Total Swimming Time Research Articles

Olfactory behavioural and neural responses of planktivorous lacustrine sockeye salmon (Oncorhynchus nerka) to prey odours.

Fish use a variety of sensory systems when foraging. Salmonids are generally considered visual feeders. However, some species feed on zooplanktons under dark conditions, suggesting they also detect prey using nonvisual cues. Under experimental conditions, hatchery-reared rainbow trout (Oncorhynchus mykiss) have been shown to use olfaction when searching for food pellets, but olfactory foraging has not been documented in wild salmonids. In the present study, to examine their behavioural response and neural activity in the olfactory nervous system using c-fos expression as a neural molecular marker, immature wild-caught lacustrine sockeye salmon (Oncorhynchus nerka) in a flow-through aquarium were exposed to zooplanktons (Daphnia spp.) extract including zooplanktons odorant and to dimethyl sulfide. The salmon exposed to zooplanktons odour increased their total swimming distance and time, numbers of turns and ascents, and c-fos expression in the olfactory bulb, suggesting that they can detect zooplanktons extract to locate prey in the laboratory experiments. However, no response was seen in those exposed to dimethyl sulfide. The results of this study suggest that prey odour may serve as a chemosensory cue for wild immature salmonids.

Neuromotor activity inhibition in zebrafish early-life stages after exposure to environmental relevant concentrations of caffeine

Caffeine (CAF), a neuroactive compound, has been found in surface waters at concentrations ranging from few nanograms up to micrograms and may induce adverse effects in aquatic vertebrates. Thus, the aim of this study was to evaluate the potential of CAF in affecting fish early-life stages in a wide concentration range, including occurring levels in surface waters. Specimens of zebrafish in early-life stages were exposed to CAF for 168 h and survival, developmental alterations, locomotor activity and acetylcholinesterase activity were evaluated. CAF induced mortality in embryos unable to hatch or in larvae after hatching (LC50 − 168 h = 283.2 mg/L). Tail deformities were observed in organisms exposed to concentrations ≥ 40 mg/L, while edemas were found at concentrations of 100 mg/L. CAF also decreased the total swimming time and distance moved of exposed organisms (LOEC = 0.0006 mg/L). Locomotor inhibition may be associated with an acetylcholinesterase inhibition observed at concentration ≥ 0.0088 mg/L. Therefore, the hazard of CAF for fish populations deserves further attention since unexpected effects on neuro-behavioral parameters occurs at concentrations often detected in natural aquatic ecosystems.

The behavior response in Zrbrafish Danio rerio to mirror images

Behavioral response experiment of fish to mirror images is one of the main ways to test the social and aggressive behavior. The behavior changes of Zrbrafish Danio rerio in tanks contain different number of mirrors was tested in this study. The result indicated that the latency of zebrafish from entry tank which contains mirrors to start moving (P < 0.05) and their frequency of midline crossing (P < 0.001) were all lower than control group (contains no mirror), and decreased with increasing numbers of mirrors. The total swimming time of zebrafish in tank contains mirrors increased with increasing numbers of mirrors and significantly higher than control group (P < 0.001). Additionally, the time spent of zebrafish in side that contains mirrors significantly higher than the reverse side (P < 0.05), and this difference degree increased with increasing numbers of mirrors.

