Crawl Stroke Research Articles

Pacing Strategies in Elite Individual-Medley Swimmers: A Decision-Tree Approach.

This study aimed to examine pacing strategies and identify the stroke that has the most significant impact on overall performance in men's and women's 200-m and 400-m individual-medley events from 2000 to 2021. The time in each lap and overall race was retrieved from the World Aquatics website. The standardized time for each stroke in individual medley was calculated by dividing the actual time by a reference time specific to each stroke. The reference time was derived from the respective laps in single-stroke finals in the 2017 World Swimming Championships. The decision-tree method was used for analysis. The dependent variables were qualified or nonqualified in heats and semifinals, and winning medals in finals. The independent variables were the ratio of standardized time in each stroke to the sum of standardized time in all 4 strokes. Swimmers who spent a higher ratio of standardized time in the butterfly stroke(>0.236-0.245) are associated with a higher likelihood of winning medals or qualifying for the next stage in most men's and women's 200-m and 400-m individual medley. Butterfly exhibited the highest normalized importance that distinguished medalists from nonmedalists in the finals. The front-crawl stroke is the second most important determinant in medalists in men's and women's 200-m individual medley, whereas backstroke and breaststroke were the second most important in men's and women's 400-m individual medley, respectively. Individual-medley swimmers who were excellent in butterfly and conserved energy in butterfly had a higher likelihood of success.

Shoulder and Neck Pain in Swimmers: Front Crawl Stroke Analysis, Correlation with the Symptomatology in 61 Masters Athletes and Short Literature Review.

Background: Swimming and, specifically, front crawl, can be included among the "overhead" sports. Overhead sports are a risk factor for some problems of the musculoskeletal system, especially the shoulder. The aim of this study was to assess the incidence of shoulder and neck pain in a Masters Swimming Team and its correlation with the crawl stroke. Methods: This is an observational study through video-analysis of the stroke and a questionnaire. The participants selected for the present study were 61 athletes of a Masters team, whose prevailing training stroke was the front crawl. Their stroke was analyzed during training using a go-pro camera mounted on a sliding trolley on a track, evaluating their technical defects with their trainer. A questionnaire about frequency of shoulder and neck pain during the last five years was administered to all the participants at the study. Results: From the questionnaire, 45 and 55 out of 61 athletes had suffered from shoulder pain and cervical pain, respectively. Both types of pain were correlated with the weekly swimming volume. The swimmers with hyperflexion of the wrist and prolonged internal rotation in the pulling phase had shoulder problems. Those who suffered from current shoulder pain reduced the underwater time. The four swimmers with an excessive body roll during breathing and those who kept their heads extended, reported cervical pain. Conclusions: Shoulder and neck pain could be prevented with the correction of specific technical errors in crawl stroke.

Interaction of Kinematic, Kinetic, and Energetic Predictors of Young Swimmers' Speed.

The aim of this study was to assess the interaction of kinematic, kinetic, and energetic variables as speed predictors in adolescent swimmers in the front-crawl stroke. Ten boys (mean age [SD] = 16.4 [0.7]y) and 13 girls (mean age [SD] = 14.9 [0.9]y) were assessed. The swimming performance indicator was a 25-m sprint. A set of kinematic, kinetic (hydrodynamic and propulsion), and energetic variables was established as a key predictor of swimming performance. Multilevel software was used to model the maximum swimming speed. The final model identified time (estimate = -0.008, P = .044), stroke frequency (estimate = 0.718, P < .001), active drag coefficient (estimate = -0.330, P = .004), lactate concentration (estimate = 0.019, P < .001), and critical speed (estimate = -0.150, P = .035) as significant predictors. Therefore, the interaction of kinematic, hydrodynamic, and energetic variables seems to be the main predictor of speed in adolescent swimmers. Coaches and practitioners should be aware that improvements in isolated variables may not translate into faster swimming speed. A multilevel evaluation may be required for a more effective assessment of the prediction of swimming speed based on several key variables rather than a single analysis.

