scholarly journals Key Parameters Affecting Kick Start Performance in Competitive Swimming

2021 ◽  
Vol 18 (22) ◽  
pp. 11909
Author(s):  
Ivan Matúš ◽  
Pavel Ružbarský ◽  
Bibiana Vadašová
Keyword(s):  
Knee Angle ◽  
Time Block ◽  
Kinematic Parameters ◽  
Competitive Swimming ◽  
Flight Phase ◽  
Ankle Angle ◽  
Block Time ◽  
Key Block ◽  
Takeoff Angle ◽  
Competitive Swimmers

The study aims to determine the contribution of kinematic parameters to time to 5 m without underwater undulating and kicking. Eighteen male competitive swimmers started from three weighted positions and set the kick plate to positions 1–5. We used SwimPro cameras and the Dartfish© software. In the on-block phase, we found significant correlations (p < 0.01) between the front ankle angle and block time. The correlations between start phases were statistically significant (p < 0.01) between block time and rear ankle angle, respectively, to time to 2 m; rear knee angle and glide time; block time and time to 5 m; time to 2 m and time to 5 m; and flight distance and glide distance. The multiple regression analysis showed that the on-block phase and flight phase parameters, respectively, contributed 64% and 65% to the time to 5 m. The key block phase parameters included block time and rear knee angle. The key flight phase parameters determining time to 5 m included take-off angle and time to 2 m. The key parameters determining the performance to 5 m during the above-water phase include rear knee angle, block time, takeoff angle, and time to 2 m.

scholarly journals Kinematic analysis of the kick start from OSB12

2020 ◽  
Vol 8 (2) ◽  
pp. 86-96
Author(s):  
Ivan Matúš ◽  
Róbert Kandráč
Keyword(s):  
Body Height ◽  
Performance Level ◽  
Test Results ◽  
Knee Angle ◽  
Kinematic Parameters ◽  
Entry Angle ◽  
Camera System ◽  
Flight Phase ◽  
Starting Position ◽  
Takeoff Angle

Introduction: Start performance in swimming plays a major role in determining the final standings, especially in sprint races. The purpose of the study was to determine kinematic parameters underlying the kick start from OSB12 in terms of the kick plate position and shoulder positioning at the start. Material and methods: The sample included 8 non-randomly recruited performance-level swimmers whose average age, body height, and body weight was 17.4 ± 1.8 years, 182.2 ± 3.4 cm and 81.00 ± 3.9 kg, respectively. To measure the kinematic parameters, we used the SwimPro camera system. The parameter rs measured included angular parameters and kinematic parameters for each of the start phases: block phase, flight phase, and water phase. We processed the collected biomechanical data using the Statistica 12.0 software. To determine significant differences between the kick plate positions in three types of start, we applied the Mann-Whitney U test. Results: We found significant differences (p<0.05) in the selected kinematic parameters in all phases, which depended on the OSB12 kick plate position and basic starting position (front-, neutral-, and rear-weighted). The greatest differences in the parameters measured were found between the front-weighted start and rear-weighted start. We may conclude that performance-level swimmers should adjust the rear kick plate to positions 3 and 4 and assume the following starting position: front knee angle between 131° and 133°, rear knee angle around 80°, and trunk angle between 40° and 41°. This starting position affects the flight phase, namely takeoff angle (40⁰-41⁰), head position at takeoff (1.33-1.38 m), flight time and distance (0.346-0.368 s; 2.74-2.79 m), entry angle (38⁰). The starting position also affects the glide phase, namely the glide time and distance (0.532-0.536 s; 2.22-2.26 m) and maximum depth (-0.91-0.92 m). Conclusions: The results of the study show that swimmers produced shorter times to 5 meters and higher velocity at 5 meters compared with other starting positions and OSB12 kick plate positions.

scholarly journals Real-Time Block Rate Targeting

Ledger ◽  
2020 ◽  
Vol 5 ◽  
Author(s):  
Thomas M Harding
Keyword(s):  
Real Time ◽  
Production Rate ◽  
The Other ◽  
Time Block ◽  
Block Time

A proof-of-work blockchain uses a retargeting algorithm, also termed a difficulty adjustment algorithm, to manage the rate of block production in the presence of changing hashrate. To derive the parameters that guide the search for the next block, nearly all such algorithms rely on averages of past inter-block time observations, as measured by on-chain timestamps. We are motivated to seek better responsiveness to changing hashrate, while improving stability of the block production rate and retaining the progress-free property of mining. We describe a class of retargeting algorithms for which the sole inter-block time input is that of the block being searched for, and whose response is nonlinear in that time. We discuss how these algorithms allow the other consensus rules that govern allowable timestamps to be tightened, which may improve the blockchain’s effectiveness as a time-stamping machine.

