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At least 1,261 records · Page 70Linked to original sources
PubMed1990

Recreational swimming in CHD patients and healthy control subjects in relation to left heart function.

We examined the influence on heart rate, blood pressure, lactate, glucose, and catecholamine levels of moderate recreational swimming at a mean time of 5.2 to 9 minutes with mean speed of 0.33 to 0.49 m/s in 25 CHD patients and 8 healthy control subjects. During swimming, changes in these exercise-related parameters were observed such as were only found in seated ergometry trials at levels above 100 to 175 W. We consider these changes tolerable for patients with mild left heart damage (n = 13; ejection fraction 54 +/- 7%; exercise capacity 2.1 +/- 0.4 W/kg). They may indicate overexertion in patients with marked damage to the left heart (n = 12; ejection fraction 44 +/- 5%; exercise capacity 1.3 +/- 0.4 W/kg). Six of the 12 patients with marked left heart damage stopped swimming before the planned time had elapsed for subjective (overexertion) or objective (arrhythmia) reasons.

Analysis of Variance↗
PubMed2006

Evolution of high-performance swimming in sharks: transformations of the musculotendinous system from subcarangiform to thunniform swimmers.

In contrast to all other sharks, lamnid sharks perform a specialized fast and continuous "thunniform" type of locomotion, more similar to that of tunas than to any other known shark or bony fish. Within sharks, it has evolved from a subcarangiform mode. Experimental data show that the two swimming modes in sharks differ remarkably in kinematic patterns as well as in muscle activation patterns, but the morphology of the underlying musculotendinous system (red muscles and myosepta) that drives continuous locomotion remains largely unknown. The goal of this study was to identify differences in the musculotendinous system of the two swimming types and to evaluate these differences in an evolutionary context. Three subcarangiform sharks (the velvet belly lantern shark, Etmopterus spinax, the smallspotted catshark, Scyliorhinus canicula, and the blackmouth catshark, Galeus melanostomus) from the two major clades (two galeans, one squalean) and one lamnid shark, the shortfin mako, Isurus oxyrhinchus, were compared with respect to 1) the 3D shape of myomeres and myosepta of different body positions; 2) the tendinous architecture (collagenous fiber pathways) of myosepta from different body positions; and 3) the association of red muscles with myoseptal tendons. Results show that the three subcarangiform sharks are morphologically similar but differ remarkably from the lamnid condition. Moreover, the "subcarangiform" morphology is similar to the condition known from teleostomes. Thus, major features of the "subcarangiform" condition in sharks have evolved early in gnathostome history: Myosepta have one main anterior-pointing cone and two posterior-pointing cones that project into the musculature. Within a single myoseptum cones are connected by longitudinally oriented tendons (the hypaxial and epaxial lateral and myorhabdoid tendons). Mediolaterally oriented tendons (epineural and epipleural tendons; mediolateral fibers) connect vertebral axis and skin. An individual lateral tendon spans only a short distance along the body (a fraction between 0.05 and 0.075 of total length, L, of the shark). This span is similar in all tendons along the body. Red muscles insert into the midregion of the lateral tendons. The shortfin mako differs substantially from this condition in several respects: Red muscles are internalized and separated from white muscles by a sheath of lubricative connective tissue. They insert into the anterior part of the hypaxial lateral tendon. Rostrocaudally, this tendon becomes very distinct and its span increases threefold (0.06L anteriorly to 0.19L posteriorly). Mediolateral fibers do not form distinct epineural/epipleural tendons in the mako. Since our morphological findings are in good accordance with experimental data it seems likely that the thunniform swimming mode has evolved along with the described morphological specializations.

Animals↗
PubMed2005

Acute effects of guarana (Paullinia cupana Mart.) on mouse behaviour in forced swimming and open field tests.

Guarana, a herbal extract from the seeds of Paullinia cupana Mart. has been evaluated in comparison with caffeine on mouse behaviour in forced swimming and open field tests. Guarana (25 and 50 mg/kg, p.o.) and caffeine (10 and 20 mg/kg, p.o.) each significantly reduced the duration of immobility in the forced swimming test suggesting an antidepressant-like effect in mice. At these doses, neither substance affected ambulation in the open field test. However, a high dose of guarana (100 mg/kg) and caffeine (30 mg/kg) significantly enhanced the locomotor activity in the open field test. Caffeine, but not guarana, could effectively block an adenosine agonist, cyclopentyl adenosine (CPA)-induced increase in swimming immobility suggesting that mechanism(s) other than the adenosinergic mechanism are involved in the antidepressant-like activity of guarana.

