Kinematic differences between front crawl sprint and distance swimmers at a distance pace

Abstract

The purpose of the study was to determine whether there are differences in kinematics between sprint and distance front crawl specialists when swimming at a distance pace using a six beat kick. Seven sprint and eight distance male specialists performed one maximum 400 m swim through a 6.75 m³ calibrated space recorded by six gen-locked cameras. The following variables were calculated: average swim velocity, stroke length, stroke frequency, upper limb and foot displacement, elbow angle, the shoulder and hip roll angle, duration of the stroke phases and time corresponding to particular events within the stroke cycle relative to hand entry. Differences between the groups were assessed by an independent t-test and effect size (d) calculations for each variable. The groups only differed significantly with respect to the average swim velocity, with the distance swimmers maintaining a greater velocity throughout the 400 m. However, effect sizes were moderate for elbow angle range during the pull phase (d = 0.78) and the total hip roll magnitude (d = 0.76). There was little evidence to suggest that sprint and distance swimmers using a six beat kick pattern differ in technique when swimming at a distance pace and therefore coaches should not encourage the development of different techniques between these groups.     

Kinematic differences between front crawl sprint and distance swimmers at a distance pace

The purpose of the study was to determine whether there are differences in kinematics between sprint and distance front crawl specialists when swimming at a distance pace using a six beat kick. Seven sprint and eight distance male specialists performed one maximum 400 m swim through a 6.75 m3 calibrated space recorded by six gen-locked cameras. The following variables were calculated: average swim velocity, stroke length, stroke frequency, upper limb and foot displacement, elbow angle, the shoulder and hip roll angle, duration of the stroke phases and time corresponding to particular events within the stroke cycle relative to hand entry. Differences between the groups were assessed by an independent t-test and effect size (d) calculations for each variable. The groups only differed significantly with respect to the average swim velocity, with the distance swimmers maintaining a greater velocity throughout the 400 m. However, effect sizes were moderate for elbow angle range during the pull phase (d = 0.78) and the total hip roll magnitude (d = 0.76). There was little evidence to suggest that sprint and distance swimmers using a six beat kick pattern differ in technique when swimming at a distance pace and therefore coaches should not encourage the development of different techniques between these groups.     

Effects of phase ratio and velocity conversion coefficient on the performance of the triple jump

Abstract

Phase ratio is a measure of effort distribution in the triple jump. Hop-dominant, balanced, and jump-dominant techniques were three triple jump techniques defined based on phase ratio. The purpose of this study was to determine the effect of the phase ratio on the performance of the triple jump. Three-dimensional kinematic data of 13 elite male triple jumpers were obtained during a competition. Computer simulations were performed using a biomechanical model of the triple jump to optimise the phase ratio for the longest actual distance using each of the three techniques for a given athlete with altered velocity conversion coefficients. The velocity conversion coefficient affected which technique achieved the longest actual distance. The actual distance obtained using the hop-dominant technique was significantly longer than that obtained using the other two techniques (P = 0.007, P = 0.001) when the velocity coefficient was between 0.35 and 0.55. The actual distance obtained using the jump-dominant technique was significantly longer than that obtained using the other two techniques (P = 0.001, P = 0.002) when the velocity coefficient was between 0.80 and 1.30. No consistent optimum technique across participants and no significant difference in performance among the three techniques were found (P > 0.524) when the velocity coefficient was between 0.60 and 0.75.     

Kinematic differences between front crawl sprint and distance swimmers at sprint pace

The purpose of this study was to use three-dimensional methods to determine whether there are distinct kinematic differences between sprint and distance front crawl swimmers when swimming at a sprint pace. Seven sprint and eight distance specialists performed four 25-m sprints through a 6.75-m(3) calibrated space recorded by six gen-locked cameras. The variables of interest were: average swim velocity, stroke length, stroke frequency, upper limb and foot displacement, elbow angle, shoulder and hip roll angles, duration of stroke phases, and the time corresponding to particular events within the stroke cycle relative to hand entry. Differences between sprint and distance swimmers were assessed with an independent t-test for each variable, in addition to effect size calculations. Differences between sprint and distance front crawl swimmers were generally small and not significant when swimming at a sprint pace. Differences were limited to temporal aspects of the stroke cycle. These findings suggest that coaches should not train sprint and distance specialists differently in terms of technique development.     