Ankle Angle but Not Knee Angle Influences Force Fluctuations During Plantar Flexion

2021 ◽  
Author(s):  
Georgios Trypidakis ◽  
Ioannis G. Amiridis ◽  
Roger Enoka ◽  
Irini Tsatsaki ◽  
Eleftherios Kellis ◽  
...  
Keyword(s):  
Knee Joint ◽  
Coefficient Of Variation ◽  
Discharge Rate ◽  
Dominant Role ◽  
Plantar Flexion ◽  
Motor Units ◽  
Medial Gastrocnemius ◽  
Knee Angle ◽  
Plantar Flexors ◽  
Ankle Angle

AbstractThe purpose of the study was to evaluate the influence of changes in ankle- and knee-joint angles on force steadiness and the discharge characteristics of motor units (MU) in soleus when the plantar flexors performed steady isometric contractions. Submaximal contractions (5, 10, 20, and 40% of maximum) were performed at two ankle angles (75° and 105°) and two knee angles (120° and 180°) by 14 young adults. The coefficient of variation of force decreased as the target force increased from 5 to 20% of maximal force, then remained unaltered at 40%. Independently of knee angle, the coefficient of variation for force at the ankle angle of 75° (long length) was always less (p<0.05) than that at 105° (shorter length). Mean discharge rate, discharge variability, and variability in neural activation of soleus motor units were less (p<0.05) at the 75° angle than at 105°. It was not possible to record MUs from medial gastrocnemius at the knee angle of 120° due to its minimal activation. The changes in knee-joint angle did not influence any of the outcome measures. The findings underscore the dominant role of the soleus muscle in the control of submaximal forces produced by the plantar flexor muscles.

scholarly journals Prediction of Shoulder Pain in Youth Competitive Swimmers: The Development and Internal Validation of a Prognostic Prediction Model

2020 ◽  
Vol 49 (1) ◽  
pp. 154-161
Author(s):  
Stef Feijen ◽  
Thomas Struyf ◽  
Kevin Kuppens ◽  
Angela Tate ◽  
Filip Struyf
Keyword(s):  
Logistic Regression ◽  
Shoulder Pain ◽  
Muscle Endurance ◽  
Internal Validation ◽  
Competitive Swimming ◽  
Final Model ◽  
Shoulder Muscle ◽  
Multivariable Logistic Regression ◽  
Posterior Shoulder ◽  
Competitive Swimmers

Background: Knowledge of predictors for shoulder pain in swimmers can assist professionals working with the athlete in developing optimal prevention strategies. However, study methodology and limited available data have constrained a comprehensive understanding of which factors cause shoulder pain. Purpose: To investigate risk factors and develop and internally validate a multivariable prognostic model for the prediction of shoulder pain in swimmers. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 201 pain-free club- to international-level competitive swimmers were followed for 2 consecutive seasons. The cohort consisted of 96 male (mean ± SD age, 13.9 ± 2.2 years) and 105 female (13.9 ± 2.2 years) swimmers. Demographic, sport-specific, and musculoskeletal characteristics were assessed every 6 months. Swim-training exposure was observed prospectively. Shoulder pain interfering with training was the primary outcome. Multiple imputation was used to cope with missing data. The final model was estimated using multivariable logistic regression. We applied bootstrapping to internally validate the model and correct for overoptimism. Results: A total of 42 new cases of shoulder pain were recorded during the study. Average duration of follow-up was 1.1 years. Predictors included in the final model were acute:chronic workload ratio (odds ratio [OR], 4.31; 95% CI, 1.00-18.54), competitive level (OR, 0.19; 95% CI, 0.06-0.63), shoulder flexion range of motion, posterior shoulder muscle endurance (OR, 0.96; 95% CI, 0.92-0.99), and hand entry position error (OR, 0.37; 95% CI, 0.16-0.91). After internal validation, this model maintained good calibration and discriminative power (area under the receiver operating characteristic curve, 0.71; 95% CI, 0.60-0.94). Conclusion: Our model consists of parameters that are readily measurable in a swimming setting, allowing the identification of swimmers at risk for shoulder pain. Multivariable logistic regression showed the strongest predictors for shoulder pain were regional competitive swimming level, acute:chronic workload ratio, posterior shoulder muscle endurance, and hand entry error.

scholarly journals Body Composition and Kinematic Analysis of the Grab Start in Youth Swimmers

2014 ◽  
Vol 42 (1) ◽  
pp. 15-26 ◽  
Author(s):  
Ahmet Alptekin
Keyword(s):  
Body Composition ◽  
Vertical Velocity ◽  
Center Of Mass ◽  
Random Order ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Kinematic Parameters ◽  
Total Distance ◽  
Block Time ◽  
The Relationship

