding until the point of loss of consciousness has not previously been published. The recordings show that blackout was preceded by a period of persistent alterations in R-R intervals, whereby an ectopic beat followed every normal heartbeat. Explanations for this deviating heart rate pattern could be either premature atrial contractions or premature ventricular contractions following every atrial beat, i.e., bigeminy, which could have compromised cardiac pumping function and caused/contributed to blackout.

Keywords
bigeminy, freediving, static apnea, syncope, unconsciousness
National Category
Physiology
Identifiers
urn:nbn:se:miun:diva-48169 (URN)10.1152/japplphysiol.00708.2022 (DOI)000969168600006 ()36825646 (PubMedID)2-s2.0-85151574701 (Scopus ID)
Available from: 2023-04-19 Created: 2023-04-19 Last updated: 2023-05-22Bibliographically approved
Pernett, F., Bergenhed, P., Holmström, P., Mulder, E. & Schagatay, E. (2023). Effects of hyperventilation on oxygenation, apnea breaking points, diving response, and spleen contraction during serial static apneas. European Journal of Applied Physiology, 123(8), 1809-1824
Open this publication in new window or tab >>Effects of hyperventilation on oxygenation, apnea breaking points, diving response, and spleen contraction during serial static apneas
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2023 (English)In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 123, no 8, p. 1809-1824Article in journal (Refereed) Published
Abstract [en]

Purpose

Hyperventilation is considered a major risk factor for hypoxic blackout during breath-hold diving, as it delays the apnea breaking point. However, little is known about how it affects oxygenation, the diving response, and spleen contraction during serial breath-holding.

Methods

18 volunteers with little or no experience in freediving performed two series of 5 apneas with cold facial immersion to maximal duration at 2-min intervals. In one series, apnea was preceded by normal breathing and in the other by 15 s of hyperventilation. End-tidal oxygen and end-tidal carbon dioxide were measured before and after every apnea, and peripheral oxygen saturation, heart rate, breathing movements, and skin blood flow were measured continuously. Spleen dimensions were measured every 15 s.

Results

Apnea duration was longer after hyperventilation (133 vs 111 s). Hyperventilation reduced pre-apnea end-tidal CO2 (17.4 vs 29.0 mmHg) and post-apnea end-tidal CO2 (38.5 vs 40.3 mmHg), and delayed onset of involuntary breathing movements (112 vs 89 s). End-tidal O2 after apnea was lower in the hyperventilation trial (83.4 vs 89.4 mmHg) and so was the peripheral oxygen saturation nadir after apnea (90.6 vs 93.6%). During hyperventilation, the nadir peripheral oxygen saturation was lower in the last apnea than in the first (94.0% vs 86.7%). There were no differences in diving response or spleen volume reduction between conditions or across series.

Conclusions

Serial apneas  revealed a previously undescribed aspect of hyperventilation; a progressively increased desaturation across the series, not observed after normal breathing and could heighten the risk of a blackout.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
Hypoxia, Breath-hold diving, Blackout, Hypocapnia
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-48188 (URN)10.1007/s00421-023-05202-7 (DOI)001161293300019 ()37060440 (PubMedID)2-s2.0-85152582783 (Scopus ID)
Available from: 2023-04-20 Created: 2023-04-20 Last updated: 2024-03-08Bibliographically approved
Mulder, E., Pernett, F. & Schagatay, E. (2023). Reply to Lemaître and Costalat [Letter to the editor]. Journal of applied physiology, 135(4), 728-729
Open this publication in new window or tab >>Reply to Lemaître and Costalat
2023 (English)In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 135, no 4, p. 728-729Article in journal, Letter (Refereed) Published
Place, publisher, year, edition, pages
American Physiological Society, 2023
National Category
Physiology
Identifiers
urn:nbn:se:miun:diva-50155 (URN)10.1152/japplphysiol.00483.2023 (DOI)001143735700001 ()2-s2.0-85172680711 (Scopus ID)
Available from: 2023-12-20 Created: 2023-12-20 Last updated: 2024-02-05Bibliographically approved
Mulder, E., Sieber, A., McKnight, C. & Schagatay, E. (2023). Underwater pulse oximetry reveals increased rate of arterial oxygen desaturation across repeated freedives to 11 metres of freshwater. Diving and Hyperbaric Medicine, 53(1), 16-23
Open this publication in new window or tab >>Underwater pulse oximetry reveals increased rate of arterial oxygen desaturation across repeated freedives to 11 metres of freshwater
2023 (English)In: Diving and Hyperbaric Medicine, ISSN 1833-3516, Vol. 53, no 1, p. 16-23Article in journal (Refereed) Published
Abstract [en]

