Crawl Swimming Research Articles

An adaptive integral terminal sliding mode controller to track the human upper limb during front crawl swimming

ABSTRACT Injuries are inevitable during swimming. The main goal of athletes especially competitive ones and coaches is to do the most mechanically effective movement patterns. In this case, biomechanical assessments could be beneficial in the management and prevention of injuries and pain in swimmers’ vulnerable joints. As the upper limb in swimming causes the highest propulsive force, the arm is exposed to more injuries. A skeletal model with 5 degrees of freedom is developed to simulate the swimmer’s arm during front crawl swimming. This model includes shoulder and elbow joints with all of their degrees of freedom. An adaptive integral sliding mode (AITSM) controller is employed to track the desired joint trajectories during swimming. This controller can converge the tracking errors to zero in finite time. For tuning the controller gains regardless of the upper bounds of the system uncertainties, an adaptive controller is applied. The results demonstrate the performance of the AITSM strategy in tracking the desired trajectory of an underwater arm model during swimming. During the down sweep to catch phase, arm movements cause more stress in the shoulder than the elbow. The applied moment at the shoulder is almost triple of the elbow’s moment. Therefore, the most vulnerable joint is the shoulder. By considering shoulder strength, the injury risk is predicted about 10% for the considered swimmer. Highlights The human upper limb during front crawl swimming is simulated. A 5-DOF skeletal model is considered to simulate the arm. An adaptive integral sliding mode (AITSM) controller is employed to track the desired trajectory. The results show that the controller has the proper performance to track the desired motion. The most vulnerable joint is the shoulder and higher moments are induced at this joint.

Understanding the Role of Propulsion in the Prediction of Front-Crawl Swimming Velocity and in the Relationship Between Stroke Frequency and Stroke Length.

Introduction: This study aimed to: 1) determine swimming velocity based on a set of anthropometric, kinematic, and kinetic variables, and; 2) understand the stroke frequency (SF)–stroke length (SL) combinations associated with swimming velocity and propulsion in young sprint swimmers. Methods: 38 swimmers (22 males: 15.92 ± 0.75 years; 16 females: 14.99 ± 1.06 years) participated and underwent anthropometric, kinematic, and kinetic variables assessment. Exploratory associations between SL and SF on swimming velocity were explored using two two-way ANOVA (independent for males and females). Swimming velocity was determined using multilevel modeling. Results: The prediction of swimming velocity revealed a significant sex effect. Height, underwater stroke time, and mean propulsion of the dominant limb were predictors of swimming velocity. For both sexes, swimming velocity suggested that SL presented a significant variation (males: F = 8.20, p < 0.001, η2 = 0.40; females: F = 18.23, p < 0.001, η2 = 0.39), as well as SF (males: F = 38.20, p < 0.001, η2 = 0.47; females: F = 83.04, p < 0.001, η2 = 0.51). The interaction between SL and SF was significant for females (F = 8.00, p = 0.001, η2 = 0.05), but not for males (F = 1.60, p = 0.172, η2 = 0.04). The optimal SF–SL combination suggested a SF of 0.80 Hz and a SL of 2.20 m (swimming velocity: 1.75 m s−1), and a SF of 0.80 Hz and a SL of 1.90 m (swimming velocity: 1.56 m s−1) for males and females, respectively. The propulsion in both sexes showed the same trend in SL, but not in SF (i.e., non-significant variation). Also, a non-significant interaction between SL and SF was observed (males: F = 0.77, p = 0.601, η2 = 0.05; females: F = 1.48, p = 0.242, η2 = 0.05). Conclusion: Swimming velocity was predicted by an interaction of anthropometrics, kinematics, and kinetics. Faster velocities in young sprinters of both sexes were achieved by an optimal combination of SF–SL. The same trend was shown by the propulsion data. The highest propulsion was not necessarily associated with higher velocity achievement.