Abstract The purposes of this study were to compare the kinematic variables in youth swimmers during the grab start between sexes and to investigate the relationship between body composition and kinematic variables of the participants. Six female (Mage = 13.71 ± 0.49 yrs) and seven male (Mage = 14.00 ± 1.07 yrs) swimmers participated in this study. All participants were required to perform grab start tests in random order (three trials by each participant), while the best attempt was analyzed. Nineteen kinematic parameters consisting of block time, flight time, flight distance, total time, total distance, horizontal and vertical displacement of the center of mass (CM) at take-off, horizontal and vertical displacement of the CM at entry, height of take-off and entry, relative height of take-off, horizontal and vertical velocity of the CM at take-off, horizontal and vertical velocity of the CM at entry, angle of take-off, angle of entry and angle of knee at block were analyzed. Out of the 19 evaluated kinematic parameters, a statistical difference between the female and male group was found only in the total distance. Therefore, both female and male groups are considered as only one group and merged after analyzing the results. Statistical analysis showed positive and negative correlations between horizontal / vertical velocity of CM at take-off and several kinematic variables (e.g. angle of entry (rhorizontal = -.868, p=.000 / rvertical = .591, p=.02), total distance (rhorizontal = .594, p=.02 / rvertical = .54, p=.04), and height of take-off (rvertical = .888, p=.000), respectively). On the other hand, positive and negative correlations were found between somatotype components and several kinematic variables (e.g. horizontal displacement of CM at entry (rendomorphy = -.626, p=.013), angle of entry (rmesomorphy = -.686, p=.005 / rectomorphy = .52, p=.047), total distance (rendomorphy = -.626, p=.012), and height of take-off (rendomorphy = -.633, p=.011 / rectomorphy = .515, p=.05)). In conclusion, results show that in order to be successful at grab start performance, a swimmer should target to get higher horizontal velocity of CM at take-off and optimize the angle of take-off so this movement form supplies more total distance to the swimmer. Coaches should consider improving start performance and adding start training to regular training sessions. Moreover, youth male and female swimmers can participate together in the grab start training

Blood Lactate Concentration and Clearance in Elite Swimmers During Competition

2011 ◽  
Vol 6 (1) ◽  
pp. 106-117 ◽  
Author(s):  
Jason D. Vescovi ◽  
Olesya Falenchuk ◽  
Greg D. Wells
Keyword(s):  
Blood Lactate ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Active Recovery ◽  
Competitive Swimming ◽  
Elite Swimmers ◽  
Lactate Removal ◽  
The Relationship ◽  
Competitive Swimmers ◽  
Effect Of Age

Purpose:Blood lactate concentration, [BLa], after swimming events might be influenced by demographic features and characteristics of the swim race, whereas active recovery enhances blood lactate removal. Our aims were to (1) examine how sex, age, race distance, and swim stroke influenced [BLa] after competitive swimming events and (2) develop a practical model based on recovery swim distance to optimize blood lactate removal.Methods:We retrospectively analyzed postrace [BLa] from 100 swimmers who competed in the finals at the Canadian Swim Championships. [BLa] was also assessed repeatedly during the active recovery. Generalized estimating equations were used to evaluate the relationship between postrace [BLa] with independent variables.Results:Postrace [BLa] was highest following 100–200 m events and lowest after 50 and 1500 m races. A sex effect for postrace [BLa] was observed only for freestyle events. There was a negligible effect of age on postrace [BLa]. A model was developed to estimate an expected change in [BLa] during active recovery (male = 0; female = 1): [BLa] change after active recovery = –3.374 + (1.162 × sex) + (0.789 × postrace [BLa]) + (0.003 × active recovery distance).Conclusions:These findings indicate that swimmers competing at an elite standard display similar postrace [BLa] and that there is little effect of age on postrace [BLa] in competitive swimmers aged 14 to 29 y.

scholarly journals Drag Characteristics of Competitive Swimming Children and Adults

2008 ◽  
Vol 24 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Per-Ludvik Kjendlie ◽  
Robert Keig Stallman
Keyword(s):  
Perturbation Method ◽  
Froude Number ◽  
Wave Drag ◽  
Maximal Velocity ◽  
Evaluation Tool ◽  
Competitive Swimming ◽  
Velocity Decay ◽  
Competitive Swimmers ◽  
Drag Factor ◽  
Swimming Technique

The aims of this study were to compare drag in swimming children and adults, quantify technique using the technique drag index (TDI), and use the Froude number (Fr) to study whether children or adults reach hull speed at maximal velocity (vmax). Active and passive drag was measured by the perturbation method and a velocity decay method, respectively, including 9 children aged 11.7 ± 0.8 and 13 adults aged 21.4 ± 3.7. The children had significantly lower active (kAD) and passive drag factor (kPD) compared with the adults. TDI (kAD/kPD) could not detect any differences in swimming technique between the two groups, owing to the adults swimming maximally at a higher Fr, increasing the wave drag component, and masking the effect of better technique. The children were found not to reach hull speed atvmax, and their Fr were 0.37 ± 0.01 vs. the adults 0.42 ± 0.01, indicating adults’ larger wave-making component of resistance atvmaxcompared with children. Fr is proposed as an evaluation tool for competitive swimmers.

