Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 737
Filtrar
1.
Wilderness Environ Med ; 30(3): 321-327, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31178366

RESUMO

Sudden death during whitewater recreation often occurs through understandable mechanisms such as underwater entrapment or trauma, but poorly defined events are common, particularly in colder water. These uncharacterized tragedies are frequently called flush drownings by whitewater enthusiasts. We believe the condition referred to as cold water immersion syndrome may be responsible for some of these deaths. Given this assumption, the physiologic alterations contributing to cold water immersion syndrome are reviewed with an emphasis on those factors pertinent to flush drowning.


Assuntos
Temperatura Baixa/efeitos adversos , Afogamento/mortalidade , Hipotermia/mortalidade , Imersão/efeitos adversos , Esportes Aquáticos , Afogamento/etiologia , Afogamento/fisiopatologia , Humanos , Hipotermia/etiologia , Hipotermia/fisiopatologia , Imersão/fisiopatologia , Síndrome
2.
Wilderness Environ Med ; 30(2): 141-149, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30979538

RESUMO

INTRODUCTION: We tested the hypothesis that individual susceptibility to freezing cold injury might be reflected in an attenuated cold-induced vasodilatation (CIVD) response by comparing the CIVD responses of an elite alpinist with a history of freezing cold injury in the feet (case alpinist) with those of an age- and ability- matched noninjured alpinists control group (controls). According to this hypothesis, the vasomotor responses to a CIVD test of the case alpinist would represent a pathophysiological response when compared with the normal physiological response of a noninjured cohort. METHODS: The case alpinist and the controls in the cohort group conducted a cold water immersion test comprising sequential immersion of a hand and foot for 5 min in 35°C water, followed by a 30-min immersion in 8°C water and a 10-min recovery period in room air. During this test we monitored the finger and toe skin temperatures. RESULTS: The case alpinist had a significantly attenuated CIVD response and a lower skin temperature in all injured and noninjured digits during immersion (∼2°C lower than in the control group) and an attenuated recovery of finger skin temperatures (∼6°C lower than in the control group). CONCLUSIONS: The attenuated CIVD response of the case alpinist may reflect a previously unrecognized enhanced susceptibility to frostbite. In addition to the poor vasomotor response observed in the injured toes, he also exhibited a poor vasomotor response in his noninjured fingers. The results of the present study indicate that a test of vasomotor activity during thermal stress may identify individuals predisposed to cold injury.


Assuntos
Temperatura Baixa/efeitos adversos , Temperatura Cutânea/fisiologia , Vasodilatação/fisiologia , Adulto , Estudos de Casos e Controles , Dedos/fisiologia , Congelamento das Extremidades/fisiopatologia , Humanos , Imersão/fisiopatologia , Masculino , Montanhismo/fisiologia , Dedos do Pé/lesões , Dedos do Pé/fisiologia
3.
Clin Res Cardiol ; 108(5): 468-476, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30267153

RESUMO

BACKGROUND: Patients with chronic conditions, such as heart failure, swim regularly and most rehabilitation exercises are conducted in warm hydrotherapy pools. However, little is known about the acute effects of warm water immersion (WWI) on cardiac haemodynamics in patients with chronic heart failure (CHF). METHODS: Seventeen patients with CHF (NYHA I and II; mean age 67 years, 88% male, mean left ventricular ejection fraction 33%) and 10 age-matched normal subjects were immersed up to the neck in a hydrotherapy pool (33-35 °C). Cardiac haemodynamics were measured non-invasively, and echocardiography was performed at baseline, during WWI, 3 min after kicking in the supine position and after emerging. RESULTS: In patients with CHF, compared to baseline, WWI immediately increased stroke volume (SV, mean ± standard deviation; from 65 ± 21 to 82 ± 22 mL, p < 0.001), cardiac output (CO, from 4.4 ± 1.4 to 5.7 ± 1.6 L/min, p < 0.001) and cardiac index (CI, from 2.3 ± 0.6 to 2.9 ± 0.70 L/min/m², p < 0.001) with decreased systemic vascular resistance (from 1881 ± 582 to 1258 ± 332 dynes/s/cm5, p < 0.001) and systolic blood pressure (132 ± 21 to 115 ± 23 mmHg, p < 0.001). The haemodynamic changes persisted for 15 min of WWI. In normal subjects, compared to baseline, WWI increased SV (from 68 ± 11 to 80 ± 18 mL, p < 0.001), CO (from 5.1 ± 1.9 to 5.7 ± 1.8 L/min, p < 0.001) and CI (from 2.7 ± 0.9 to 2.9 ± 1.0 L/min/m², p < 0.001).In patients with CHF, compared to baseline, WWI caused an increase in left atrial volume (from 57 ± 44 to 72 ± 46 mL, p = 0.04), without any changes in left ventricular size or function or amino terminal pro B-type natriuretic peptide. CONCLUSIONS: In patients with CHF, WWI causes an acute increase in cardiac output and a fall in systemic vascular resistance. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (Identifier: NCT02949544) https://clinicaltrials.gov/ct2/show/NCT02949544?cond=NCT02949544&rank=1 .