Administration, Oral↗
PubMed2000

Swimming eliminates the weight gain and abdominal fat associated with ovariectomy in the retired breeder rat despite high-fat diet selection.

The effects of swim-training on choice of dietary fat, carbohydrate or protein, weight gain, energy intake, and energy efficiency were examined in ovariectomized and sham-operated retired breeder rats. After a 3 week training period of increased duration, rats swam for 75 min per session (5 days per week) for 4 weeks. Ovariectomized rats gained more weight than sham rats, while swimming reduced weight gain and abdominal fat. As a percentage of total intake, macronutrient choices (weight and energy) were similar for all groups, ovariectomized animals consumed more food and more energy, compared with sham animals. All rats freely chose the majority of their food (g) as carbohydrate and the majority of energy (kJ) as fat. Results indicate that a moderate intensity training program of swimming prevented the weight gain following ovariectomy in older rats despite their excessive caloric intake of fat.

Adipose Tissue↗
PubMed1996

Delayed nociceptive response following cold-water swim in the formalin test: possible mechanisms of action.

Exposure of animals to aversive events produces stress-induced analgesia. A common method of producing stress in animals is the cold-water swim (CWS). The present series of experiments examines the effect of CWS on tonic pain, as measured by the formalin test, and explores possible mechanisms of action. Experiment 1 demonstrates that a 3.5-min swim in 2 degrees C water produces a delayed nociceptive response (DNR), characterized by a prolonged period of no formalin responding which then begins and continues during the time when control animals, which have not received the CWS, are finished responding. The delayed response begins at 50-60 min postformalin injection, peaks at 80 min, and is still present at 120 min. Experiment 2 indicates that paw temperature effects are not responsible for the DNR, although core body temperature effects are a possible mechanism. However, systematic delays in the formalin injection following the CWS (Experiment 3) drastically altered the DNR even though core body temperature remained unchanged, suggesting that a decrease of core body temperature is insufficient to account for the DNR. Experiment 4 demonstrates that the NMDA antagonist MK-801 administered prior to the CWS dramatically reduces the DNR. The present experiment is the first study that reports a delay as long as 60 min in pain responding. It is concluded that the delayed response to formalin injection is the result of complex interactions involving peripheral mechanisms and central neuronal plasticity in which activity initiated by a noxious input persists after the cessation of the input as a consequence of a stressful event such as the cold-water swim.

Animals↗
PubMed1997

A biased random walk model for the trajectories of swimming micro-organisms.

The motion of swimming micro-organisms that have a preferred direction of travel, such as single-celled algae moving upwards (gravitaxis) or towards a light source (phototaxis), is modelled as the continuous limit of a correlated and biased random walk as the time step tends to zero. This model leads to a Fokker-Planck equation for the probability distribution function of the orientation of the cells, from which macroscopic parameters such as the mean cell swimming direction and the diffusion coefficient due to cell swimming can be calculated. The model is tested on experimental data for gravitaxis and phototaxis and used to derive values for the macroscopic parameters for future use in theories of bioconvection, for example.

Algorithms↗
PubMed1996

Parametric features of habituation of swim cycle number in the marine mollusc tritonia diomedea.

When repeatedly elicited, the oscillatory escape swim of the marine mollusc Tritonia diomedea undergoes habituation of the number of cycles per swim. Because the neural circuit for this behavior is reasonably well understood, a cellular analyses of habituation in Tritonia is feasible. Since such a study must ultimately relate cellular correlates to behavioral modifications, we have sought to increase our understanding of the parametric features of cycle number habituation in Tritonia. Habituation was compared when using different intertrial intervals, repeated training sessions, and different stimulus locations. Stimulus site generalization of habituation was demonstrated, suggesting that at least one site of plasticity underlying habitation is located postsynaptic to the sensory neurons for the response. Dishabituation from an above-zero baseline response level was not obtained. An isolated brain preparation was tested as a potential simplified system for cellular studies of habituation mechanisms. Repeated stimulation of a nerve containing sensory afferent processes resulted in a progressive reduction of swim motor program cycle number, with a rate similar to that seen in the behavior. Together, these findings: (1) establish a set of parametric features of cycle numbers habituation to be explained by physiological studies; (2) suggest that at least one circuit modification underlying the habituation is located among the circuit interneurons; and (3) indicate that the isolated brain preparation may serve as a useful neural analogue for studies of the cellular mechanisms of cycle number habituation in Tritonia.