The effect of differential and traditional training methods on electromyographic changes of lower body muscles in performing and learning crawl swimming

هدف: ایجاد تغییر و نوسان در اجزای تمرینی نسبت به تمرین تکراری می‌تواند براساس اصول خودسازماندهی دستگاه، به یادگیری حرکتی بیشتر بیانجامد. هدف از پژوهش حاضر بررسی تأثیر روش­های تمرین افتراقی و سنتی بر تغییرات الکترومایوگرافی عضلات پایین تنه در اجرا و یادگیری شنای کرال سینه بود.روش­ها: در این پژوهش 36 شناگر 20 تا 25 سال که هیچ‌گونه سابقه آموزش شنا نداشتند؛ به عنوان نمونه انتخاب و به صورت تصادفی ساده به سه گروه کنترل، تمرینات سنتی و تمرینات افتراقی تقسیم شدند. آزمودنی‌های گروه‌های تجربی طی 12 جلسه به یادگیری شنای کرال سینه به دو شیوه سنتی و افتراقی پرداختند. قبل و بعد از 12 جلسه تمرین، میزان فعالیت عضلات بر اساس شاخص مجذور میانگین ریشه و میانگین زمان فعالیت عضلات راست رانی، ساقی قدامی و دوقلوی داخلی شناگران با استفاده از سیگنال الکترومایوگرافی اندازه گیری شد.نتایج: براساس نتایج حاصل از آزمون بن فرونی، در پس آزمون، میانگین RMS فعالیت عضله راست رانی، دو سر رانی (001/0=P)، ساقی قدامی (04/0=P) و دوقلوی (005/0=P) شناگران گروه افتراقی به طور معناداری از گروه کنترل بیشتر بود. این تفاوت میان گروه تمرین افتراقی و سنتی نیز معنا‌دار بود (05/0≥P). اما تفاوت معناداری میان گروه کنترل و تمرین سنتی وجود نداشت (05/0<P). در پس آزمون فقط میانگین زمان فعالیت عضله راست رانی گروه تمرین افتراقی بیشتر از گروه سنتی بود (046/0=P). میانگین زمان فعالیت عضله ساقی قدامی در شرایط پس آزمون در هر دو گروه تمرینی بیشتر از گروه کنترل بود (05/0>P) اما میان گروه تمرین افتراقی و سنتی تفاوت معنا داری وجود ندارد (05/0<P). میانگین زمان فعالیت عضله دوقلو گروه تمرینات افتراقی (001/0=P) و تمرین سنتی (041/0=P) به‌طور معنا‌دار بیشتر از گروه کنترل بود، اما این تفاوت میان گروه تمرین افتراقی و تمرین سنتی معنادار نبود (05/0<P). همچنین میانگین زمان فعالیت عضله دو سر رانی در شرایط پس آزمون در گروه تمرین افتراقی بیشتر از گروه کنترل بود (001/0=P)، ولی تفاوتی میان گروه افتراقی و سنتی و همچنین گروه سنتی و کنترل وجود نداشت (05/0<P). نتیجه ­گیری : نتایج پژوهش حاضر حاکی از اثر گذاری بیشتر تمرینات افتراقی در یادگیری شنای کرال سینه نسبت به تمرینات سنتی است.

Listening to Fast-Tempo Music Improves Physical Performance in Recreational Swimmers

ABSTRACT Purpose: To determine whether swimming while listening to fast (140 bpm) or moderate tempo (120 bpm) music enhances physical performance compared to a non-music condition.Methods: Sixteen healthy university students (21.5 ± 2.3 years) with a minimum of one year of experience swimming front crawl were recruited. All completed four testing sessions. In the first session, a graded exercise treadmill test was performed to establish baseline fitness. The next three visits were at the swimming pool and participants were asked to swim as far as possible in 12-minutes (i.e., Swimming Cooper Test) under each of three randomly assigned conditions: 120 bpm (M120), 140 bpm (M140) and a non-music condition (NM).Results: No significant differences were found between conditions for either heart rate (p > .05) or rating of perceived exertion (p > .05). However, differences were found on distance covered (p = .014) between M120 (305.7 ± 19.7 m) and M140 (321.2 ± 19.4 m; p = .035), and on stroke frequency (p = .009) between M120 (48.4 ± 1.8) and M140 (51.6 ± 1.9; p = .028).Conclusion: These results suggest that distance covered and the frequency of strokes per minute were greater when participants were exposed to fast tempo music (M140) compared to moderate tempo music (M120) and a non-music condition (NM) in a 12-minute swimming test.

Correlations between Crawl Kinematics and Speed with Morphologic, Functional, and Anaerobic Parameters in Competitive Swimmers.