The Effect of Training on the Relationships Among Velocity,Stroke Rate and Distance per Stroke in Untrained Subjects Swimming the Breaststroke

Abstract

The present study was undertaken to reveal the relationships among velocity (V), stroke rate (S), and distance per stroke (d/s) in the breaststroke, and to determine whether the swim velocity of the breaststroke is increased by an increased stroke rate induced by breaststroke training. A total of 168 ordinary high school students were engaged for the present study. In order to measure the swimming time and strokes during breaststroke at maximum effort for the 50m distance, a videotape recorder (VTR) with video timer system was employed, and the recordings were used in analyses. The S and d/s were calculated for each subject. It was found in this study that V is significantly related to d/s before and after training, but has no relation to S. From these results, it is suggested that improvement of velocity during breaststroke depends upon an increase of d/s, rather than S. This is considered to be an index of efficiency or technique in the breaststroke.     

Predicting the throwing velocity of the ball in handball with anthropometric variables and isotonic tests

Abstract

The aims of this study were to (1) investigate the influence of general anthropometric variables, handball-specific anthropometric variables, and upper-limb power and strength on ball-throwing velocity in a standing position (ν_ball), and (2) predict this velocity using multiple regression methods. Forty-two skilled male handball players (age 21.0 ± 3.0 years; height = 1.81 ± 0.07 m; body mass = 78.3 ± 11.3 kg) participated in the study. We measured general anthropometric variables (height, body mass, lean mass, body mass index) and handball-specific anthropometric parameters (hand size, arm span). Upper-limb dynamic strength was assessed using a medicine ball (2 kg) throwing test, and power using a one-repetition maximum bench-press test. All the variables studied were correlated with ball velocity. Medicine ball throwing performance was the best predictor (r = 0.80). General anthropometric variables were better predictors (r = 0.55–0.70) than handball-specific anthropometric variables (r = 0.35–0.51). The best multiple regression model accounted for 74% of the total variance and included body mass, medicine ball throwing performance, and power output in the 20-kg bench press. The equation formulated could help trainers, athletes, and professionals detect future talent and test athletes' current fitness.     

Acute responses of biomechanical parameters to different sizes of hand paddles in front-crawl stroke

Abstract

This study investigated the acute effects of different sizes of paddles on the force-time curve during tethered swimming and swimming velocity in front-crawl stroke. Fourteen male swimmers (20.0 ± 3.7 years; 100-m best time: 53.70 ± 0.87 s) performed two 10-s maximal efforts in tethered swimming to obtain peak force, average force, impulse, rate of force development, stroke duration and time to peak force. Swimming velocity, stroke rate and stroke length were obtained from two 25-m maximal swims. Both tests were repeated in five conditions: free swimming, wearing small (280 cm ² ), medium (352 cm ² ), large (462 cm ² ) and extra-large (552 cm ² ) hand paddles. Compared to free swimming, paddles provided significant increases of peak force (medium: 11.5%, large: 16.7%, extra-large: 21.7%), impulse (medium: 15.2%, large: 22.4%, extra-large: 30.9%), average force (medium: 5.1%, large: 7.5%), rate of force development (extra-large: 11.3%), stroke duration (medium: 9.3%, large: 11.8%, extra-large: 18.5%), time to peak force (medium: 11.1%, large: 15.9%, extra-large: 22.1%), swimming velocity (medium: 2.2%, large: 3.2%, extra-large: 3.7%) and stroke length (medium: 9.0%, large: 9.0%, extra-large: 14.8%), while stroke rate decreased (medium: –6.2%, large: –5.5%, extra-large: –9.5%). It is concluded that medium, large and extra-large paddles influence the force-time curve and change swimming velocity, suggesting these sizes may be useful for force development in water.     