Animals↗
PubMed1996

Age and stress history effects on spatial performance in a swim task in Fischer-344 rats.

This study determined whether prior habituation to water immersion would ameliorate age-related deficits in learning and memory in a swim task. Aged (22 months) and young adult (3 months) rats were immersed in water (30 degrees C) for 15 min on each of 28 consecutive days before training in the swim task. Additional groups of age-matched animals served as handled controls. Training on a spatial discrimination version of the water task was conducted over 5 days with two trials per day (1-h intertrial interval). A probe trial was substituted for the last trial on the fifth day to assess the rats' use of spatial information. Three days later, rats received cue discrimination training to find a visible platform. In the spatial task, prior habituation to water immersion ameliorated deficits in acquisition within each day (i.e., at a 1-h intertrial interval) but not across days (at 24 h). The results obtained with the 24-h interval confirm the rapid forgetting characteristic of aged rats in many tasks. The stress-habituation procedures reduced age-related deficits seen on the probe trial and on cue discrimination training. These findings indicate that several aspects of age-related impairments in the swim task, often attributed to primary age-related deficits in learning and memory processes per se, may instead be secondary to age-related differences in stress responses to water immersion.

Aging↗
PubMedDate not supplied

Behavioural effects of pinoline in the rat forced swimming, open field and elevated plus-maze tests.

Pinoline (6-methoxy-1,2,3,4-tetrahydro-beta-carboline) is a naturally occurring compound in the mammalian body which inhibits serotonin (5-hydroxytryptamine) uptake and monoamine oxidase-A activity. The present study was designed to assess potential antidepressant- or anxiolytic-like behavioural effects of pinoline in rat forced swimming, open field and elevated plus-maze tests. In the forced swimming test pinoline dose-dependently reduced the immobility time, starting from a dose of 8 mg kg-1. In the open field test pinoline reduced the total open field activity. This effect was significant at 20 mg kg-1, whereas the dose of 15 mg kg-1 only significantly reduced the number of rearings. In the plus-maze test pinoline decreased the total number of arm entries, the number of line crossings and time spent in the open part of the apparatus, but increased the number of approaches to the open part of the maze. The effects of pinoline were dose-dependent in all three behavioural tests used. Since antidepressant drugs reduce the immobility time in the forced swimming test but typically inhibit activity in open field and elevated plus-maze tests, the behavioural effects of pinoline resemble those of drugs with an antidepressant profile.

Animals↗
PubMed1990

Seasonal variation of serotonin content and nonassociative learning of swim induction in the leech Hirudo medicinalis.

It is possible to obtain habituation of swim induction by stimulating the leech with repetitive light electrical trains. After obtaining this simple form of non-associative learning, it is also possible to potentiate its response by a series of nociceptive skin brushings (dishabituation). Serotonin applied to the animal is the only neurotransmitter found to mimick dishabituation. We have observed that in the period April-June most animals did not exhibit potentiation of the swimming response after nociceptive stimulation while injection of serotonin mimicked dishabituation as in the animals treated in the period October-March. We have seen correlation between the changes in nonassociative learning and the seasonal variation of serotonin levels in segmental ganglia. This finding strengthens the hypothesis of serotonin as the neurotransmitter mediating dishabituation in swim induction of the leech.

Animals↗
PubMed1985

Swimming and loss of consciousness.

Under certain circumstances, even a good swimmer may drown during swimming exercise. Two cases of drowning, a survivor and a dead, during swimming exercise in swimming-pool are described. These cases and experimental researches with dogs indicate that the initial aspiration of water may cause extremely low heart rate and low blood pressure by reflex vagal inhibition, which deprive a good swimmer of his consciousness and make him drown.

