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At least 343 records · Page 19Linked to original sources
PubMed2003

Technique and timing in women's backward two and one half somersault tuck (205C) and the men's backward two and one half somersault pike (205B) 3m springboard dives.

The purpose of this study was to compare the backward two and one half somersault dive in a tuck position (205C) performed by females (n = 22) and the backward two and one half somersault dive in a pike position (205B) performed by males (n = 27) and by females (n = 6) to determine changes required by females to successfully perform 205B. Video data of the dives performed at the 1999 FINA World Diving Cup were captured and digitised to obtain times and postures of the divers at specific events including maximum depression, takeoff, and entry. Estimates of mass-normalised work done on the springboard were obtained from flight times. Males performed 31% more mass-normalised work on the springboard to gain height than females. Based on the dive scores and the short time to extend and prepare for entry it was concluded that females are not yet able to perform 205B with the same quality as they perform 205C. Females performing backward dives need to adjust their techniques to allow increased work on the springboard to generate height and rotation. Also, faster contraction of the hip flexors may allow them to achieve the tightest position more quickly to complete rotations with more time to prepare for entry.

Analysis of Variance↗
PubMed2005

Effects of diving and swimming behavior on body temperatures of pacific leatherback turtles in tropical seas.

Mathematical models and recordings of cloacal temperature suggest that leatherback turtles (Dermochelys coriacea) maintain core body temperature higher than ambient water temperature (T(W)) while freely swimming at sea. We investigated the thermoregulatory capabilities of free-ranging leatherbacks and, specifically, the effect that changes in diving patterns and ambient temperatures have on leatherback body temperatures (T(B)). Data loggers were used to record subcarapace and gastrointestinal tract temperatures (T(SC) and T(GT), respectively), T(W), swim speed, dive depth, and dive times of female leatherback turtles during internesting intervals off the coast of Guanacaste, Costa Rica. Mean T(SC) (28.7 degrees -29.0 degrees C) was significantly higher than mean T(W) (25.0 degrees -27.5 degrees C). There was a significant positive relationship between T(SC) and T(W) and a significant negative correlation between T(SC) and dive depth and T(GT) and dive depth. Rapid fluctuations in T(GT) occurred during the first several days of the internesting interval, which suggests that turtles were ingesting prey or water during this time. Turtles spent 79%-91% of the time at sea swimming at speeds greater than 0.2 m s(-1), and the average swim speed was 0.7 +/- 0.2 m s(-1). Results from this study show that alterations in diving behavior and T(W) affect T(B) of leatherback turtles in the tropics. Body temperatures of free-ranging leatherback turtles correspond well with values for T(B) predicted by mathematical models for tropical conditions.

Animals↗
PubMed2005

A theoretical analysis of diving performance in the Weddell seal (Leptonychotes weddelli).

Marine mammals are constrained in their foraging behaviour because, as obligate air breathers, they must undertake regular trips to the water surface to satisfy the need for respiratory gas exchange. Maximum underwater endurance time is determined by O2 supply and demand, but this does not necessarily imply that O2 is the main factor regulating individual dive and surface times. This study presents a theoretical analysis of diving performance that emphasizes a key role for CO2 in the proximate control of diving behaviour. Computer simulations, based on a mathematical model of the mammalian cardiorespiratory control system, are used to investigate the influence of swimming to depth and other energetic stresses (feeding, thermogenesis, sleep) on predicted diving behaviour in an average adult Weddell seal. The plausibility of the proposed model is supported by the study, which replicated published observations of natural diving behaviour in this species. It is suggested that diving behaviour is tuned to oscillations in respiratory drive and that behavioural and physiological factors can alter the dynamic characteristics of the system to achieve a highly adaptable reciprocal interaction that blurs the boundary between physiology and behaviour.

Animals↗
PubMed2003

An in-field demonstration of the true relationship between skin infections and their sources in occupational diving systems in the North Sea.