INTRODUCTION: Recreational freedivers typically perform repeated dives to moderate depths with short recovery intervals. According to freediving standards, these recovery intervals should be twice the dive duration; however, this has yet to be supported by scientific evidence. METHODS: Six recreational freedivers performed three freedives to 11 metres of freshwater (mfw), separated by 2 min 30 s recovery intervals, while an underwater pulse oximeter measured peripheral oxygen saturation (SpO2) and heart rate (HR). RESULTS: Median dive durations were 54.0 s, 103.0 s and 75.5 s (all dives median 81.5 s). Median baseline HR was 76.0 beats per minute (bpm), which decreased during dives to 48.0 bpm in dive one, 40.5 bpm in dive two and 48.5 bpm in dive three (all P < 0.05 from baseline). Median pre-dive baseline SpO2 was 99.5%. SpO2 remained similar to baseline for the first half of the dives, after which the rate of desaturation increased during the second half of the dives with each subsequent dive. Lowest median SpO2 after dive one was 97.0%, after dive two 83.5% (P < 0.05 from baseline) and after dive three 82.5% (P < 0.01 from baseline). SpO2 had returned to baseline within 20 s after all dives. CONCLUSIONS: We speculate that the enhanced rate of arterial oxygen desaturation across the serial dives may be attributed to a remaining 'oxygen debt', leading to progressively increased oxygen extraction by desaturated muscles. Despite being twice the dive duration, the recovery period may be too short to allow full recovery and to sustain prolonged serial diving, thus does not guarantee safe diving. Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.

Keywords
Breath-hold diving, Diving reflex, Hypoxia, Oxygen consumption, Safety, Unconsciousness
National Category
Physiology
Identifiers
urn:nbn:se:miun:diva-48063 (URN)10.28920/dhm53.1.16-23 (DOI)000965255900004 ()36966518 (PubMedID)2-s2.0-85151043338 (Scopus ID)
Available from: 2023-04-12 Created: 2023-04-12 Last updated: 2023-05-26Bibliographically approved
Mulder, E., Staunton, C. A., Sieber, A. & Schagatay, E. (2023). Unlocking the depths: multiple factors contribute to risk for hypoxic blackout during deep freediving. European Journal of Applied Physiology, 123(11), 2483-2493
Open this publication in new window or tab >>Unlocking the depths: multiple factors contribute to risk for hypoxic blackout during deep freediving
2023 (English)In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 123, no 11, p. 2483-2493Article in journal (Refereed) Published
Abstract [en]

Purpose: To examine the effect of freediving depth on risk for hypoxic blackout by recording arterial oxygen saturation (SpO2) and heart rate (HR) during deep and shallow dives in the sea. Methods: Fourteen competitive freedivers conducted open-water training dives wearing a water-/pressure proof pulse oximeter continuously recording HR and SpO2. Dives were divided into deep (&gt; 35 m) and shallow (10–25 m) post-hoc and data from one deep and one shallow dive from 10 divers were compared. Results: Mean ± SD depth was 53 ± 14 m for deep and 17 ± 4 m for shallow dives. Respective dive durations (120 ± 18 s and 116 ± 43 s) did not differ. Deep dives resulted in lower minimum SpO2 (58 ± 17%) compared with shallow dives (74 ± 17%; P = 0.029). Overall diving HR was 7 bpm higher in deep dives (P = 0.002) although minimum HR was similar in both types of dives (39 bpm). Three divers desaturated early at depth, of which two exhibited severe hypoxia (SpO2 ≤ 65%) upon resurfacing. Additionally, four divers developed severe hypoxia after dives. Conclusions: Despite similar dive durations, oxygen desaturation was greater during deep dives, confirming increased risk of hypoxic blackout with increased depth. In addition to the rapid drop in alveolar pressure and oxygen uptake during ascent, several other risk factors associated with deep freediving were identified, including higher swimming effort and oxygen consumption, a compromised diving response, an autonomic conflict possibly causing arrhythmias, and compromised oxygen uptake at depth by lung compression possibly leading to atelectasis or pulmonary edema in some individuals. Individuals with elevated risk could likely be identified using wearable technology. 

Place, publisher, year, edition, pages
Springer, 2023
Keywords
Apneic diving, Bradycardia, Breath-hold diving, Diving response, Shallow water blackout, Syncope
National Category
Physiology
Identifiers
urn:nbn:se:miun:diva-48551 (URN)10.1007/s00421-023-05250-z (DOI)001006631000002 ()2-s2.0-85161454346 (Scopus ID)
Available from: 2023-06-20 Created: 2023-06-20 Last updated: 2023-11-01Bibliographically approved
Mulder, E., Holmström, P. & Schagatay, E. (2022). Effects of dynamic apnea training on diving bradycardia and short distance swimming performance. Journal of Sports Medicine and Physical Fitness, 62(8), 1037-1044
Open this publication in new window or tab >>Effects of dynamic apnea training on diving bradycardia and short distance swimming performance
2022 (English)In: Journal of Sports Medicine and Physical Fitness, ISSN 0022-4707, E-ISSN 1827-1928, Vol. 62, no 8, p. 1037-1044Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Apnea training enhances bradycardia and improves competitive apnea performance, and has been proposed as a training method for other sports, such as swimming. We evaluated the effects of apneic underwater swimming, i.e. dynamic apnea (DYN), in 9 competitive swimmers (TR) who completed ten DYN sessions over 2 weeks.