Apnea↗
PubMed1991

Validity of heart rate and ratings of perceived exertion as indices of exercise intensity in a group of children while swimming.

The purpose of this study was to investigate the validity of heart rate (fc) and ratings of perceived exertion (RPE) as indices of exercise intensity in a group of children while swimming. Six healthy male swimmers, aged 10-12, swam tethered using the breast-stroke in a flume. The resistance started at 1.0 kg and increased in 1.0 kg steps up to the point of their exhaustion. The subjects swam for 5 min during each period, with a rest of 10-20 min until they had returned to their resting fc level. The last exercise intensity was with the maximal mass the subjects could support for 2 min. The last min of oxygen consumption (VO2) and 30 s of fc were measured during each exercise period. The subjects gave their RPE assessment at the end of exercise. The individual relationships between fc and VO2, and percentage maximal oxygen consumption (%VO2max) were linear with a high correlation r = 0.962-0.996 and r = 0.962-0.996, respectively. Therefore, it was concluded that fc was valid as an index of the exercise intensity of children while swimming. Compared to the results found in adults using a similar protocol, the children's fc were 8.3-26.9 beats.min-1 higher than those of the adults at the given %VO2max. The present study showed two different patterns in the relationship between VO2 and RPE in individuals. In two subjects the RPE increased linearly with VO2 while in the other four subjects the increase was discontinuous. If fc and RPE were to be applied to the setting and evaluation of exercise intensity during swimming, it would seem that fc would be a more useful guide than RPE for some children.

Body Height↗
PubMed1980

The neuronal correlate of locomotion in fish. "Fictive swimming" induced in an in vitro preparation of the lamprey spinal cord.

An in vitro preparation of the lamprey spinal cord was developed to enable detailed studies of the neuronal organization of the central spinal network generating fish swimming movements, one basic type of vertebrate locomotion. 1. In the isolated lamprey spinal cord, stable bursting activity recorded in the ventral roots was initiated by adding, e.g., D-glutamate or L-DOPA to the bathing solution. Less stable rhythmic activity could also be induced by tonic electrical stimulation of the spinal cord. 2. The isolated spinal cord is capable of producing rhythmic activity with the same type of intra- and intersegmental coordination as in the swimming fish, i.e., with alternation between the two sides of the segment and and intersegmental phase coupling. Hence, the in vitro preparation of the lamprey spinal cord may be said to represent the neuronal correlate of the undulatory swimming movements of fish. 3. By performing spinal cord transections it was demonstrated that as few as four segments can produce rhythmic activity with maintained coordination. It was concluded that the capacity to produce coordinated burst activity is distributed throughout the lamprey spinal cord. 4. A longitudinal midline lesion as long as four segments did not prevent the ventral roots on each side from bursting with maintained coordination between adjacent hemisegments. Thus, one side of a segment can produce bursting without interaction with its opposite side, at least when connected to its rostral and caudal neighbors. 5. The rate of bursting was found to vary from one cycle to the next with the period length tending to oscillate about a mean value. Burst duration and intersegmental phase lag varied in the same manner.

Animals↗
PubMed1980

Skeletal muscle fibre size adaptation to an eight-week swimming programme.

To evaluate the effects of short-term physical training on muscle fibre size, seven males were submitted to an eight-week swimming programme. Biopsy samples from the triceps brachii muscle were obtained before and after the training period, and compared with controls. After training, free swimming maximal oxygen uptake was significantly higher in the exercise subject (3.61 to 3.76 l x min-1), whereas the type I fibre distribution in the triceps was not affected (45.5 vs 44.6%). However, a significant increase in type II fibre area was observed (23.8%) and the type II/type I fibre area ratio increased from 1.63 to 1.83 with training. Muscle succinate dehydrogenase and phosphofructokinase activities were not significantly affected by the training programme. No significant changes were observed in the control group. It is concluded that type II fibres are recruited preferentially during a short-term swim-training programme...

Adult↗
PubMed1978

Resting values of left ventricular work to coronary blood flow ratio in rats exposed to intermittent high altitude hypoxia and swimming.

