SEARCH · Search PubMed

Results for “SWIMMING”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31Linked to original sources

PubMed1994

A longitudinal gradient of synaptic drive in the spinal cord of Xenopus embryos and its role in co-ordination of swimming.

1. Intersegmental co-ordination in Xenopus embryos could be influenced by longitudinal gradients in neuronal properties or synaptic drive. To determine if such gradients exist intracellular recordings were made from putative motoneurones at different spinal levels. 2. No evidence was found of a longitudinal gradient in neuronal resting potentials. In a rostrocaudal direction the duration of current-evoked spikes increased and the amplitude of the spike after-hyperpolarization (AHP) decreased. 3. During fictive swimming the amplitude of the tonic excitatory synaptic input and the mid-cycle IPSPs declined in a rostrocaudal direction. The rise-time and fall-time of mid-cycle IPSPs increased in a rostrocaudal direction. 4. Rostral to the eighth post-otic segment mid-cycle IPSPs occurred on all cycles of fictive swimming episodes. More caudally IPSPs became irregular in occurrence and caudal to the twelfth post-otic segment no mid-cycle IPSPs could be detected, even during the injection of depolarizing current or when recording with KCl-filled electrodes. 5. The duration of spikes occurring during fictive swimming increased and the amplitude of spike AHP decreased in a rostrocaudal direction. A spike AHP was absent during fictive swimming activity in neurones caudal to the ninth post-otic segment even though it was present in current-evoked spikes in the same neurones. 6. On-cycle IPSPs (occurring shortly after the spike at phase values less than 0.4) were observed predominantly at the beginning of swimming episodes in neurones recorded rostral to the eighth segment, but were not detected at all in more caudal neurones. 7. If the rostrocaudal gradients in synaptic excitatory and inhibitory drive to putative motoneurones during fictive swimming are also present in premotor spinal interneurones they would be expected to have a strong influence on rostrocaudal delays. Such gradients could therefore be important components of the mechanism underlying intersegmental co-ordination.

Action Potentials↗

PubMed1995

Microbiological quality in Finnish public swimming pools and whirlpools with special reference to free living amoebae: a risk factor for contact lens wearers?

To assess the possible risk of microbial keratitis associated with swimming or bathing in public pools, the microbiological quality as well as the presence of free living amoebae in 16 halogenated swimming pools and whirlpools, located in Helsinki, Finland, was determined. Five additional whirlpools situated in the ferries cruising from Finland to Sweden were included in the study. Other parameters investigated were the total bacterial count, identification of Pseudomonas aeruginosa and Staphylococcus aureus, measurement of free residual and combined chlorine, potassium permanganate index, urine, pH, and turbidity. Amoebae were detected in 41% of the pool water samples studied. Seven of 11 whirlpools and four of 10 swimming pools were shown to contain amoebae. An Acanthamoeba species was isolated from only one outdoor swimming pool; the other amoebae belonged to the genera Vexillifera, Flabellula, Hartmannella, and Rugipes. Although not a single verified case of Acanthamoeba keratitis has been found in Finland, the findings show that there is a theoretical risk of amoebic and bacterial keratitis associated with swimming or bathing in properly cleaned public pools. Consequently, we do not recommend swimming or bathing with contact lenses.

Amoeba↗

PubMed2005

Specificity of VO2MAX and the ventilatory threshold in free swimming and cycle ergometry: comparison between triathletes and swimmers.

OBJECTIVES: To compare maximal heart rate (HRmax), maximal oxygen consumption (VO2MAX), and the ventilatory threshold (VT; %VO2MAX) during cycle ergometry and free swimming between swimmers and triathletes. METHODS: Nine swimmers and ten triathletes completed an incremental swimming and cycling test to exhaustion. Whole body metabolic responses were determined in each test. RESULTS: The swimmers exhibited a significantly higher VO2MAX in swimming than in cycling (58.4 (5.6) v 51.3 (5.1) ml/kg/min), whereas the opposite was found in the triathletes (53.0 (6.7) v 68.2 (6.8) ml/kg/min). HRmax was significantly different in the maximal cycling and swimming tests for the triathletes (188.6 (7.5) v 174.8 (9.0) beats/min). In the maximal swimming test, HRmax was significantly higher in the swimmers than in the triathletes (174.8 (9.0) v 184.6 (9.7) beats/min). No significant differences were found for VT measured in swimming and cycling in the triathletes and swimmers. CONCLUSION: This study confirms that the exercise testing mode affects the VO2MAX value, and that swimmers have very specific training adaptations even compared with triathletes. This may be a function of acute physiological responses combined with the specialist training status of the different athletes influencing maximal cardiac output or oxygen extraction. In contrast, the different training regimens do not seem to influence the VT, as this variable did not differ between the two testing modes in either group.

