| 1. |
- Barlow, Matthew J., et al.
(författare)
-
The Effect of a Dietary Nitrate Supplementation in the Form of a Single Shot of Beetroot Juice on Static and Dynamic Apnea Performance
- 2018
-
Ingår i: International Journal of Sport Nutrition & Exercise Metabolism. - : Human Kinetics. - 1526-484X .- 1543-2742. ; 28:5, s. 497-501
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present study was to assess the effects of acute nitrate (NO3-)-rich beetroot juice (BRJ) supplementation on peripheral oxygen saturation (SpO(2)), heart rate (HR), and pulmonary gas exchange during submaximal static and dynamic apnea. Methods: Nine (six males and three females) trained apneists (age: 39.6 +/- 8.2 years, stature: 170.4 +/- 11.5 cm, and body mass: 72.0 +/- 11.5 kg) performed three submaximal static apneas at 60%, 70%, and 80% of the participant's current reported personal best time, followed by three submaximal (similar to 75% or personal best distance) dynamic apneas following the consumption of either a 70-ml concentrated BRJ (7.7 mmol NO3-) or a NO3--depleted placebo (PLA; 0.1 mmol NO3-) in doubleblind randomized manner. HR and SpO(2) were measured via fingertip pulse oximetry at the nadir, and online gas analysis was used to assess pulmonary oxygen uptake ((V)over dotO2) during recovery following breath-holds. Results: There were no differences (p < .05) among conditions for HR (PLA = 59 +/- 11 bpm and BRJ = 61 +/- 12 bpm), SpO(2) (PLA = 83% +/- 14% and BRJ = 84% +/- 9%), or (V)over dotO2 (PLA = 1.00 +/- 0.22 L/min and BRJ = 0.97 +/- 0.27 L/min). Conclusion: The consumption of 7.7 mmol of beetroot juice supplementation prior to a series of submaximal static and dynamic apneas did not induce a significant change in SpO(2), HR, and (V)over dotO2 when compared with placebo. Therefore, there is no apparent physiological response that may benefit free divers as a result of the supplementation.
|
|
| 2. |
- Eiken, Ola, et al.
(författare)
-
Adaptation to 5 weeks of intermittent local vascular pressure increments; Mechanisms to be considered in the development of primary hypertension?
- 2021
-
Ingår i: American Journal of Physiology. Heart and Circulatory Physiology. - : American Physiological Society. - 0363-6135 .- 1522-1539. ; 320:4, s. H1303-H1312
-
Tidskriftsartikel (refereegranskat)abstract
- The aims were to study effects of iterative exposures to moderate elevations of local intravascular pressure on arterial/arteriolar stiffness and plasma levels of vasoactive substances. Pressures in the vasculature of an arm were increased by 150mmHg in healthy men (n = 11) before and after a 5-wk regimen, during which the vasculature in one arm was exposed to fifteen 40-min sessions of moderately increased transmural pressure (+65 to +105 mmHg). This vascular pressure training and the pressuredistension determinations were conducted by exposing the subjects' arm versus remaining part of the body to differential ambient pressure. During the pressure-distension determinations, venous samples were simultaneously obtained from pressurized and unpressurized vessels. Pressure training reduced arterial pressure distension by 40 ± 23% and pressure-induced flow by 33 ± 30% (P < 0.01), but only in the pressure-trained arm, suggesting local adaptive mechanisms. The distending pressure-diameter and distending pressure-flow curves, with training-induced increments in pressure thresholds and reductions in response gains, suggest that the increased precapillary stiffness was attributable to increased contractility and structural remodeling of the walls. Acute vascular pressure provocation induced local release of angiotensin-II (ANG II) and endothelin-1 (ET-1) (P < 0.05), suggesting that these vasoconstrictors limited the pressure distension. Pressure training increased basal levels of ET-1 and induced local pressure release of matrix metalloproteinase 7 (P < 0.05), suggesting involvement of these substances in vascular remodeling. The findings are compatible with the notion that local intravascular pressure load acts as a prime mover in the development of primary hypertension.
|
|
| 3. |
- Eiken, Ola, et al.
