Swimming Performance in Elite Triathletes: Comparison Between Open Water and Pool Conditions.

This study aimed to compare performance, kinematic, and physiological variables between open water and pool swimming conditions in elite triathletes and to examine the associations between conditions on these variables. Fourteen elite triathletes (10 males and 4 females [23.4 ± 3.8 years]) performed two 1500-m swimming tests in open water and in a 25-m pool. Swimming speed, stroke rate (SR), length (SL) and index (SI), heart rate (HR), blood lactate concentrations [La-], and end-exercise oxygen uptake (EEV̇O2) were assessed in both conditions. Lower SL and SI and higher SR were obtained in open water compared with pool swimming (p < 0.05). Moreover, kinematic variables changed as a function of distance in both conditions (p < 0.05). No differences were found in the main physiological variables (HR, [La-], and EEV̇O2) between conditions. Respiratory exchange ratio presented lower values in open water than in pool conditions (p < 0.05), while time constant was higher in open water (p = 0.032). The fastest triathletes in open water obtained the best performance in the pool (r = 0.958; p < 0.001). All kinematic variables, HR and peak [La-] presented positive associations between conditions (r > 0.6; p < 0.05). Despite physiological invariance, triathletes and coaches should monitor specific open water training to adapt their swimming technique to the competitive environment.

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

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.

Spatial Precision Tailoring the Catalytic Activity of Graphene Monolayers for Designing Janus Swimmers.

Graphene monolayers have interesting applications in many fields due to their intrinsic physicochemical properties, especially when they can be postmodified with high precision. Herein, we describe the highly site-selective functionalization of freestanding graphene monolayers with platinum (Pt) clusters by bipolar electrochemistry. The deposition of such metal spots leads to catalytically active hybrid two-dimensional (2D) nanomaterials. Their catalytic functionality is illustrated by the spatially controlled decomposition of hydrogen peroxide, inducing motion at the water/air interface due to oxygen bubble evolution. A series of such 2D Janus structures with Pt deposition at predefined positions (corners and edges) is studied with respect to the generation of autonomous motion. The type and speed of motion can be fine-tuned by controlling the deposition time and location of the Pt clusters. These proof-of-principle experiments indicate that this type of hybrid 2D object opens up interesting perspectives in terms of applications, such as environmental detection or remediation.

Chemically-Driven Autonomous Janus Electromagnets as Magnetotactic Swimmers.

An electromagnet is a particular device that takes advantage of electrical currents to produce concentrated magnetic fields. The most well-known example is a conventional solenoid, having the form of an elongated coil and creating a strong magnetic field through its center when it is connected to a current source. Spontaneous redox reactions located at opposite ends of an anisotropic Janus swimmer can effectively mimic a standard power source, due to their ability to wirelessly generate a local electric current. Herein, we propose the coupling of thermodynamically spontaneous redox reactions occurring at the extremities of a hybrid Mg/Pt Janus swimmer with a solenoidal geometry to generate significant magnetic fields. These chemically driven electromagnets spontaneously transform the redox-induced electric current into a magnetic field with a strength in the range of µT upon contact with an acidic medium. Such on-board magnetization allows them to perform compass-like rotational motion and magnetotactic displacement in the presence of external magnetic field gradients, without the need of using ferromagnetic materials for the swimmer design. The torque force experienced by the swimmer is proportional to the internal redox current, and by varying the composition of the solution, it is possible to fine-tune its angular velocity.

Performance progression and variability in 100 m freestyle Paralympic swimmers: A comparison of medallists and para classifications.

This study quantified the performance progression and variability of elite 100 m freestyle para swimmers according to classification and medal status. To depict progression, annual world ranking times from 2009 to 2016 were obtained for 253 male and 236 female para swimmers and expressed relative to their respective (2012 & 2016) Paralympic Games performances. Comparisons according to medalling status and para classification were made using linear mixed models. Although not always continuous, swimmers generally progressed year-on-year by≈0.53%. Medallists made significantly greater performance progressions (2.76 ± 0.63%) than non-medallists (2.15 ± 0.31%) over the years preceding a Paralympic Games. The most physically impaired swimmers (S1-S4 classes) made significantly greater performance progressions in the final 3 years before a Paralympic Games than all other subgroups (S5-S6, S7-S10 & S11-S13). Within-swimmer variation in swimmers overall, expressed as coefficient of variation, was 0.56 ± 0.39%, whilst between-swimmer variation was 0.9 ± 0.2%. In both scenarios, S1-S4 swimmers evidenced greater overall variation. These findings have implications for para swimmers, coaches and support staff when planning training and analysing competition outcomes. We also propose performance variation to be a useful metric in the identification of para swimmers warranting (re-)classification.