Core Temperature While Swimming In A Wetsuit During 1000-m Race Pace Swim

Majority of fatalities that occur in the sport of triathlon happen during the swim portion of the race (Harris et al., 2010, JAMA). The potential risk of death while swimming has raised safety concerns. The governing body, USA Triathlon (USAT), has implemented guidelines related to water temperatures and the use of wetsuits. The varying water temperatures allow for a wide selection of wetsuits. Using a wetsuit while swimming in warm water may increase body heat storage which could increase core temperature. Currently, there are only limited data on the influence of triathlon wetsuits on core temperature when swimming in warm water while swimming a short distance at a somewhat hard swim pace (Aura et al., 2019, MSSE). PURPOSE: The purpose of this study was to examine core temperature while swimming a long distance (1000 m) at a fast pace in warm water (25.5 °C) while wearing a wetsuit. METHODS: Two experienced triathletes (mean ± standard deviation (SD), age 38.5 ± 23.3 years, height 1.83 ± 0.03 m, weight 80.1 ± 1.1 kg) participated in the study. At least 8 hours prior to attending the test session, participants swallowed an ingestible core temperature pill (BodyCap). Before beginning data collection, core temperature (Tc) data were transferred to a computer and sample rate was set to 0.1 Hz (1 sample every 10 s). Testing consisted of a self-directed warm up of 250-m followed by a 1000-m swim in an indoor pool (set to 25-m length) for each condition: no wetsuit (NW) and full sleeve wetsuit (FS). Participants swam at a self-selected pace at a “race pace” intensity (Borg Rating of Perceived Exertion = 16). Participants were required to rest until core temperature was within 0.5 °C of baseline before starting the next condition. Core temperature data were transferred to a computer after each swim. Average Tc of each swim was computed for analysis. RESULTS: The average core temperatures of NW and FS were 37.75 ± 0.11°C and 37.74 ± 0.46°C, respectively. The total swim time for the NW and FS conditions were 14:04 ± 1:43 and 13:05 ± 1:06 minutes. Mean stroke rate calculated for NW and FS were 30.12 ± 0.17 and 30.68 ± 0.45 strokes per minutes. Average swim speeds for NW and FS were 1.19 ± 0.15 and 1.28 ± 0.11 meters per second. CONCLUSIONS: Based upon the analysis of the results, the use of a wetsuit while swimming in warm water does not influence core temperature.

Embryonic development, locomotor behavior, biochemical, and epigenetic effects of the pharmaceutical drugs paracetamol and ciprofloxacin in larvae and embryos of Danio rerio when exposed to environmental realistic levels of both drugs.

For several years, the scientific community has been concerned about the presence of pharmaceuticals in the wild, since these compounds may have unpredictable deleterious effects on living organisms. Two examples of widely used pharmaceuticals that are present in the environment are paracetamol and ciprofloxacin. Despite their common presence in the aquatic environment due to their poor removal by sewage treatment plants, knowledge concerning their putative toxic effects is still scarce. This work aimed to characterize the effects of paracetamol (0.005, 0.025, 0.125, 0.625, and 3.125 mg/L) and ciprofloxacin (0.005, 0.013, 0.031, 0.078, 0.195, and 0.488 μg/L) in zebrafish embryos and larvae, exposed to environmentally relevant levels, close to the real concentrations of these pharmaceuticals in surface waters and effluents. The adopted toxic end points were developmental, a behavioral parameter (total swimming time), and a biomarker-based approach (quantification of the activities of catalase, glutathione-S-transferase, cholinesterases, glutathione peroxidase, and lipid peroxidation levels) combined with epigenetic analysis (immunohistochemical detection of 5-methylcytidine). Exposure to paracetamol had effects on all of the adopted toxic end points; however, ciprofloxacin only caused effects on behavioral tests and alterations in biomarkers. It is possible to ascertain the occurrence of oxidative stress following exposure to both drugs, which was more evident regarding paracetamol, an effect that may be related to the observed epigenetic modifications.