Assuntos
Insuficiência Cardíaca/reabilitação , Hidroterapia/métodos , Imersão/fisiopatologia , Volume Sistólico/fisiologia , Resistência Vascular/fisiologia , Função Ventricular Esquerda/fisiologia , Idoso , Ecocardiografia , Feminino , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Resultado do Tratamento
4.
Undersea Hyperb Med ; 45: 495-503, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30428238

RESUMO

Introduction: Head-out water immersion (HOWI) results in diuresis, which could potentially limit performance after egress to land. We examined the effect of rehydration on endurance, cardiovascular stability, and overnight recovery following a four-hour thermoneutral HOWI on 12 subjects. Methods: Twelve males completed a crossover design consisting of no hydration, replacement of fluid loss during immersion (RD), and replacement of fluid after the immersion period (RA). Sixty minutes following immersion, subjects ran to exhaustion at ~80% maximum heart rate. After completing the run, each subject submitted to a head-up tilt test (HUTT). Vital signs and ECG were monitored overnight. Results: HOWI resulted in a transient diuresis in NH and RA, while it was sustained throughout immersion in the RD protocol, resulting in greater urine [l] output (1.27 ± 0.48 (NH), 1.18 ± 0.43 (RA), 2.32 ± 0.77 (RD) (p ⟨ 0.001). Body mass change (%) was greater in NH than RD, but not RA (-1.58 ± 0.56 (NH), -0.66 ± 0.47 (RD), and -0.92 ± 0.76 (RA)). Run times were 17% versus 20% in NH compared to RD and RA, respectively, but were not statistically different. Time to orthostasis during the HUTT did not differ by condition. Overnight heart rate variability and blood pressures were not different. Conclusion: Rehydration during water immersion resulted in a large, sustained diuresis without improving performance or recovery after exiting the water. Loss of body water during thermoneutral HOWI was modest, and both rehydration strategies minimally affected aerobic performance and overnight recovery in young, healthy males.


Assuntos
Pressão Sanguínea/fisiologia , Diurese/fisiologia , Hidratação/métodos , Frequência Cardíaca/fisiologia , Imersão/fisiopatologia , Resistência Física/fisiologia , Corrida/fisiologia , Adulto , Análise de Variância , Índice de Massa Corporal , Água Corporal/metabolismo , Estudos Cross-Over , Eletrocardiografia , Deslocamentos de Líquidos Corporais/fisiologia , Cabeça , Humanos , Masculino , Sono/fisiologia , Decúbito Dorsal/fisiologia , Temperatura , Teste da Mesa Inclinada/métodos , Fatores de Tempo , Micção/fisiologia , Água , Adulto Jovem
5.
Braz J Med Biol Res ; 51(11): e7702, 2018 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-30304134

RESUMO

When exercises are done in intense or exhaustive modes, several acute biochemical mechanisms are triggered. The use of cryotherapy as cold-water immersion is largely used to accelerate the process of muscular recovery based on its anti-inflammatory and analgesic properties. The present study aimed to study the biochemical effects of cold-water immersion treatment in mice submitted to exercise-induced exhaustion. Swiss albino mice were divided into 4 treatment groups: control, cold-water immersion (CWI), swimming exhaustive protocol (SEP), and SEP+CWI. Treatment groups were subdivided into times of analysis: 0, 1, 3, and 5 days. Exhaustion groups were submitted to one SEP session, and the CWI groups submitted to one immersion session (12 min at 12°C) every 24 h. Reactive species production, inflammatory, cell viability, and antioxidant status were assessed. The SEP+CWI group showed a decrease in inflammatory damage biomarkers, and reactive species production, and presented increased cell viability compared to the SEP group. Furthermore, CWI increased acetylcholinesterase activity in the first two sessions. The present study showed that CWI was an effective treatment after exercise-induced muscle damage. It enhanced anti-inflammatory response, decreased reactive species production, increased cell viability, and promoted redox balance, which could decrease the time for the recovery process.


Assuntos
Crioterapia/métodos , Imersão/fisiopatologia , Músculo Esquelético/lesões , Músculo Esquelético/fisiopatologia , Condicionamento Físico Animal/efeitos adversos , Condicionamento Físico Animal/fisiologia , Natação/fisiologia , Acetilcolinesterase/análise , Animais , Antioxidantes/análise , Sobrevivência Celular/fisiologia , Temperatura Baixa , Fluoresceínas/análise , Masculino , Camundongos , Miosite/prevenção & controle , Espécies Reativas de Oxigênio/análise , Reprodutibilidade dos Testes , Natação/lesões , Sais de Tetrazólio , Tiazóis , Fatores de Tempo , Resultado do Tratamento , Água/fisiologia
6.
Biosci Rep ; 38(5)2018 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-30201695

RESUMO

Immersion pulmonary edema (IPE) is a serious complication of water immersion during scuba diving. Myocardial ischemia can occur during IPE that worsens outcome. Because myocardial injury impacts the therapeutic management, we aim to evaluate the profile of cardiac markers (creatine phosphokinase (CPK), brain natriuretic peptide (BNP), highly sensitive troponin T (TnT-hs) and ultrasensitive troponin I (TnI-us) of divers with IPE. Twelve male scuba divers admitted for suspected IPE were included. The collection of blood samples was performed at hospital entrance (T0) and 6 h later (T0 + 6 h). Diagnosis was confirmed by echocardiography or computed-tomography scan. Mean ± S.D. BNP (pg/ml) was 348 ± 324 at T0 and 223 ± 177 at T0 + 6 h (P<0.01), while mean CPK (international units (IUs)), and mean TnT-hs (pg/ml) increased in the same times 238 ± 200 compared with 545 ± 39, (P=0.008) and 128 ± 42 compared with 269 ± 210, (P=0.01), respectively; no significant change was observed concerning TnI-us (pg/ml): 110 ± 34 compared with 330 ± 77, P=0.12. At T0 + 6 h, three patients had high TnI-us, while six patients had high TnT-hs. Mean CPK was correlated with TnT-hs but not with TnI-us. Coronary angiographies were normal. The increase in TnT during IPE may be secondary to the release of troponin from non-cardiac origin. The measurement of TnI in place of TnT permits in some cases to avoid additional examinations, especially unnecessary invasive investigations.