(författare)
-
Decompression strain in parachute jumpmasters during simulated high-altitude missions : a special reference to preoxygenation strategies.
- 2023
-
Ingår i: European Journal of Applied Physiology. - : Springer Nature. - 1439-6319 .- 1439-6327.
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Military parachute operations are often executed at high altitude, from an unpressurized aircraft compartment. Parachute jumpmasters (JM) are thus regularly exposed to 29,500 ft for 60 min. The aim was to investigate the decompression strain during a simulated JM mission at high altitude and to compare two strategies of preoxygenation, conducted either at sea-level or below 10,000 ft, during ascent to mission altitude.METHODS: Ten JM completed, on separate occasions, a 45-min preoxygenation either at sea-level (normobaric: N) or 8200ft (hypobaric: H), followed by exposure to 28,000 ft for 60 min, whilst laying supine and breathing 100% oxygen. At min 45 of the exposure to 28,000 ft, the JM performed 10 weighted squats. Decompression strain was determined from ultrasound assessment of venous gas emboli (VGE) during supine rest (5-min intervals), after three unloaded knee-bends (15-min intervals) and immediately following the weighted squats. The VGE were scored using a six-graded scale (0-5).RESULTS: In condition H, two JM experienced decompression sickness (DCS), whereas no DCS incidents were reported in condition N. The prevalence of VGE was higher in the H than the N condition, at rest [median(range), 3(0-4) vs 0(0-3); p = 0.017], after unloaded knee-bends [3(0-4) vs 0(0-3); p = 0.014] and after the 10 weighted squats [3(0-4) vs 0(0-3); p = 0.014]. VGE were detected earlier in the H (28 ± 20 min, p = 0.018) than the N condition (50 ± 19 min).CONCLUSIONS: A preoxygenation/altitude procedure commonly used by JM, with a 60-min exposure to 28,000 ft after pre-oxygenation for 45 min at 8200 ft is associated with high risk of DCS. The decompression strain can be reduced by preoxygenating at sea level.
|
|
| 4. |
- Elia, Antonis, Dr, et al.
(författare)
-
Cerebral, cardiac and skeletal muscle stress associated with a series of static and dynamic apnoeas
- 2022
-
Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 32:1, s. 233-241
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study sought to explore, for the first time, the effects of repeated maximal static and dynamic apnoeic attempts on the physiological milieu by assessing cerebral, cardiac and striatal muscle stress-related biomarkers in a group of elite breath-hold divers (EBHD). Methods: Sixteen healthy males were recruited (EBHD = 8; controls = 8). On two separate occasions, EBHD performed two sets of five repeated maximal static apnoeas (STA) or five repeated maximal dynamic apnoeas (DYN). Controls performed a static eupnoeic protocol to negate any effects of water immersion and diurnal variation on haematology (CTL). Venous blood samples were drawn at 30, 90, and 180 min after each protocol to determine S100β, neuron-specific enolase (NSE), myoglobin, and high sensitivity cardiac troponin T (hscTNT) concentrations. Results: S100β and myoglobin concentrations were elevated following both apnoeic interventions (p < 0.001; p ≤ 0.028, respectively) but not after CTL (p ≥ 0.348). S100β increased from baseline (0.024 ± 0.005 µg/L) at 30 (STA, +149%, p < 0.001; DYN, +166%, p < 0.001) and 90 min (STA, +129%, p < 0.001; DYN, +132%, p = 0.008) following the last apnoeic repetition. Myoglobin was higher than baseline (22.3 ± 2.7 ng/ml) at 30 (+42%, p = 0.04), 90 (+64%, p < 0.001) and 180 min (+49%, p = 0.013) post-STA and at 90 min (+63%, p = 0.016) post-DYN. Post-apnoeic S100β and myoglobin concentrations were higher than CTL (STA, p < 0.001; DYN, p ≤ 0.004). NSE and hscTNT did not change from basal concentrations after the apnoeic (p ≥ 0.146) nor following the eupnoeic (p ≥ 0.553) intervention. Conclusions: This study suggests that a series of repeated maximal static and dynamic apnoeas transiently disrupt the blood-brain barrier and instigate muscle injury but do not induce neuronal-parenchymal damage or myocardial damage.
|
|
| 5. |
- Elia, Antonis, et al.