The purpose of this study was to examine the relationship between a unique complex of predictors and 100 m front crawl race kinematics and swimming speed. In 28 male competitive swimmers (age: 19.6 ± 2.59 years), the following groups of predictors were assessed: (a) the morphologic, (b) the functional upper limb range of motion, and (c) the anaerobic indices of arm-cranking and a series of countermovement jumps. The Pearson product-moment correlation coefficient was calculated to distinguish the predictors and the swimming results. The main finding was that the indices of the power (arm-cranking) and the work (countermovement jump) generated in the anaerobic tests showed a significant and higher correlation with stroke length and stroke index than total body length, upper limb range of motion, or hand and forearm surface area. These results were obtained in accordance with the high swimming economy index relation to clear surface swimming speed. This study reveals that the strength generated by the limbs may represent a predictor of swimming kinematics in a 100 m front crawl performance.

The Effect of Breathing Laterality on Hip Roll Kinematics in Submaximal Front Crawl Swimming.

The purpose of this study was to determine the effect of breathing laterality on hip roll kinematics in submaximal front crawl swimming. Eighteen elite competitive swimmers performed three 100 m front crawl trials at a consistent sub-maximal speed (70% of seasonal best time) in a 25 m pool. Each trial was performed with one of three different breathing conditions: (1) unilateral breathing (preferred side), (2) bilateral breathing (alternating left/right-side every 3 strokes) and (3) simulated non-breathing using a swim snorkel. A waist-mounted triaxial accelerometer was used to determine continuous hip roll angle throughout the trial, from which peak hip roll angles (Ө) and average angular velocities (ω) were calculated. Two-way repeated measures ANOVAs were used to identify significant main effects for laterality (preferred vs. non-preferred breathing sides) and condition (unilateral, bilateral and snorkel breathing) for both Ө and ω. Peak hip roll to the preferred side was significantly greater (p < 0.001) in the unilateral condition, while ω to the non-preferred side was significantly greater in the unilateral (p < 0.01) and bilateral (p < 0.04) conditions. Significant same-side differences were also found between the different breathing conditions. The results demonstrate that breathing laterality affects hip roll kinematics at submaximal speeds, and that unilateral and snorkel breathing are associated with the least and most symmetric hip roll kinematics, respectively. The findings show that a snorkel effectively balances and controls bilateral hip rotation at submaximal speeds that are consistent with training, which may help to minimize and/or correct roll asymmetries that are the result of unilateral breathing.

Sprint Performance in Arms-Only Front Crawl Swimming Is Strongly Associated With the Power-To-Drag Ratio.

To date, optimal propulsion in swimming has been studied predominantly using physical or computational models of the arm and seldom during real-life swimming. In the present study we examined the contributions of selected power, technique and anthropometric measures on sprint performance during arms-only front crawl swimming. To this end, 25 male adult competitive swimmers, equipped with markers on their arms and hands, performed four 25-m sprint trials, which were recorded on video. For the fastest trial of each swimmer, we determined the average swim speed as well as two technique variables: the average stroke width and average horizontal acceleration. Each participant also swam 10–12 trials over a custom-made system for measuring active drag, the MAD system. Since the propelling efficiency is 100% while swimming over the MAD system, the power output of the swimmer is fully used to overcome the drag acting on the body. The resulting speed thus represents the ratio between power output and drag. We included this power-to-drag ratio, the power output and the drag coefficient of the fastest trial on the MAD system in the analysis. Finally, the body height and hand surface area of each swimmer were determined as anthropometric variables. A model selection procedure was conducted to predict the swim speed from the two technique variables, three power variables and the two anthropometric variables. The ratio between power output and the drag was the only significant predictor of the maximal swimming speed (v = 0.86·power/drag). The variations in this ratio explained 65% of the variance in swimming performance. This indicates that sprint performance in arms-only front crawl swimming is strongly associated with the power-to-drag ratio and not with the isolated power variables and the anthropometric and technique variables selected in the present study.

Acute and Long-Term Effects of Concurrent Resistance and Swimming Training on Swimming Performance.

Dry-land resistance exercise (RT) is routinely applied concurrent to swimming (SWIM) training sessions in a year-round training plan. To date, the impact of the acute effect of RT on SWIM or SWIM on RT performance and the long-term RT-SWIM or SWIM-RT training outcome has received limited attention. The existing studies indicate that acute RT or SWIM training may temporarily decrease subsequent muscle function. Concurrent application of RT-SWIM or SWIM-RT may induce similar physiological alterations. Such alterations are dependent on the recovery duration between sessions. Considering the long-term effects of RT-SWIM, the limited existing data present improvements in front crawl swimming performance, dry-land upper and lower body maximum strength, and peak power in swim turn. Accordingly, SWIM-RT training order induces swimming performance improvements in front crawl and increments in maximum dry-land upper and lower body strength. Concurrent application of RT-SWIM or SWIM-RT training applied within a training day leads in similar performance gains after six to twelve weeks of training. The current review suggests that recovery duration between RT and SWIM is a predisposing factor that may determine the training outcome. Competitive swimmers may benefit after concurrent application with both training order scenarios during a training cycle.