Assuntos
Isquemia Miocárdica/sangue , Edema Pulmonar/sangue , Troponina I/sangue , Troponina T/sangue , Adulto , Biomarcadores/sangue , Vasos Sanguíneos/diagnóstico por imagem , Vasos Sanguíneos/fisiopatologia , Angiografia Coronária , Creatina Quinase/sangue , Mergulho/efeitos adversos , Humanos , Imersão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/etiologia , Isquemia Miocárdica/fisiopatologia , Peptídeo Natriurético Encefálico/sangue , Edema Pulmonar/etiologia , Edema Pulmonar/fisiopatologia
7.
Rev Infirm ; 67(242): 29-30, 2018.
Artigo em Francês | MEDLINE | ID: mdl-29907176

RESUMO

The speciality of the hyperbaric nurse, whether practised in the civil or military setting, has a wide-reaching scope. Two teams of professionals from Lyon and Toulon share their motivations and demonstrate, through the words of two nurses, a real collective passion for this original and highly technical practice.


Assuntos
Oxigenação Hiperbárica/enfermagem , Imersão , Papel do Profissional de Enfermagem , Humanos , Imersão/fisiopatologia , Enfermeiras e Enfermeiros , Especialidades de Enfermagem
8.
J Appl Physiol (1985) ; 125(2): 429-444, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29745801

RESUMO

Effects of regular use of cold-water immersion (CWI) on fiber type-specific adaptations in muscle K+ transport proteins to intense training, along with their relationship to changes in mRNA levels after the first training session, were investigated in humans. Nineteen recreationally active men (24 ± 6 yr, 79.5 ± 10.8 kg, 44.6 ± 5.8 ml·kg-1·min-1) completed six weeks of sprint-interval cycling, either without (passive rest; CON) or with training sessions followed by CWI (15 min at 10°C; COLD). Muscle biopsies were obtained before and after training to determine abundance of Na+, K+-ATPase isoforms (α1-3, ß1-3) and phospholemman (FXYD1) and after recovery treatments (+0 h and +3 h) on the first day of training to measure mRNA content. Training increased ( P < 0.05) the abundance of α1 and ß3 in both fiber types and ß1 in type-II fibers and decreased FXYD1 in type-I fibers, whereas α2 and α3 abundance was not altered by training ( P > 0.05). CWI after each session did not influence responses to training ( P > 0.05). However, α2 mRNA increased after the first session in COLD (+0 h, P < 0.05) but not in CON ( P > 0.05). In both conditions, α1 and ß3 mRNA increased (+3 h; P < 0.05) and ß2 mRNA decreased (+3 h; P < 0.05), whereas α3, ß1, and FXYD1 mRNA remained unchanged ( P > 0.05) after the first session. In summary, Na+,K+-ATPase isoforms are differently regulated in type I and II muscle fibers by sprint-interval training in humans, which, for most isoforms, do not associate with changes in mRNA levels after the first training session. CWI neither impairs nor improves protein adaptations to intense training of importance for muscle K+ regulation. NEW & NOTEWORTHY Although cold-water immersion (CWI) after training and competition has become a routine for many athletes, limited published evidence exists regarding its impact on training adaptation. Here, we show that CWI can be performed regularly without impairing training-induced adaptations at the fiber-type level important for muscle K+ handling. Furthermore, sprint-interval training invoked fiber type-specific adaptations in K+ transport proteins, which may explain the dissociated responses of whole-muscle protein levels and K+ transport function to training previously reported.


Assuntos
Proteínas de Transporte/metabolismo , Exercício Físico/fisiologia , Fibras Musculares Esqueléticas/metabolismo , Proteínas Musculares/metabolismo , Potássio/metabolismo , Adaptação Fisiológica/fisiologia , Adulto , Temperatura Baixa , Treinamento Intervalado de Alta Intensidade/métodos , Humanos , Imersão/fisiopatologia , Masculino , Fibras Musculares Esqueléticas/fisiologia , Isoformas de Proteínas/metabolismo , RNA Mensageiro/metabolismo , Treinamento de Resistência/métodos , ATPase Trocadora de Sódio-Potássio/metabolismo , Água , Adulto Jovem
9.
High Alt Med Biol ; 19(2): 185-192, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29608373