Adolescent↗

PubMed1991

Wetsuits, body density and swimming performance.

To determine the influence of body composition upon swimming performance with and without wetsuits, 14 competitive female swimmers (mean (s.d.) age, 19.9 (0.9) years) were measured for body density while wearing both wetsuits and normal swimsuits. Subjects swam 400 and 1500 m trials with and without wetsuits, randomly, over a 12-day period. Six subjects participated in an additional trial while wearing neoprene leg-bands fitted over the wetsuit. Mean (s.d.) subject density without and with wetsuits was 1.048 (.009) and 1.021 (.007) g/ml respectively. Wetsuits reduced (P less than 0.05) swim times for the 400 (-4.96%) and 1500 m swim (-3.23%) compared with swimsuit trials. The neoprene bands increased (P less than 0.05) swim times relative to swimsuit and wetsuit trials. With wetsuits, swim times were inversely (P less than 0.05) related to density for the 400 (r = -0.46) and 1500 m swim (r = -0.54) suggesting that wetsuits increase performance by increasing buoyancy and that lean subjects benefit more from wearing wetsuits than do fatter subjects.

Adult↗

PubMed1997

Time course of changes in bilateral arm power of swimmers during recovery from injury using a swim bench.

OBJECTIVES: There has been little research on the time course of recovery from injury in athletes. This is especially the case for recovery in arm power in injured swimmers. The purpose of this study was to compare the power output of the injured and non-injured arms of swimmers during recovery from injury by use of a maximal exercise test on a computer interfaced isokinetic swim bench. METHODS: Thirteen swimmers (five men and eight women; age 18.8 (3.2) years; stature 1.76 (0.05) m; body mass 61.7 (5.9) kg; mean (SD)) gave written informed consent and were recruited to this study throughout a three year period. All subjects had experienced non-aquatic soft tissue injury to their dominant-side shoulder or upper arm in the three months before participation, but had been allowed to return to swimming training. All of the subjects had injured their dominant arm and the mean time for absence from training was 3.7 (1.1) weeks. At return to training and at four, eight, and twelve weeks thereafter, subjects performed two all-out 30 second tests on the swim bench by simulating the swimming arm action. From these tests, peak power output (PPO), mean power output (MPO), and power decay (PD) for each arm during the 30 seconds of exercise could be determined by averaging the two tests. The differences between return to training and the four, eight, and twelve week periods were analysed using repeated measures analysis of variance with Tukey b post hoc test. RESULTS: The repeated testing showed 95% confidence intervals of +/- 11.4 W for PPO, +/- 9.5 W for MPO and +/- 0.5 for PD. When the swimmers returned to training the results showed that PPO was 179 (21.9) v 111 (18.1) W (P = 0.02), MPO was 122 (9.8) v 101 (8.8) W (P = 0.01), and PD was 2.5 (0.6) v 5.2 (1.9) (P = 0.001) for non-injured and injured arms respectively (all values mean (SEM)). There were similar differences at four weeks which disappeared after eight weeks, except for that of PPO which was still evident (187.3 (21.9) v 156.8 (18.1) W; P = 0.01). At 12 weeks there were no differences between the non-injured and injured arm on any of the indices of arm power (P > 0.05). CONCLUSIONS: These results suggest that, using the swim bench power test, differences in bilateral arm power output after injury persist for at least eight weeks after return to swimming training. These findings support the need for prolonged rehabilitation after such injury. This would best include physiotherapy and a training programme within which special consideration is given to the recuperation process.

