Intense Swimming Research Articles

Impact of Swimming Training on the Course and Symptoms of Bronchial Asthma and Respiratory System Function: A Literature Review

Introduction: Bronchial asthma is one of the most common inflammatory diseases among adults and children. It is characterized by the occurrence of bronchial obstruction, which is manifested, for instance, by a feeling of shortness of breath, wheezing, a feeling of tightness in the chest, a feeling of squeezing in the chest. In addition to pharmacological treatment, health behavior including sport is of great importance. In this publication, we will attempt to discuss the effects of swim training on asthma and respiratory system function. We will try to answer the question whether swimming is a safe form of exercise for patients with bronchial asthma.Material and methods: Review of the specialized literature in the field of pulmonology, guidelines for treatment of bronchial asthma and articles available on PubMed and Google Scholar database searching by the keywordsAim of the study: The aim of this publication is to review the available literature to answer the question of whether swimming training is a suitable form of exercise for asthmatic patients and what effect it has on respiratory functionConclusions: The treatment of bronchial asthma is based on the pharmacological treatment. In addition to medications, non-pharmacological methods and health behaviours are important. Appropriate physical activity for people with asthma may include swimming training, which has a beneficial effect on lung function and asthma symptoms management, especially in the paediatric population. There are studies that suggest that swimming carries a lower risk of causing bronchospasm than other sport activities, however, there are inconclusive reports on the effect of attending chlorinated swimming pools on the development of asthma and allergies. Studies on competitive and elite swimmers show that intensive swimming training, especially in chlorinated pools, can induce bronchial hyperresponsiveness and the risk of developing asthma, but this requires further research.

Effects of different temperatures on the embryonic development of the Lebranche mullet Mugil liza.

We herein investigated the influence of temperature on theembryonic development (from fertilisation to hatching) of Mugil liza larvae. For this purpose, oocytes (>600 μm) and sperm were obtained from breeding stock at the laboratory of marine fish culture (LAPMAR). After fertilisation, 1200 eggs were distributed in 12 cylindrical experimental units of 400 mL under four different temperatures 18, 22, 26 and 30 ºC, all in triplicate. Every 15 min until hatching, about 10 eggs were randomly sampled in each treatment. The eggs were visualized and photographed, and the classification of embryonic stages was performed. Temperature influenced the main events of the embryonic development of M. liza. More accelerated development was observed according to the increase in temperature until the gastrula phase. At temperatures of 22 and 26 °C, embryonic development occurred from fertilisation to hatching of the larvae. In the 18 °C treatment, it was verified that most of the embryos ceased development during the final phase of cleavage and the beginning of blastula formation, while in the 30 °C treatment patterns of embryo malformation were also verified, with erratic divisions of the blastomeres, resulting in irregular cells. Unlike what was observed at a temperature of 18 °C, none of the embryos incubated at 30 °C reached the blastopore closure phase, stopping in the gastrula. The larvae hatched in the treatments at 22 and 26 °C were viable and exhibited intense swimming, with a large amount of reserve material (yolk) and an evident drop of oil.

Acute effects of dryland muscular endurance and maximum strength training on sprint swimming performance in young swimmers

ABSTRACT The study examined acute effects of dryland muscular endurance (ME) and maximum strength (MS) sessions on performance, physiological, and biomechanical variables during a subsequent sprint swimming session. Twenty-seven swimmers (16.5 ± 2.6 yrs) completed three experimental conditions including: i) ME, 55% of 1-repetition maximum, ii) MS, 90% of 1-repetition maximum, and iii) control (CON, no dry-land). Twenty minutes following ME, MS and CON sessions swimmers performed a 10-s tethered swimming sprint, four by 50-m (4 × 50-m), and a 100-m front crawl sprints. Performance time, blood lactate, heart rate (HR), stroke rate (SR), stroke length (SL), stroke index (SI), and stroke efficiency (ηF) were measured during 4 × 50-m and 100-m. Hand grip strength (HG), and shoulder muscles isometric strength (ISO) were measured after each session. Mean 4 × 50-m time increased in ME compared to CON by 1.7 ± 2.7% (p = 0.01), while 100-m time was similar among conditions (p > 0.05). ISO was lower after dry-land training in all conditions (p = 0.01). Tethered force, HG, HR, SR, SL, SI, and ηF were no different between conditions (p > 0.05). Dryland ME session decrease swimming performance; however, ME and MS sessions did not affect technical ability during a subsequent maximum intensity swimming.