Relationship Between Hand Kinematics, Hand Hydrodynamic Pressure Distribution and Hand Propulsive Force in Sprint Front Crawl Swimming.

PurposeThis study investigated the relationship between hand kinematics, hand hydrodynamic pressure distribution and hand propulsive force when swimming the front crawl with maximum effort.MethodsTwenty-four male swimmers participated in the study, and the competition levels ranged from regional to national finals. The trials consisted of three 20 m front crawl swims with apnea and maximal effort, one of which was selected for analysis. Six small pressure sensors were attached to each hand to measure the hydrodynamic pressure distribution in the hands, 15 motion capture cameras were placed in the water to obtain the actual coordinates of the hands.ResultsMean swimming velocity was positively correlated with hand speed (r = 0.881), propulsive force (r = 0.751) and pressure force (r = 0.687). Pressure on the dorsum of the hand showed very high and high negative correlations with hand speed (r = −0.720), propulsive force (r = −0.656) and mean swimming velocity (r = −0.676). On the contrary, palm pressure did not correlate with hand speed and mean swimming velocity. Still, it showed positive correlations with propulsive force (r = 0.512), pressure force (r = 0.736) and angle of attack (r = 0.471). Comparing the absolute values of the mean pressure on the palm and the dorsum of the hand, the mean pressure on the dorsum was significantly higher and had a larger effect size (d = 3.71).ConclusionIt is suggested that higher hand speed resulted in a more significant decrease in dorsum pressure (absolute value greater than palm pressure), increasing the hand propulsive force and improving mean swimming velocity.

Integrated Timing of Stroking, Breathing, and Kicking in Front-Crawl Swimming: A Novel Stroke-by-Stroke Approach Using Wearable Inertial Sensors.

Quantitative evaluation of synergic action among the different body segments is fundamental to swimming performance. The aim of the present study was to develop an easy-to-use tool for stroke-by-stroke evaluation of a swimmer’s integrated timing of stroking, kicking, and breathing. Twelve swimmers were evaluated during one trial of 100 m front-crawl swimming at self-selected speed. Five three-axial inertial sensors were mounted on the head, wrists, and ankles. Algorithms for the wrist entry into the water, the lower limb beat during the downward action, and the exit/entry of the face from/into the water were developed. Temporal events identified by video-based technique, using one sagittal moving camera, were assumed as the gold standard. The performance was evaluated in terms of the root-mean-square error, 90th percentile of absolute error, coefficient of variation, Bland–Altman plots, and correlation analysis. Results of all temporal events showed high agreement with the gold standard, confirmed by a root-mean-square error of less than 0.05 s for absolute temporal parameters and less than 0.7% for the percentages of the stroke cycle duration, and with correlation coefficients higher than 0.856. The protocol proposed was not only accurate and reliable, but also user-friendly and as unobtrusive as possible for the swimmer, allowing a stroke-by-stroke analysis during the training session.

An updated methodology to estimate critical velocity in front crawl swimming: A scoping review