RESUMO

Gorjanc, Jurij, Shawnda A. Morrison, Rok Blagus, and Igor B. Mekjavic. Cold susceptibility of digit stumps resulting from amputation after freezing cold injury in elite alpinists. High Alt Med Biol. 19:185-192, 2018. AIM: The aim of the study was to assess whether previous freezing cold injury in fingers and/or toes might predispose alpinists to greater risk of further freezing cold injury, primarily due to a greater vasoconstrictor response to cold, resulting in a lower perfusion, reflected in lower skin temperature. METHODS: Ten elite alpinists (N = 10; 8 male and 2 female) with amputations after freezing cold injury participated in a cold-water (8°C) immersion stress test of the hands and feet. Digit skin temperatures of amputated digits, their noninjured counterparts, noninjured digits of the affected side and noninjured digits of the corresponding side were measured. The skin temperatures were compared during three consecutive phases of the cold stress test: prewarming, cold water immersion, and passive heating. RESULTS: Amputated toes cooled much faster compared to their uninjured counterparts (n = 26, p < 0.001), and attained lower skin temperatures during the cold exposure test (n = 26, p < 0.001). Higher cooling rate was observed in all the toes on the injured limb compared with the toes on the uninjured limb (n = 40, p < 0.001). In contrast to the toes, the fingers on the injured limb after freezing cold injury were warmer during cooling phase compared to uninjured fingers (n = 15, p < 0.001). CONCLUSIONS: The lower digit temperatures observed in affected toe stumps during the cold stress test compared to the nonamputated toes may indicate a heightened risk of future freezing cold injury with subsequent cold exposures, as a consequence of less perfusion, reflected in the lower skin temperature. This relationship was not confirmed in the fingers.


Assuntos
Cotos de Amputação/fisiopatologia , Amputação Traumática/complicações , Lesão por Frio/cirurgia , Temperatura Baixa/efeitos adversos , Montanhismo/lesões , Cotos de Amputação/cirurgia , Amputação Traumática/fisiopatologia , Lesão por Frio/etiologia , Feminino , Dedos/fisiopatologia , Dedos/cirurgia , Humanos , Imersão/efeitos adversos , Imersão/fisiopatologia , Masculino , Temperatura Cutânea/fisiologia , Dedos do Pé/fisiopatologia , Dedos do Pé/cirurgia , Resultado do Tratamento
10.
Exp Physiol ; 103(5): 714-727, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29527752

RESUMO

NEW FINDINGS: What is the central question of the study? Is central chemosensitivity blunted during thermoneutral head-out water immersion in healthy humans? What is the main finding and its importance? Central chemosensitivity is augmented during thermoneutral head-out water immersion in healthy men and women. Thus, we suggest that the central chemoreceptors do not contribute to CO2 retention during head-out water immersion. ABSTRACT: Carbon dioxide retention occurs during water immersion. Therefore, we tested the hypothesis that central chemosensitivity to hypercapnia is blunted during 2 h of thermoneutral head-out water immersion (HOWI) in healthy young adults. Twenty-six participants (age 22 ± 2 years; body mass index 24 ± 3 kg m-2 ; 14 women) participated in two experimental visits: a HOWI visit (HOWI) and a dry time-control visit (Control). Central chemosensitivity was assessed via a rebreathing test at baseline, 10, 60, 90 and 120 min and after HOWI and Control. End-tidal CO2 tension (P ET ,CO2), minute ventilation, blood pressure and heart rate were recorded continuously. The P ET ,CO2 increased from baseline throughout HOWI (peak increase at 120 min 2 ± 2 mmHg; P < 0.001), and the change in P ET ,CO2 was greater throughout HOWI than Control (P < 0.001). The change in minute and alveolar ventilation was not different throughout time (P ≥ 0.173) or between conditions (P ≥ 0.052). Central chemosensitivity was greater than at baseline throughout HOWI (peak increase 0.74 ± 1.01 l min-1  mmHg-1 at 120 min; P < 0.001), and the change in central chemosensitivity was greater throughout HOWI than Control (P  ≤  0.006). We also divided the cohort into tertiles based on baseline central chemosensitivity (i.e. Low, Intermediate and High) and compared Low versus High during HOWI. Low demonstrated an increase in P ET ,CO2 starting at 10 min (2 ± 3 mmHg; P < 0.001), whereas High did not exhibit an increase in P ET ,CO2 until 60 min (2 ± 2 mmHg; P = 0.018). These data indicate that CO2 retention occurs throughout HOWI despite augmented central chemosensitivity and that having a high baseline central chemosensitivity might delay the onset of CO2 retention.


Assuntos
Células Quimiorreceptoras/fisiologia , Hipercapnia/fisiopatologia , Imersão/fisiopatologia , Água/metabolismo , Adulto , Pressão Sanguínea/fisiologia , Dióxido de Carbono/sangue , Células Quimiorreceptoras/metabolismo , Feminino , Frequência Cardíaca/fisiologia , Humanos , Hipercapnia/metabolismo , Masculino , Adulto Jovem
11.
Stress ; 21(3): 267-273, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29451058

RESUMO

Adolescence is a distinct developmental period characterized by behavioral and physiological maturation. Rapid ongoing changes during neurodevelopment in particular present potential opportunities for stress to have lasting effects on longitudinal outcomes of behavioral and neuroendocrine function. While adult stress effects on outcomes during adulthood have been characterized, little is known about the lasting effects of adolescent repeated stressor exposure on outcomes during adolescence. We have previously reported different stress responses in adolescent rats relative to adult rats, including a blunted fear response outcome in adulthood in rats stressed during adolescence. The present study characterized the ontogeny of behavioral and neuroendocrine responses to eight underwater trauma (UWT) exposures in rats over a two week poststress time period during adolescence (P34) or adulthood (P83) relative to age-matched control groups that underwent eight swimming episodes without UWT. Repeated UWT exposures starting in adolescence, but not adulthood, resulted in adverse behavioral responses on the elevated plus maze 1 day post-stress. Corticosterone responses did not differ between UWT-exposed and controls for either age group at 1 day or at 7 days poststress, although there was an effect of age on corticosterone levels. We conclude that repeated UWT stress events have a lasting, negative behavioral effect on adolescent rats that is not observed in adult rats after the two-week exposure window. These results suggest that neurophysiological mechanisms underlying recovery from a repeated stressor are immature in adolescence relative to adulthood in rats.