Cardiomyocyte and endothelial cells play distinct roles in the tumour necrosis factor (TNF)-dependent atrial responses and increased atrial fibrillation vulnerability induced by endurance exercise training in mice.

Endurance exercise is associated with an increased risk of atrial fibrillation (AF). We previously established that adverse atrial remodelling and AF susceptibility induced by intense exercise in mice require the mechanosensitive and pro-inflammatory cytokine tumour necrosis factor (TNF). The cellular and mechanistic basis for these TNF-mediated effects is unknown. We studied the impact of Tnf excision, in either atrial cardiomyocytes or endothelial cells (using Cre-recombinase expression controlled by Nppa or Tie2 promoters, respectively), on the cardiac responses to six weeks of intense swim exercise training. TNF ablation, in either cell type, had no impact on the changes in heart rate, autonomic tone, or left ventricular structure and function induced by exercise training. Tnf excision in atrial cardiomyocytes did, however, prevent atrial hypertrophy, fibrosis, and macrophage infiltration as well as conduction slowing and increased AF susceptibility arising from exercise training. In contrast, endothelial-specific excision only reduced the training-induced atrial hypertrophy. Consistent with these cell-specific effects of Tnf excision, inducing TNF loss from atrial cardiomyocytes prevented activation of p38MAPKinase, a strain-dependent downstream mediator of TNF signalling, without affecting the atrial stretch as assessed by atrial pressures induced by exercise. Despite TNF's established role in innate immune responses and inflammation, neither acute nor chronic exercise training caused measurable NLRP3 inflammasome activation. Our findings demonstrate that adverse atrial remodelling and AF vulnerability induced by intense exercise require TNF in atrial cardiomyocytes whereas the impact of endothelial-derived TNF is limited to hypertrophy modulation. The implications of the cell autonomous effects of TNF and crosstalk between cells in the atria are discussed.

AVALIAÇÃo MUSCULO-ARTICULAR DOS EFEITOS DA HIDROTERAPIA NA RECUPERAÇÃo PÓS-TREINO EM JOGADORES DE BASQUETEBOL

ABSTRACT Objective: To evaluate the effects of hydrotherapy on post-training recovery of basketball players. Methods: 60 basketball players from the sports representative team were divided equally into test and control group for evaluation according to the Partridge method. The experimental group received hydrotherapy for 15 minutes after intense winter training. Pain degrees in joint flexion and extension, adduction, external rotation, and internal rotation were evaluated. Results: The HL value of blood immediately after 800m hydrotherapy swimming was not significantly different between the experimental group and the control group by t-test (P>0.05). Before treatment, there was no significant difference in the Partridge score between the two groups (P<0.01). The improvement of the Partridge score in the two groups of patients was significantly reduced after treatment (P<0.01), and the improvement of the experimental group was significantly better than that of the control group (P<0.01). Before treatment, there was no significant difference between the two groups (P<0.01). After treatment, it was significantly reduced (P<0.01), but the experimental group’s improvement was significantly better than the control group (P<0.01). Conclusion: The method of introducing hydrotherapy as post-workout swimming has a significant effect on relieving swelling of the brachial and quadriceps muscles. However, intense swimming may affect the effect of muscle recovery. Level of evidence II; Therapeutic studies - investigation of treatment results.

The effect of ingestion of red dragon fruit extract on levels of malondialdehyde and superoxide dismutase after strenuous exercise in rats (Rattus norvegicus)