The Effect of an Educational Program by Using Assistive Devices on Improving the Performance Level of Crawl Stroke Swimming among Female Students of the Faculty of Physical Education

The study aimed to identify the effect of an educational program using assistive devices on improving the performance of crawl stroke swimming among female students of the Faculty of Physical Education. The researchers used the experimentl method by using the pre- and post- tests. The sample of the study consisted of 12 students who enrolled in Learning Swimming Course in the Faculty of Physical Education at Yarmouk University. The sample of the study was chosen in an intentional way, and the educational program consisted of (8) weeks with a rate of (3) units per week, with a period of (60) minutes. The study variables were measured through the speed test, the periodic respiratory endurance test, the test of the movements of the arms and the feet, and the performance of swimming 25 meters crawling stroke. In the statistical treatment, the researcher used the arithmetic means, standard deviations, and the t-test for the related samples. . The results showed that there were statistically significant differences at the level of significance (α ≤ 0.05) between the pre-and post-measurements of the experimental group members in the tests: speed test, periodic respiratory endurance test, arm and foot movements test, and 25m swimming performance crawling stroke, among the sample of the study and in favor of post test.&#x0D;

Kinetics and tethered strength influence the 200-m front crawl stroke kinematics and speed in young male swimmers.

Background: The aim of this research was to examine the relationship between the fast component of oxygen consumption developed in 1-min and force indices both measured in tethered swimming test and to assess the influence of the gathered indices on speed and swimming kinematics in 200-m front crawl race. Methods: Forty-eight male swimmers (aged 13.5 ± 0.9years old) participated in this study. Testing included 1) 1-min all-out front crawl tethered swimming while oxygen consumption (breath by breath) and tethered forces were measured, 2) 200-m front crawl race-like swimming featuring kinematic analysis, and 3) biological age (BA) examination. Results: During the 1-min all-out tethered swimming test, a linear increase in oxygen consumption was observed. There were moderate to high partial correlations between particular periods of seconds in the 1-min : 31-60, 41-60, and 51-60 and F max, F ave , and I ave of tethered swimming, while 41-60 and 51-60 were moderately to highly interrelated with all the swimming speed indices and SI. The swimming speed indices significantly interplayed with SL, SI, F max, F ave , and I ave . Partial correlations were computed with BA control. Conclusion: The ability of reaching a high level of fast is essential for a swimmer's energy production at short- and middle-distance events. Reaching a high level of significantly determines tethered strength and swimming kinematics. The level of influences the maintenance of a proper pulling force and the stroke technique of front crawl swimming in young male swimmers.

Manipulation of Stroke Rate in Swimming: Effects on Oxygen Uptake Kinetics.

The study aimed to assess the effect of different front crawl stroke rates (SRs) in the oxygen uptake (̇VO2) kinetics and ̇VO2 peak, the total time to exhaustion (TTE), and blood lactate concentration ([La]) at 95% of the 400-m front crawl test (T400) mean speed (S400). Twelve endurance swimmers performed a T400 and four trials at 95% of the S400: (i) free SR, (ii) fixed SR (100% of the average free SR trial), (iii) reduced SR (90% of the average free SR trial), and (iv) increased SR (110% of the average free SR trial). ̇VO2 was accessed continuously with breath-by-breath analysis. The results highlighted: (i) the time constant at increased SR (13.3±4.2 s) was lower than in the reduced SR condition (19.5±2.6 s); (ii) the amplitude of the primary phase of ̇VO2 kinetics in the fixed SR (44.0±5.8 ml·kg-1·min-1) was higher than in the increased SR condition (39.5±6.4 ml·kg-1·min-1); and (iii) TTE was lower in the fixed SR (396.1±189.7 s) than the increased SR condition (743.0±340.0 s). The results indicate that controlled SR could be considered a swimming training strategy, focusing on physiological parameters overload.