Assuntos
Imersão/fisiopatologia , Estresse Psicológico/psicologia , Ferimentos e Lesões/fisiopatologia , Envelhecimento/psicologia , Animais , Ansiedade/psicologia , Comportamento Animal , Corticosterona/sangue , Comportamento Exploratório , Ratos , Ratos Sprague-Dawley , Reflexo de Sobressalto , Natação/psicologia , Água
12.
Exp Physiol ; 103(4): 512-522, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29345019

RESUMO

NEW FINDINGS: What is the central question of this study? Does the cold-water immersion (14°C) of profoundly hyperthermic individuals induce reductions in cutaneous and limb blood flow of sufficient magnitude to impair heat loss relative to the size of the thermal gradient? What is the main finding and its importance? The temperate-water cooling (26°C) of profoundly hyperthermic individuals was found to be rapid and reproducible. A vascular mechanism accounted for that outcome, with temperature-dependent differences in cutaneous and limb blood flows observed during cooling. Decisions relating to cooling strategies must be based upon deep-body temperature measurements that have response dynamics consistent with the urgency for cooling. ABSTRACT: Physiologically trivial time differences for cooling the intrathoracic viscera of hyperthermic individuals have been reported between cold- and temperate-water immersion treatments. One explanation for that observation is reduced convective heat delivery to the skin during cold immersion, and this study was designed to test both the validity of that observation, and its underlying hypothesis. Eight healthy men participated in four head-out water immersions: two when normothermic, and two after exercise-induced, moderate-to-profound hyperthermia. Two water temperatures were used within each thermal state: temperate (26°C) and cold (14°C). Tissue temperatures were measured at three deep-body sites (oesophagus, auditory canal and rectum) and eight skin surfaces, with cutaneous vascular responses simultaneously evaluated from both forearms (laser-Doppler flowmetry and venous-occlusion plethysmography). During the cold immersion of normothermic individuals, oesophageal temperature decreased relative to baseline (-0.31°C over 20 min; P < 0.05), whilst rectal temperature increased (0.20°C; P < 0.05). When rendered hyperthermic, oesophageal (-0.75°C) and rectal temperatures decreased (-0.05°C) during the transition period (<8.5 min, mostly in air at 22°C), with the former dropping to 37.5°C only 54 s faster when immersed in cold rather than in temperate water (P < 0.05). Minimal cutaneous vasoconstriction occurred during either normothermic immersion, whereas pronounced constriction was evident during both immersions when subjects were hyperthermic, with the colder water eliciting a greater vascular response (P < 0.05). It was concluded that the rapid intrathoracic cooling of asymptomatic, hyperthermic individuals in temperate water was a reproducible phenomenon, with slower than expected cooling in cold water brought about by stronger cutaneous vasoconstriction that reduced convective heat delivery to the periphery.


Assuntos
Regulação da Temperatura Corporal/fisiologia , Temperatura Corporal/fisiologia , Febre/fisiopatologia , Imersão/fisiopatologia , Pele/irrigação sanguínea , Adulto , Temperatura Baixa , Exercício Físico/fisiologia , Temperatura Alta , Humanos , Fluxometria por Laser-Doppler/métodos , Masculino , Fluxo Sanguíneo Regional/fisiologia , Vasoconstrição/fisiologia , Água/metabolismo , Adulto Jovem
13.
Int J Hyperthermia ; 34(6): 834-839, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29157042

RESUMO

PURPOSE: Brain-derived neurotrophic factor (BDNF) is an important neurotrophin. The present study investigated the effects of head-out water immersion (HOI) on serum BDNF concentrations. METHODS: Eight healthy men performed 20 min head-out water immersion at 42 °C (hot-HOI) and 35 °C (neutral-HOI). These experimental trials were administered in a randomised order separated by at least 7 days. Venous blood samples were withdrawn at rest, immediately after the 20-min HOI, as well as at 15 and 30 min after the end of the HOI. Serum BDNF and S100ß, plasma cortisol, platelet and monocyte counts, and core body temperature (Tcb) were measured. RESULTS: Tcb was higher at the end of the hot-HOI and 15 min after hot-HOI (p < 0.01), but recovered to pre-HOI level at 30 min after hot-HOI. No change in Tcb was recorded during neutral-HOI. BDNF level was higher (p < 0.05) at the end of the hot-HOI and at 15 min after the end of hot-HOI, and returned to the baseline at 30 min after hot-HOI. S100ß, platelet count and monocyte count remained stable throughout the study. Cortisol level was lower at the end of the hot-HOI and returned to pre-HOI level during the recovery period. BDNF and S100ß, cortisol, and platelet and monocyte counts did not change throughout the neutral-HOI study. CONCLUSIONS: The present findings suggested that the increase in BDNF during 20-min hot-HOI was induced by hyperthermia through enhanced production, rather than by changes in permeability of the blood-brain barrier (BBB), platelet clotting mechanisms or secretion from monocytes.