Adolescent↗

PubMed2002

Distribution and determinants of trihalomethane concentrations in indoor swimming pools.

OBJECTIVES: For many decades chlorination has been used as a major disinfectant process for public drinking and swimming pool water in many countries. However, there has been rising concern over the possible link between disinfectant byproducts (DBPs) and adverse reproductive outcomes. The purpose of this study was to estimate the concentrations of trihalomethanes (THMs) in some indoor swimming pools in London and their variation within and between pools and any correlation with other factors. METHODS: Water samples were collected from eight different indoor swimming pools in London. A total of 44 pool samples were collected and analysed for total organic content (TOC) and THMs. Water and air temperature were measured along with the pH during the collection of pool samples. The level of turbulence and the number of people in the pool at the time were also assessed. RESULTS: The geometric mean concentration for all swimming pools of TOC was 5.8 mg/l, of total THMs (TTHMs) 132.4 microg/l, and for chloroform 113.3 microg/l. There was a clear positive linear correlation between the number of people in the swimming pool and concentrations of TTHMs and chloroform (r=0.7, p<0.01), and a good correlation between concentrations of TOC and TTHMs (r=0.5, p<0.05) and water temperature and concentrations of TTHMs (r=0.5, p<0.01). There was a larger variation in THMs within pools than between pools. CONCLUSION: Relatively high concentrations of THMs were found in London's indoor swimming pools. The levels correlated with the number of people in the pool, water temperature, and TOC. The variation in concentrations of THMs was greater within pools than between pools.

Air Pollutants↗

PubMed2003

[Effects of swimming with a wet suit on energy expenditure during subsequent cycling].

The aim of this study was to investigate the effects of swimming with a wetsuit on energy expenditure during subsequent cycling. Nine well-trained triathletes underwent three submaximal trials. The first trial (SC) consisted of a 750-m swim realised at a competition pace, followed by a 10-min cycling exercise at a power output corresponding to the ventilatory threshold . The two other trials were composed of the same cycling exercise, preceded either by a 750-m swim with a wetsuit (WSC) or by a cycling warm-up (Ctrl). The main results are that the WSC trial was characterised by significantly lower swimming cadence (-14%), heart rate (-11%), and lactate values (-47%) compared to the SC trial, p < 0.05. Moreover, cycling efficiency was significantly higher in the WSC trial compared to the SC trial (12.1% difference, p < 0.05). The lower relative intensity observed during swimming with a wetsuit suggest the relative importance of swimming condition on the total performance in a sprint triathlon.

Adult↗

PubMed2006

Effects of a high-intensity swim test on kinematic parameters in high-level athletes.

The present study aimed to investigate the effects of a high-intensity swim test among top-level swimmers on (i) the spatial and temporal parameters of both the stroke and the 3-D fingertip pattern and (ii) the mechanical, muscular, and physiological parameters. Ten male international swimmers performed a 4 x 50 m swim at maximal intensity. Isometric arm flexion force with the elbow at 90 degrees (F90 degrees ), EMG signals of right musculus biceps brachii and triceps brachii and blood lactate concentrations were recorded before and after the swim test. Kinematic stroke (stroke length, rate, and velocity) and spatiotemporal parameters of the fingertip trajectory were measured by two underwater cameras during the first and last 50 m swims. After the swim test, F90 degrees and mean power frequencies of the EMG decreased significantly when blood lactate concentration increased significantly, attesting the reaching of fatigue. From the first to the last 50 m, stroke rate, stroke velocity, and temporal parameters of the fingertip trajectory exhibited significant increases although stroke length and spatial fingertip trajectory remained unchanged. General and individual adaptations were observed among the top-level swimmers studied. The present findings could be useful for coaches in evaluating fatigue effects on the technical parameters of swimming.

Adaptation, Physiological↗

PubMed1995

Caffeine ingestion and performance of a 1,500-metre swim.