Comparison and Agreement between Simplified and Three-dimensional Methods for Estimating the Front Crawl Stroke Arm Stroke Efficiency

Aims: To compare and verify the agreement of the arm stroke efficiency (ȠF) results obtained by simplified (ȠFS) and three-dimensional (ȠF 3D) methods. Background: Arm stroke efficiency (ȠF) estimates how much of the force applied by the swimmers’ upper limbs contribute to their propulsion. To estimate ȠF, in front crawl stroke, three-dimensional (ȠF3D) and simplified (ȠFS) methods are highlighted. Objective: To verify if different methods estimate similar arm stroke efficiency values. Methods: Ten male swimmers (age: 21.5 ± 2.6 years; height: 1.78 ± 0.05 m; competitive swimming experience: 12.2 ± 5.0 years) were tested in three 25 m front crawl stroke bouts at low, moderate, and high intensities. The ȠF data were obtained after collecting swimming images with six synchronized cameras and later analyzed in motion reconstruction software. Results: The mean results of ȠF, respectively for ȠF3D and ȠFS, were: 34.7±2.1% and 47.4±6.4% at a low; 34.8±2.7% and 42.3±3.3% in moderate; and 33.1±2.6% and 32.4±2.9% at high intensity. Along the intensities, ȠF remained similar with ȠF3D and reduced with ȠFS. ȠF was lower with ȠF3D than with ȠFS at low and moderate intensities (p &lt; 0.05) and similar at maximum intensity (p &gt; 0.05). Conclusion: At maximum intensity, the ȠF values agree between the methods. The results obtained by both methods were not fully similar. ȠF3D and ȠFS results agree just at high intensity. The differences between the methods may be due to the different variables used to measure ȠF, stroke rate in the ȠFS and three-dimensional hand velocity in the ȠF3D.

Young Swimmers' Classification Based on Performance and Biomechanical Determinants: Determining Similarities Through Cluster Analysis.

The aim of this study was to classify and identify young swimmers' performance, and biomechanical determinant factors, and understand if both sexes can be clustered together. Thirty-eight swimmers of national level (22 boys: 15.92 ± 0.75 years and 16 girls: 14.99 ± 1.06 years) were assessed. Performance (swim speed at front crawl stroke) and a set of kinematic, efficiency, kinetic, and hydrodynamic variables were measured. Variables related to kinetics and efficiency (p < .001) were the ones that better discriminated the clusters. All three clusters included girls. Based on the interaction of these determinant factors, there are girls who can train together with boys. These findings indicate that not understanding the importance of the interplay between such determinants may lead to performance suppression in girls.

Wearables in Swimming for Real-Time Feedback: A Systematic Review.

Nowadays, wearables are a must-have tool for athletes and coaches. Wearables can provide real-time feedback to athletes on their athletic performance and other training details as training load, for example. The aim of this study was to systematically review studies that assessed the accuracy of wearables providing real-time feedback in swimming. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were selected to identify relevant studies. After screening, 283 articles were analyzed and 18 related to the assessment of the accuracy of wearables providing real-time feedback in swimming were retained for qualitative synthesis. The quality index was 12.44 ± 2.71 in a range from 0 (lowest quality) to 16 (highest quality). Most articles assessed in-house built (n = 15; 83.3%) wearables in front-crawl stroke (n = 8; 44.4%), eleven articles (61.1%) analyzed the accuracy of measuring swimming kinematics, eight (44.4%) were placed on the lower back, and seven were placed on the head (38.9%). A limited number of studies analyzed wearables that are commercially available (n = 3, 16.7%). Eleven articles (61.1%) reported on the accuracy, measurement error, or consistency. From those eleven, nine (81.8%) noted that wearables are accurate.