Assuntos
Fator Neurotrófico Derivado do Encéfalo/metabolismo , Imersão/fisiopatologia , Água/química , Adulto , Temperatura Alta , Humanos , Masculino
14.
Undersea Hyperb Med ; 44(6): 589-600, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29281196

RESUMO

BACKGROUND: The influence of prolonged and repeated water immersions on heart rate variability (HRV) and complexity was examined in 10 U.S. Navy divers who completed six-hour resting dives on five consecutive days. Pre-dive and during-dive measures were recorded daily. METHODS: Dependent variables of interest were average heart rate (HR), time-domain measures of HRV [root mean square of successive differences of the normal RR (NN) interval (RMSSD), standard deviation of the NN interval (SDNN)], frequency-domain measures of HRV [low-frequency power spectral density (psd) (LFpsd), low-frequency normalized (LFnu), high-frequency psd (HFpsd), high-frequency normalized (HFnu), low-frequency/ high-frequency ratio (LF/HF)], and non-linear dynamics of HRV [approximate entropy (ApEn)]. A repeated-measures ANOVA was performed to examine pre-dive measure differences among baseline measures. Hierarchical linear modeling (HLM) was performed to test the effects of prolonged and repeated water immersion on the dependent variables. RESULTS: Pre-dive HR (P=0.005) and RMSSD (P⟨0.001) varied significantly with dive day while changes in SDNN approached significance (P=0.055). HLM indicated that HR decreased during daily dives (P=0.001), but increased across dive days (P=0.011); RMSSD increased during daily dives (P=0.018) but decreased across dive days (P⟨0.001); SDNN increased during daily dives (P⟨0.001); LF measures increased across dive days (LFpsd P⟨0.001; LFnu P⟨0.001), while HF measures decreased across dive days (HFpsd P⟨0.001; HFnu P⟨0.001); LF/HF increased across dive days (P⟨0.001); ApEn decreased during daily dives (P⟨0.02) and across dive days (P⟨0.001). CONCLUSIONS: These data suggest that the cumulative effect of repeated dives across five days results in decreased vagal tone and a less responsive cardiovascular system.


Assuntos
Mergulho/efeitos adversos , Mergulho/fisiologia , Frequência Cardíaca/fisiologia , Imersão/efeitos adversos , Imersão/fisiopatologia , Militares , Adulto , Análise de Variância , Eletrocardiografia/estatística & dados numéricos , Humanos , Modelos Lineares , Masculino , Modelos Cardiovasculares , Monitorização Fisiológica/estatística & dados numéricos , Estresse Fisiológico , Estados Unidos , Adulto Jovem
15.
Diving Hyperb Med ; 47(4): 239-247, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29241234

RESUMO

In most countries, immersion represents the second most common cause of accidental death in children and the third in adults. Between 2010 and 2013, 561 deaths worldwide involving recreational divers were recorded by the Divers Alert Network. Consequently, there is no room for complacency when diving. Being lost at sea is a diver's worst nightmare. In 2006, a diver was lost at sea off the coast of New Zealand for 75 hours. It is unprecedented that, after such a long time immersed in temperate (16-17°C) waters, he was found and survived. His case is presented and utilised to illustrate the many physiological and psychological factors involved in prolonged immersion and what might determine survival under such circumstances. We also briefly review options for enhancing diver location at sea and a few issues related to search and rescue operations are discussed.


Assuntos
Mergulho/fisiologia , Mergulho/psicologia , Imersão/fisiopatologia , Sobrevivência , Adulto , Constituição Corporal , Temperatura Baixa/efeitos adversos , Ingestão de Líquidos/fisiologia , Família , Humanos , Hipotermia/etiologia , Hipotermia/fisiopatologia , Imersão/efeitos adversos , Masculino , Nova Zelândia , Estado Nutricional/fisiologia , Roupa de Proteção , Recreação , Religião e Psicologia , Trabalho de Resgate , Choque/etiologia , Choque/fisiopatologia , Estresse Psicológico , Fatores de Tempo
16.
J. bras. pneumol ; 43(6): 409-415, Nov.-Dec. 2017. tab, graf
Artigo em Inglês | LILACS | ID: biblio-893881

RESUMO

ABSTRACT Objective: To determine whether different levels of CPAP improve the lung volumes and capacities of healthy subjects immersed in water. Methods: This was a randomized clinical trial, conducted between April and June of 2016, involving healthy female volunteers who were using oral contraceptives. Three 20-min immersion protocols were applied: control (no CPAP); CPAP5 (CPAP at 5 cmH2O); and CPAP10 (CPAP at 10 cmH2O). We evaluated HR, SpO2, FVC, FEV1, the FEV1/FVC ratio, peak expiratory flow rate (PEFR), and FEF25-75%) at three time points: pre-immersion; 10 min after immersion; and 10 min after the end of each protocol. Results: We evaluated 13 healthy volunteers. The CPAP10 protocol reversed the restrictive pattern of lung function induced by immersion in water, maintaining pulmonary volumes and capacities for a longer period than did the CPAP5 protocol. Conclusions: When the hemodynamic change causing a persistent lung disorder, only the application of higher positive pressures is effective in maintaining long-term improvements in the pulmonary profile.