Critical velocity and its related total distance covered above critical velocity can be used to evaluate and monitor the training and competition performance in athletes. While it is well researched in sports such as cycling and running, the literature on critical velocity in swimming is less available. Therefore, the objectives of this review are: (i) to methodologically evaluate the protocols used to obtain critical velocity; and (ii) eventually, to provide a standard operating procedure to evaluate critical velocity in front crawl swimming. The review followed “Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews” guidelines. PubMed, Web of Science and Scopus were used to find original studies written in English. No exclusion criteria were adopted for the country of origin. The results were analysed through a narrative synthesis. A total of 41 studies were included. Sixteen different protocols were adopted with different physiological thresholds as comparators with critical velocity. Critical velocity evaluation presents different testing protocols, making this performance marker potentially inaccurate. As a consequence, we propose a standard operating procedure. La vitesse critique et la distance totale parcourue au-dessus de vitesse critique peuvent être utilisées pour évaluer les performances en compétition et l’efficacité de l’entraînement chez les athlètes. Bien qu’elle soit bien documentée dans des sports comme le cyclisme et la course à pied, la littérature sur la vitesse critique en natation est plus rare. Par conséquent, les objectifs de cette revue sont : (i) d’évaluer méthodologiquement les protocoles utilisés pour obtenir la vitesse critique ; et (ii) de fournir un mode opératoire standard pour évaluer la vitesse critique en crawl. La revue a suivi les directives énoncées dans « Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews ». PubMed, Web of Science et Scopus sont les bases de données utilisées pour sélectionner les études rédigées en anglais qui seront intégrées dans l’analyse. Le pays d’origine n’a pas été un critère d’exclusion. Les résultats ont été analysés formalisés par un rapport écrit. Au total, 41 études ont été incluses. Seize protocoles différents de détermination de la vitesse critique ont été identifiés, conduisant à différentes évaluations de la vitesse critique. Différents protocoles permettent d’évaluer la vitesse critique, ce qui rend ce marqueur de performance potentiellement inexact. En conséquence, nous proposons un mode opératoire standardisé.

Effect of photobiomodulation on maximal lactate production rate on swimmers: a randomized, crossover, double-blind and placebo-controlled study

Aim: This study aimed to verify the acute effect of photobiomodulation (PBM) on maximal lactate production rate (VLamax) in front crawl swimmers. Methods: Fifteen male swimmers (20.9 ± 2.4-year-old) participated in this study. Three sets of front crawls were performed at distances of 100-, 200- and 400-m under three experimental conditions: PBM (420 J), placebo (PLA) and control (C) in this randomized, crossover, double-blind and placebo-controlled study. PBM or PLA were applied or simulated before performance tests. One-way Anova for repeated measurements were used for statistical analyses. Results: The results showed that the prior PBM application did not affect VLamax in front crawl swimmers: VLamax 100-m (PBM = 0.20 ± 0.05 mmol·L-1·s-1; PLA = 0.20 ± 0.04 mmol·L-1·s-1 and C = 0.21 ± 0.04; mmol·L-1·s-1); 200-m (PBM = 0.09 ± 0.03 mmol·L-1·s-1; PLA = 0.08 ± 0.02 mmol·L-1·s-1 and C = 0.08 ± 0.02 mmol·L-1·s-1) and 400-m (PBM = 0.04 ± 0.01 mmol·L-1·s-1; PLA = 0.04 ± 0.01 mmol·L-1·s-1 and C = 0.03 ± 0.01 mmol·L-1·s-1). Nor effect swim time (ST) performance: ST 100 m (PBM = 65.5 ± 6.3 s; PLA = 65.2 ± 5.6 s; C = 66.0 ± 5.9 s); ST 200 m (PBM = 148.5 ± 17.9 s; PLA = 149.4 ± 16.4 s; C = 150.1 ± 17.9 s); ST 400 m (PBM = 327.7 ± 38.2 s; PLA = 321.6 ± 47.7 s; C = 329.5 ± 41.2 s). Conclusions: PBM application prior front crawl swimming tests did not significantly modify the VLamax on swimmers covering distances of 100-, 200- and 400-m.

The Effects of 12 Weeks In-Water Training in Stroke Kinematics, Dry-Land Power, and Swimming Sprints Performance in Master Swimmers

Background: Master swimming is becoming increasingly popular, but research related to the training process and its effect on this population is scarce. The aim of this study was to investigate the effects of 12 weeks in-water training in stroke kinematics, dry-land power, and swimming sprints performance in master swimmers, and the relationships between these variables in this sports population. Methods: 15 healthy and physically active male master swimmers (age 32.3 ± 5.1 years, height 1.81 ± 0.04 m, body mass 77.0 ± 6.5 kg, training experience of 11 ± 4 years and average swimming training volume ~2.5 km/day, 3 times a week) participated in the study. Previously and after the intervention program, entirely water-based, swimmers were tested in a dry-land environment to assess their upper and lower body limbs (UL and LL) strength through power measurements, namely countermovement jumps (CMJ), seated 3 kg medicine ball throwing (MBT) and maximal isometric strength with handgrip (HG). In-water 50 m maximal front crawl swimming test was also completed. Swimming performance at 15, 25, and 50 m (T15, T25, and T50) was determined, and the associated stroke kinematics. During the intervention program period, swimming training comprised three sessions per week (7.5 ± 0.9 km per microcycle), with low- to high-intensity aerobic and anaerobic swimming series and technical drills. Results: T25 significantly decreased after 12 weeks of training (18.82 ± 2.92 vs. 18.60 ± 2.87 sec, p = 0.02), the same was observed in the case of T50 (40.36 ± 7.54 vs. 38.32 ± 6.41 sec, p = 0.00). Changes in stroke rate (SR), stroke length (SL) and stroke index (SI) in swimming performance at 15 m were not observed, contrarily to 25 and 50 m, where SL and SI significantly increased. MBT and HG improved, but not CMJ, and improvements in T15, T25 and T50 were mostly related to kinematic proficiency improvement. Conclusions: 12 weeks of in-water training in master swimmers significantly enhance performance time in 25 and 50 m front crawl swimming. SL and SI are also improved and are the variables that most influence T15, T25 and T50 when compared to SR and dry-land power variables. Centering the training process not only in in-water tasks in master swimmers seem to be of relevant interest since age influences stroke kinematic and power variables.