Erosive tooth wear and salivary parameters among competitive swimmers and non-swimmers in Egypt: a cross-sectional study.

INTRODUCTION: Competitive swimmers spend considerable time practicing their sport. Prolonged exposure to chlorinated water can alter salivary parameters and might compromise oral health. This study aimed to determine erosive tooth wear status and its related risk factors among competitive swimmers as compared to non-swimmers. MATERIALS AND METHODS: A cross-sectional study consisting of 180 athletes (90 competitive swimmers versus 90 competitive rowers "non-swimmers") was conducted. Participants were interviewed on the common erosion risk factors. The Basic Erosive Wear Examination system was used to assess the status of erosive tooth wear. Stimulated saliva sample was collected before and after a training session and pool pH was evaluated using pH strips for 7 days. Data were analyzed using descriptive statistics and multivariable analysis. RESULTS: The prevalence of dental erosion was significantly higher among competitive swimmers (60%) with higher BEWE scores compared to non-swimmers (25.6%). The salivary flow rate was reduced significantly after training sessions in both groups while salivary pH increased among swimmers. Evaluation of pool water revealed a continuous reduction in the pH level, reaching a very acidic pH level of 3.24. CONCLUSION: Erosive tooth wear is more prevalent among competitive swimmers. Years of practice and regular consumption of acidic drinks increase the odds of developing erosive lesions. A high incidence of erosive lesions may be attributed to a reduction in swimming pool pH level. Salivary parameters showed variations between groups after training sessions.

SwimmerNET: Underwater 2D Swimmer Pose Estimation Exploiting Fully Convolutional Neural Networks.

Professional swimming coaches make use of videos to evaluate their athletes' performances. Specifically, the videos are manually analyzed in order to observe the movements of all parts of the swimmer's body during the exercise and to give indications for improving swimming technique. This operation is time-consuming, laborious and error prone. In recent years, alternative technologies have been introduced in the literature, but they still have severe limitations that make their correct and effective use impossible. In fact, the currently available techniques based on image analysis only apply to certain swimming styles; moreover, they are strongly influenced by disturbing elements (i.e., the presence of bubbles, splashes and reflections), resulting in poor measurement accuracy. The use of wearable sensors (accelerometers or photoplethysmographic sensors) or optical markers, although they can guarantee high reliability and accuracy, disturb the performance of the athletes, who tend to dislike these solutions. In this work we introduce swimmerNET, a new marker-less 2D swimmer pose estimation approach based on the combined use of computer vision algorithms and fully convolutional neural networks. By using a single 8 Mpixel wide-angle camera, the proposed system is able to estimate the pose of a swimmer during exercise while guaranteeing adequate measurement accuracy. The method has been successfully tested on several athletes (i.e., different physical characteristics and different swimming technique), obtaining an average error and a standard deviation (worst case scenario for the dataset analyzed) of approximately 1 mm and 10 mm, respectively.

From Entry to Finals: Progression and Variability of Swimming Performance at the 2022 FINA World Championships.

The aim of the present study was two-fold: (i) to analyze the progression and variability of swimming performance (from entry times to best performances) in the 50, 100, and 200 m at the most recent FINA World Championships and (ii) to compare the performance of the Top16, semifinalists, and finalists between all rounds. Swimmers who qualified with the FINA A and B standards for the Budapest 2022 World Championships were considered. A total of 1102 individual performances swimmers were analyzed in freestyle, backstroke, breaststroke, and butterfly events. The data was retrieved from the official open-access websites of OMEGA and FINA. Wilcoxon test was used to compare swimmers' entry times and best performances. Repeated measures ANOVA followed by the Bonferroni post-hoc test were performed to analyze the round-to-round progression. The percentage of improvement and variation in the swimmers' performance was computed between rounds. A negative progression (entry times better than best performance) and a high variability (> 0.69%) were found for most events. The finalists showed a positive progression with a greater improvement (~1%) from the heats to the semifinals. However, the performance progression remained unchanged between the semifinals and finals. The variability tended to decrease between rounds making each round more homogeneous. Coaches and swimmers can use these indicators to prepare a race strategy between rounds.