The purpose of this study was to evaluate the potential ergogenic benefit of caffeine in the performance of a 1,500-meter swim. Caffeine (6 mg.kg-1) or placebo was administered 2-1/2 hrs prior to the swim trial in a double-blind crossover design. Caffeine resulted in a significantly lower perceived exertion for 100-m warm-up swims. Subjects swam significantly (p < 0.05) faster with caffeine (20:58.8 +/- 0:36.4, mean +/- SEM) than without (21:21.8 +/- 0:38). Plasma potassium was significantly lower prior to the swim with caffeine, and blood glucose was higher after that swim. Caffeine provides an ergogenic benefit for a 1,500-meter swim, an event that is completed in less than 25 min. Lower plasma potassium concentration prior to exercise and higher blood glucose following the trial suggest that electrolyte balance and glucose availability may be important aspects of the ergogenic effects of caffeine.

Adult↗

PubMed1994

Muscle glucose utilization during sustained swimming in the carp (Cyprinus carpio).

The involvement of circulatory glucose in the energy provision of skeletal muscle and heart of swimming carp was examined. Plasma glucose concentration varied from 3 to 17 mM among individual carp, and estimates of glucose turnover rate (RT) were positively correlated with plasma glucose level in resting fish (range 1.6-6.3 mumol.min-1.kg-1) and in swimming fish (range 4.2-10.7 mumol.min-1.kg-1). Carp that were exercised at 80% of their critical swimming speed displayed a twofold higher RT at any given plasma glucose concentration. Metabolic clearance rate also doubled in swimming carp (1.0 +/- 0.1 ml.min-1.kg-1) relative to resting controls (0.5 +/- 0.1 ml.min-1.kg-1). Indexes of muscle glucose utilization (GUI), determined with 2-deoxy-D-[14C]glucose, indicated that glucose utilization in red muscle was not dependent on plasma glucose concentration; however, glucose utilization in this muscle mass was threefold higher in swimming fish than in resting control fish. On the basis of whole body aerobic scope measurements in carp, it was estimated that circulatory glucose potentially comprised 25-30% of the total fuel oxidation in the active red muscle mass. GUI in heart was positively correlated with plasma glucose concentration, and it is possible that glucose availability had considerable influence on the pattern of myocardial substrate oxidation in resting and active carp. Carp are somewhat more reliant than rainbow trout on glucose for locomotor energetics, correlating with species differences in swimming capability and with the greater capacity of omnivorous carp to tolerate dietary glucose.

Animals↗

PubMed1984

Acute cardiorespiratory responses of hypertensive rats to swimming and treadmill exercise.

The acute cardiorespiratory responses of spontaneously hypertensive rats (SHR) to swimming and running exercise was investigated because SHR populations are hyperresponsive to external stimuli, of the paucity of existing data, and of the uncertainty on the role of exercise stimuli for training adaptations to occur. Male rats were assigned to one of five groups (n = 5-6/group) and designated as controls (C), inexperienced or naive free swimmers (NFS), experienced free swimmers (FS), experienced weighted swimmers (WS) (attached weights equal to 2% of their body weight) or experienced runners (R) who ran at an intensity of 75% of their VO2max. After 75 min in the water, all groups were acidotic and hypercapnic with the WS experiencing the greatest changes. Heart rate (HR) was increased in all swimmers during the initial 10 min, but declined thereafter, and after 75 min, the HR of WS (348 +/- 1 beats/min) was significantly lower than the C group (416 +/- 22 beats/min). At the same time interval, mean arterial blood pressure (MAP) was decreased in all swimming groups to values lower than the C animals. In addition, an exaggerated diving reflex was frequently noted when the rats were submerged. When the magnitudes of the changes were evaluated in the swimming animals they were directly associated with their submergence times, i.e., during 65-75 min of the swim, NFS, FS, and WS were submerged for 43, 46, and 66% of their total swim time, respectively. In sharp contrast to the swimmers, the runners exhibited increases in HR and MAP with their blood gas measurements being indicative of hyperventilation. We concluded that swimming as an exercise mode for hypertensive rats is best served to study the combined effects of excitement, prolonged submergence, and the consequences of the diving reflex.

Animals↗

PubMed1987

Effect of hypertension on hearts of rats trained by swimming.