Cold Water Immersion as a Method Supporting Post-Exercise Recovery

The aim of the study was to assess the effect of cold water immersion on changes in blood lactate concentration during post-exercise recovery in swimmers subjected to2-minute exercise test (front crawl swimming movements) using a VASA Swim Ergometer, with the maximum arm speed movements, as during the freestyle technique. The study covered 11 professional swimmers of the MKP Szczecin club, tested twice with a two-week interval. Each participant performed an exercise test twice, once with a passive recovery period, and the second time with cold water immersion after exercise, as a method potentially supporting the post-exercise recovery process. Each time before the test, immediately after and at 3, 6 and 9 minutes after exercise, the concentration of lactate in the capillary blood was measured. Statistical analysis of the obtained results showed that cold water immersion applied immediately after exercise resulted in a faster reduction of lactate concentration. The conducted research confirms that cold water immersion used in post-exercise recovery may be an effective method of restoring optimal physical fitness as part of the training process.

Comparison of muscle activity during swimming and on the Biokinetic simulator

Introduction: The aim of the study is to evaluate the coordination similarity ratio of involvement of selected muscles (m. pectoralis major; m. latissimus dorsi; m. obliquus externus abdominis; m. triceps brachii) during the crawl swimming cycle as a target movement with imitation movement act. The research set comprised 16 elite swimmers specializing in crawl sprint tracks. Methods: The key research method was surface electromyographic analysis synchronized with video recording. The study was based on a quantitative description of electromyographic recordings of the observed movement acts. The research study has the character of an intra-individual and inter-individual comparative analysis of the coordination characteristics of the movement system. This is a sequential triangulation of a quantitative-qualitative approach and an intragroup case study with an experimental way of obtaining data. Results: Muscle activation of selected muscles during the crawl did not show a significant difference in effect size compared to the imitation movements on the Biokinetic swimming simulator.

The Contribution of Leg Length, Leg Muscle Strength, Arm Span and Maximum Oxygen Volume to 100-Meter Crawl Swimming Achievement

The Contribution of Leg Length, Leg Muscle Strength, Arm Span and Maximum Oxygen Volume to 100-Meter Crawl Swimming Achievement

Are Young Swimmers Short and Middle Distances Energy Cost Sex-Specific?