METHODS: TR performed pre- and post-training tests including a static apnea test with continuous heart rate (HR) and peripheral oxygen saturation measurements, all-out 50m and 100m freestyle tests and an all-out DYN test. Control groups were competitive swimmers (SC; n=10) that trained swimming without DYN, and a non-swimmer group (AC; n=10) performing only static apnea tests.

RESULTS: Post-training, TR mean±SD time for 50m freestyle improved from 25.51±2.01s to 24.64±2.02s (p<0.01) and for 100m from 55.5±4.2s to 54.1±4.4s (p<0.05). SC also improved their 100m time from 56.7±3.3s to 56.0±3.1s (p<0.01; p=0.07 between groups). Only TR performed DYN tests; DYN distance increased from 62.1±11.5m to 70.9±18.9m (p<0.05) while DYN speed decreased from 0.74±0.14m/s to 0.64±0.18m/s (p<0.01). Static apnea duration did not change in any of the groups, but HR-reduction was enhanced posttraining only in TR (24.8±14.8% to 31.1±10.9%, p<0.01; p<0.001 between groups).

CONCLUSIONS: We conclude that 2 weeks of DYN training enhanced DYN performance, which may be caused by the enhanced apnea-induced diving bradycardia. Further research is required to determine whether DYN training enhances short distance freestyle swimming performance.

Keywords
Breath-holding, Cardiovascular diving response, Hypoxia, Front crawl, Freediving
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-44938 (URN)10.23736/s0022-4707.21.12549-6 (DOI)000835203600004 ()34546023 (PubMedID)2-s2.0-85122135121 (Scopus ID)
Available from: 2022-05-06 Created: 2022-05-06 Last updated: 2022-08-18Bibliographically approved
Blakeson, M. C., Jerome, S. P., Walsh, N. P., Schagatay, E. & Hanstock, H. G. (2022). Illness Incidence, Psychological Characteristics, and Sleep in Dogsled Drivers During the Iditarod Trail Sled Dog Race. Wilderness & environmental medicine (Print), 33(1), 92-96
Open this publication in new window or tab >>Illness Incidence, Psychological Characteristics, and Sleep in Dogsled Drivers During the Iditarod Trail Sled Dog Race
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2022 (English)In: Wilderness & environmental medicine (Print), ISSN 1080-6032, E-ISSN 1545-1534, Vol. 33, no 1, p. 92-96Article in journal (Refereed) Published
Abstract [en]

Introduction: Every March, dogsled drivers (mushers) compete in a 1569-km race across Alaska, involving physical exertion, mental exertion, and sleep deprivation for up to 2 wk. These factors may increase mushers’ vulnerability to illness, making them a relevant study population for acute infection risk factors. Specifically, the influence of psychological factors on illness risk during prolonged physical exertion has rarely been investigated. The aim of this study was to examine the relationship between psychological characteristics, sleep deprivation, and illness incidence in Iditarod mushers. Methods: Fourteen mushers completed 4 psychological instruments to assess state and trait anxiety, resilience and perceived stress, and self-reported upper respiratory symptoms (URS) in the month before the race. Mushers self-reported sleep duration and URS during the race. Results: State and trait anxiety, resilience, and perceived stress did not differ between mushers with and without pre- and in-race URS (P>0.05). However, all mushers who reported in-race URS had reported URS ≤9 d before the race, and the onset of symptoms during the race typically occurred shortly after a rest period. Sleep duration was higher in mushers who reported in-race URS, both before (4.9±0.3 h, P=0.016) and during illness (5.9±1.3 h, P=0.006), vs mushers without in-race URS (3.4±0.8 h). Conclusions: This study highlights recent illness, rest periods, and greater sleep requirements as potential risk factors for URS onset during a multiday endurance challenge, whereas psychological factors were not associated with URS.

Keywords
endurance, immunity, psychological stress, upper respiratory symptoms
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-44118 (URN)10.1016/j.wem.2021.11.002 (DOI)000766310000011 ()35000867 (PubMedID)2-s2.0-85122444871 (Scopus ID)
Available from: 2022-01-26 Created: 2022-01-26 Last updated: 2022-03-31Bibliographically approved
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