The road to 21 seconds: A case report of a 2016 Olympic swimming sprinter

This study aimed to describe training characteristics as well as physical, technical and morphological changes of an elite Olympic swimming sprinter throughout his road to 21 s in the 50 m freestyle. Over a ∼2.5-year period, the following assessments were obtained: external training load, competitive performance, instantaneous swimming speed, tethered force, dry-land maximal dynamic strength in bench press, pull-up and back squat and body composition. From 2014 to 2016, the athlete dropped 3.3% of his initial best time by reducing total swimming time (i.e. the total time minus 15-m start time – from 17.07 s to 16.21 s) and improving the stroke length (from 1.83 m to 2.00 m). Dry-land strength (bench press: 27.3%, pull-up: 9.1% and back squat: 37.5%) and tethered force (impulse: 30.5%) increased. Competitive performance was associated to average (r = −0.82, p = 0.001) and peak speeds (r = −0.71; p = 0.009) and to lean body mass (r = −0.55; p = 0.03), which increased in the first year and remained stable thereafter. External training load presented a polarized pattern in all training seasons. This swimmer reached the sub-22 s mark by reducing total swimming time, which was effected by a longer stroke length. He also considerably improved his dry-land strength and tethered force levels likely due to a combination of neural and morphological adaptations.

Effects of fluoride exposure on thyroid hormone level and intelligence in rats

Objective: To investigate the effects of fluoride exposure on the thyroid hormone level and intelligence in rats and to investigate the biomarkers of intellectual impairment induced by high fluoride exposure. Methods: A total of 24 clean healthy Sprague-Dawley rats were randomly divided into control group (tap water containing 0.344 mg/L fluoride) and low-, medium-, and high-fluoride exposure groups (tap waters containing 10, 50, and 100 mg/L sodium fluoride, respectively). One male rat was cohabited with two female rats in the same group. After the offspring rats were weaned, 12 offspring rats (male/female ratio=1∶1) with a similar body weight in each group were subjected to the same treatment for the parental offspring. The offspring rats were sacrificed on the 60th day after birth. The weight of offspring rats was measured. Serum thyrotropin (TSH) , free triiodothyronine (FT(3)) , and free thyroxine (FT(4)) levels were measured by enzyme-linked immunosorbent assay. The learning and memory abilities of the rats were evaluated by Morris water maze test. The expression of mitochondrial fission 1 (Fis1) and mitofusin 1 (Mfn1) in blood was measured by Western blot. Results: The offspring rats in the medium-and high-fluoride exposure groups had significantly lower serum TSH and FT(4) levels than those in the control group (P<0.05). The place navigation test showed that the offspring rats in the medium-and high-fluoride exposure groups had significantly longer escape latency than those in the control group (P<0.05) , and the high-fluoride exposure group had a significantly longer escape distance than those in the control group (P<0.05). The spatial probe test showed that the offspring rats in the low-, medium-, and high-fluoride exposure groups had significantly shorter swimming time and distance in the target quadrant and total swimming time and distance than those in the control group (P<0.05). Compared with the offspring rats in the control group, those in the low-, medium-, and high-fluoride exposure groups had significantly higher expression of Fis1 (P<0.05) , and those in the low- and medium-fluoride exposure groups had significantly higher expression of Mfn1 (P<0.05) . Conclusion: High fluoride exposure can reduce the secretion of thyroid hormone and the abnormality of mitochondrial dynamics in peripheral lymphocytes may provide a clue to identifying the biomarkers of intellectual impairment induced by fluoride exposure.

PIT-tagging method for small fishes: A case study using sandeel (Ammodytes tobianus)

Passive integrated transponder (PIT) tags are commonly used to assess fish movement for use in fisheries management. Here, we investigated physiological and behavioral effects of tagging on sandeels (Ammodytes tobianus) using PIT tags constituting 2.1±0.9% of their body weight. Swimming stamina (RSS), calculated as time spent swimming against the current relative to total swimming time, and tail beat frequency were compared between tagged and untagged fish as was blood hematocrit levels at 7, 14, and 42 d post-tagging. Survival and tag retention were also documented at 14, 42, and 84 d (via x-rays and dissections). RSS was not different between tagged and untagged fish with means (±SD) of 60±9% and 61±12%. Tail beat frequency was not different between tagged and untagged fish at 2.8±0.3 and 3.0±0.4 beats s−1 for tagged and untagged fish, respectively. Likewise, hematocrit was not affected by tagging and levels were between 21–26% for both groups. Survival rates were high and did not differ between groups (96% for tagged and 99% untagged fish). Tag retention was 100%. X-rays and dissections did not reveal any signs of tag movement at 14–84 d, and there was no difference between relative positions of the tags. None of the tags were encapsulated in the body cavity after 14 d, whereas 40 and 56% of the tags were encapsulated in a thin tissue membrane between the intestine and kidney after 42 and 84 d, respectively. After 14 d all incisions had healed with only minor or no signs of the tag insertion site. Collectively, these data provide substantial evidence for the possibility of conducting large-scale tagging studies on this species in the field.