INTRODUCTION: Skin infections in saturation diving are caused by microbes that flourish in saturation environments. Improvements in the prevention of infections must therefore be based on environmental control and elimination. Furthermore, only a few genotypes seem to be responsible for the majority of infections in the Norwegian sector of the North Sea, and these have all been demonstrated in saturation systems for many years. Although reservoirs of infectious genotypes have been identified, their true sources have not been identified. OBJECTIVES: The purpose of this field study was to log the contamination by Pseudomonas aeruginosa of the saturation system throughout a diving operation. MATERIALS AND METHODS: Daily water samples from the vessels drinking water system and from the heated seawater systems to divers suits were taken throughout the diving period of 1 month in the summer of 2001. All P.aeruginosa isolates were genotyped by pulsed field gel electrophoresis. RESULTS: A total of 17 P.aeruginosa genotypes were identified in the course of this field study. None of the most common infectious genotypes previously observed in the Norwegian sector were among these strains. Two genotypes were involved in skin infections during the period of operation: TP2 and TP12. TP2 was shown to be an inhabitant of the diving systems throughout the investigation period, while TP12 was introduced from seawater in the course of the operation and rapidly spread and established itself throughout the diving system. CONCLUSIONS: The study has demonstrated seawater as a true source of an infectious P.aeruginosa genotype in occupational diving systems.

DNA, Bacterial↗
PubMed2005

Does competitive apnea diving have a long-term risk? Cardiopulmonary findings in breath-hold divers.

STUDY PURPOSE: The aim of this study was to investigate the cardiopulmonary status in a competitive apnea diving team. DESIGN: This study was conducted with a cross-sectional study design in which subjects had to undergo a predefined series of cardiopulmonary examinations. SUBJECTS: Eight competitive apnea divers (mean age, 26.9 +/- 5.3 years) who were participating in international apnea diving contests. METHODS: Electrocardiographic, 2-dimensional echocardiographic, Doppler-echocardiographic, and oxymetric examinations were performed in each subject during an apnea test. RESULTS: Apnea diving experience was 2.5 +/- 0.58 years, with a training frequency of 8.9 +/- 6.0 dives per week. During an apnea test, mean apnea time was 4.5 +/- 0.96 minutes. While 2-dimensional echocardiography showed normal morphologic findings of cardiac dimensions and function, electrocardiography, and Doppler echocardiography revealed indicators suggesting the beginning of right ventricular strain. CONCLUSIONS: We interpret the findings of our study as the onset of pulmonary hypertension resulting from repetitive pulmonary vasoconstriction together with severe hypoxia during apnea diving. We conclude that regular competitive apnea diving over a period of >2 to 3 years might carry a chronic cardiopulmonary risk that may lead from early functional changes to manifestation of pulmonary hypertension.

Adult↗
PubMed2005

Temporomandibular disorders in association with scuba diving.

OBJECTIVE: To determine the prevalence of temporomandibular disorders (TMD) in scuba divers and to identify the risk factors for the development of pain in the stomatognathic system before and after diving by the use of a questionnaire. DESIGN: : Retrospective cohort study based on questionnaires. PARTICIPANTS: A total of 296 active divers, aged 18 to 65 years, participating in scuba diving meetings in Heidelberg, Germany. INTERVENTIONS: Each diver answered a questionnaire containing 29 questions, predominantly on symptoms of TMD. MAIN OUTCOME MEASURES: The data collected from the divers were calculated by the use of logistic regression tests. Risk factors for the development of TMD were evaluated. RESULTS: Clenching seemed to be the greatest risk factor for pain while holding the mouthpiece and for pain in the masticatory muscle system after diving. Limited mouth opening and clenching were responsible for the development of pain in the temporomandibular joint after the dive. The prevalence of TMD-related symptoms was higher in women before, during, and after the dive. CONCLUSIONS: Individuals exhibiting TMD-related symptoms seem to be at the greatest risk of developing pain in the masticatory muscle system and/or the temporomandibular joint during or after the dive.

Adolescent↗
PubMed1985

Central nervous dysfunction associated with deep-sea diving.

A group of 23 professional divers was investigated before and after dives to 300 and 350 metres of sea water. 12 divers were also studied during the actual dive. All divers presented neurological symptoms and signs during compression. Intention tremor, ataxia, motor weakness, sensory symptoms, vertigo, nausea and reduced memory were the most prominent features of the High Pressure Nervous Syndrome (HPNS). There were considerable individual differences. Neuropsychological and neurophysiological investigations performed after one dive showed no significant changes in any of the divers, while there was a clear-cut impairment in a group of 6 divers who had performed 2 dives 3 months apart. These changes indicate that there may be pressure-induced brain dysfunction which persists for a transient post-dive period. Loss of short-term memory is a prominent part of this dysfunction. Transitory neurological signs indicating focal cerebral dysfunction were found immediately post-dive in 4 divers, presumably reflecting the unmasking of pre-existing subclinical minimal CNS lesions.