To determine whether a prior chronic swimming program would alter the heart's response to chronic hypertension, female rats were made to swim for 10 wk, and then the left renal artery was stenosed. Heart perfusions were performed 10 wk later. The five groups studied were: control (C), normotensive swimmers (Sw), sedentary hypertensives (H), swimming rats made hypertensive and then allowed to be sedentary (Sw-H-Sd); and swimming animals made hypertensive and continued in a swimming program (Sw-H-Sw). Total heart and left ventricular weights were increased in increasing degrees in the sequence Sw, H, Sw-H-Sd, and Sw-H-Sw. Right ventricular weight was only increased in Sw and Sw-H-Sw. Swimming before the onset of hypertension enhanced total cardiac output and stroke work. Ejection fractions and mean velocity of circumferential fiber shortening (Vcf) were increased in Sw-H-Sd or Sw-H-Sw vs. controls. Myocardial O2 extraction was increased and coronary flow and myocardial O2 consumption were diminished in all hypertensive groups. However, lactate production was similar in all groups. Myosin adenosinetriphosphatase activity was increased in Sw but decreased in the three H groups. The percent of V1 myosin isozyme was greater and the percent of V3 less in Sw than in C; V1 was diminished and V3 increased in H and Sw-H-Sd; isozymes were normal in Sw-H-Sw.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗

PubMed1990

Influence of thyroid hormones and catecholamines on myosin of swim-exercised rats.

To define the physiological signals involved in the redirection of myosin expression in the swim-exercised rat, the relative influence of thyroid hormones and beta-adrenergic blockade was determined. Swimming exercise resulted in an increased proportion of myosin V1 (60.9 +/- 9.7 vs. 38.0 +/- 4.1% of sedentary rats fed ad libitum) but did not increase serum concentrations of total and free thyroxine or triiodothyronine determined either 17-21 h or immediately after swimming. The proportion of V1 increased, although intermittently food-deprived rats with the body weight of swimming rats exhibited a reduced proportion of V1 (23.5 +/- 2.7). When swimming rats had only intermittent access to food, they had reduced concentrations of all thyroid hormones, but the proportion of V1 (51.5 +/- 7.6) was nonetheless increased. Thus the redirection of myosin expression cannot be attributed to an increased secretion of thyroid hormones. The influence of the adrenergic system was assessed by treating swimming rats with the beta-blocking drug atenolol. Because the proportion of V1 was reduced, but thyroid hormones were not affected, beta-adrenergic blockade seems to influence myosin expression independently of thyroid hormones.

Animals↗

PubMed1991

Pregnancy-induced changes in the maximal physiological responses during swimming.

The effect of pregnancy on peak O2 uptake (VO2 peak) during tethered swimming was evaluated in 10 women during their 25th and 35th wk of pregnancy, as well as 9-11 wk postpartum. The swim results were compared with cycle ergometry results obtained at similar times. The results indicated that exercise-induced maximal heart rates remained the same and were similar for the swim and cycle trials, approximately 184 +/- 4 beats/min. Cycling VO2 peak was not affected by pregnancy, averaging 1.94 +/- 0.11 l/min. Postpartum swim VO2 peak was similar to the cycle results; however, during pregnancy it was significantly lower than cycling VO2 peak (P less than 0.05; postpartum, 1.78 +/- 0.14 l/min; 25th wk, 1.64 +/- 0.12; 35th wk, 1.48 +/- 0.11). Hemoglobin concentrations and hematocrits were lower during pregnancy; however, changes in plasma volume (based on hematocrit and hemoglobin) were found to be significantly greater during cycling than during swimming and also greater during pregnancy for both modes of exercise. It was concluded that, unlike cycling, the VO2 peak of pregnant women during swimming is reduced. This reduction in VO2 peak was associated with a decreased peak ventilation (r = 0.864) but was not correlated to exercise-induced hemoconcentration (r = -0.29). Furthermore, pregnancy results in a greater-than-normal exercise-induced hemoconcentration, which may be related to pregnancy-induced changes in capillary dynamics.

Adult↗

PubMed1998

Effects of high-intensity intermittent swimming on glucose transport in rat epitrochlearis muscle.

Recently (K. Kawanaka, I. Tabata, and M. Higuchi. J. Appl. Physiol. 83: 429-433, 1997), we demonstrated that glucose transport activity after repeated 10-s-long in vitro tetani in rat epitrochlearis (Epi) muscle was negatively correlated with the postcontraction muscle glycogen concentration. Therefore, we examined whether high-intensity intermittent swimming, which depletes muscle glycogen to a lower level than that observed after ten 10-s-long in vitro tetani, elicits higher glucose transport than that observed after ten 10-s-long in vitro tetani, which has been regarded as the exercise-induced maximal stimulus for glucose transport. In male rats, 2-deoxy-D-glucose transport rate in Epi muscle after eight bouts of high-intensity intermittent swimming with a weight equal to 18% of body mass (exercise duration: 20 s, rest duration between exercise bouts: 40 s) was higher than that observed after the ten 10-s-long tetani (2.25 +/- 0.08 vs. 1.02 +/- 0.16 micromol . ml intracellular water-1 . 20 min-1). Muscle glycogen concentration in Epi after eight bouts of high-intensity intermittent swimming was significantly lower than that observed after ten 10-s-long in vitro tetani (7.6 +/- 0.5 vs. 14.8 +/- 1.4 micromol glucose/g muscle). These observations show that the high-intensity intermittent swimming increases glucose transport in rat Epi to a much higher level than that induced by ten 10-s-long in vitro tetani, which has been regarded as the exercise-related maximal stimulus for glucose transport. Furthermore, this finding suggests that the lower muscle glycogen level after high-intensity intermittent swimming than after in vitro tetani may play a role, because there was a significant negative correlation between glucose transport and muscle glycogen concentration in Epi after high-intensity swimming and in vitro tetani.

Animals↗

PubMed1989

Swimming in Aplysia brasiliana: behavioral and cellular effects of serotonin.

1. Aplysia brasiliana is a marine mollusk that swims by repeated metachronal flapping movements of its bilateral fleshy parapodia. Animals with bilateral cerebropedal connective (CPC) lesions do not swim when suspended above the substrate, although tonic CPC stimulation can elicit normal parapodial flapping. Although the parapodial opener-phase (POP) cells, a previously identified group of neurons, fire synchronous bursts of efferent spikes in-phase with parapodial opening movements in both intact animals and dissected preparations, they are not likely to be primary parapodial motoneurons. These cells receive one or more large, apparently monosynaptic excitatory postsynaptic potentials (EPSPs) during CPC stimulation that are effective in producing the swimming motor program (SMP). 2. In suspended CPC-lesioned animals, injections of serotonin (5-HT) that produce an average hemolymph concentration of 10(-5) M induced full-amplitude parapodial flapping. Selected episodes of flapping were similar in frequency to normal suspended swimming. 3. In suspended CPC-lesioned animals, 5-HT injections elicited an apparently normal swimming motor program that was associated with synchronous bursts of large-amplitude efferent spikes in the parapodial nerves. In many semi-intact preparations, exposing the circumoesophageal ganglia to 5-HT elicited a similar rhythmic motor program, but usually at a lower frequency than during normal swimming or during tonic CPC stimulation. 4. In isolated-ganglion preparations, bath application of 5-HT produced immediate depolarization and tonic firing of individual POP neurons, followed by smooth and regular bursting in the apparent absence of synaptic input. In such preparations, the motor program elicited by bath-applied 5-HT differed from the one elicited by tonic CPC stimulation in that the 5-HT-elicited rhythmic bursting usually was not synchronous in different POP neurons. Tonic CPC stimulation during bath applications of 5-HT produced immediate synchronization of bursts among the POP neurons. 5. Hyperpolarization (or depolarization) of a POP neuron during bath application of 5-HT increased (or decreased) the burst period, but membrane polarization did not change the burst period elicited during tonic CPC stimulation.

Animals↗

PubMed1993

Fictive swimming elicited by electrical stimulation of the midbrain in goldfish.