Unveiling the neurotoxicity of methylmercury in fish (Diplodus sargus) through a regional morphometric analysis of brain and swimming behavior assessment

The current study aims to shed light on the neurotoxicity of MeHg in fish (white seabream – Diplodus sargus) by the combined assessment of: (i) MeHg toxicokinetics in the brain, (ii) brain morphometry (volume and number of neurons plus glial cells in specific brain regions) and (iii) fish swimming behavior (endpoints associated with the motor performance and the fear/anxiety-like status). Fish were surveyed for all the components after 7 (E7) and 14 (E14) days of dietary exposure to MeHg (8.7μgg−1), as well as after a post-exposure period of 28days (PE28). MeHg was accumulated in the brain of D. sargus after a short time (E7) and reached a maximum at the end of the exposure period (E14), suggesting an efficient transport of this toxicant into fish brain. Divalent inorganic Hg was also detected in fish brain along the experiment (indicating demethylation reactions), although levels were 100–200 times lower than MeHg, which pinpoints the organic counterpart as the great liable for the recorded effects. In this regard, a decreased number of cells in medial pallium and optic tectum, as well as an increased hypothalamic volume, occurred at E7. Such morphometric alterations were followed by an impairment of fish motor condition as evidenced by a decrease in the total swimming time, while the fear/anxiety-like status was not altered. Moreover, at E14 fish swam a greater distance, although no morphometric alterations were found in any of the brain areas, probably due to compensatory mechanisms. Additionally, although MeHg decreased almost two-fold in the brain during post-exposure, the levels were still high and led to a loss of cells in the optic tectum at PE28. This is an interesting result that highlights the optic tectum as particularly vulnerable to MeHg exposure in fish. Despite the morphometric alterations reported in the optic tectum at PE28, no significant changes were found in fish behavior. Globally, the effects of MeHg followed a multiphasic profile, where homeostatic mechanisms prevented circumstantially morphometric alterations in the brain and behavioral shifts. Although it has become clear the complexity of matching brain morphometric changes and behavioral shifts, motor-related alterations induced by MeHg seem to depend on a combination of disruptions in different brain regions.

Effects of the lipid regulator drug gemfibrozil: A toxicological and behavioral perspective

Pharmaceuticals are emerging contaminants as their worldwide consumption increases. Fibrates such as gemfibrozil (GEM) are used in human medicine to reduce blood concentrations of cholesterol and triacylglycerol and also are some of the most frequently reported pharmaceuticals in waste waters and surface waters. Despite some studies have already demonstrated the negative impact in physiological and/or reproductive endpoints in adult fish, data on survival and behavioral effects in fish larvae are lacking. This study aimed to assess the effects of GEM on zebrafish eleutheroembryo development and locomotor behavior. A fish embryo toxicity (FET) test was undertaken to evaluate GEM acute toxicity by exposing embryos to 0, 6.58, 9.87, 14.81, 22.22, 33.33 and 50mg/L. Developmental endpoints such as hatching success, edemas and malformations were recorded. A second test was undertaken by exposing embryos to 0, 1.5, 3 and 6mg/L in order to evaluate the effects of GEM on 120 and 144h post fertilization (hpf) larvae locomotor activity by video tracking, using a Zebrabox® (Viewpoint, France) device. From the data recorded, several parameters such as total swimming distance (TSD) and total swimming time (TST) in each 120s integration time were calculated. Data showed that this compound has a moderate toxic effect on fish embryo development, affecting both survival and hatching success with a calculated 96h LC50 of 11.01mg/L and no effects at the developmental level at 6mg/L. GEM seems to impair locomotor activity, even at concentrations where developmental abnormalities were unperceived, at concentrations as low as 1.5mg/L. Both TSD and TST were sensitive to GEM exposure. These effects do not seem to be independent of the developmental stage as 120hpf larvae seem to present a development bias with repercussions in locomotor behavior. This study highlights the need to include behavioral endpoints in ecotoxicological assays as this seems to be a more sensitive endpoint often disregarded.