scholarly journals Swimmers Are At Risk For Stress Fractures? A Systematic Review

2018 ◽  
Vol 6 (3) ◽  
pp. 25 ◽  
Author(s):  
Angelo V. Vasiliadis ◽  
Vasileios Lampridis ◽  
Dimitrios Georgiannos ◽  
Ilias Bisbinas
Keyword(s):  
Systematic Review ◽  
Stress Fracture ◽  
Weight Bearing ◽  
Sport Activity ◽  
Stress Fractures ◽  
Extrinsic Factors ◽  
Rare Type ◽  
Stress Injury ◽  
Competitive Swimming ◽  
Competitive Swimmers

Background: Stress fractures occur most commonly in the weight-bearing bones of the lower extremities. Swimming, a non-weight-bearing activity, is a potential activity form which associated with stress fractures? Objective: This systematic review aims to provide an answer in the above question and also to identify the reported cases of stress fractures among swimmers. Method: A systematic and comprehensive search was conducted using PubMed and Research Gate databases before January 2017. The search process was completed using the keywords: “stress fracture”, “stress injury”, “fatigue fracture”, “swimming” and “swimmers”. Results: There have been only 10 studies describing stress fractures in swimmers. This rare type of injury is commonly diagnosed in the ribs of young competitive swimmers, irrespective of their preferred swimming stroke. The etiology is multifactorial and includes a combination of intrinsic and/or extrinsic factors. Conclusion: Although any sport activity can potential cause a stress fracture, competitive swimming seems to be relatively safe in this respect. Rib stress fractures appear as the most common stress fracture in competitive swimmers that clinicians should consider. A prompt diagnosis can shorten the time required for healing and decrease the risk of complication.

scholarly journals A Biomechanical Analysis into Backstroke Start Kinematics: The Influence of a Backstroke Start Device.

2019 ◽  
Author(s):  
Emily Budzynski-Seymour ◽  
James Steele ◽  
Louis Langdown ◽  
David Jessop
Keyword(s):  
Biomechanical Analysis ◽  
Flight Distance ◽  
Male And Female ◽  
Flight Phase ◽  
Maximum Effort ◽  
Scientific Attention ◽  
Competitive Swimmers

Background: Backstroke starts have received little scientific attention; this may be due to the ongoing modifications to rules but also the fact that the majority of swim starts occur from a dive. As such, this has been the focus for much swim start research. Backstrokers face the problem of slipping from the wall which is a reasonably common mishap and has serious consequences for the competitor. FINA approved the use of a new backstroke start ledge to help avoid this mishap and therefore the aim of the study was to investigate what advantages come from using this ledge (L) over the wall (W). Methods: Twelve well trained male and female competitive swimmers took part in the study and completed six maximum effort sprints; three under each condition. Results: The results showed significantly greater flight distance (L = 4.22m±0.42, W = 4.06m±0.35, p&lt;0.05) and peak hip height during the flight phase (L = 0.39m±0.15, W = 0.20m±0.14, p&lt;0.01) when using the ledge. Discussion: It was concluded therefore that the ledge positively effects backstroke start performance during the flight phase of the start.

scholarly journals Talent Selection and Management in View of Relative Age: the Case of Swimming

2018 ◽  
Vol 80 (1) ◽  
pp. 57-67
Author(s):  
Nikoletta Nagy ◽  
Gyöngyi Földesi ◽  
Csaba Sós ◽  
Csaba Ökrös
Keyword(s):  
Talent Management ◽  
Potential Effect ◽  
Management Program ◽  
Chi Square ◽  
Competitive Swimming ◽  
Relative Age ◽  
Talent Selection ◽  
Highly Sensitive ◽  
Research Population ◽  
Competitive Swimmers

AbstractBased on our empirical research, through the analysis of the birthdates of young competitive swimmers, the present paper aims to examine the system of talent selection and management in Hungarian competitive swimming complemented with a new element. The research population consisted of the registered junior competitive swimmers participating in the new talent management program of the Hungarian Swimming Association (N=235; average age: 11.44) due to the decision of the Coaches’ Committee. Our research was based on the analysis of documents and databases. Besides the descriptive statistics, Chi-square tests and the Kruskal-Wallis test were applied. The results show that swimmers born in the first three months of the year are still more likely to be recruited in the program than their relatively younger counterparts. Furthermore, as a potential effect of the new program, the dominance of the first quarter of the year is also characteristic among those eligible for the next level of talent management. The new selection system of Hungarian swimmers is still highly sensitive to the relative age. Thus, it is recommended to further investigate the functioning of the new talent management program in terms of selection and success.

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