Investigating The Association Between Supraspinatus Tendon Abnormality, Shoulder Pain and Isokinetic Strength in Elite Swimmers: A Cross-Sectional Study.

Shoulder pain is common among elite swimmers due to the tremendous stress over shoulders during swimming. Supraspinatus muscle is one of the major prime movers and stabilizers of shoulder and is highly susceptible to overloading and tendinopathy. An understanding of the relationship between supraspinatus tendon and pain; and between supraspinatus tendon and strength would assist health care practitioners for developing training regime. The objectives of this study are to evaluate 1) the association between structural abnormality of supraspinatus tendon and shoulder pain and 2) the association between structural abnormality of supraspinatus tendon and shoulder strength. We hypothesized that structural abnormality of supraspinatus tendons positively associated with shoulder pain and negatively associated with shoulder muscle strength among elite swimmers. 44 elite swimmers were recruited from the Hong Kong China Swimming Association. Supraspinatus tendon condition was evaluated using diagnostic ultrasound imaging and shoulder internal and external rotation strength was evaluated by the isokinetic dynamometer. Pearson's R was used to study the correlation between shoulder pain and supraspinatus tendon condition and to evaluate the association between isokinetic strength of shoulders and supraspinatus tendon condition. 82 shoulders had supraspinatus tendinopathy or tendon tear (93.18%). However, there was no statistically significant association between structural abnormality of supraspinatus tendon and shoulder pain. The results showed that there was no association between supraspinatus tendon abnormality and shoulder pain and there was a significant correlation between left maximal supraspinatus tendon thickness (LMSTT) and left external rotation/ concentric (LER/Con) and left external rotation/ eccentric (LER/Ecc) shoulder strength (p < 0.05) while internal rotation/ external rotation (IR/ER) ratio can also be a significant predicator on LMSTT >6mm (R2 = 0.462, F = 7.016, df = 1, p = 0.038). Structural change of supraspinatus tendon was not associated with shoulder pain, but could be a predictor on MSTT >6mm in elite swimmers.

Comparison of the risk of infection of human rotavirus and astrovirus according to fishing and swimming activities at Las Cañas beach, Uruguay.

AIMS: To estimate the risk of human rotavirus (RV) and astrovirus (HAstV) infections for swimmers and fishers at Las Cañas beach, Uruguay. METHODS AND RESULTS: Surface water samples were collected monthly for 1 year. The dose-response models used were ß-Poisson and 1 F1 hypergeometric for RV and HAstV, respectively. The probabilities of infection were calculated using a kernel density estimate to fitting the data and then sampling from this distribution (Monte Carlo simulation). The probability of RV infection for fishers was between 0 and 65% and for swimmers was between 0 and 50% (<18 years old) and between 0 and 38% (>18 years old). For HAstV, the probability of infection for fishers was between 0% and 45% and for swimmers was between 0 and 38% (<18 years old) and between 0 and 18% (>18 years old). CONCLUSIONS: This study suggests that fishers are at higher risk of infection for both viruses compared with swimmers mainly due to higher viral frequency and concentration at the site for fishing activities.

The determinant factors of undulatory underwater swimming performance: A systematic review.

The prominence of undulatory underwater swimming (UUS) has been clearly observed during recent international events. Improvement of this phase is important for overall performance. The aim of this systematic review was to identify the key factors that modulate UUS performance and provide coaches and sports science practitioners with valuable and practical information to optimise it. PubMed, Web of Science, Scopus, and SPORTDiscus databases were searched up to 14 October 2021. Studies involving competitive swimmers and which included UUS performance assessment were considered. Methodological quality assessment was conducted for the included articles. From the 193 articles screened, 15 articles were included. There was a substantial body of research conducted on kicking frequency, vertical toe and body wave velocity, angular velocity of the joints, distance per kick, joint amplitudes and mobility, and body position in UUS performance. However, further investigation is required for muscle activation and muscle strength influence. The results from this review contribute to understanding of how to optimise UUS performance, identifying the key aspects that must be addressed during training. Specifically, the caudal momentum transfer should be maximised, the upbeat duration reduced, and the frequency that best suits swimmers' characteristics should be identified individually.