(författare)
-
Considerations for scuba and breath-hold divers during the COVID-19 pandemic : A call for awareness
- 2020
-
Ingår i: Diving and Hyperbaric Medicine. - : Diving and Hyperbaric Medicine Journal. - 1833-3516 .- 2209-1491. ; 50:4, s. 413-416
-
Tidskriftsartikel (refereegranskat)abstract
- In late 2019, a highly pathogenic novel coronavirus (CoV), severe acute respiratory syndrome (SARS)-CoV-2 emerged from Wuhan, China and led to a global pandemic. SARS-CoV-2 has a predilection for the pulmonary system and can result in serious pneumonia necessitating hospitalisation. Computed tomography (CT) chest scans of patients with severe symptoms, show signs of multifocal bilateral ground or ground-glass opacities (GGO) associated with consolidation areas with patchy distribution. However, it is less well known that both asymptomatic and mild symptomatic patients may exhibit similar lung changes. Presumably, the various pathological changes in the lungs may increase the risk of adverse events during diving (e.g., lung barotrauma, pulmonary oedema, etc.), thus these lung manifestations need to be considered prior to allowing resumption of diving. Presently, it is not known how the structural changes in the lungs develop and to what extent they resolve, in particular in asymptomatic carriers and patients with mild disease. However, current evidence indicates that a month of recovery may be too short an interval to guarantee complete pulmonary restitution even after COVID-19 infections not demanding hospital care. 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.
|
|
| 6. |
- Elia, Antonis, Dr, et al.
(författare)
-
Effects of hyperventilation on repeated breath-holding while in a fasting state: do risks outweigh the benefits?
- 2024
-
Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : the American Physiological Society. - 0363-6119 .- 1522-1490. ; 326, s. R319-R329
-
Tidskriftsartikel (refereegranskat)abstract
- Breath-holding preceded by either an overnight fast or hyperventilation has been shown to potentiate the risk of a hypoxic blackout. However, no study has explored the combined effects of fasting and hyperventilation on apneic performance and associated physiological responses. Nine nondivers (8 males) attended the laboratory on two separate occasions (≥48 h apart), both after a 12-h overnight fast. During each visit, a hyperoxic rebreathing trial was performed followed by three repeated maximal static apneas preceded by either normal breathing (NORM) or a 30-s hyperventilation (HYPER). Splenic volume, hematology, cardiovascular, and respiratory variables were monitored. There were no interprotocol differences at rest or during hyperoxic rebreathing for any variable (P ≥ 0.09). On nine occasions (8 in HYPER), the subjects reached our safety threshold (oxygen saturation 65%) and were asked to abort their apneas, with the preponderance of these incidents (6 of 9) occurring during the third repetition. Across the sequential attempts, longer apneas were recorded in HYPER [median(range), 220(123–324) s vs. 185(78–296) s, P ≤ 0.001], with involuntary breathing movements occurring later [134(65–234) s vs. 97(42–200) s, P ≤ 0.001] and end-apneic partial end-tidal pressures of oxygen (PETO2) being lower (P ≤ 0.02). During the final repetition, partial end-tidal pressure of carbon dioxide [(PETCO2), 6.53 ± 0.46 kPa vs. 6.01 ± 0.45 kPa, P = 0.005] was lower in HYPER. Over the serial attempts, preapneic tidal volume was gradually elevated [from apnea 1 to 3, by 0.26 ± 0.24 L (HYPER) and 0.28 ± 0.30 L (NORM), P ≤ 0.025], with a correlation noted with preapneic PETCO2 (r = −0.57, P < 0.001) and PETO2 (r = 0.76, P < 0.001), respectively. In a fasted state, preapnea hyperventilation compared with normal breathing leads to longer apneas but may increase the susceptibility to a hypoxic blackout.
|
|
| 7. |
- Elia, Antonis, et al.