Comment on ‘Ventilation and blood lactate increase exponentially during incremental exercise’ : A reply

Oar force and oar angle data resulting from a 6‐min maximal rowing ergometer test undertaken by novice (n = 9), good (n ‐ 23) and national (n = 9) level male rowers, were used to identify biomechanical performance variables which accurately discriminated between rowers of differing ability levels. The variables included two work capacity measures, mean propulsive power output per kilogram of body mass (W kg^‐1) and propulsive work consistency (%), and two skill variables, stroke‐to‐stroke consistency (%) and stroke smoothness (%). Discriminant function analysis indicated the presence of two functions, both of which clearly indicated the importance of mean propulsive power output per kilogram of body mass as a discriminating variable. Function 2 gave greater weight to stroke‐to‐stroke consistency and stroke smoothness than function 1; however, function 1 was the most powerful discriminator. Classification procedures were used to predict the ability level to which a rower most likely belonged and involved defining the ‘distance’ between each rower and each ability level centroid, with the rower being classified into the ‘nearest’ ability level. These procedures indicated that 100% of the elite, 73.9% of the good, 88.9% of the novice and 82.9% of all rowers were correctly classified into their respective skill levels. Stepwise discriminant analysis included the variables in the following order: mean propulsive power output per kilogram of body mass, stroke‐to‐stroke consistency, stroke smoothness and propulsive work consistency (P < 0.001). The results of this study indicate that biomechanical performance variables related to rowing capacity and skill may be identified and used to discriminate accurately between rowers of differing skill levels, and that, of these variables, propulsive work consistency is the least effective discriminator.     

Conference communications

Abstract

The objective of this study was to provide anthropometric, physiological, and performance characteristics of an elite international handball team. Twenty-one elite handball players were tested and categorized according to their playing positions (goalkeepers, backs, pivots, and wings). Testing consisted of anthropometric and physiological measures of height, body mass, percentage body fat and endurance ([Vdot]O_2max), performance measures of speed (5, 10, and 30 m), strength (bench press and squat), unilateral and bilateral horizontal jumping ability, and a 5-jump horizontal test. Significant differences were found between player positions for some anthropometric characteristics (height and percentage body fat) but not for the physiological or performance characteristics. Strong correlations were noted between single leg horizontal jumping distances with 5-, 10-, and 30-m sprint times (r = 0.51–0.80; P < 0.01). The best predictors of sprint times were single leg horizontal jumping with the dominant leg and the distance measured for the 5-jump test, which when combined accounted for 72% of the common variance associated with sprint ability. In conclusion, performance abilities between positions in elite team-handball players appear to be very similar. Single leg horizontal jumping distance could be a specific standardized test for predicting sprinting ability in elite handball players.     

Two-Handed Movement Control

Abstract

The purpose of this study was to investigate the discrepancy between the finding that when two hands make movements to targets of different distances, they have the same movement time (Kelso, Southard & Goodman, 1979a, b) and the finding that they have different movement times (Marteniuk & MacKenzie, 1980). The present experiment shows that when the ratio of the distance traveled by the two hands is 4:1, they do not take the same time. The hand moving the shorter distance lakes less time, although it takes more lime than when moving alone or when moving the same distance as the other hand. This finding is highlighted when individual data are examined. It appears that there is no difference between using homologous or nonhomologous muscle groups.     

A deterministic model based on evidence for the associations between kinematic variables and sprint kayak performance

The aim of this narrative review was to propose a deterministic model based on a review of previous research documenting the evidence for the associations between average kayak velocity and kinematic variables in sprint kayaking. Literature was reviewed after searching electronic databases using key words ‘kayak,’ ‘biomechanics,’ ‘velocity,’ ‘kinematics,’ and ‘performance.’ Our kinematic deterministic model for sprint kayaking performance shows that the average kayak velocity is determined by kayak stroke displacement and stroke time. Stroke time had the strongest correlation with 200-m race time (r = 0.86, p < 0.001), and stroke rate (inversely proportional to stroke time) was strongly correlated with average horizontal velocity over two consecutive strokes at race pace (r = ? 0.83, p < 0.05). Increased stroke rate via decreased absolute water phase time and increased relative water phase time were indicative of more elite performance. There was no significant relationship between stroke displacement and velocity; however, a large decrease in stroke displacement may be detrimental to performance. Individual characteristics may be responsible for a paddlers’ ability to achieve and sustain a given stroke rate. Coaches should theoretically focus interventions on increasing stroke rate while maintaining stroke displacement; however this hypothesis should be confirmed with prospective studies.     