Adult↗
PubMed2005

The human diving response, its function, and its control.

The purpose of this review is to outline the physiological responses associated with the diving response, its functional significance, and its cardiorespiratory control. This review is separated into four major sections. Section one outlines the diving response and its physiology. Section two provides support for the hypothesis that the primary role of the diving response is the conservation of oxygen. The third section describes how the diving response is controlled and provides a model that illustrates the cardiorespiratory interaction. Finally, the fourth section illustrates potential adaptations that result after regular exposure to an asphyxic environment. The cardiovascular and endocrine responses associated with the diving response and apnea are bradycardia, vasoconstriction, and an increase in secretion of suprarenal catecholamines. These responses require the integration of both the cardiovascular system and the respiratory system. The primary role of the diving response is likely to conserve oxygen for sensitive brain and heart tissue and to lengthen the time before the onset of serious hypoxic damage. We suggest that future research should be focused towards understanding the role of altered ventilatory responses in human breath-hold athletes as well as in patients suffering from sleep-disordered breathing.

Bradycardia↗
PubMed1991

Temporomandibular dysfunction syndrome associated with scuba diving mouthpieces.

As previous reports have highlighted that temporomandibular joint dysfunction syndrome can occur during scuba diving due to the use of a diving mouthpiece, 74 divers of varied experience (62 male, 12 female) were asked to evaluate the efficiency of the mouthpiece for the ease of grip, insertion into the mouth, clearing of water, air sharing, comfort and overall efficiency. They also recorded the level of muscle and joint discomfort experienced during diving and non-diving activities. The results indicate that temporomandibular joint problems unrelated to diving are compounded by the use of a diving mouthpiece. The diver's assessment of muscle tension and comfort while using the mouthpiece was found to be a good predictor of whether temporomandibular dysfunction would occur and the assessment scores have been used in a formula to aid selection of a mouthpiece.

Diving↗
PubMed1991

Neurological long term consequences of deep diving.

Forty commercial saturation divers, mean age 34.9 (range 24-49) years, were examined one to seven years after their last deep dive (190-500 metres of seawater). Four had by then lost their divers' licence because of neurological problems. Twenty seven (68%) had been selected by neurological examination and electroencephalography before the deep dives. The control group consisted of 100 men, mean age 34.0 (range 22-48) years. The divers reported significantly more symptoms from the nervous system. Concentration difficulties and paraesthesia in feet and hands were common. They had more abnormal neurological findings by neurological examination compatible with dysfunction in the lumbar spinal cord or roots. They also had a larger proportion of abnormal electroencephalograms than the controls. The neurological symptoms and findings were highly significantly correlated with exposure to deep diving (depth included), but even more significantly correlated to air and saturation diving and prevalence of decompression sickness. Visual evoked potentials, brainstem auditory evoked potentials, and magnetic resonance imaging of the brain did not show more abnormal findings in the divers. Four (10%) divers had had episodes of cerebral dysfunction during or after the dives; two had had seizures, one had had transitory cerebral ischaemia and one had had transitory global amnesia. It is concluded that deep diving may have a long term effect on the nervous system of the divers.

Adult↗
PubMed1985

Coronary blood flow and myocardial segment dimensions during simulated dives in seals.

Three harbor seals Phoca vitulina richardsi and five spotted seals Phoca vitulina largha were used in studies of acute episodes of local myocardial ischemia in open-chest, anesthetized animals and of coronary blood flow and regional function as indicated by left ventricular segment dimensions during experimentally simulated dives of conscious, instrumented animals. We observed that seal myocardium, in which there are few coronary anastomoses, responded to brief local occlusion with prompt local dysfunction and systolic bulging; coronary flow in the nondiving seal oscillated irregularly and declined with spontaneous apnea and related falling heart rate; flow continued to oscillate but was much reduced during dives, frequently ceasing entirely for periods as long as 45 s; ventricular segment dimension shortening was reduced intermittently during dives; and elevated heart rate induced during dives by cardiac pacing or by administration of atropine diminished or eliminated the reductions in coronary blood flow. Responses of seal heart reflect the reduction in cardiac metabolic demand during diving and the seal's myocardial adaptation for enhanced anaerobic glycolysis. The seal heart can maintain mechanical function during dives with minimal coronary perfusion, despite the progressive and ultimately profound hypoxia, hypercapnia, and acidosis. Reduced cardiac metabolism, copious glycolytic reserves, and metabolite washout by intermittent brief bursts of coronary blood flow are apparently sufficient to support continued cardiac function, even though the seal heart has little tolerance for acute localized ischemia.