RESUMO Objetivo: Verificar se continuous positive airway pressure (CPAP, pressão positiva contínua nas vias aéreas) em diferentes pressões melhora os volumes e capacidades pulmonares de sujeitos saudáveis em imersão em água. Métodos: Estudo clínico randomizado realizado entre abril e junho de 2016 com voluntárias saudáveis em uso de anticoncepcional oral. Foram aplicados três protocolos em imersão em água, todos com duração de 20 min: controle (sem aplicação de CPAP); CPAP5 (CPAP de 5 cmH2O); e CPAP10 (CPAP de 10 cmH2O). Avaliaram-se FC, SpO2, CVF, VEF1, relação VEF1/CVF em % do previsto, taxa de pico de fluxo expiratório e FEF25-75% em três momentos distintos: pré-imersão, 10 min após a imersão e 10 min após o final dos protocolos. Resultados: Foram avaliadas 13 voluntárias saudáveis. O protocolo CPAP10 foi capaz de reverter o padrão restritivo pulmonar induzido pela imersão em água em indivíduos saudáveis, mantendo normais os volumes e as capacidades pulmonares por um período mais prolongado quando comparado ao protocolo CPAP5. Conclusões: Nossos resultados indicam que, em condições cuja alteração hemodinâmica causadora do distúrbio pulmonar seja persistente, apenas a aplicação de pressões positivas mais elevadas é efetiva para manter as melhoras no quadro pulmonar por um maior tempo após a sua aplicação.


Assuntos
Humanos , Feminino , Adulto , Adulto Jovem , Pico do Fluxo Expiratório/fisiologia , Pressão Positiva Contínua nas Vias Aéreas , Imersão/fisiopatologia , Pulmão/fisiopatologia , Água , Índice de Massa Corporal , Modalidades de Fisioterapia
17.
Arch. med. deporte ; 34(181): 274-279, sept.-oct. 2017. tab, graf
Artigo em Espanhol | IBECS | ID: ibc-170317

RESUMO

Over the last years, sport diving has become one of the most studied physical activities. Several physiological responses have been described and analyzed during immersions of static, dynamic, and deep apnea sessions. These analyses, and several others, have been focused mainly on the cardiovascular and hemodynamic changes that this activity produces. Objective: To determine the influence of aerobic performance of static and dynamic apnea before and after an out-water training based on the average velocity of a 12-minute test. Material and Method: Eight apnea scuba divers of the Chilean Navy were part of this study. The variables measured were: aerobic performance measured through a 12-minute test, static and dynamic apnea. The protocol used for the aerobic performance development was a study based on the average velocity of a 12-minute test. The statistical analysis was performed with Student's t-test and the size of the effect with Cohen's d test. Results: The aerobic performance showed a significant increase between the pre and post-test (p < 0.001; size of the effect = 1.263). The static apnea did not show significant modifications (p > 0.05; size of the effect = 0.025). Lastly, the dynamic apnea showed a significant increase in both measurements (p < 0.05; size of the effect = 0.404). Conclusions: The result of the study showed that increasing the aerobic performance generates a rise in the distance of dynamic apnea. For that reason, it is suggested that apnea scuba divers perform out-water trainings based on the average velocity of 12-minute test as a complement to their immersion training


En los últimos años, el buceo deportivo se ha convertido en una de las actividades físicas más estudiadas. Dentro de estas investigaciones, se han descrito y analizado las respuestas fisiológicas corporales durante las inmersiones de apnea estática y dinámica. De forma específica, los análisis se han centrado principalmente en los cambios cardiovasculares y hemodinámicos que esta actividad deportiva produce. Objetivo: Determinar la influencia del rendimiento aeróbico en la apnea estática y dinámica antes y después de un entrenamiento fuera del agua basado en la velocidad promedio obtenida a través del test de 12 minutos. Material y Método: Ocho buceadores de apnea perteneciente a la Escuela Naval de la Armada de Chile fueron parte del estudio. Las variables medidas fueron: rendimiento aeróbico a través del test de 12 minutos, apnea estática y dinámica. El protocolo usado para el desarrollo del rendimiento aeróbico fue basado en la velocidad promedio del test de 12 minutos. El análisis estadístico fue realizado a través de una t de Student y el tamaño del efecto con una d de Cohen. Resultados: El rendimiento aeróbico mostró incrementos significativos entre el pre test y el post test (p < 0,001; tamaño del efecto = 1,263). La apnea estática no mostró cambios significativos (p > 0,05; tamaño del efecto = 0,025). Finalmente, la apnea dinámica mostró incrementos significativos entre ambas mediciones (p < 0,05; tamaño del efecto = 0,404). Conclusiones: El resultado del estudio mostró que un incremento en el rendimiento aeróbico genera un aumento en la distancia alcanzada en apnea dinámica. Por tal razón, se sugiere que los buceadores de apnea realicen entrenamientos fuera del agua. Por último, los entrenamientos pedestres basados en la velocidad promedio de la prueba de 12 minutos, son un buen complemento del entrenamiento de inmersión