Body Composition of Cold-Water Swimmers: The San Francisco Polar Bear Swim Study

Objectives: To assess the body composition of recreational cold-water swimmers, to determine if cold-water swimmers have an increased % body fat when compared to average Americans, and to examine the relationships between body composition and total swim distance and time in the water per swim. Methods: Following 3 months of swimming regularly in cold water in the San Francisco Bay (water temperature range: 9.6° C (49.3° F) to 12.6° C (54.7° F)) during the winter months, body mass index (BMI), % body fat (assessed by circumference technique), and surface/volume ratio were measured in 88 subjects (70 men and 18 women). The total cumulative swim distance was recorded by each subject and each subject estimated his or her average time in the water per swim.

Quantifying and assessing biomechanical differences in swim turn using wearable sensors

The swim turn makes up a substantial portion of the total swim time in competition, and efficient turns can determine finishing positions in many competitions. Swim turns can be a neglected area of performance gain. This is largely due to the difficulty in extracting performance measures that might lead to improvement. An inertial sensor was used to assess the different phases of the swimming turn and the data were then compared to the synchronised video data. As a case study, two elite swimmers, a competitive pool swimmer and an elite Triathlete, were compared as a demonstration of the technology as a potential tool for routine use. The participants were asked to perform their typical tumble turn at two velocities. Timing of the rotation relative to the turn's push off was measured. The inertial sensor detected differences in rotation between the two swimmers tested. The sensor reported that push off occurred for the competitive swimmer before 90°and for the Triathlete after 90°of rotation and was confir...

Maximal Lactate Steady State In A Tethered Swimming Model For Rats

PURPOSE: The goal of this work is to use a device for tethered swimming of rats to the assessment of the aerobic capacity by the maximal lactate steady state (MLSS) test adapted to the forced swimming model. METHODS: All proceedings were approved by the Ethical Committee for animal experimentation of the Federal University of Sao Carlos - Brazil (protocol 020/08). Eleven wistar rats, 150 days of age and 471±31 (g) weight, were used. The animals were tethered by a velcro vest connected to a latex elastic, tied to a microfilament thread, totally flexible and not elastic. The thread was conducted through 2 pulleys in series and connected to a load cell. The overload or activity intensity was regulated by the dislocation of the load cell vertical position by pulling down the animal. Each animal performed 3 to 5 constant efforts until reaching exhaustion or completing 30 minutes of exercise, sustaining a swimming intensity equivalent of 2 to 7 % of body weight (%BW) to keep itself on the surface. The exercise intensity was chosen randomly, never repeated for the same animal and only 1 test was carried out by day. Blood samples of 25 μL were collected for lactate measurement from a cut at the distal end of the tail during rest, at the 10th and 30 th minute of the test. The swimming effort was measured by a load cell, a data acquisition device and software (National Instruments®). The swimming effort was captured in a frequency of 1000 hz and filtrated by mean per second (every 1000 points), the swimming force and lactate concentration were presented as the mean and standard deviation of all rats total swimming time. Thus, the individual MLSS intensity was the highest constant exercise intensity which had the maximal blood lactate stead state concentration in which blood lactate entrance was equal to the removal with a variation inferior of 1 mM between the 10 th and the 30 th minute of exercise. RESULTS: The mean MLSS swimming force and blood lactate concentration were of 3.76±0.61 %BW and 3.12±1.17 mM respectively. The tethered swimming model can be used as tool for the precise determination of exercise intensity and the real time swimming force monitoring during all activity time in the swimming protocols for rats. CONCLUSION: It was possible to use a tethered swimming device to perform the assessment of the aerobic capacity of swimming rats by the MLSS test.