Background: Prolonged activation of skeletal muscles causes a decrease in the production of fatigue. Exercise with strenuous intensity causes an increase in Reactive Oxygen Species (ROS). An increase in free radicals causes oxidative stress resulting in damage to cell function to mitochondrial dysfunction, and fatigue. This study aimed to determine the antioxidant potential of red dragon fruit (RDF) to delay fatigue due to oxidative stress, which improves cell function in mitochondria. Methods: 25 male rats (Rattus norvegicus) aged three months were divided into five groups: Group K1 was N.A. (No Activity) but drinking and eating; Group K2 performed strenuous exercise without RDF treatment; Groups 3, 4, and 5 (P1, P2 and P3, respectively) performed strenuous exercise and were treated with 75 mg kg-1.bw, 150 mg kg-1.bw, and 300 mg kg-1.bw of RDF extract, respectively. The exercise for the rats involved intense swimming for 20 minutes a day three time a week for fouweeks. Malondialdehyde (MDA) dan SOD was measured with the ELISA and histopathology for muscle soleus and lung tissue. Results: Strenuous exercise followed by RDF extract ingestion was compared for fatigue in terms of duration and time; before (24.55±1.38 minute) and after (95.31±7.82 minute) and led to a significant difference of 39% (p<0.01). The study also compared MDA before and after RDF extract ingestion in the K2 vs. the P1 group (p<0.05). At the same time, P2 differed more significantly (p<0.01). This indicated a spread of free radicals and featured histopathological damage of muscle cells. However, ingestion of RDF extract leads to improvement of soleus muscle cells; thus, repairs cell function, delaying fatigue. Conclusion: This study confirmed that strenuous exercise, which causes an increase in ROS, intensifies free radicals with RDF extract ingestion and declines oxidative stress, repairing cell function and delaying fatigue.

The effect of rehabilitation exercise on the expression of glutaminase and cardiopulmonary remodeling in pulmonary hypertension

Pulmonary hypertension (PH) is featured by pulmonary vascular and cardiac remodeling. Rehabilitation exercise can improve patients’ quality of life. We previously pinpointed a potential glutamine metabolism dysfunction in PH. Hence, we aim to investigate whether rehabilitation exercise could mitigate right ventricular and pulmonary vascular remodeling and its effect on glutaminase (GLS). We collected clinical indicators of PH patients and analyzed their correlation with GLS. Rehabilitation exercise (moderate intensity swimming exercise) was performed in monocrotaline-induced PH (MCT-PH) rats. We found that plasma GLS1 level in patients was lower than healthy subjects, and it was negatively correlated with end-systolic stage eccentricity index, right atrial transverse dimension and right atrial longitudinal dimension. MCT-PH rats displayed pulmonary vascular remodeling and right ventricular hypertrophy. Compared to control rats, higher levels of GLS1 and GLS2 mRNA in lung and lower levels of these two isoforms of GLS in right ventricle (RV) were displayed in MCT-PH rats. After swimming exercise, GLS mRNA levels in the lung and RV were significantly upregulated, and the cross-sectional area of right ventricular cardiomyocytes was significantly decreased although the percentage of pulmonary arteriolar medial wall thickness was not significantly changed. Therefore, we hold the opinion that plasma GLS1 level was decreased in PH. The transcriptional levels of GLS1 and GLS2 were increased in the lung tissues in PH, but were decreased in the RV tissues. Meanwhile, the changes of GLS levels indicated the pulmonary vascular and right ventricular remodeling. Whereas moderate intensity swimming exercise might improve the right ventricular remodeling by regulating the levels of GLS.

The effect of ingestion of red dragon fruit extract on levels of malondialdehyde and superoxide dismutase after strenuous exercise in rats (Rattus norvegicus)

Background: Prolonged activation of skeletal muscles causes a decrease in the production of fatigue. Exercise with strenuous intensity causes an increase in Reactive Oxygen Species (ROS). An increase in free radicals causes oxidative stress resulting in damage to cell function to mitochondrial dysfunction, and fatigue. This study aimed to determine the antioxidant potential of red dragon fruit (RDF) to delay fatigue due to oxidative stress, which improves cell function in mitochondria. Methods: 25 male rats ( Rattus norvegicus) aged three months were divided into five groups: Group K1 was N.A. (No Activity) but drinking and eating; Group K2 performed strenuous exercise without RDF treatment; Groups 3, 4, and 5 (P1, P2 and P3, respectively) performed strenuous exercise and were treated with 75 mg kg -1.bw, 150 mg kg -1.bw, and 300 mg kg -1.bw of RDF extract, respectively. The exercise for the rats involved intense swimming for 20 minutes every day, four days a week for 31 days. Malondialdehyde (MDA) was measured with the ELISA and histopathology for muscle soleus and lung tissue. Results: Strenuous exercise followed by RDF extract ingestion was compared for fatigue in terms of duration and time; before (24.55±1.38 minute) and after (95.31±7.82 minute) and led to a significant difference of 39% (p<0.01). The study also compared MDA before and after RDF extract ingestion in the K2 vs. the P1 group (p<0.05). At the same time, P2 differed more significantly (p<0.01). This indicated a spread of free radicals and featured histopathological damage of muscle cells. However, ingestion of RDF extract leads to improvement of soleus muscle cells; thus, repairs cell function, delaying fatigue. Conclusion: This study confirmed that strenuous exercise, which causes an increase in ROS, intensifies free radicals with RDF extract ingestion and declines oxidative stress, repairing cell function and delaying fatigue.