Three-dimensional front crawl arm-stroke efficiency and hand displacement in male and female swimmers

ABSTRACT This study aimed (i) to verify if underwater horizontal, vertical and medio-lateral hand displacements (HD), in pull and push phases of the front crawl stroke, can be associated with arm-stroke efficiency (ƞp) and (ii) to compare np and selected kinematic variables between male and female swimmers. Ten male and 10 female swimmers performed an all-out front crawl 25-m test. Data were obtained with six synchronised video cameras (60 Hz) and analysed with a three-dimensional method. Results for males and females were respectively, as follows: (i) horizontal HD: 0.55 ± 0.06 m and 0.61 ± 0.09 m (p = 0.062; d = 0.78); vertical HD: 0.68 ± 0.06 m and 0.58 ± 0.07 m (p < 0.001; d = 1.53); and medio-lateral HD: 0.22 ± 0.07 m and 0.16 ± 0.03 m (p = 0.012; d = 1.11); (ii) ƞp: 0.33 ± 0.02 and 0.32 ± 0.03 (p = 0.48; d = 0.39); (iii) vCOM: 1.77 ± 0.06 m∙s−1 and 1.55 ± 0.10 m∙s−1 (p < 0.001; d = 2.42). Multiple linear regression (p = 0.019) indicated that horizontal and medio-lateral HD were able to predict np. The lower the horizontal hand displacement, the higher the ƞp.

Hard Mouth by Amanda Goldblatt

Reviewed by: Hard Mouth by Amanda Goldblatt CM Sears (bio) hard mouth Amanda Goldblatt Counterpoint Press https://www.counterpointpress.com/dd-product/hard-mouth/ 256 pages; Cloth, $25.00 Amanda Goldblatt's first book of fiction Hard Mouth is a fascinating tale of a young protagonist's search for meaning, hope, and consolation as she copes with her father's long-term battles with cancer and his slow decline. The novel is starkly original. Goldblatt portrays the internal conflict of Denny, a woman set against herself, with quick wit, bracing energy, and ironic humor. Unable to cope with her father's mortality and recurrent battles with cancer, Denny devises a prolonged and risky immersion in the wild. [End Page 66] Denny's character is a typical typical twenty-something woman facing her own struggles and inadequacies as a daughter, woman, and scientist, but there are marked examples of how Denny is a tougher character than most. She is an especially refreshing female character set in her decisions, fiercely independent and driven to create meaning and authenticity. Denny is not easily swayed: by affection, loyalty, or even by duty. An only child, she could easily slip into a care-giving role, as adult children in small families often do. Instead, Denny finds solace in isolation, abnegation, and almost self-sacrificing atonement. The protagonist of Goldblatt's blazing novel is the human epitome of a hard-mouthed hound. With dogged persistence, the heroine digs herself into her own pit of alienation, cutting herself off from her job, sabotaging her research position. She impulsively releases the specimens—a move that results in her termination. Goldblatt's terse and witty writing style shines especially in character development and dialogue. Take the blunt manner in which the character is introduced in the first few pages: All around me there were stripped fringes of grass. I had made a bald clearing of dirt on the lawn. I was already in trouble and so went on making my harvest. It pleased me. There is, I'd learn, some freedom in the compounding of bad behavior. The bold absence of social niceties and people-pleasing is astonishing. In the above passage, Goldblatt's introduction of Denny as a hard-headed child sets the character on a particularly rocky path. Denny's experiences in school are truncated by the heavy burden of witnessing her father's battle with cancer. Denny begins by escaping her situation with indulgent drinking and meaningless sex. The story slows as gradually the veneer of the character is cracked open. We gain more perspective as the family backstory is revealed. While Denny was a college student, the two enjoyed practicing a quiet morning routine of swimming thirty laps together. Beginning "on the green-tile pool deck, where it smells like chlorine with a secret of mildew" they absorb into the natatorium's reflective surfaces: "tall windows along the length of the water shower wet grass, or melting snow, or blotting sun." Practicing a rhythmic if "messy" crawl stroke—in parallel lanes—normalized the disruption of serious illness. But the comfort and order of the swimming ritual is cut short. [End Page 67] Between my graduation and the mountain, our swimming outings ceased. First I stopped, saying I was too busy, though I was not. Then Pop stopped, sick; started again, then stopped, sick again. In this ignorant, organic way we began to abandon one another. On Denny's first full day in the woods, she considers her options. "Here in the wild I had every option of movement and space, a self-serving roamer's delight. Once the sun was high and I could see it like an opponent, I rose from the dock and slipped into the water." This recreational swim in the lake allows for flashbacks about the best times between father and daughter. Cancer is a loaded word, and a hefty diagnosis. Oftentimes, as is the case with chronic illness, the patient and the supporting team, family and friends, are in for a shock, as medical staff and technology run chess-like strategies with symptom management and interventions. As an adult coping with the last round of her father's illness, prior...