(författare)
-
Erythropoietic responses to a series of repeated maximal dynamic and static apnoeas in elite and non-breath-hold divers
- 2019
-
Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 119:11-12, s. 2557-2565
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Serum erythropoietin (EPO) concentration is increased following static apnoea-induced hypoxia. However, the acute erythropoietic responses to a series of dynamic apnoeas in non-divers (ND) or elite breath-hold divers (EBHD) are unknown.METHODS: Participants were stratified into EBHD (n = 8), ND (n = 10) and control (n = 8) groups. On two separate occasions, EBHD and ND performed a series of five maximal dynamic apnoeas (DYN) or two sets of five maximal static apnoeas (STA). Control performed a static eupnoeic (STE) protocol to control against any effects of water immersion and diurnal variation on EPO. Peripheral oxygen saturation (SpO2) levels were monitored up to 30 s post each maximal effort. Blood samples were collected at 30, 90, and 180 min after each protocol for EPO, haemoglobin and haematocrit concentrations.RESULTS: No between group differences were observed at baseline (p > 0.05). For EBHD and ND, mean end-apnoea SpO2 was lower in DYN (EBHD, 62 ± 10%, p = 0.024; ND, 85 ± 6%; p = 0.020) than STA (EBHD, 76 ± 7%; ND, 96 ± 1%) and control (98 ± 1%) protocols. EBHD attained lower end-apnoeic SpO2 during DYN and STA than ND (p < 0.001). Serum EPO increased from baseline following the DYN protocol in EBHD only (EBHD, p < 0.001; ND, p = 0.622). EBHD EPO increased from baseline (6.85 ± 0.9mlU/mL) by 60% at 30 min (10.82 ± 2.5mlU/mL, p = 0.017) and 63% at 180 min (10.87 ± 2.1mlU/mL, p = 0.024). Serum EPO did not change after the STA (EBHD, p = 0.534; ND, p = 0.850) and STE (p = 0.056) protocols. There was a significant negative correlation (r = - 0.49, p = 0.003) between end-apnoeic SpO2 and peak post-apnoeic serum EPO concentrations.CONCLUSIONS: The novel findings demonstrate that circulating EPO is only increased after DYN in EBHD. This may relate to the greater hypoxemia achieved by EBHD during the DYN.
|
|
| 8. |
- Elia, Antonis, Dr, et al.
(författare)
-
Inter- and Intra-Rater Level of Agreement in Ultrasonic Video Grading of Venous Gas Emboli
- 2022
-
Ingår i: Aerospace Medicine and Human Performance. - : Aerospace Medical Association. - 2375-6314 .- 2375-6322. ; 93:1, s. 54-57
-
Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: This study aimed to evaluate whether a short familiarization session is sufficient for individuals with no prior experience of sonography to both reliably and consistently evaluate the prevalence of venous gas emboli (VGE) from precordial ultrasonic videos.METHODS: A total of 10 adults with no prior experience of sonography were introduced to the Eftedal-Brubakk 6-grade scale and were shown 6 video sequences, each of a maximum of 10 heartbeats, representing each grading level. Thereafter, they independently evaluated the prevalence of VGE in 70 ultrasonic videos before and after a 14-d interval (test-retest; intra-rater), with these being compared to an experienced sonographer's grading (inter-rater).RESULTS: A significant inter-rater level of agreement was found between the naïve and experienced sonographers' bubble grading both during the first (W = 0.945) and second (W = 0.952) round of bubble evaluation. The naïve observers' evaluations were on average 79% (range: 61-95%) and 75% (range: 48-95%) in complete agreement with the experienced sonographer's gradings, while the level of agreement was 99% and 98% within 1 grade unit. There was a significant intra-rater level of agreement (κ = 0.845) during the test-retest series, with a mean percentage level of agreement of 87% (range: 72-93%).CONCLUSION: This study demonstrates that a short familiarization session enables individuals with no prior sonography experience to consistently evaluate VGE prevalence from precordial ultrasonic videos.Elia A, Ånell R, Eiken O, Grönkvist M, Gennser M. Inter- and intra-rater level of agreement in ultrasonic video grading of venous gas emboli. Aerosp Med Hum Perform. 2022; 93(1):54-57.
|
|
| 9. |
- Elia, Antonis, et al.