Chlorine exposure and intensive exercise induces airway hyperreactivity in a 3-week murine exercise model

RationaleExercise-induced bronchoconstriction (EIB) is defined as acute narrowing of the airways during or immediately after exercise. EIB has a high prevalence in elite swimmers probably due to the high ventilation rate and exposure to the chlorine by-products. It is still puzzling which pathophysiological mechanisms drive EIB. ObjectiveIn this study, we evaluated airway hyperreactivity, permeability, integrity and inflammation in a murine swimmers EIB model with and without chlorine exposure. MethodsMice performed a 3-week swimming protocol in a swimming pool with counter current. Three hours after the last swimming session, airway hyperreactivity to methacholine was assessed. Cytokine levels and cellular differential analysis was performed in BAL fluid. Airway permeability and tight junction expression was measured in serum and lung tissue. T-, B-, dendritic and innate lymphoid cells were determined in lung tissue via flow cytometry. ResultsA significant higher airway resistance (Rn; P < 0.0001) was observed in mice swimming in chlorinated water (mean Rn = 1.26 cmH2O.s/ml) compared to mice swimming in tap water (mean Rn = 0.76 cmH2O.s/ml) and both inhalation groups in the absence of cellular inflammation. No significant differences were found in lung immune cell populations or in lung tight junction mRNA expression. Experiments in SCID, Rag2−/−γc−/− or Cpa3cre/+ mice showed a limited involvement of the innate, adaptive immune system or the mast cells. ConclusionOur 3-week swimming murine model mimics intensive swimming in chlorinated water with the presence of airway hyperreactivity in mice swimming in chlorinated water in the absence of airway inflammation and airway epithelial damage.

Effects of High Intensity Swimming on Heat Shock Protein 70, Superoxide Dismutase and Malondialdehyde of Rattus norvegicus Male Rats

Effects of High Intensity Swimming on Heat Shock Protein 70, Superoxide Dismutase and Malondialdehyde of Rattus norvegicus Male Rats

Menstrual status and perceived coaching strategy and training methodology in high-performance female swimmers from Slovenia - Preliminary study

Female swimmers participate in intensive swimming training during their menstrual periods, and they may appreciate additional understanding and flexibility regarding their training volume/intensity. Male coaches often view menstruation contemptuously as an unfortunate state that “is not a disease,” and high-performance female swimmers perceive coaching methods differently. Our study aimed to examine menstrual status and perceived coaching and training methodology. In a cross-sectional study, members of the Slovenian women’s national swim team (n = 14, age: 16.6 ± 3.1 years, body mass index: 20.1 ± 1.9 kg/m2) competing at international and national levels were included. The menstrual status (i.e., regularity, duration, perceived pain before and during menstruation, bleeding) and the opinion of these female swimmers regarding training during their menstrual periods were assessed via our in-depth questionnaire, and the athletes responded to additional questions pertaining to the motivation of swimming, coaching strategy and training methods via a questionnaire. All swimmers included in our study had experienced their first menstrual period, and the majority (85%) reported moderate or heavy menstrual bleeding. Most swimmers (93%) reported that their swimming training was “undisturbed” during their menstrual period; however, 64% of swimmers requested a reduction in training frequency or at least the usual training volume/intensity. In terms of the motivation for swimming, 74% of swimmers reported that they like swimming and like spending time with their friends. In terms of coaching and training methods, the swimmers reported polarized responses, probably because most of them are members of two major swimming clubs with different coaching styles. To conclude, when executed correctly, a similar kind of systematic screening method (i.e., anonymously and perhaps by experienced psychologists) may serve as a valuable tool to further modify training methods at a high-performance level. Moreover, unpleasant issues related to menstrual periods from the athlete’s perspective (i.e., pain, bleeding, malaise, discomfort, inability to achieve maximum effort) should not be ignored, left for swimmers to handle alone, or taken for granted. Male coaches need to seek to understand the impact of menstruation and work with athletes to maximize training.