Effect of Photobiomodulation on Critical Swimming Velocity: A Randomized, Crossover, Double-Blind, and Placebo-Controlled Study.

To analyze the acute effect of photobiomodulation (PBM) on swimming critical velocity (CV). A total of 15 male federated swimmers (20.9 [2.4]y old) participated in this study. Three sets of front crawl were performed at distances of 100, 200, and 400m to determine the CV under 3 experimental conditions: PBM (420J), placebo (PLA), and control (C) in this randomized, crossover, double-blind, and placebo-controlled study. One-way analysis of variance for repeated measurements was used for statistical analyses. The results showed that the prior application of PBM did not have ergogenic effects on CV and front crawl swimming performance: CV (PBM = 1.15 [0.15]; PLA = 1.20 [0.25]; C = 1.15 [0.14]m·s-1), swim time (ST) 100m (PBM = 65.5 [6.3]; PLA = 65.2 [5.6]; C = 66.0 [5.9]s), ST 200m (PBM = 148.5 [17.9]; PLA = 149.4 [16.4]; C = 150.1 [17.9]s), and ST 400m (PBM = 327.7 [38.2]; PLA = 321.6 [47.7]; C = 329.5 [41.2]s). A PBM application prior to front crawl swimming test did not significantly modify the CV, ST, physiological factors of metabolic fatigue, perceptual, and front crawl stroke efficiency parameters in competition swimmers covering distances of 100, 200, and 400m.

Predicting the individual lactate minimum speed by T10 and T30 in swimming.

This study investigated the relationship between the lactate minimum (LAC<inf>min</inf>) and the 10- (T10) and 30-min (T30) continuous tests in swimmers. Twelve swimmers (78.1±3.1% of the world record) performed the LAC<inf>min</inf> (hyperlactatemia: 2×50 m all-out 8-min apart, incremental part: N.×300 m 30-s apart), T30 and T10 using the front-crawl stroke. Blood samples were collected after each stage of LAC<inf>min</inf> for lactate analysis. Swimmers were oriented to swim as fast and as constant as possible in T10 and T30. Speeds in T10 (1.28±0.10 m/s) and T30 (1.21±0.09 m/s) were different from LAC<inf>min</inf> (1.24±0.09 m/s). T10 and T30 speeds presented a nearly perfect relationship with LAC<inf>min</inf> and acceptable prediction errors (T10: r=0.938, P<0.001, 0.033 m/s; T30: r=0.927, P<0.001, 0.036 m/s, respectively). T10 and T30 can be used as indirect tests for evaluating LAC<inf>min</inf> in swimming.