Sodium Bicarbonate Ingestion and Repeated Swim Sprint Performance

The purpose of the present investigation was to observe the ergogenic potential of 0.3 g·kg-1 of sodium bicarbonate (NaHCO3) in competitive, nonelite swimmers using a repeated swim sprint design that eliminated the technical component of turning. Six male (181.2 ± 7.2 cm; 80.3 ± 11.9 kg; 50.8 ± 5.5 ml·kg-1·min-1 VO2max) and 8 female (168.8 ± 5.6 cm; 75.3 ± 10.1 kg; 38.8 ± 2.6 ml·kg-1·min-1 VO2max) swimmers completed 2 trial conditions (NaHCO3 [BICARB] and NaCl placebo [PLAC]) implemented in a randomized (counterbalanced), single blind manner, each separated by 1 week. Swimmers were paired according to ability and completed 8, 25-m front crawl maximal effort sprints each separated by 5 seconds. Blood acid-base status was assessed preingestion, pre, and postswim via capillary finger sticks, and total swim time was calculated as a performance measure. Total swim time was significantly decreased in the BICARB compared to PLAC condition (p = 0.04), with the BICARB condition resulting in a 2% decrease in total swim time compared to the PLAC condition (159.4 ± 25.4 vs. 163.2 ± 25.6 seconds; mean difference = 4.4 seconds; 95% confidence interval = 8.7-0.1). Blood analysis revealed significantly elevated blood buffering potential preswim (pH: BICARB = 7.48 ± 0.01, PLAC = 7.41 ± 0.01) along with a significant decrease in extracellular K+ (BICARB = 4.0 ± 0.1 mmol·L-1, PLAC = 4.6 ± 0.1 mmol·L-1). The findings suggest that 0.3 g·kg-1 NaHCO3 ingested 2.5 hours before exercise enhances the blood buffering potential and may positively influence swim performance.

Acute exercise reduces hepatic glucose production through inhibition of the Foxo1/HNF‐4α pathway in insulin resistant mice

Protein hepatocyte nuclear factor 4alpha (HNF-4alpha) is atypically activated in the liver of diabetic rodents and contributes to hepatic glucose production. HNF-4alpha and Foxo1 can physically interact with each other and represent an important signal transduction pathway that regulates the synthesis of glucose in the liver. Foxo1 and HNF-4alpha interact with their own binding sites in the phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) promoters, and this binding is required for their effects on those promoters. However, the effect of physical activity on the HNF-4alpha/Foxo1 pathway is currently unknown. Here, we investigate the protein levels of HNF-4alpha and the HNF-4alpha/Foxo1 pathway in the liver of leptin-deficient (ob/ob) and diet-induced obese Swiss (DIO) mice after acute exercise. The ob/ob and DIO mice swam for four 30 min periods, with 5 min rest intervals for a total swimming time of 2h. Eight hours after the acute exercise protocol, the mice were submitted to an insulin tolerance test (ITT) and determination of biochemical and molecular parameters. Acute exercise improved insulin signalling, increasing insulin-stimulated Akt and Foxo1 phosphorylation and decreasing HNF-4alpha protein levels in the liver of DIO and ob/ob mice under fasting conditions. These phenomena were accompanied by a reduction in the expression of gluconeogenesis genes, such as PEPCK and G6Pase. Importantly, the PI3K inhibitor LY292004 reversed the acute effect of exercise on fasting hyperglycaemia, confirming the involvement of the PI3K pathway. The present study shows that exercise acutely improves the action of insulin in the liver of animal models of obesity and diabetes, resulting in increased phosphorylation and nuclear exclusion of Foxo1, and a reduction in the Foxo1/HNF-4alpha pathway. Since nuclear localization and the association of these proteins is involved in the activation of PEPCK and G6Pase, we believe that the regulation of Foxo1 and HNF-4alpha activities are important mechanisms involved in exercise-induced improvement of glucose homeostasis in insulin resistant states.