Oxygen uptake kinetics and ventilatory and metabolic parameters do not differ between moderate‐intensity front crawl and breaststroke swimming

Pulmonary oxygen uptake (V˙O2) kinetics have been well studied during land‐based exercise. However, less is known about V˙O2 kinetics during swimming exercise and comparisons between strokes is non‐existent. We aimed to characterize and compare the V˙O2 kinetics, ventilatory,e and metabolic response to constant velocity moderate‐intensity freely breathing front crawl (FC) and breaststroke (BR) swimming in a swimming flume. These two strokes reflect predominantly upper body versus lower body modes of swimming locomotion, respectively. Eight trained swimmers (4 females, 20 ± 1 years, 1.74 ± 0.06 m; 66.8 ± 6.3 kg) attended 5–6 laboratory‐based swimming sessions. The first two trials determined FC and BR V˙O2max and the ventilatory threshold (VT), respectively, during progressive intensity swimming to the limit of tolerance. Subsequent trials involved counterbalanced FC and BR transitions from prone floating to constant velocity moderate‐intensity swimming at 80% of the velocity at VT (vVT), separated by 30‐min recovery. Breath‐by‐breath changes in pulmonary gas exchange and ventilation were measured continuously using a snorkel and aquatic metabolic cart system. The ventilatory and metabolic responses were similar (p > 0.05) between strokes during maximal velocity swimming, however, vVT and maximal velocity were slower (p < 0.05) during BR . During moderate‐intensity swimming, V˙O2 kinetics, ventilatory and metabolic parameters were similar (p > 0.05) between strokes. In conclusion, when breathing ad libitum, V˙O2 kinetics during moderate‐intensity constant velocity swimming, and ventilatory and metabolic responses during moderate‐intensity and maximal velocity swimming, are similar between FC and BR strokes.

Short-term behavioural impacts of air-exposure in three species of recreationally angled freshwater fish

Fish captured and released by recreational anglers are often exposed to air to enable hook removal and for admiration (e.g., photography). It is necessary to identify thresholds for air exposure that minimize sublethal alterations to inform best practice guidelines yet doing so in ecological-relevant field settings is challenging. We developed a novel attachment method for tri-axial accelerometer and depth biologgers to quantify short-term post-release behaviour in recreationally angled northern pike (Esox lucius), smallmouth bass (Micropterus dolomieu), and walleye (Sander vitreus) following a range of air exposure treatments (i.e., 0, 15, 30, 60, and 180 s). The biologgers were attached to the fish using a quick-release Velcro® harnesses that facilitated easy retrieval of the device from free-swimming fish without the need to recapture the individual. For this study, biologgers were retrieved after a 10 min observational period. Overall dynamic body acceleration (ODBA) was calculated from accelerometric data to estimate post-release swimming activity. Clustering of ODBA via k-means was used to classify distinct movement patterns: resting, steady-state swimming, and high intensity swimming occurrences. In northern pike, ODBA in the first minute after release was significantly higher in the 0 s air exposure treatment compared to the 15 s, 30 s, 60 s, and 180 s treatments, however the same patterns were not observed for smallmouth bass or walleye. We did not observe differences in the time spent resting, time spent steady-state swimming, or the number of high intensity swimming occurrences among air exposure treatments across all study species. This proof-of-concept study demonstrated the utility of this non-invasive bio-logger approach for the short-term study of catch-and-release and also revealed that for the species and context (e.g., water temperatures of 17–25 º C) studied here, air exposure had relatively little negative short-term impact on behaviour or reflex impairment. Nonetheless, we encourage air exposure to be minimized as longer fight times or higher water temperatures may interact with air exposure to increase behaviour impairments and negatively impact survival.