Front crawl stroke in swimming: Phase durations and self-similarity

Human movements, such as walking and running, are able to generate rhythmic motor patterns, with the consequent appearance of hidden time-harmonic structures. Such harmonic structures are represented (at comfortable speed) by the occurrence of the golden ratio as ratio of durations of specific walking and running gait sub-phases. Preliminary experimental evidences suggest that front crawl swimming may behave, under this point of view, like walking and running. This paper aims to demonstrate that a mathematical connection between the golden ratio and the front crawl swimming stroke actually exists, at a pace that plays the role of the comfortable speed in walking and running. Generalized Fibonacci sequences are used to this purpose. They rely on the durations of aggregate phases of the front crawl swimming stroke with a clear physical meaning, while characterizing self-similarity of front crawl strokes in its simple nature and enhanced (stronger) variant. Experimental data on front crawl swimmers illustrate the theoretical derivations, suggesting that the pace playing the role of the comfortable speed in walking and running is the middle/long-distance one, while showing that the self-similarity level increases with the swimming technique and the enhanced self-similarity is associated with the performance of top-level swimmers.

Crawl technique observation sheet for beginning swimmers: an evaluation proposal for swimming teachers

Abstract Aims: This study aimed to present a technical evaluation proposal for the crawl stroke that can be used with large groups of swimmers, based on an observation sheet. Methods: Fifteen healthy university students aged between 18 and 30 years were chosen to participate in the study. The subjects were recorded swimming at a distance of 50 meters using the crawl technique at a comfortable and self-determined speed. The recordings simulated docent observation capacity. Five swimming teachers were selected to evaluate the proposed checklist and the subjects’ technique. An observation sheet was created based on references present in literature containing ten items that are considered fundamental for swimming movements. The study was divided into (i) checklist validation, (ii) intra-evaluator consistency, and (iii) inter-evaluator consistency. Results: The proposed checklist fulfilled the validity criteria, with intra-evaluator consistency varying between reasonable and substantial, with k varying between 0.36 and 0.73 respectively, while inter-evaluator consistency was deemed reasonable (k = 0.24). Conclusion: According to the results that were obtained, the suggested list is valid and adequate for what it proposes to do.

THE RELATIONSHIP BETWEEN ARM MUSCLE STRENGTH AND LEG MUSCLE STRENGTH TOWARDS 50-METER FREESTYLE SWIMMING SPEED

This study aims to determine the relationship between arm muscle strength and leg muscle strength towards 50-meter freestyle swimming speed of Physical Education Students Major, at FKIP Unpatti Ambon. Based on the results of the analysis of leg muscle strength variables with a swimming speed of 50 meters crawl stroke of male students in Health and Sport Study Program of FKIP Unpatti Ambon Fcount = 3,61 &gt; Ftable (dk = 28 and α = 0,05) = 1,70 at the level α = 0.05 and means the null hypothesis (H0) is rejected. Based on the analysis of the variable arm muscle strength with a swimming speed of 50 meters crawl stroke of male students in Health and Sport Study Program of FKIP Unpatti Ambon, the results obtained Fcount = 3,47 &gt; Ftable (dk = 28 and α = 0,05) = 1.70 at the level α = 0,05 and means the null hypothesis (H0) is rejected. Based on the analysis of the relationship between leg muscle strength, arm muscle strength, and swimming speed 50 meters crawl stroke of male students in Health and Sport Study Program of FKIP Unpatti Ambon, the result obtained Fcount = 14,99 &gt; Ftable (dk = 28 and α = 0,05) = 1,70 at the level α = 0,05 and means the null hypothesis (H0) is rejected. Thus, the stronger the leg muscles and arm muscles, the better the crawl stroke speed of students of the Health and Sport Study Program of FKIP Unpatti Ambon