Total hemodynamic values and left ventricular blood flow were studied using Sapirstein's method of 86Rb uptake in female rats 24 h after a last exposure to high altitude. A stimulated altitude of 1350 m was used, initial exposure being for 30 min, gradually increased by 30 min daily up to 330 min daily for 5 days a week; the total number of exposures was 32. In another animal group the hypobaric exposure was combined with swimming in water at 37 degrees C. In both experimental groups the cardiac output and stroke volume increased, and in rats undergoing swimming the total peripheral resistance decreased as well. In the rats exposed to intermittent hypoxia only, left ventricular blood flow increased by about the same proportion as the cardiac output. The ratio of left ventricular work to coronary blood flow was significantly increased. In rats exposed to the combined influence of hypoxia and swimming, the increase in left ventricular blood flow did not match either the increase in cardiac output, or the weight gain of the left ventricle. The ventricular work to coronary blood flow ratio was the same as in controls.

Animals↗
PubMed1980

Metabolic changes in man during long-distance swimming.

Sixteen young adults were investigated before, immediately after and 24 h after swimming 5,200 +/- 618 m in 90 min. Mean pulse rate at the end of exercise was 151.3 min-1; skin and rectal temperature both slightly increased. Except for a marked leukocytosis, no changes were observed in other blood parameters (hematocrit, hemoglobin, erythrocytes). Serum enzyme activities showed (except for triosephosphate dehydrogenase) marked increases which in the case of creatine kinase and of malate dehydrogenase did not return to preexercise level on the next day. No hypoglycemia occurred in any of the subjects. Blood lactate increased to 4.2 mmol/l at the 15th min of exercise and at the end was still slightly above the resting value. Free fatty acids, free glycerol, 3-hydroxybutyrate, serum urea and uric acid rose markedly after swimming, whereas alpha-amino nitrogen, triglycerides, and serum magnesium significantly decreased. The electrical excitability of the two investigated muscles (M. vastus med. quadr. and M. deltoides) showed opposite changes, which was ascribed to their different involvement during swimming.

Adult↗
PubMed1982

Plasma renin activity and plasma catecholamines in intact and splenectomized running and swimming beagle dogs.

The influence of splenectomy in the dog on plasma catecholamine levels and plasma renin activity during treadmill running and swimming was investigated. Plasma catecholamines were measured by a radioenzymatic assay and plasma renin activity by a radioimmunoassay. Exercise consistently increased plasma catecholamine levels before and after splenectomy (range of increase:3--38 pmol X ml-1). Swimming, however, was a stronger stimulus than running. No change in the ratio between noradrenaline and adrenaline was found. In intact dogs exercise results in a marked increase in hematocrit due to splenic contraction (range of increase 3--8 volume %), while renal blood flow and plasma renin activity remain virtually constant. In splenectomized dogs, exercise has been reported to induce a decrease in renal blood flow. In contrast to this known effect on renal blood flow, splenectomy did not affect plasma renin activity in treadmill running dogs. In swimming dogs, however, plasma renin activity was increased after splenectomy (range of increase 3.3--6.9 ng X Ang I X ml-1 X h-1). Possibly, a threshold in sympathetic tone is required to increase renin release in the dog.

Animals↗
PubMed1982

Differences between swimming and running as stimuli for exercise-induced asthma.

Thirteen children each exercised for 6 min by running on a treadmill and by tethered swimming, breathing air at room temperature and either 8% or 99% relative humidity continuously. Ventilation, gas exchange and heart rate were closely matched in all four tests in each child, with a mean oxygen consumption of 32.3 +/- 1.7 ml x min-1 x kg-1. The post-exercise fall in FEV1 expressed as a percentage of the baseline FEV1 (delta FEV1) was significantly greater after running compared with swimming breathing either humid or dry air. The delta FEV1 was also related to respiratory heat loss (RHL) calculated from measurements of inspired and expired gas temperature and humidity. At a standardised RHL, the difference between running and swimming was highly significant [delta FEV1 (%) +/- SE = 39 +/- 5 and 28 +/- 4 respectively, p less than 0.01]. These experiments suggest that the type of exercise influences the severity of exercise-induced asthma even under conditions of the same metabolic stress and respiratory heat loss.

Adolescent↗