Evaluation of silymarin extract from Silybum marianum in mice: anti-fatigue activity

Silymarin has been used for centuries for its hepatoprotective properties. The specific objective of this study was to evaluate the anti-fatigue properties of silymarin. The silymarin was administered orally at doses of 50, 100, and 200mg/kg for 4 weeks; the fatigue level and exercise performance were evaluated using exhaustive swimming time and pole-climbing time, as well as levels of plasma lactate, ammonia, glucose, creatine kinase (CK), serum urea nitrogen (SUN), blood lactic acid (BLA), muscle glycogen (MG), and liver glycogen (LG) contents after an intensive swimming session. The results demonstrated that silymarin treatment decreased the BLA and SUN levels while increased the LG and MG levels. In addition, silymarin decreased plasma lactate and ammonia levels and CK activity after swimming test, this is related to the mechanism that increases energy storage (as glycogen) and release (as blood glucose), and decreases plasma levels of lactate, ammonia, and CK. The observation of the skeletal muscle structures of mice also confirmed that skeletal muscles became more damaged in the control group compared with the silymarin-treated mice after prolonged endurance exercise. Therefore, it is reasonable to infer that silymarin may bear potential pharmacological effects in combating fatigue.

The effect of ingestion of red dragon fruit extract on levels of malondialdehyde and superoxide dismutase after strenuous exercise in rats ( Rattus norvegicus)

Background: Prolonged activation of skeletal muscles causes a decrease in the production of fatigue. Exercise with strenuous intensity causes an increase in Reactive Oxygen Species (ROS). An increase in free radicals causes oxidative stress resulting in damage to cell function to mitochondrial dysfunction, and fatigue. This study aimed to determine the antioxidant potential of red dragon fruit (RDF) to delay fatigue due to oxidative stress, which improves cell function in mitochondria. Methods: 25 male rats ( Rattus norvegicus) aged three months were divided into five groups: Group K1 was N.A. (No Activity) but drinking and eating; Group K2 performed strenuous exercise without RDF treatment; Groups 3, 4, and 5 (P1, P2 and P3, respectively) performed strenuous exercise and were treated with 75 mg kg -1.bw, 150 mg kg -1.bw, and 300 mg kg -1.bw of RDF extract, respectively. The exercise for the rats involved intense swimming for 20 minutes a day three time a week for fouweeks. Malondialdehyde (MDA) dan SOD was measured with the ELISA and histopathology for muscle soleus and lung tissue. Results: Strenuous exercise followed by RDF extract ingestion was compared for fatigue in terms of duration and time; before (24.55±1.38 minute) and after (95.31±7.82 minute) and led to a significant difference of 39% (p<0.01). The study also compared MDA before and after RDF extract ingestion in the K2 vs. the P1 group (p<0.05). At the same time, P2 differed more significantly (p<0.01). This indicated a spread of free radicals and featured histopathological damage of muscle cells. However, ingestion of RDF extract leads to improvement of soleus muscle cells; thus, repairs cell function, delaying fatigue. Conclusion: This study confirmed that strenuous exercise, which causes an increase in ROS, intensifies free radicals with RDF extract ingestion and declines oxidative stress, repairing cell function and delaying fatigue.

Body mass conversion and improved insulin response in Colombian Paso horses subjected to a swimming training program

Overweight and obesity in horses affect their athletic performance negatively, making it therefore necessary to develop training protocols that reduce their body fat without causing hoof injuries. The objective of the study was to describe the effect of the application of a swimming training program on metabolic and endocrine variables, in addition to evaluating the changes in subcutaneous fat thickness (SFT) in a group of overweight Colombian Paso Horses (CPHs). Six CPHs were subjected to a decreasing intensity swimming program for four months. The effect of this training on metabolic variables (i.e. aspartate aminotransferase, creatine kinase, triglycerides, cholesterol, glucose) and endocrines (cortisol and insulin) was studied every two months. Additionally, changes in the neck, lumbar, and gluteal SFTs were evaluated. The information was analysed using descriptive statistics, in addition to repeated measures analysis of variance for non-parametric data in the three training moments (P&lt;0.1) and correlation analysis between the SFT and the metabolic and endocrine variables of interest. The swimming training program for CPHs tested in this study produced more evident redistribution of adipose tissue in the gluteal region (Initial SFT = 5.2±2.08 mm; Final SFT = 3.45±2.8 mm), conversion of body mass without weight modification, and use of energy sources such as triglycerides and increased sensitivity to insulin. A limitation of the study was that the horses were not selected according to age, nor were control animals used. In addition, the limited number of horses makes extrapolation of the results inappropriate. In conclusion, the swimming training program with decreasing intensity carried out over a four-month period modified body adipose tissue in CPHs, promoting the use of energy sources, such as triglycerides and increased insulin sensitivity.