This study assessed the energy cost in swimming (C) during short and middle distances to analyze the sex-specific responses of C during supramaximal velocity and whether body composition account to the expected differences. Twenty-six swimmers (13 men and 13 women: 16.7 ± 1.9 vs. 15.5 ± 2.8 years old and 70.8 ± 10.6 vs. 55.9 ± 7.0 kg of weight) performed maximal front crawl swimming trials in 50, 100, and 200 m. The oxygen uptake (O2) was analyzed along with the tests (and post-exercise) through a portable gas analyser connected to a respiratory snorkel. Blood samples were collected before and after exercise (at the 1st, 3rd, 5th, and 7th min) to determine blood lactate concentration [La–]. The lean mass of the trunk (LMTrunk), upper limb (LMUL), and lower limb (LMLL) was assessed using dual X-ray energy absorptiometry. Anaerobic energy demand was calculated from the phosphagen and glycolytic components, with the first corresponding to the fast component of the O2 bi-exponential recovery phase and the second from the 2.72 ml × kg–1 equivalent for each 1.0 mmol × L–1 [La–] variation above the baseline value. The aerobic demand was obtained from the integral value of the O2 vs. swimming time curve. The C was estimated by the rate between total energy releasing (in Joules) and swimming velocity. The sex effect on C for each swimming trial was verified by the two-way ANOVA (Bonferroni post hoc test) and the relationships between LMTrunk, LMUL, and LMLL to C were tested by Pearson coefficient. The C was higher for men than women in 50 (1.8 ± 0.3 vs. 1.3 ± 0.3 kJ × m–1), 100 (1.4 ± 0.1 vs. 1.0 ± 0.2 kJ × m–1), and 200 m (1.0 ± 0.2 vs. 0.8 ± 0.1 kJ × m–1) with p < 0.01 for all comparisons. In addition, C differed between distances for each sex (p < 0.01). The regional LMTrunk (26.5 ± 3.6 vs. 20.1 ± 2.6 kg), LMUL (6.8 ± 1.0 vs. 4.3 ± 0.8 kg), and LMLL (20.4 ± 2.6 vs. 13.6 ± 2.5 kg) for men vs. women were significantly correlated to C in 50 (R2adj = 0.73), 100 (R2adj = 0.61), and 200 m (R2adj = 0.60, p < 0.01). Therefore, the increase in C with distance is higher for men than women and is determined by the lean mass in trunk and upper and lower limbs independent of the differences in body composition between sexes.

Basic Swimming Style Crawl Engineering Skills Survey in Athletes Ages 10-12

This study aims to: 1.To know the basic technique skills of crawl style swimming in the Kebumen swimming club association students. 2. Knowing the factors of difficulty experienced by students in learning the basic motion skills of crawl style swimming 3. Students are able to apply the basic movements of swimming with the right steps. This research was conducted on the students of the Kebumen swimming club association in Gossi Kebumen. The research plan is carried out in November 2021. The sample referred to in this study is 20 students in the 10-12 year age group who take part in basic swimming skills training. Descriptive data analysis was entered to get an overview of the data including the average, standard deviation, maximum data, minimum data, range, frequency table and graphs. Based on the results of the research that has been carried out, it can be concluded: 1. Freestyle swimming skills measured using a stopwatch on students aged 10-12 years at the swimming club association in Kebumen showed that 50% of students had very poor swimming skills, 25% students have poor swimming skills and 25% of students have sufficient skills. 2. The category of skills that dominates the most in students is very low ability. Contributing to further research is to conduct research on more intense exercises on crawl swimming style techniques need to be done by athletes and also strategies to improve the ability of athletes in crawl style swimming.Keywords: Swimming, Crawl Style, Basic Swimming Technique

The effect of hand posture on swimming efficiency

Our quest is for the thumb and finger positions that maximize drag in front crawl swimming and thus maximize propulsion efficiency. We focus on drag in a stationary flow. Swimming is in water, but using Reynolds similarity the drag experiments are done in a wind tunnel. We measure the forces on real-life models of a forearm with hands, flexing the thumb and fingers in various positions. We study the influence on drag of cupping the hand and flexing the thumb. We find that cupping the hand is detrimental for drag. Swimming is most efficient with a flat hand. Flexing the thumb has a small effect on the drag, such that the drag is largest for the opened (abducted) thumb. Flow structures around the hand are visualized using robotic volumetric particle image velocimetry. From the time-averaged velocity fields we reconstruct the pressure distribution on the hand. These pressures are compared to the result of a direct measurement. The reached accuracy of approx 10% does not yet suffice to reproduce the small drag differences between the hand postures.Graphical

Kinematic Variables of Disabled Swimmers and Their Correlation With the International Paralympic Committee Classification.

This study described the kinematic variables of disabled swimmers' performance and correlated them with their functional classification. Twenty-one impaired swimmers (S5-S10) performed 50-m maximum front-crawl swimming while being recorded by four underwater cameras. Swimming velocity, stroke rate, stroke length, intracycle velocity variation, stroke dimensions, hand velocity, and coordination index were analyzed. Kendall rank was used to correlate stroke parameters and functional classification with p < .05. Swimming velocity, stroke length, and submerged phase were positively correlated with the para swimmers functional classification (.61, .50, and .41; p < .05, respectively), while stroke rate, velocity hand for each phase, coordination index, and intracyclic velocity variation were not (τ between -.11 and .45; p > .05). Thus, some objective kinematic variables of the impaired swimmers help to support current classification. Improving hand velocity seems to be a crucial point to be improved among disabled swimmers.