Performances by College Students in Handball Being Taught by Three Different Teaching Methods

Abstract

The purpose of this study was to determine whether differences in handball knowledge and skill existed between three teaching methods: traditional, contractual, and independent study. Each subject (N = 36) was given pretests in handball: a knowledge test, a wall volley test, and a serve placement test. Pre- and posttest reliabilities were reported. The three intact classes used for the study started out equal in handball knowledge and skill. After 10 weeks of instruction, the three classes were given posttests for handball knowledge and skill. No significant differences, in handball knowledge and skill, were found between the three teaching methods at the .05 level.     

Anticipatory strategies of team-handball goalkeepers

Abstract

This study seeks to discover whether handball goalkeepers employ a general anticipatory strategy when facing long distance throws and the effect of uncertainty on these strategies. Seven goalkeepers and four throwers took part. We used a force platform to analyse the goalkeeper's movements on the basis of reaction forces and two video cameras synchronised at 500 Hz to film the throw using 3D video techniques. The goalkeepers initiated their movement towards the side of the throw 193 ± 67 ms before the release of the ball and when the uncertainty was reduced the time increased to 349 ± 71 ms. The kinematics analysis of their centre of mass indicated that there was an anticipatory strategy of movement with certain modifications when there was greater uncertainty. All the average scores referring to velocity and lateral movement of the goalkeeper's centre of mass are significantly greater than those recorded for the experimental situation with bigger uncertainty. The methodology used has enabled us to tackle the study of anticipation from an analysis of the movement used by goalkeepers to save the ball.     

Injuries in handball: Examination of the risk factors

Abstract

This paper examines the influence of selected risk factors on injuries among male players of competition handball. Data relating to risk factors were collected using a self-report questionnaire. The factors that were examined were age, height, weight, body mass index, field position, past sport experience, level of competition, pre-season conditioning, number of practices per week, frequency of participation in games, use of prophylactic equipment, use of stretching exercises, and technical training. The questionnaire was administered to 216 male handball players. Nearly half of the players (42.6% or n=92) reported that they had been injured during the previous two years. The injury incidence was 8.14 injuries per 1,000 game hours for the preceding two years. Logistic regression analysis revealed that the variables “use of prophylactic equipment” and the “number of practices per week” contributed significantly to the prediction of an injury in handball players. The results of this study suggest that it is possible to reduce injury occurrence by giving specific attention to players using prophylactic equipment and to the lower-competition-level players.     

The Kinematics and Kinetics of the Running Pattern of Two-, Four-, and Six-Year-Old Children

Abstract

Selected kinematic and kinetic variables in the running pattern of 2-, 4-, and 6-year-old children were investigated. Cinematographic records and force-plate tracings were used to study the running patterns of the 28 Caucasian subjects, 15 male and 13 female. A 2 × 3 (sex × age) factorial analysis of variance was used to determine whether effects of variation between and within age and sex factors for each of the dependent variables of selected kinematic (displacement and velocity) and kinetic (ground reaction force) variables were significant. The running speeds improved with age. Although height and weight gains influenced the improvement shown in performance, certain biomechanical variables also contributed to the development of the running pattern. In the majority of the selected kinematic and kinetic variables there were significant differences between the 2-year-old group and the other two groups. Where there were significant differences in the variables, the differences tended to be in displacement, velocity, and magnitude of force measures, rather than in time of occurrence measures. Significant differences between male and female subjects appeared in five kinematic variables related to the swing leg.     