Animals↗
PubMed2007

Estimating the rate of oxygen consumption during submersion from the heart rate of diving animals.

How animals manage their oxygen stores during diving and other breath-hold activities has been a topic of debate among physiologists for decades. Specifically, while the behavior of free-ranging diving animals suggests that metabolism during submersion must be primarily aerobic in nature, no studies have been able to determine their rate of oxygen consumption during submersion (Vo(2)d) and hence prove that this is the case. In the present study, we combine two previously used techniques and develop a new model to estimate Vo(2)d accurately and plausibly in a free-ranging animal and apply it to data for macaroni penguins (Eudyptes chrysolophus) as an example. For macaroni penguins at least, Vo(2)d can be predicted by measuring heart rate during the dive cycle and the subsequent surface interval duration. Including maximum depth of the dive improves the accuracy of these predictions. This suggests that energetically demanding locomotion events within the dive combine with the differing buoyancy and locomotion costs associated with traveling to depth to influence its cost in terms of oxygen use. This will in turn effect the duration of the dive and the duration of the subsequent recovery period. In the present study, Vo(2)d ranged from 4 to 28 ml.min(-1).kg(-1), indicating that, at least as far as aerobic metabolism was concerned, macaroni penguins were often hypometabolic, with rates of oxygen consumption usually below that for this species resting in water (25.6 ml.min(-1).kg(-1)) and occasionally lower than that while resting in air (10.3 ml.min(-1).kg(-1)).

Animals↗
PubMed1986

Microcomputer-assisted metabolic studies of voluntary diving of Weddell seals.

Utilizing a microprocessor-controlled peristaltic withdrawal pump, arterial blood samples were obtained from Weddell seals (Leptonychotes weddelli) while diving voluntarily under the sea ice at McMurdo Sound, Antarctica. Plasma concentrations of glucose, lactate, free fatty acids, urea, and amino acids were determined in seals at various times during rest, diving, and recovery. In addition, radiolabeled palmitate, glucose, lactate, p-aminohippurate, inulin, galactose, and cholate were injected into the descending aorta of seals in the resting state or during voluntary diving at sea. Sequential plasma samples were collected, and the kinetics of wash-in and clearance of each component were determined. Under resting conditions, the change in specific activity of palmitate, glucose, and lactate after bolus injection followed smooth multiexponential decay kinetics as in terrestrial animals. Similar decay curves for the clearance of organ-specific compounds were also obtained in seals at rest. If, during voluntary diving, Weddell seals were analogous to exercising animals, the wash-in and clearance kinetics of all metabolites and organ-specific compounds would be qualitatively similar to those observed at rest. In contrast, wash-in and clearance appeared to be qualitatively and quantitatively modified in a way consistent with utilization of the classical Scholander diving response in both short and long dives.

Amino Acids↗
PubMed1982

Effect of cardiovascular variables on hyperpnea during recovery from diving in ducks.

Control of hyperpnea during recovery from diving in unanesthetized White Pekin ducks, Anas platyrhynchos, was examined. Postdive minute ventilation (VE) increased five times regardless of the length of the preceding dive (1-4 min), although longer dives resulted in slower return of VE towards predive levels. Manipulation of arterial blood gases showed that both hypoxia and hypercapnia contributed to hyperpnea on emergence. Although chronic bilateral carotid body denervation depressed VE before and after diving, VE still increased four times after 1-min dives. Postdive hyperpnea was accompanied by dramatic elevations in heart rate, cardiac output, and the ventilation/perfusion ratio. However, artificially maintaining heart rate at abnormally low levels did not affect the postdive hyperpnea. In addition, postdive hyperpnea was unaffected by systemic arterial baroreceptor denervation. Postdive hyperpnea in ducks depends on blood gas changes occurring during a dive, yet a substantial part of the response is independent of input from carotid body chemoreceptors and the accompanying rises in heart rate and cardiac output.

Animals↗
PubMed1983

Energetics of wet-suit diving in Korean women breath-hold divers.