거울을 활용한 미러링 코칭이 자유형 스트로킹 변화에 미치는 영향

본 연구는 자유형 스트로크를 교정하기 위해 수영장 바닥 거울을 사용한 코칭이 효과적인지 분석하는데 목적이 있다, 1년 이상 수영 강습을 받은 성인 30명을 무작위로 Mirror group(MG)과 No mirror group(NMG)으로 나누어 실시하였다. MG(men=12, 32.25±8.2 yrs, 175±5.5 ㎝, 70.9±9.2 ㎏; women=3, 37.6±13.7 yrs, 160.0±3.4 ㎝, 55.6±3.5 ㎏), NMG(men=7, 28.7±6.1 yrs, 176.2±3.7 ㎝, 72.4±14.4 ㎏; women=8, 38.8±14.6 yrs, 162.1±4.4 ㎝, 54.1±7.3 ㎏)은 2.43 m x 4.57 m x 1.37 m 크기의 인공 수조에서 자유형 1분을 실시하였다. 거울제공 여부와 시간의 상호작용이 스트로크 기준점과의 차이에 미치는 효과는 1차 검사에서 NMG: 6.0±3.982 ㎝, MG: 7.67±3.266 ㎝로 집단 간 차이가 1.67 ㎝인 반면, 2차 검사결과 NMG: 5.07±3.788 ㎝, MG: 2.47±3.502 ㎝ 로 집단 간 차이가 2.6 cm 로 나타나 통계적으로 유의하였다(F=20.627, p<.001). 거울 제공 여부와 시간에 따른 스트로크 빈도에 대한 분산분석 결과, 피드백 종류와 1차, 2차 검사의 상호작용이 스트로크 빈도에 미치는 효과는 1차 결과 NMG: 57.67±6.821 score, MG: 60.73±7.294 score에서 2차 결과 NMG: 56.33±6.586 score, MG: 53.67±5.447 score로 통계적으로 유의한 차이가 있는 것으로 나타났다(F=24.807, p<.001). 거울 제공 여부와 사전사후 검사 따른 스트로크 시간에 대한 분산분석을 실시한 결과, 피드백 종류와 1차, 2차 검사의 상호작용이 스트로크 시간에 미치는 효과는 1차 NMG: 2.04±.208 sec, MG: 2.05±.250sec에서 2차 NMG: 2.15±.287 sec, MG: 2.39±.307 sec로 통계적으로 유의한 차이가 나타났다(F=10.813, p<.01).

Use Of Pool Bottom Mirror In Coaching Front Crawl Stroke Correction

Use Of Pool Bottom Mirror In Coaching Front Crawl Stroke Correction

Symmetry in the front crawl stroke of different skill level of able-bodied and disabled swimmers.

Although swimming is recognized as a symmetrical sport, equivalence between each body side cannot be insured. Swimmers with physical and motor impairment may present asymmetries that are even more pronounced. Therefore, the objective of this study was to assess the symmetry of temporal coordination in the front crawl stroke phases and their dimensional characteristics among swimmers of different levels of skill and disabled swimmers. Forty-one swimmers (28 men and 13 women, 18,8 ± 3,3 years, divided 21 of them into groups of high and low level of skill and 20 in disabled swimmers group) performed a 50m maximum of front-crawl test while they were recorded by six synchronized cameras (four underwater and two above water) for analysis of the stroke phases, stroke dimensions (anteroposterior, mediolateral and vertical amplitude), index of coordination and hand speed. The symmetry index was calculated by the difference between the right and the left strokes. Comparisons were made using the Kruskal-Wallis test and multivariate comparisons were made using the Mann-Whitney test, with p <0.05. Asymmetry was noted in anteroposterior and mediolateral amplitudes of the stroke, index of coordination, duration of the recovery phase, each of the underwater phases and in the hand speed during the downseep phase, regardless of the level of skill or impairment. The disabled swimmers also showed asymmetry in the vertical amplitude of the stroke as well as in the insweep and upsweep speed. The reasons for these asymmetries may be the preference for unilateral breathing, force imbalance between pairs of homologous muscles and motor control deficit. The training with stereotypic movements may explain the similarity of asymmetries among the different groups of swimmers.

Improvement of rolling performance in crawl stroke for the swimming humanoid robot

Improvement of rolling performance in crawl stroke for the swimming humanoid robot