The effects of plyometric jump training on jump and sport-specific performances in prepubertal female swimmers.

BACKGROUND/OBJECTIVE: Dry land-training (e.g., plyometric jump training) can be a useful mean to improve swimming performance. This study examined the effects of an 8-week plyometric jump training (PJT) program on jump and sport-specific performances in prepubertal female swimmers. METHODS: Twenty-two girls were randomly assigned to either a plyometric jump training group (PJTG; n = 12, age: 10.01 ± 0.57 years, maturity-offset = -1.50 ± 0.50, body mass = 36.39 ± 6.32 kg, body height = 146.90 ± 7.62 cm, body mass index = 16.50 ± 1.73 kg/m2) or an active control (CG; n = 10, age: 10.50 ± 0.28 years, maturity-offset = -1.34 ± 0.51, body mass = 38.41 ± 9.42 kg, body height = 143.60 ± 5.05 cm, body mass index = 18.48 ± 3.77 kg/m2). Pre- and post-training, tests were conducted for the assessment of muscle power (e.g., countermovement-jump [CMJ], standing-long-jump [SLJ]). Sport-specific-performances were tested using the timed 25 and 50-m front crawl with a diving-start, timed 25-m front crawl without push-off from the wall (25-m WP), and a timed 25-m kick without push-off from the wall (25-m KWP). RESULTS: Findings showed a significant main effect of time for the CMJ (d = 0.78), the SLJ (d = 0.91), 25-m front crawl test (d = 2.5), and the 25-m-KWP (d = 1.38) test. Significant group × time interactions were found for CMJ, SLJ, 25-m front crawl, 50-m front crawl, 25-m KWP, and 25-m WP test (d = 0.29-1.63) in favor of PJTG (d = 1.34-3.50). No significant pre-post changes were found for CG (p > 0.05). CONCLUSION: In sum, PJT is effective in improving muscle power and sport-specific performances in prepubertal swimmers. Therefore, PJT should be included from an early start into the regular training program of swimmers.

How Much the Swimming Performance Leading to Tokyo 2020 Olympic Games Was Impaired Due to the Covid-19 Lockdown?

The aim of this study was to analyze the progression and stability in the performance of world-ranked swimmers from 2015 to 2020, and the impairment induced by the COVID-19 lockdown. An observational retrospective design over five consecutive competitive seasons was selected. FINA's male Top-50 who were qualified for the Tokyo Olympic Games were considered in freestyle, backstroke, backstroke, and butterfly events. A total of 515 male swimmers and 2060 season-best performances were analyzed. All data was retrieved from two open-access and public websites (Swimrankings and Swimcloud). Repeated measures ANOVA followed by the Bonferroni post-hoc test was performed to analyze the variation between seasons. Stabilization in performance was assessed using spearman correlation coefficients. A significant improvement in performance ≈0.5-2.5% was found in most of the strokes and race distances until the 2018-2019 season. The 2020 lockdown impaired the performance by 1-2%. Moderate to high associations were found in the 2017-2018 season when considering the 2019-2020 performance. The breaststroke was the only stroke with a moderate-high stability (r > 0.40) in all race distances considering the overall time period. It can be concluded that world-ranked swimmers' performance was impaired by 1-2% due to the COVID-19 lockdown, returning to levels that were reached two years earlier.

A Systematic Review and Meta-Analysis: Biomechanical Evaluation of the Effectiveness of Strength and Conditioning Training Programs on Front Crawl Swimming Performance.

The objectives of this systematic review were to summarize and evaluate the effectiveness of strength and conditioning trainings on front crawl swimming, starts and turns performance with relevant biomechanical parameters. Four online databases including PudMed, ESCSOhost, Web of Science and SPORTDiscus were searched according to different combination of keywords. 954 articles were extracted from databases, and ultimately 15 articles were included in this study after removal of duplicate and articles screening according to inclusion and exclusion criteria. Meta-analyses were adopted when appropriate and Egger's regression symmetry was adopted to assess the publication bias and the results were presented with forest plots and funnel plots respectively. Fifteen articles studied the effects of strength and resistance, core, and plyometric trainings. The quality of the investigation was assessed by the checklist developed by Downs and Black. Most of the investigations found out that training programs were beneficial to front crawl sprinting swimming performance, stroke biomechanics, force, and muscle strength. First, strength and resistance trainings and core trainings were effective on sprinting performance enhancement. Second, resistance trainings were found to have positive effects on stroke rate. Plyometric trainings were beneficial to start performance, while there was no sufficient evidence for confirming the positive improvement on turn biomechanical, also overall swimming performance, after weeks of plyometric trainings. Strength and Conditioning trainings are suggested to implement in regular training regime regarding to the positive effects on swimming performance, including starts, turns and front crawl swim, and relevant biomechanical parameters, instead of swimming training only. Further research with higher quality is recommended to conduct and more investigations on the training effects to other stroke styles are also suggested.

Chemotaxis and autochemotaxis of self-propelling droplet swimmers.

Chemotaxis and autochemotaxis play an important role in many essential biological processes. We present a self-propelling artificial swimmer system that exhibits chemotaxis as well as negative autochemotaxis. Oil droplets in an aqueous surfactant solution are driven by interfacial Marangoni flows induced by micellar solubilization of the oil phase. We demonstrate that chemotaxis along micellar surfactant gradients can guide these swimmers through a microfluidic maze. Similarly, a depletion of empty micelles in the wake of a droplet swimmer causes negative autochemotaxis and thereby trail avoidance. We studied autochemotaxis quantitatively in a microfluidic device of bifurcating channels: Branch choices of consecutive swimmers are anticorrelated, an effect decaying over time due to trail dispersion. We modeled this process by a simple one-dimensional diffusion process and stochastic Langevin dynamics. Our results are consistent with a linear surfactant gradient force and diffusion constants appropriate for micellar diffusion and provide a measure of autochemotactic feedback strength vs. stochastic forces. This assay is readily adaptable for quantitative studies of both artificial and biological autochemotactic systems.

Chemo- and Magnetotaxis of Self-Propelled Light-Emitting Chemo-electronic Swimmers.

Miniaturized autonomous chemo-electronic swimmers, based on the coupling of spontaneous oxidation and reduction reactions at the two poles of light-emitting diodes (LEDs), are presented as chemotactic and magnetotactic devices. In homogeneous aqueous media, random motion caused by a bubble-induced propulsion mechanism is observed. However, in an inhomogeneous environment, the self-propelled devices exhibit positive chemotactic behavior, propelling themselves along a pH or ionic strength gradient (∇pH and ∇I, respectively) in order to reach a thermodynamically higher active state. In addition, the intrinsic permanent magnetic moment of the LED allows self-orientation in the terrestrial magnetic field or following other external magnetic perturbations, which enables a directional motion control coupled with light emission. The interplay between chemotaxis and magnetotaxis allows fine-tuning of the dynamic behavior of these swimmers.

Static and Dynamic Lung Volumes in Swimmers and Their Ventilatory Response to Maximal Exercise.

PURPOSE: While the static and dynamic lung volumes of active swimmers is often greater than the predicted volume of similarly active non-swimmers, little is known if their ventilatory response to exercise is also different. METHODS: Three groups of anthropometrically matched male adults were recruited, daily active swimmers (n = 15), daily active in fields sport (Rugby and Football) (n = 15), and recreationally active (n = 15). Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and maximal voluntary ventilation (MVV) was measured before and after exercise to volitional exhaustion. RESULTS: Swimmers had significantly larger FVC (6.2 ± 0.6 l, 109 ± 9% pred) than the other groups (5.6 ± 0.5 l, 106 ± 13% pred, 5.5 ± 0.8, 99% pred, the sportsmen and recreational groups, respectively). FEV1 and MVV were not different. While at peak exercise, all groups reached their ventilatory reserve (around 20%), the swimmers had a greater minute ventilation rate than the recreational group (146 ± 19 vs 120 ± 87 l/min), delivering this volume by breathing deeper and slower. CONCLUSIONS: The swimmers utilised their larger static volumes (FVC) differently during exercise by meeting their ventilation volume through long and deep breaths.

Rhinitis and its impact on quality of life in swimmers.

INTRODUCTION: Limited data suggest that swimmers might be affected by rhinitis significantly more often than the general population. This can have impact on quality of life but also on performance. The aim of this study was to determine the prevalence and impact of QOL of rhinitis in swimming compared to nonswimming athletes and controls. MATERIALS AND METHODS: This was an observational case-control, questionnaire-based study involving elite (n = 101) and nonelite swimming athletes (n = 107), nonswimming athletes (n = 38) and sex- and age-matched controls (n = 50). The survey instrument consisted of a general and the miniRQLQ. Main question used to assess the prevalence of rhinitis was from the ISAAC study. RESULTS: Rhinitis was reported significantly more often by the elite swimmers (45%) than nonelite swimmers (31%), nonswimming athletes (32%) and controls (24%). Allergic rhinitis prevalence was similar in all groups (12%-18%). The prevalence of nonallergic rhinitis (NAR) was significantly higher in elite swimmers (33%) and nonelite swimmers (22%) compared to nonswimming athletes and controls. Overall mean miniRQLQ score and all subdomains except the "eye" domain showed significantly reduced QOL in elite and nonelite swimmers compared to nonswimming athletes and controls. Regular nasal medication was used significantly less by elite swimmers (18%) compared to controls (67%) and nonswimming athletes (42%). CONCLUSION: This study revealed a high prevalence of NAR in swimmers and related impact on QoL. These findings highlight the importance to increase the awareness towards upper airway disorders in the swimming athletes and to ensure adequate management.

The effect of short-term coenzyme Q10 supplementation and pre-cooling strategy on cardiac damage markers in elite swimmers.

Strenuous physical exercise and hyperthermia may paradoxically induce oxidative stress and adverse effects on myocardial function. The purpose of this study was to investigate the effect of 14-d coenzyme Q10 (CoQ10) supplementation and pre-cooling on serum creatine kinase-MB (CK-MB), cardiac Troponin I (cTnI), myoglobin (Mb), lactate dehydrogenase (LD), total antioxidant capacity (TAC), lipid peroxidation (LPO) and CoQ10 concentration in elite swimmers. In total, thirty-six healthy males (mean age 17 (sd 1) years) were randomly selected and divided into four groups of supplementation, supplementation with pre-cooling, pre-cooling and control. During an eighteen-session protocol in the morning and evening, subjects attended speed and endurance swimming training sessions for 5 km in each session. Blood sampling was done before (two stages) and after (two stages) administration of CoQ10 and pre-cooling. ANCOVA and repeated measurement tests with Bonferroni post hoc test were used for the statistical analysis of the data. There was no significant statistical difference among groups for the levels of CK-MB, cTnI, Mb, LD, TAC, LPO and CoQ10 at the presampling (stages 1 and 2) (P>0·05). However, pre-cooling and control groups show a significant increase in the levels of CK-MB, cTnI, Mb, LD and LPO compared with the supplementation and supplementation with pre-cooling groups in the post-sampling (stages 1 and 2) (P<0·05), except for the TAC and CoQ10. Consequently, CoQ10 supplementation prevents adverse changes of myocardial damage and oxidative stress during swimming competition phase. Meanwhile, the pre-cooling strategy individually has no desired effect on the levels of CK-MB, cTnI, Mb, LD, LPO, TAC and CoQ10.

Analysis of a model microswimmer with applications to blebbing cells and mini-robots.

Recent research has shown that motile cells can adapt their mode of propulsion depending on the environment in which they find themselves. One mode is swimming by blebbing or other shape changes, and in this paper we analyze a class of models for movement of cells by blebbing and of nano-robots in a viscous fluid at low Reynolds number. At the level of individuals, the shape changes comprise volume exchanges between connected spheres that can control their separation, which are simple enough that significant analytical results can be obtained. Our goal is to understand how the efficiency of movement depends on the amplitude and period of the volume exchanges when the spheres approach closely during a cycle. Previous analyses were predicated on wide separation, and we show that the speed increases significantly as the separation decreases due to the strong hydrodynamic interactions between spheres in close proximity. The scallop theorem asserts that at least two degrees of freedom are needed to produce net motion in a cyclic sequence of shape changes, and we show that these degrees can reside in different swimmers whose collective motion is studied. We also show that different combinations of mode sharing can lead to significant differences in the translation and performance of pairs of swimmers.