Contemporary Korean women divers wear wet suits during diving work to avoid the cold water stress. The present study was undertaken to evaluate the effect of wearing wet suits on the daily thermal balance of divers and on the duration of diving work. Rectal (TR) and skin temperatures and O2 consumption (VO2) were measured in four divers before and during diving work in summer (22.5 degrees C water) and winter (10 degrees C water). Subjects wore either wet suits (protected) or cotton suits (unprotected) for comparison. TR decreased 0.4 degrees C in summer and 0.6 degrees C in winter after 2 h of diving work in protected divers, while it decreased to 35 degrees C in 60 min in summer and in 30 min in winter in unprotected divers. Mean skin temperature of protected divers decreased to 31 degrees C in summer and 28 degrees C in winter, while that of unprotected divers decreased to 24 degrees C in summer and 13 degrees C in winter. VO2 toward the end of the diving work period increased by 80 (summer) and 140% (winter) in protected divers and by 160 (summer) and 250% (winter) in unprotected divers. From these values total thermal cost of diving work was estimated to be 260 and 370 kcal . day-1 in summer and winter, respectively.

Adult↗
PubMed1985

Potentially conflicting metabolic demands of diving and exercise in seals.

Metabolic replacement rates (Ra) for glucose and free fatty acids (FFA) were determined during rest, exercise, and diving conditions in the gray seal using bolus injections of radiotracers. In the exercise experiments the seal swam at a metabolic rate elevated twofold over resting Ra for glucose and FFA while resting were similar to values found in terrestrial mammals and other marine mammal species. During exercise periods glucose turnover increased slightly while FFA turnover changes were variable. However, the energetic demands of exercise could not be met by the increase in the replacement rates of glucose or FFA even if both were completely oxidized. Under diving conditions the tracer pool displayed radically different specific activity curves indicative of the changes in perfusion and metabolic rate associated with a strong dive response. Since the radiotracer curves during exercise and diving differed qualitatively and quantitatively, it is possible that similar studies on freely diving animals can be used to assess the role of the diving response during underwater swimming in nature.

Animals↗
PubMed1993

Effect of a single air dive on pulmonary diffusing capacity in professional divers.

The aim of this study was to determine whether venous gas embolism after a single air dive, evaluated using precordial Doppler monitoring, was associated with alterations in spirometry, lung volumes, arterial blood gases, or pulmonary diffusing capacity for carbon monoxide (DLCO). Postdive time course monitoring of pulmonary function was undertaken in 10 professional divers exposed to absolute air pressure of 5.5 bar for 25 min in a dry walk-in chamber. The US Navy decompression table was followed. Venous bubbles were detected by precordial Doppler monitoring. Two types of decompression were used: air and 100% O2 applied for 21 min during decompression stops. Spirometry, flow-volume, and body plethysmography parameters were unchanged after the dive with air decompression (AD) as well as with O2 decompression (OD). A significant reduction in arterial PO2, on average 20 Torr, was found after the dive with AD. DLCO was decreased in all divers 20, 40, 60, and 80 min after diving with AD (P < 0.001), whereas it was not significantly decreased after diving with OD. Maximal DLCO decrease of approximately 15% occurred 20 min postdive. In AD diving, maximum bubble grade for each individual vs. maximum DLCO reduction correlated significantly (r = 0.85, P = 0.002), as well as DLCO vs. arterial PO2 (r = 0.64, P = 0.017). In conclusion, a reduction in pulmonary diffusing capacity is observed in parallel with the appearance of venous bubbles detected by precordial Doppler. We suggest that bubbles cause pulmonary microembolization, triggering a complex sequence of events that remains to be resolved. Measuring DLCO complements Doppler bubble detection in postdiving assessment of pulmonary function.

Adult↗
PubMed1995

Complement activation in divers after repeated air/heliox dives and its possible relevance to DCS.

Plasma levels of the anaphylatoxin C5a were measured in 19 divers performing repeated air dives. Blood samples were collected immediately before the first dive and 2 h after the first and the second or third dive. Serum obtained at the same times was subjected to complement activation in vitro by air bubbles. Six divers developed symptoms of decompression sickness (DCS). Most intravascular bubbles were observed in divers with the lowest plasma levels of C5a. Postdive plasma levels of C5a did not increase compared with predive levels, nor were postdive levels significantly different after two or three dives compared with the first dive. Repeated dives did not influence the amounts of C5a generated in vitro. Neither plasma levels of C5a nor C5a generated in vitro were significantly different in divers who experienced symptoms of DCS vs. divers without symptoms of DCS. We conclude that plasma level of C5a and measurement of C5a generation in vitro cannot be used to predict DCS.

Adult↗