Antifatigue Effect of Coenzyme Q10 in Mice

The aim of this study was to investigate whether coenzyme Q10 (CoQ10) has an antifatigue effect in mice. ICR male mice were orally given CoQ10 in the form of Bio-Quinone (Pharma Nord, Vejle, Denmark) at doses of 0, 1.5, 15, or 45 mg/kg/day for 4 weeks. Mice were made to perform swimming exercise with loads attached to their tails, corresponding to approximately 5% of their body weights, and the total swimming time until exhaustion was measured. Furthermore, the post-exercise concentration of serum urea nitrogen (SUN), pre-/post-exercise and post-rest concentration of lactic acid (LA), and pre-exercise hepatic glycogen were determined. Mice treated with CoQ10 showed a significantly prolonged exhaustive swim time (15 mg/kg/day; P < .05), increased liver glycogen contents (15 and 45 mg/kg/day; P < .01 and P < .05, respectively), and decreased SUN levels (1.5, 15, and 45 mg/kg/day; P < .01) compared to control animals. The LA level was not significantly changed. These results suggest that CoQ10 improves swimming endurance and has an antifatigue effect.

Effects of a Flavonoid Extract from Cynomorium songaricum on the Swimming Endurance of Rats

The present study investigated the effects of a flavonoid extract from Cynomorium songaricum on the swimming endurance of rats by measuring changes of free radical scavenging enzymes, such as CuZn-SOD (copper, zinc-superoxide dismutase) and GSH-px (glutathione peroxidase), and body weights. Significant and dose-dependent antioxidant and anti-fatigue effects of flavonoids (rutin, catechin and isoquercitrin) on swimming rats were observed during 10 days of swimming exercise. After treatment with the flavonoid extract at doses of 0.5, 1.0, and 2.0 g/kg body weight, the CuZn-SOD and GSH-px activities in swimming rats were increased by 1.4%, 3.3%, 4.1% and 112.2%, 208.7%, 261.7%, respectively, while the levels of MDA (malondialdehyde) were decreased by 64.7%, 79.4%, and 86.4% respectively. Furthermore, the average body weight and the total swimming time were increased by 3.1%, 8.8%, 10.6%, and 7.7%, 34.5%, 61.5%, respectively. Our experimental results suggest that flavonoid supplementation could not only reduce free radical formation and scavenge free radicals, but also enhance endurance exercise performance by reducing muscle fatigue.

Effects of penicillin-induced developmental epilepticus on hippocampal regenerative sprouting, related gene expression and cognitive deficits in rats

For the purpose of investigating the long-term effects of seizures in developmental rats on spatial learning ability and hippocampal mossy fiber sprouting related gene expressions in adult rat brain, a seizure was induced by penicillin quaque die alterna in Sprague-Dawley rats from postnatal day 29 (P29). Rats were assigned into the recurrent seizure group (RS, seizures were induced in 11 consecutive days) and the control group. During P51-P56, P81-P84 and P92-P95, the rats were tested for spatial learning ability with the Morris water maze task. On P95, the authors examined mossy fiber sprouting and gene expression of zinc transporters 1 and 3 (ZnT-1, ZnT-3), calcium/calmodulin-dependent protein kinase IIalpha (CaMK-IIalpha), NMDA receptor 2C (NR2C) and glutamate receptor 2 (GluR2) in hippocampus by Timm staining and real-time RT-PCR analysis. The escape latencies from the water maze of the rats in the RS group were significantly longer than those of the control rats at d5 of the first test, at d1 of the second test, and at d2 of the third test. In the spatial probe test, the ratio between the swim time in the third quadrant and the total swim time in control group was significantly higher than RS group (p<0.05) in the entire three probe tests. The Timm scores in CA3 and dentate gyrus in the RS animals were significantly higher than that in the control. Compared with the control rats, the expressions of ZnT-1, CaMK-IIalpha and GluR2 transcripts in the hippocampus of the RS group was significantly decreased while unchanged in transcriptional levels of ZnT-3 and NR2C. There were positive linear correlations among ZnT-3, CaMKIIalpha, and NR2C in control group and among CaMKIIalpha, ZnT-1 and GluR2 in RS group. The results suggest that recurrent seizures induced in developmental rats could cause long-term disturbance on the hippocampal mossy fiber sprouting related gene expressions, which might play an important role in long-term cognitive deficit and hippocampal aberrant mossy fiber sprouting.