Assuntos
Humanos , Desempenho Atlético/fisiologia , Exercício Físico/fisiologia , Apneia/fisiopatologia , Imersão/fisiopatologia , Teste de Esforço/métodos , Mergulho/fisiologia
18.
PLoS One ; 12(9): e0184240, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28877225

RESUMO

This study assessed the effectiveness of water immersion to the shoulders in enhancing blood lactate removal during active and passive recovery after short-duration high-intensity exercise. Seventeen cyclists underwent active water- and land-based recoveries and passive water and land-based recoveries. The recovery conditions lasted 31 minutes each and started after the identification of each cyclist's blood lactate accumulation peak, induced by a 30-second all-out sprint on a cycle ergometer. Active recoveries were performed on a cycle ergometer at 70% of the oxygen consumption corresponding to the lactate threshold (the control for the intensity was oxygen consumption), while passive recoveries were performed with subjects at rest and seated on the cycle ergometer. Blood lactate concentration was measured 8 times during each recovery condition and lactate clearance was modeled over a negative exponential function using non-linear regression. Actual active recovery intensity was compared to the target intensity (one sample t-test) and passive recovery intensities were compared between environments (paired sample t-tests). Non-linear regression parameters (coefficients of the exponential decay of lactate; predicted resting lactates; predicted delta decreases in lactate) were compared between environments (linear mixed model analyses for repeated measures) separately for the active and passive recovery modes. Active recovery intensities did not differ significantly from the target oxygen consumption, whereas passive recovery resulted in a slightly lower oxygen consumption when performed while immersed in water rather than on land. The exponential decay of blood lactate was not significantly different in water- or land-based recoveries in either active or passive recovery conditions. In conclusion, water immersion at 29°C would not appear to be an effective practice for improving post-exercise lactate removal in either the active or passive recovery modes.


Assuntos
Imersão , Ácido Láctico/sangue , Esforço Físico/fisiologia , Adulto , Ciclismo/fisiologia , Estudos Cross-Over , Método Duplo-Cego , Humanos , Imersão/fisiopatologia , Ácido Láctico/metabolismo , Consumo de Oxigênio/fisiologia
19.
Am J Physiol Regul Integr Comp Physiol ; 313(4): R372-R384, 2017 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28679683

RESUMO

We investigated the underlying molecular mechanisms by which postexercise cold-water immersion (CWI) may alter key markers of mitochondrial biogenesis following both a single session and 6 wk of sprint interval training (SIT). Nineteen men performed a single SIT session, followed by one of two 15-min recovery conditions: cold-water immersion (10°C) or a passive room temperature control (23°C). Sixteen of these participants also completed 6 wk of SIT, each session followed immediately by their designated recovery condition. Four muscle biopsies were obtained in total, three during the single SIT session (preexercise, postrecovery, and 3 h postrecovery) and one 48 h after the last SIT session. After a single SIT session, phosphorylated (p-)AMPK, p-p38 MAPK, p-p53, and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) mRNA were all increased (P < 0.05). Postexercise CWI had no effect on these responses. Consistent with the lack of a response after a single session, regular postexercise CWI had no effect on PGC-1α or p53 protein content. Six weeks of SIT increased peak aerobic power, maximal oxygen consumption, maximal uncoupled respiration (complexes I and II), and 2-km time trial performance (P < 0.05). However, regular CWI had no effect on changes in these markers, consistent with the lack of response in the markers of mitochondrial biogenesis. Although these observations suggest that CWI is not detrimental to endurance adaptations following 6 wk of SIT, they question whether postexercise CWI is an effective strategy to promote mitochondrial biogenesis and improvements in endurance performance.


Assuntos
Adaptação Fisiológica/fisiologia , Temperatura Baixa , Treinamento Intervalado de Alta Intensidade , Imersão/fisiopatologia , Músculo Esquelético/fisiologia , Resistência Física/fisiologia , Adulto , Temperatura Corporal , Feminino , Humanos , Masculino , Músculo Esquelético/anatomia & histologia , Recuperação de Função Fisiológica/fisiologia , Transdução de Sinais/fisiologia
20.
PLoS One ; 12(7): e0180765, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28742137

RESUMO

Water immersion alters the autonomic nervous system (ANS) response in humans. The effect of water immersion on executive function and ANS responses related to executive function tasks was unknown. Therefore, this study aimed to determine whether water immersion alters ANS response during executive tasks. Fourteen healthy participants performed color-word-matching Stroop tasks before and after non-immersion and water immersion intervention for 15 min in separate sessions. The Stroop task-related skin conductance response (SCR) was measured during every task. In addition, the skin conductance level (SCL) and electrocardiograph signals were measured over the course of the experimental procedure. The main findings of the present study were as follows: 1) water immersion decreased the executive task-related sympathetic nervous response, but did not affect executive function as evaluated by Stroop tasks, and 2) decreased SCL induced by water immersion was maintained for at least 15 min after water immersion. In conclusion, the present results suggest that water immersion decreases the sympathetic skin response during the color-word Stroop test without altering executive performance.


Assuntos
Função Executiva/fisiologia , Imersão/fisiopatologia , Sistema Nervoso Simpático/fisiologia , Sistema Nervoso Autônomo/fisiologia , Cor , Eletrocardiografia , Feminino , Resposta Galvânica da Pele/fisiologia , Humanos , Masculino , Modelos Neurológicos , Tempo de Reação/fisiologia , Teste de Stroop , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA