Swimming Phase Research Articles

Development of an evidence-based swimming representative military task to assess swimming competency in the British Army.

There is a requirement for British Army personnel to operate in/around water. Assessing role-related swimming/water competence will support personnel to conduct their job-roles safely and effectively. To undertake a Job-Task Analysis (JTA) of British Army personnel when working in/around water and use this information to develop a Swimming Representative Military Task (RMT) to assess swimming/water competence. Workshops, surveys, and observations were used to conduct a JTA, which identified and described job-tasks conducted by British Army personnel in/around water. Ergonomic analysis of these job-tasks identified seven water-based physical actions, which were considered fundamental for all personnel to be competent in performing. These seven actions guided design of a Swimming RMT, which was subsequently conducted twice by 103 serving personnel (89 men, 11 women) and once by 65 recruits (49 men, 16 women). The RMT comprised of entering the water in combat fatigues and webbing, removing webbing, swimming 50 m, and staying afloat for up to 10 minutes. During RMT trials, in trial 1, 85% of serving personnel and 74% of recruits successfully completed the RMT, which increased to 93% in serving personnel for trial 2. Across trials 1 and 2, all three timed RMT elements showed moderate-high correlational reliability (ICC range: 0.462-0.791). On average, serving personnel were quicker to complete the 50 m swim phase compared to recruits (91±24 s vs. 100±26 s; U = 2575.0, rb = -0.192, p = 0.039). The JTA-informed Swimming RMT provides an assessment of the minimum role-related swimming/water competence standard for British Army personnel.

The Effect of Swimming Exercise on Memory Impairment and Inflammatory Cytokines Caused by Lipopolysaccharide Injection in Male Rats

Memory is a fundamental human ability that enables the nervous system to encode, store, and retrieve various types of information. The aim of this study was to examine the effect of swimming exercise on memory impairment and the inflammatory cytokines TNFα and IL1 caused by lipopolysaccharide injection in male rats. In this study, 40 NMRI mice, approximately 70 days old and weighing 23 ± 1 grams, were used. The mice were randomly divided into four groups: a control group (no exercise with saline, no exercise with lipopolysaccharide) and an experimental group (exercise with saline, exercise with lipopolysaccharide). The training program included two phases of swimming: an adaptation phase and a swimming phase. The adaptation phase consisted of three 10-minute sessions with a 10-minute rest interval between each session. The duration of swimming was progressively increased from 20 minutes in the second week to 30 minutes in the third week. The data collected were analyzed using SPSS software with a two-way analysis of variance. The findings of this study demonstrated that swimming significantly reduced the levels of TNFα and IL1 in male rats (p<0.05). Lipopolysaccharide reduces spontaneous activity and impairs memory, whereas swimming exercise enhances memory function and spontaneous activity. Therefore, swimming exercise has anti-inflammatory effects and improves memory.

Factors driving dispersal and habitat use of loggerhead sea turtle post-hatchlings and its conservational implications

Nesting events of loggerhead sea turtles (Caretta caretta) are on the rise in the Western Mediterranean Sea, far from their usual nesting areas in the Mediterranean and Atlantic basins. The study of dispersal behavior toward potential developmental areas of loggerhead post-hatchlings from this new nesting area is crucial to comprehend this colonization process and determining grounded conservation strategies. To fill this gap, we investigated, for the first time in the Mediterranean Sea, the dispersal strategies and habitat use based on data from 19 head-started loggerhead post-hatchlings released from the Spanish Mediterranean coast and satellite-tracked between 2016 and 2018. Turtles dispersed over large areas and showed active swimming phases, as they frequently dispersed against sea currents. Dispersal routes varied for each individual, although they consistently dispersed south-eastwards, especially during the coldest periods. Several post-hatchlings traveled through the Sicilian Channel to reach deep and warmer areas in the eastern Mediterranean basin. The most year-round suitable areas corresponded to the Ionian and Levantine Seas, which correspond with those found in their traditional nesting areas. Therefore, conservation measures focused on this stage should be taken in the path toward and these developmental areas.

A Novel Gait Phase Recognition Method Based on DPF-LSTM-CNN Using Wearable Inertial Sensors.

Gait phase recognition is of great importance in the development of rehabilitation devices. The advantages of Long Short-Term Memory (LSTM) and Convolutional Neural Network (CNN) are combined (LSTM-CNN) in this paper, then a gait phase recognition method based on LSTM-CNN neural network model is proposed. In the LSTM-CNN model, the LSTM layer is used to process temporal sequences and the CNN layer is used to extract features A wireless sensor system including six inertial measurement units (IMU) fixed on the six positions of the lower limbs was developed. The difference in the gait recognition performance of the LSTM-CNN model was estimated using different groups of input data collected by seven different IMU grouping methods. Four phases in a complete gait were considered in this paper including the supporting phase with the right hill strike (SU-RHS), left leg swimming phase (SW-L), the supporting phase with the left hill strike (SU-LHS), and right leg swimming phase (SW-R). The results show that the best performance of the model in gait recognition appeared based on the group of data from all the six IMUs, with the recognition precision and macro-F1 unto 95.03% and 95.29%, respectively. At the same time, the best phase recognition accuracy for SU-RHS and SW-R appeared and up to 96.49% and 95.64%, respectively. The results also showed the best phase recognition accuracy (97.22%) for SW-L was acquired based on the group of data from four IMUs located at the left and right thighs and shanks. Comparably, the best phase recognition accuracy (97.86%) for SU-LHS was acquired based on the group of data from four IMUs located at left and right shanks and feet. Ulteriorly, a novel gait recognition method based on Data Pre-Filtering Long Short-Term Memory and Convolutional Neural Network (DPF-LSTM-CNN) model was proposed and its performance for gait phase recognition was evaluated. The experiment results showed that the recognition accuracy reached 97.21%, which was the highest compared to Deep convolutional neural networks (DCNN) and CNN-LSTM.

Case Series of Triathletes with Takotsubo Cardiomyopathy Presenting with Swimming-Induced Pulmonary Edema.

To report three cases of triathletes who presented with swimming-induced pulmonary edema (SIPE) following water immersion. They were subsequently diagnosed with Takotsubo cardiomyopathy (TCM). Retrospective case series. All cases were recreational athletes competing in mass participation triathlons between June 2018 and 2019. They were initially managed by the event medical team and subsequently at the local tertiary level hospital. Written consent was gained from all the subjects. The three triathletes were aged between 50 and 60 years, two were females, and all presented with acute dyspnoea on exiting the water. Two also presented with chest pain and haemoptysis. A diagnosis of SIPE was suspected by the medical event team on initial presentation of low oxygen saturations and clinical signs of pulmonary oedema. All were transferred to the local emergency department and had signs of pulmonary oedema on chest radiographs. Further investigations led to a diagnosis of TCM with findings of T wave inversion in anterolateral electrocardiogram leads and apical hypokinesia on transthoracic echocardiogram and unobstructed coronary arteries. This case series presents triathletes diagnosed with SIPE and TCM following the open water swim phase. It is unclear whether the myocardial dysfunction contributed to causation of SIPE or was the result of SIPE. Mass participation race organizers must be prepared that both SIPE and TCM can present in this population. Those presenting with an episode of SIPE require prompt evaluation of their cardiac and pulmonary physiology. Further research is required to ascertain the exact nature of the relationship between TCM and SIPE.

Kinematic Determinants of the Swimming Push Start in Competitive Swimmers

(1) Background: The aim of the present research is to describe the kinematic characteristics of push start in competitive swimmers and to examine the role of the push start sub-phases on the overall start performance. (2) Methods: Seventy-four swimmers (33 males and 41 females) of national and international level performed one 25 m trial at maximum velocity with a push start at butterfly, backstroke and/or front-crawl techniques and were filmed with two sequential underwater cameras during the glide, leg kicking, transition and surface swimming phases. (3) Results: Backstroke starts showed greater emersion distances but slower times to 10 m than the remaining strokes. Distances and average velocities in each of the start sub-phases predicted the overall push start performance (times to 10 m) on the butterfly (R2: 0.50) and backstroke (R2: 0.58) strokes, with the velocity of the leg kicking phase having a statistical effect on both regression analysis and the glide and transition phases in backstroke. (4) Conclusions: Push starts performed in a dorsal body position seemed to present kinematic differences with ventral techniques and a greater technical complexity with all glide, leg kicking and transition sub-phases meaningfully impacting the overall push start performance. This should be considered when executing the daily training repetitions with swimmers in water.

Monitoring weekly progress of front crawl swimmers using IMU-based performance evaluation goal metrics.

Technical evaluation of swimming performance is an essential factor in preparing elite swimmers for their competitions. Inertial measurement units (IMUs) have attracted much attention recently because they can provide coaches with a detailed analysis of swimmers’ performance during training. A coach can obtain a quantitative and objective evaluation from IMU. The purpose of this study was to validate the use of a new phase-based performance assessment with a single IMU worn on the sacrum during training sessions. Sixteen competitive swimmers performed five one-way front crawl trials at their maximum speed wearing an IMU on the sacrum. The coach recorded the lap time for each trial, as it remains the gold standard for swimmer’s performance in competition. The measurement was carried out once a week for 10 consecutive weeks to monitor the improvement in the swimmers’ performance. Meaningful progress was defined as a time decrease of at least 0.5 s over a 25 m lap. Using validated algorithms, we estimated five goal metrics from the IMU signals representing the swimmer’s performance in the swimming phases (wall push-off, glide, stroke preparation, free-swimming) and in the entire lap. The results showed that the goal metrics for free-swimming phase and the entire lap predicted the swimmer’s progress well (e.g., accuracy, precision, sensitivity, and specificity of 0.91, 0.89, 0.94, and 0.95 for the lap goal metric, respectively). As the goal metrics for initial phases (wall push-off, glide, stroke preparation) achieved high precision and specificity (≥0.79) in progress detection, the coach can use them for swimmers with satisfactory free-swimming phase performance and make further improvements in initial phases. Changes in the values of the goal metrics have been shown to be correlated with changes in lap time when there is meaningful progress. The results of this study show that goal metrics provided by the phase-based performance evaluation with a single IMU can help monitoring swimming progress. Average velocity of the lap can replace traditional lap time measurement, while phase-based goal metrics provide more information about the swimmer’s performance in each phase. This evaluation can help the coach quantitatively monitor the swimmer’s performance and train them more efficiently.

Kinematic factors determining differences in performance in the start phase of sprint swimming:

Kinematic factors determining differences in performance in the start phase of sprint swimming:

Swimming Phase-Based Performance Evaluation Using a Single IMU in Main Swimming Techniques.

Comprehensive monitoring of performance is essential for swimmers and swimming coaches to optimize the training. Regardless of the swimming technique, the swimmer passes various swimming phases from wall to wall, including a dive into the water or wall push-off, then glide and strokes preparation and finally, swimming up to the turn. The coach focuses on improving the performance of the swimmer in each of these phases. The purpose of this study was to assess the potential of using a sacrum-worn inertial measurement unit (IMU) for performance evaluation in each swimming phase (wall push-off, glide, stroke preparation and swimming) of elite swimmers in four main swimming techniques (i.e. front crawl, breaststroke, butterfly and backstroke). Nineteen swimmers were asked to wear a sacrum IMU and swim four one-way 25 m trials in each technique, attached to a tethered speedometer and filmed by cameras in the whole lap as reference systems. Based on the literature, several goal metrics were extracted from the instantaneous velocity (e.g. average velocity per stroke cycle) and displacement (e.g. time to reach 15 m from the wall) data from a tethered speedometer for the swimming phases, each one representing the goodness of swimmer’s performance. Following a novel approach, that starts from swimming bout detection and continues until detecting the swimming phases, the IMU kinematic variables in each swimming phase were extracted. The highly associated variables with the corresponding goal metrics were detected by LASSO (least absolute shrinkage and selection operator) variable selection and used for estimating the goal metrics with a linear regression model. The selected kinematic variables were relevant to the motion characteristics of each phase (e.g. selection of propulsion-related variables in wall push-off phase), providing more interpretability to the model. The estimation reached a determination coefficient (R2) value more than 0.75 and a relative RMSE less than 10% for most goal metrics in all swimming techniques. The results show that a single sacrum IMU can provide a wide range of performance-related swimming kinematic variables, useful for performance evaluation in four main swimming techniques.

Adaptive and Plastic Responses to Environmental Variation: Introduction to a Virtual Symposium in The Biological Bulletin.

Adaptive and Plastic Responses to Environmental Variation: Introduction to a Virtual Symposium in The Biological Bulletin.

A Novel Macro-Micro Approach for Swimming Analysis in Main Swimming Techniques Using IMU Sensors.

Inertial measurement units (IMU) are proven as efficient tools for swimming analysis by overcoming the limits of video-based systems application in aquatic environments. However, coaches still believe in the lack of a reliable and easy-to-use analysis system for swimming. To provide a broad view of swimmers' performance, this paper describes a new macro-micro analysis approach, comprehensive enough to cover a full training session, regardless of the swimming technique. Seventeen national level swimmers (5 females, 12 males, 19.6 ± 2.1 yrs) were equipped with six IMUs and asked to swim 4 × 50 m trials in each swimming technique (i.e., frontcrawl, breaststroke, butterfly, and backstroke) in a 25 m pool, in front of five 2-D cameras (four under water and one over water) for validation. The proposed approach detects swimming bouts, laps, and swimming technique in macro level and swimming phases in micro level on all sensor locations for comparison. Swimming phases are the phases swimmers pass from wall to wall (wall push-off, glide, strokes preparation, swimming, and turn) and micro analysis detects the beginning of each phase. For macro analysis, an overall accuracy range of 0.83–0.98, 0.80–1.00, and 0.83–0.99 were achieved, respectively, for swimming bouts detection, laps detection and swimming technique identification on selected sensor locations, the highest being achieved with sacrum. For micro analysis, we obtained the lowest error mean and standard deviation on sacrum for the beginning of wall-push off, glide and turn (−20 ± 89 ms, 4 ± 100 ms, 23 ± 97 ms, respectively), on shank for the beginning of strokes preparation (0 ± 88 ms) and on wrist for the beginning of swimming (−42 ± 72 ms). Comparing the swimming techniques, sacrum sensor achieves the smallest range of error mean and standard deviation during micro analysis. By using the same macro-micro approach across different swimming techniques, this study shows its efficiency to detect the main events and phases of a training session. Moreover, comparing the results of both macro and micro analyses, sacrum has achieved relatively higher amounts of accuracy and lower mean and standard deviation of error in all swimming techniques.

BLOCK SLOPE IS THE MAIN DETERMINANT OF BLOCK PHASE PERFORMANCE IN SWIMMING

ABSTRACT Introduction Swimming starts are an important component for decreasing the total race time, especially in short events. In this phase of swimming, the aim is to increase performance using many different techniques and starting platforms. Objectives The effects of height and slope of the starting block on kick-start performance were assessed in this study. Methods Six male competitive swimmers performed 24 kick-starts using four block settings: 65 cm & 75 cm flat and 65 cm & 75 cm sloped. Two-dimensional kinetic and three-dimensional kinematic data were analyzed, including average and maximum horizontal/vertical forces and impulses; reaction times; movement and block times; and take-off vertical/horizontal velocities. Two-way within-subject design ANOVAs were implemented to test the effects of block height and slope on the kinetic and kinematic variables. Results Block slope was the main factor affecting most of the dependent variables. Shorter block and movement times, greater average and maximum vertical forces, vertical impulse, and maximum horizontal force were found for the sloped settings. An inverse relationship was found between block height and 0-5 m times. Conclusion Based on the results, blocks with height of 75 cm and slope of 10° provided better results in swimmers’ performance in the block phase. Level of evidence II, Therapeutic Studies -Investigating the Results of Treatment

Swimming Stroke Phase Segmentation Based on Wearable Motion Capture Technique

Wearable motion capture technique is widely used in kinematic analysis, which contributes to understanding motion patterns and provides quantitative data on human postures. Swimming stroke phase plays an important role in spatial–temporal swimming parameters. As a sporting pattern that involves all limbs, the swimming phase is more complicated than gait phase and makes the swimming phase segmentation a new issue of pattern recognition. This article focuses on the swimming phase segmentation as pattern classification. By analyzing the human posture data given by motion capture system, swimming phase could be described qualitatively and used to obtain posture features. The swimming phase of the four competitive swimming styles is studied in this article and classified accurately. In the tenfold cross-validation, the mean values of accuracy, sensitivity, and specificity could reach 98.22%, 95.65%, and 98.67%, respectively, under the 2.5-ms timing tolerance. In terms of leave-one-subject-out cross-validation, performance metrics perform best under a relatively small timing tolerance. The results of the experiment show that the study could well-address the issue of swimming phase segmentation and provide spatial–temporal parameters for further swimming motion analysis.

Cue hierarchy in the foraging behaviour of the brackish cladoceran Daphniopsis australis

Zooplankton communities are an essential component of marine and freshwater food webs. However, there is still a relative lack of information on how these organisms behaviourally respond to a range of abiotic and biotic stressors. Specifically, the behaviour of the cladoceran Daphniopsis australis, a species endemic to South-eastern Australian saline lakes and ponds, is still unknown despite its potential role in the structure and function of inland water ecosystems. The swimming behaviour of males, parthenogenetic females and epiphial females was investigated under various conditions and combinations of food and conspecific cues. In the absence of cues, males displayed the most extensive swimming behaviour, exploring all areas of the container, and swimming in a series of relatively straight trajectories. In contrast, females typically exhibited a hop-and-sink motion characterised by the alternation between short bursts of swimming and sinking phases. Both females spent long periods near the bottom of the container, but epiphial females appeared to be more active than parthenogenetic ones that rarely made an excursion in the water column. In the presence of cues, males and females showed abilities to detect infochemicals from food and conspecifics, but exhibited specific behavioural strategies. Males essentially increased their swimming speed in the presence of food and/or conspecific infochemicals, and this increase was independent on the source of the cues, i.e. food, conspecific or a mixture of food and conspecifics. In contrast, females exhibited cue hierarchies that were related to their sexual status. Parthenogenetic females swam faster in the presence of food and a mixture of food and conspecific infochemicals than in the presence of cue from the opposite sex, which did not significantly differ from control observations conducted in the absence of cues. Epiphial females decreased their swimming speed in the presence of cues, with the most significant behavioural answers being driven by sex-related cues.

A polar bundle of flagella can drive bacterial swimming by pushing, pulling, or coiling around the cell body

Bacteria swim in sequences of straight runs that are interrupted by turning events. They drive their swimming locomotion with the help of rotating helical flagella. Depending on the number of flagella and their arrangement across the cell body, different run-and-turn patterns can be observed. Here, we present fluorescence microscopy recordings showing that cells of the soil bacterium Pseudomonas putida that are decorated with a polar tuft of helical flagella, can alternate between two distinct swimming patterns. On the one hand, they can undergo a classical push-pull-push cycle that is well known from monopolarly flagellated bacteria but has not been reported for species with a polar bundle of multiple flagella. Alternatively, upon leaving the pulling mode, they can enter a third slow swimming phase, where they propel themselves with their helical bundle wrapped around the cell body. A theoretical estimate based on a random-walk model shows that the spreading of a population of swimmers is strongly enhanced when cycling through a sequence of pushing, pulling, and wrapped flagellar configurations as compared to the simple push-pull-push pattern.

Age and serotonin effects on locomotion in marine trematode cercariae

The effect of serotonin solutions on the locomotor activity of cercariae with different swimming patterns, Cryptocotyle lingua and Himasthla elongate, was investigated during their lifespan using motion track analysis and a frame-by-frame count of behavioral elements. Serotonin caused a noticeable alteration of several locomotion parameters in both species studied, while the activity per se decreased significantly with age. In intermittently swimming C. lingua cercariae, serotonin induced an increase in the frequency of active swimming phases (spurts) without significant changes in the duration and velocity of the spurts themselves. In continuously swimming H. elongata cercariae, serotonin increased the number of stops during the first hour after the emission from the host mollusk under a constant average swimming velocity. Immunocytochemical visualization of serotonin revealed a decline in its level with age (time after emission) and different dynamics of this process in neurons located in the tail and body of C. lingua cercariae. The data are interpreted in the light of the modulatory role of serotonin known for other animals.

THE INCIDENCE OF EXERTIONAL HEAT STROKE DURING MASS-PARTICIPATION TRIATHLON RACES: OPTIMISING ATHLETE SAFETY

BackgroundExertional heat stroke (EHS) is a potentially life-threatening condition to the endurance athlete. Early recognition and rapid on-site treatment with aggressive cooling measures significantly reduces mortality, improves outcome and avoids...

Seabird diving behaviour reveals the functional significance of shelf-sea fronts as foraging hotspots.

Oceanic fronts are key habitats for a diverse range of marine predators, yet how they influence fine-scale foraging behaviour is poorly understood. Here, we investigated the dive behaviour of northern gannets Morus bassanus in relation to shelf-sea fronts. We GPS (global positioning system) tracked 53 breeding birds and examined the relationship between 1901 foraging dives (from time-depth recorders) and thermal fronts (identified via Earth Observation composite front mapping) in the Celtic Sea, Northeast Atlantic. We (i) used a habitat-use availability analysis to determine whether gannets preferentially dived at fronts, and (ii) compared dive characteristics in relation to fronts to investigate the functional significance of these oceanographic features. We found that relationships between gannet dive probabilities and fronts varied by frontal metric and sex. While both sexes were more likely to dive in the presence of seasonally persistent fronts, links to more ephemeral features were less clear. Here, males were positively correlated with distance to front and cross-front gradient strength, with the reverse for females. Both sexes performed two dive strategies: shallow V-shaped plunge dives with little or no active swim phase (92% of dives) and deeper U-shaped dives with an active pursuit phase of at least 3 s (8% of dives). When foraging around fronts, gannets were half as likely to engage in U-shaped dives compared with V-shaped dives, independent of sex. Moreover, V-shaped dive durations were significantly shortened around fronts. These behavioural responses support the assertion that fronts are important foraging habitats for marine predators, and suggest a possible mechanistic link between the two in terms of dive behaviour. This research also emphasizes the importance of cross-disciplinary research when attempting to understand marine ecosystems.

Deaths in triathletes: immersion pulmonary oedema as a possible cause.

Background/aimTo address the question as to whether immersion pulmonary oedema (IPO) may be a common cause of death in triathlons, markers of swimming-induced pulmonary oedema (SIPO) susceptibility were sought in triathletes' postmortem examinations.MethodsDeaths while training for or during triathlon events in the USA and Canada from October 2008 to November 2015 were identified, and postmortem reports requested. We assessed obvious causes of death; the prevalence of left ventricular hypertrophy (LVH); comparison with healthy triathletes.ResultsWe identified 58 deaths during the time period of the review, 42 (72.4%) of which occurred during a swim. Of these, 23 postmortem reports were obtained. Five individuals had significant (≥70%) coronary artery narrowing; one each had coronary stents; retroperitoneal haemorrhage; or aortic dissection. 9 of 20 (45%) with reported heart mass exceeded 95th centile values. LV free wall and septal thickness were reported in 14 and 9 cases, respectively; of these, 6 (42.9%) and 4 (44.4%) cases exceeded normal values. 6 of 15 individuals (40%) without an obvious cause of death had excessive heart mass. The proportion of individuals with LVH exceeded the prevalence in the general triathlete population.ConclusionsLVH—a marker of SIPO susceptibility—was present in a greater than the expected proportion of triathletes who died during the swim portion. We propose that IPO may be a significant aetiology of death during the swimming phase in triathletes. The importance of testing for LVH in triathletes as a predictor of adverse outcomes should be explored further.

Swimming patterns of the quadriflagellate Tetraflagellochloris mauritanica (Chlamydomonadales, Chlorophyceae).

Chlamydomonadales are elective subjects for the investigation of the problems related to locomotion and transport in biological fluid dynamics, whose resolution could enhance searching efficiency and assist in the avoidance of dangerous environments. In this paper, we elucidate the swimming behavior of Tetraflagellochloris mauritanica, a unicellular-multicellular alga belonging to the order Chlamydomonadales. This quadriflagellate alga has a complex swimming motion consisting of alternating swimming phases connected by in-place random reorientations and resting phases. It is capable of both forward and backward swimming, both being normal modes of swimming. The complex swimming behavior resembles the run-and-tumble motion of peritrichous bacteria, with in-place reorientation taking the place of tumbles. In the forward swimming, T.mauritanica shows a very efficient flagellar beat, with undulatory retrograde waves that run along the flagella to their tip. In the backward swimming, the flagella show a nonstereotypical synchronization mode, with a pattern that does not fit any of the modes present in the other Chlamydomonadales so far investigated.