The behaviour character of learning and memory of rats with MCAO

目的 观察MCAO模型大鼠的学习记忆行为学特征.方法对Zea Longa和Nagasawa法加以改进,采用同侧颈总动脉永久结扎大脑中动脉线栓法制备MCAO模型大鼠,造模1个月后利用Morris水迷宫检测模型大鼠空间学习记忆能力.结果 Morris水迷宫定位航行试验结果显示,从第5次游泳训练开始,模型组大鼠的逃避潜伏期[(73.9±50.5)s]和游泳路径[(1631.0±1267.1)cm]显著大于假手术组[(31.6±21.4)s/(677.0±400.9)cm]和正常组[(29.0±20.2)s/(602.0±328.3)cm]大鼠的逃避潜伏期和游泳路径.模型组大鼠空间探索试验中平台象限游泳时间和路径(tP/tT值)与总游泳时间和总路径之比(dP/dT值),[tP/tT值(0.261±0.068)和dP/dT值(0.274±0.054)]显著小于正常组[(0.351±0.065)/(0.352±0.057)]和假手术组[(0.350±0.0662)/(0.349±0.058),P <0.05].结论同侧颈总动脉永久结扎大脑中动脉线栓法VaD模型大鼠空间学习记忆能力明显下降,与脑缺血记忆障碍特征相似,是研究脑缺血后神经损伤理想的动物模型。

Transition From The Glide Phase To Free Swimming Following A Freestyle Flip Turn

Flip turns have become a crucial determinate in the outcome of a swimming competition, constituting up to one third of the total event time in some event distances. Recent studies suggest that there is “an optimal” relationship between glide distance, kick resumption speed, vertical rise path, and stroke resumption velocity. However, these articles make no mention about the form of transition from gliding or kicking to stroke resumption (defined as the initial movement of the hand from the glide position). PURPOSE The purpose of this study was to determine if there was a relationship between total swim time and three forms of stroke resumption initiation: pull with the deep arm, pull with the shallow arm, or be completely prone before pulling with either arm. It was hypothesized that the faster swimmers would tend pull with the deep arm and the slower swimmers would pull with their shallow arm or from a prone position. METHODS Male and female high school (HS) and masters (M) swimmers were videotaped while competing in short course 100 m (M), 100 yd (HS) and 500 yd (HS) freestyle events during public swim meets. Swimmers were coded according to the form of transition they used to resume free swimming following a flip turn. Final event times were recorded, and divided into thirds from fastest to slowest. Within each group of times the percentages of the forms of transitions used by the swimmers were calculated. Chi-square analyses were performed to determine if there were significant differences in percentages across groups (p < .05). RESULTS There was a significant difference in the form of transition used between groups in the HS female 100, M female 100, and M male 100. These results supported the hypothesis with the faster swimmers tending to use the deep arm and the slower swimmers tending to use the shallow arm off the walls. There were no significant differences in the form of transition used between groups in the HS female 500, HS male 500, or HS male 100 (although in the HS male 100 there was a non-significant trend supporting the hypothesis). CONCLUSION The 100 free may be more sensitive to the different forms of transition used than the 500. Reasons for this difference may include the overall ability of the swimmer to generate force during the arm pull, or perhaps the increased level of precision that is often associated with sprint events. Further investigation will focus on the total force being produced by the dominant hand in each of the forms of transition.