(författare)
-
Physiology, pathophysiology and (mal)adaptations to chronic apnoeic training: a state-of-the-art review
- 2021
-
Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 121:6, s. 1543-1566
-
Tidskriftsartikel (refereegranskat)abstract
- Breath-hold diving is an activity that humans have engaged in since antiquity to forage for resources, provide sustenance and to support military campaigns. In modern times, breath-hold diving continues to gain popularity and recognition as both a competitive and recreational sport. The continued progression of world records is somewhat remarkable, particularly given the extreme hypoxaemic and hypercapnic conditions, and hydrostatic pressures these athletes endure. However, there is abundant literature to suggest a large inter-individual variation in the apnoeic capabilities that is thus far not fully understood. In this review, we explore developments in apnoea physiology and delineate the traits and mechanisms that potentially underpin this variation. In addition, we sought to highlight the physiological (mal)adaptations associated with consistent breath-hold training. Breath-hold divers (BHDs) are evidenced to exhibit a more pronounced diving-response than non-divers, while elite BHDs (EBHDs) also display beneficial adaptations in both blood and skeletal muscle. Importantly, these physiological characteristics are documented to be primarily influenced by training-induced stimuli. BHDs are exposed to unique physiological and environmental stressors, and as such possess an ability to withstand acute cerebrovascular and neuronal strains. Whether these characteristics are also a result of training-induced adaptations or genetic predisposition is less certain. Although the long-term effects of regular breath-hold diving activity are yet to be holistically established, preliminary evidence has posed considerations for cognitive, neurological, renal and bone health in BHDs. These areas should be explored further in longitudinal studies to more confidently ascertain the long-term health implications of extreme breath-holding activity.
|
|
| 10. |
- Elia, Antonis, et al.
(författare)
-
Six weeks of dynamic apnoeic training stimulates erythropoiesis but does not increase splenic volume
- 2021
-
Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media Deutschland GmbH. - 1439-6319 .- 1439-6327. ; 121:3, s. 827-838
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study examined the influence of dynamic apnoea training on splenic volume and haematological responses in non-breath-hold divers (BHD). Methods: Eight non-BHD performed ten maximal dynamic apnoeas, four times a week for six weeks. Splenic volumes were assessed ultrasonically, and blood samples were drawn for full blood count analysis, erythropoietin, iron, ferritin, albumin, protein and osmolality at baseline, 24 h post the completion of each week’s training sessions and seven days post the completion of the training programme. Additionally, blood samples were drawn for haematology at 30, 90, and 180 min post session one, twelve and twenty-four. Results: Erythropoietin was only higher than baseline (6.62 ± 3.03 mlU/mL) post session one, at 90 (9.20 ± 1.88 mlU/mL, p = 0.048) and 180 min (9.04 ± 2.35 mlU/mL, p = 0.046). Iron increased from baseline (18 ± 3 µmol/L) post week five (23 ± 2 µmol/L, p = 0.033) and six (21 ± 6 µmol/L; p = 0.041), whereas ferritin was observed to be lower than baseline (111 ± 82 µg/L) post week five (95 ± 75 µg/L; p = 0.016), six (84 ± 74 µg/L; p = 0.012) and one week post-training (81 ± 63 µg/L; p = 0.008). Reticulocytes increased from baseline (57 ± 12 × 109/L) post week one (72 ± 17 × 109/L, p = 0.037) and six (71 ± 17 × 109/L, p = 0.021) while no changes were recorded in erythrocytes (p = 0.336), haemoglobin (p = 0.124) and splenic volumes (p = 0.357). Conclusions: Six weeks of dynamic apnoeic training increase reticulocytes without altering mature erythrocyte concentration and splenic volume.
|
|