The effect of ingestion of red dragon fruit extract on levels of malondialdehyde and superoxide dismutase after strenuous exercise in rats ( Rattus norvegicus).

Background: Prolonged activation of skeletal muscles causes a decrease in the production of fatigue. Exercise with strenuous intensity causes an increase in Reactive Oxygen Species (ROS). An increase in free radicals causes oxidative stress resulting in damage to cell function to mitochondrial dysfunction, and fatigue. This study aimed to determine the antioxidant potential of red dragon fruit (RDF) to delay fatigue due to oxidative stress, which improves cell function in mitochondria. Methods: 25 male rats (Rattus norvegicus) aged three months were divided into five groups: Group K1 was N.A. (No Activity) but drinking and eating; Group K2 performed strenuous exercise without RDF treatment; Groups 3, 4, and 5 (P1, P2 and P3, respectively) performed strenuous exercise and were treated with 75 mg kg -1.bw, 150 mg kg -1.bw, and 300 mg kg -1.bw of RDF extract, respectively. The exercise for the rats involved intense swimming for 20 minutes every day, four days a week for 31 days. Malondialdehyde (MDA) was measured with the ELISA and histopathology for muscle soleus and lung tissue. Results: Strenuous exercise followed by RDF extract ingestion was compared for fatigue in terms of duration and time; before (24.55±1.38 minute) and after (95.31±7.82 minute) and led to a significant difference of 39% (p<0.01). The study also compared MDA before and after RDF extract ingestion in the K2 vs. the P1 group (p<0.05). At the same time, P2 differed more significantly (p<0.01). This indicated a spread of free radicals and featured histopathological damage of muscle cells. However, ingestion of RDF extract leads to improvement of soleus muscle cells; thus, repairs cell function, delaying fatigue. Conclusion: This study confirmed that strenuous exercise, which causes an increase in ROS, intensifies free radicals with RDF extract ingestion and declines oxidative stress, repairing cell function and delaying fatigue.

ATRIAL STRETCH-DEPENDENT TUMOR NECROSIS FACTOR-MEDIATED ADVERSE ATRIAL REMODELING AND ATRIAL ARRHYTHMIA INDUCIBILITY IN A MOUSE MODEL OF AORTIC REGURGITATION

<h3>BACKGROUND</h3> Atrial fibrillation (AF) is the most common sustained supraventricular arrhythmia worldwide, with its incidence linked to cardiovascular (CV) disease and, paradoxically, endurance exercise. Most conditions linked to AF are associated with elevated atrial pressures and stretch, which are powerful stimuli for atrial hypertrophy, fibrosis, and inflammation. We previously established adverse atrial changes and arrhythmogenesis required the pro-inflammatory and mechanosensitive cytokine tumor necrosis factor (TNF) in intense swim exercised mice. Thus, we hypothesize that stretch-mediated TNF-dependent signaling may provide a unifying mechanism linking AF in exercise and disease. <h3>METHODS AND RESULTS</h3> We developed a clinically-relevant mouse model of aortic regurgitation (AR), which is characterized by diastolic volume overload and elevated left ventricular end-diastolic (LVEDPs) and atrial pressures, to study atrial stretch-dependent TNF-mediated AF pathogenesis. AR was induced by retrograde puncture of the aortic valve in 8-week-old CD1 wild-type and whole-body TNF knockout (TNF-/-) mice. Four weeks after regurgitation, AR resulted in volume overload-mediated progressive LV dilatation, functional impairment, hypertrophy, and elevated LVEDPs in the absence of ventricular arrhythmia inducibility in both groups. In wild-type mice, AR resulted in adverse atrial remodeling, characterized by atrial hypertrophy and fibrosis, decreased conduction velocity, reduced atrial effective refractory period and action potential duration, and increased in vivo and ex vivo AF susceptibility. By contrast, TNF-/- prevented AR-induced adverse atrial remodeling and arrhythmia inducibility, independent of ventricular changes. <h3>CONCLUSION</h3> Our results establish that adverse atrial remodeling and AF vulnerability with AR requires TNF, providing a mechanistic link between elevated atrial pressures, adverse remodeling, and AF susceptibility with CV disease and exercise.