1. We developed a fictive swimming preparation of goldfish that will allow us to study the cellular basis of interactions between swimming and escape networks in fish. 2. Stimulation of the midbrain in decerebrate goldfish produced rhythmic alternating movements of the body and tail similar to swimming movements. The amplitude and frequency of the movements were dependent on stimulus strength. Larger current strengths or higher frequencies of stimulation produced larger-amplitude and/or higher-frequency movements. Tail-beat frequency increased roughly linearly with current strength over a large range, with plateaus in frequency sometimes evident at the lowest and highest stimulus strengths. 3. Electromyographic (EMG) recordings from axial muscles on opposite sides at the same rostrocaudal position showed that stimulation of the midbrain led to alternating EMG bursts, with bursts first on one side, then the other. These bursts occurred at a frequency equal to the tail-beat frequency and well below the frequency of brain stimulation. EMG bursts recorded from rostral segments preceded those recorded from caudal segments on the same side of the body. The interval between individual spikes within EMG bursts sometimes corresponded to the interval between brain stimuli. Thus, whereas the frequency of tail beats and EMG bursts was always much slower than the frequency of brain stimulation, there was evidence of individual brain stimuli in the pattern of spikes within bursts. 4. After paralyzing fish that produced rhythmic movement on midbrain stimulation, we monitored the motor output during stimulation of the midbrain by using extracellular recordings from spinal motor nerves. We characterized the motor pattern in detail to determine whether it showed the features present in the motor output of swimming fish. The fictive preparations showed all of the major features of the swimming motor pattern recorded in EMGs from freely swimming fish. 5. The motor nerves, like the EMGs produced by stimulating midbrain, showed rhythmic bursting at a much lower frequency than the brain stimulus. Bursts on opposite sides of the body alternated. The frequency of bursting ranged from 1.5 to 13.6 Hz and was dependent on stimulus strength, with higher strengths producing faster bursting. Activity in rostral segments preceded activity in caudal ones on the same side of the body. Some spikes within bursts of activity occurred at the same frequency as the brain stimulus, but individual brain stimuli were not as evident as those seen in some of the EMGs. 6. The duration of bursts of activity in a nerve was positively and linearly correlated with the time between successive bursts (cycle time).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1997

Epaxial and limb muscle activity during swimming and terrestrial stepping in the adult newt, Pleurodeles waltl.

We have investigated the patterns of activation of epaxial musculature during both swimming and overground stepping in an adult newt (Pleurodeles waltl) with the use of electromyographic (EMG) recordings from different sites of the myomeric muscle dorsalis trunci along the body axis. The locomotor patterns of some limb muscles have also been investigated. During swimming, the epaxial myomeres are rhythmically active, with a strict alternation between opposite myomeres located at the same longitudinal site. The pattern of intersegmental coordination consists of three successively initiated waves of EMG activity passing posteriorly along the anterior trunk, the midtrunk, and the posterior trunk, respectively. Swimming is also characterized by a tonic activation of forelimb (dorsalis scapulae and extensor ulnae) and hindlimb (puboischiotibialis and puboischiofemoralis internus) muscles and a rhythmic activation of muscles (latissimus dorsi and caudofemoralis) acting both on limb and body axis. The latter matched the activation pattern of epaxial myomeres at the similar vertebral level. During overground stepping, the midtrunk myomeres express single synchronous bursts whereas the myomeres of the anterior trunk and those of the posterior trunk display a double bursting pattern in the form of two waves of EMG activity propagating in opposite directions. During overground stepping, the limb muscles and muscles acting on both limb and body axis were found to be rhythmically active and usually displayed a double bursting pattern. The main conclusion of this investigation is that the patterns of intersegmental coordination during both swimming and overground stepping in the adult newt are related to the presence of limbs and that they can be considered as hybrid lampreylike patterns. Thus it is hypothesized that, in newt, a chain of coupled segmental oscillatory networks, similar to that which constitutes the central pattern generator (CPG) for swimming in the lamprey, can account for both trunk motor patterns if it is influenced by limb CPGs in a way depending on the locomotor mode. During swimming, the segmental networks located close to the girdles receive extra tonic excitation coming from the limb CPGs, whereas during stepping, the axial CPGs are entrained to some extent by the limb oscillators.

Animals↗