The effect of red-fleshed pitaya ( Hylocereus polyrhizus) on heat shock protein 70 and cortisol expression in strenuous exercise induced rats.

Background: Oxidative stress from exercise can contribute to damaging cells, increasing heat shock protein 70 (HSP70) and suppressing the immune system in the body. This research aimed to determine the antioxidant potential of red-fleshed pitaya extract on HSP70 and cortisol expression in rats which were subjected to strenuous exercise. Methods: The subjects of this research were 32 Sprague Dawley male rats, aged 3 months, with an average weight of 200 g. Red-fleshed pitaya extract was obtained from methanol extraction process; a maceration technique was performed and the extract was concentrated using an air-drying method. Rats were randomly divided into four groups. Group 1 were subjected to strenuous exercise and treated with distilled water only; while Groups 2, 3 and 4 were subjected to strenuous exercise and treated with 100 mg/kg body weight, 200 mg/kg body weight and 300 mg/kg body weight of red-fleshed pitaya extract, respectively. Strenuous exercises in rats was performed by intense swimming of 20 min/day, 3 days a week for 3 weeks. HSP70 expression and cortisol were measured with Enzyme-Linked Immune Sorbent Assay (ELISA) method. Results: There was a significant reduction of HSP70 (p=0.000) and cortisol expression (p=0.000) between the groups. Also, there was a significant difference in the average decreasing of HSP70 expression between group 4 and either groups 1 or 2 (p=0.000). However, a significant difference between groups 4 and 3 was not observed (p=0.813). Lastly, a significant difference was found in the average decrease of cortisol expression between groups 4 and 1 (p=0.000), 2 (p=0.000), and 3 (p=0.000) respectively. Conclusion: Red-fleshed pitaya is potential to be utilized as antioxidant to decrease the HSP70 and cortisol expression.

Previous Intensive Running or Swimming Negatively Affects CPR Effectiveness.

Survival outcomes increase significantly when cardiopulmonary resuscitation (CPR) is provided correctly, but rescuers’ fatigue can compromise its delivery. We investigated the effect of two exercise modes on CPR effectiveness and physiological outputs. After 4 min baseline conditions, 30 lifeguards randomly performed a 100 m run and a combined water rescue before 4 min CPR (using an adult manikin and a 30:2 compression–ventilation ratio). Physiological variables were continuously measured during baseline and CPR using a portable gas analyzer (K4b2, Cosmed, Rome, Italy) and CPR effectiveness was analyzed using two HD video cameras. Higher oxygen uptake (23.0 ± 9.9 and 20.6 ± 9.1 vs. 13.5 ± 6.2 mL·kg·min−1) and heart rate (137 ± 19 and 133 ± 15 vs. 114 ± 15 bpm), and lower compression efficacy (63.3 ± 29.5 and 62.2 ± 28.3 vs. 69.2 ± 28.0%), were found for CPRrun and CPRswim compared to CPRbase. In addition, ventilation efficacy was higher in the rescues preceded by intense exercise than in CPRbase (49.5 ± 42.3 and 51.9 ± 41.0 vs. 33.5 ± 38.3%), but no differences were detected between CPRrun and CPRswim. In conclusion, CPRrun and CPRswim protocols induced a relevant physiological stress over each min and in the overall CPR compared with CPRbase. The CPRun protocol reduces the compression rate but has a higher effectiveness percentage than the CPRswim protocol, in which there is a considerably higher compression rate but with less efficacy.