Effects of adding a weekly eccentric-overload training session on strength and athletic performance in team-handball players

To investigate the influence of adding a weekly eccentric-overload training (EOT) session in several athletic performance’s tests, 18 team-handball players were assigned either to an EOT (n?=?11) or a Control (n?=?7) group. Both groups continued to perform the same habitual strength training, but the EOT group added one session/week during a 7-week training programme consisting of four sets of eight repetitions for the bilateral half-squat and unilateral lunge exercises. The test battery included handball throwing velocity, maximum dynamic strength (1RM), countermovement jump (CMJ), 20?m sprint, triple hop for distance, and eccentric/concentric power in both the half-squat and lunge exercises. Data were analysed using magnitude-based inferences. Both groups improved their 1RM in the half squat, 20?m sprint time, and CMJ performance to a similar extent, but the EOT group showed a beneficial effect for both right [(42/58/0), possibly positive] and left [(99/1/0), very likely positive] triple hop for distance performance. In addition, the EOT group showed greater power output improvements in both eccentric and concentric phases of the half-squat (difference in percent of change ranging from 6.5% to 22.0%) and lunge exercises (difference in per cent of change ranging from 13.1% to 24.9%). Nevertheless, no group showed changes in handball throwing velocity. Selected variables related to team-handball performance (i.e. functional jumping performance, power output) can be improved by adding a single EOT session per week, highlighting the usefulness of this low-volume/high-intensity training when aiming at optimizing dynamic athletic performance.     

Reference power values for the jump squat exercise in elite athletes: A multicenter study

ABSTRACT

The present study aimed to provide reference values for lower-limb muscle power assessed during the incremental jump squat (JS) test in elite athletes (i.e., professional athletes competing at international level). We pooled data from all JS tests performed by elite athletes of different sports in two high-performance centres between 2015 and 2019, and computed reference values (i.e., terciles) for mean power (MP), mean propulsive power (MPP), and peak power (PP). Reference values were obtained from 684 elite athletes (458 male and 226 female) of 16 different sports (boxing, judo, karate, fencing, taekwondo, wrestling, basketball, soccer, futsal, handball, rugby union, badminton, tennis, long distance running, triathlon, and sprinting). Significant differences (p < 0.001) were found between male and female athletes for MP (7.47 ± 1.93 and 6.15 ± 1.68 W·Kg^?1, respectively), MPP (10.50 ± 2.75 and 8.63 ± 2.43 W·Kg^?1), and PP (23.64 ± 6.12 and 19.35 ± 5.49 W·Kg^?1). However, the velocity at which these power measures was attained seemed to be independent of sex (~0.95, 1.00 and 2.00 m·s^?1 for mean, mean propulsive, and peak velocity, respectively) and homogeneous across different sport disciplines (coefficient of variation <10%). These data can be used to classify athletes’ power capabilities, and the optimum velocity ranges provided here could be useful for training purposes.     

Profiling elite male 100-m sprint performance: The role of maximum velocity and relative acceleration

Purpose:This study aimed to determine the accuracy of a 4 split time modelling method to generate velocity-time and velocity-distance variables in elite male 100-m sprinters and subsequently to assess the roles of key sprint parameters with respect to 100-m sprint performance.Additionally,this study aimed to assess the differences between faster and slower sprinters in key sprint variables that have not been assessed in previous work.Methods:Velocity-time and velocity-distance curves were generated using a mono-exponential function from 4 split times for 82 male sprinters during major athletics competitions.Key race variables-maximum velocity,the acceleration time constant(τ),and percentage of velocity lost(vLoss)-were derived for each athlete.Athletes were divided into tertiles,based on 100-m time,with the first and third tertiles considered to be the faster and slower groups,respectively,to facilitate further analysis.Results:Modelled split times and velocities displayed excellent accuracy and close agreement with raw measures(range of mean bias was-0.2%to 0.2%,and range of intraclass correlation coefficients(ICCs)was 0.935 to 0.999)except for 10-m time(mean bias was 1.6%±1.3%,and the ICC was 0.600).The 100-m sprint performance time and all 20-m split times had a significant near-perfect negative correlation with maximum velocity(r≥-0.90)except for the 0 to 20-m split time,where a significantly large negative correlation was found(r=-0.57).The faster group had a significantly higher maximum velocity andτ(p<0.001),and no significant difference was found for vLoss(p=0.085).Conclusion:Coaches and researchers are encouraged to utilize the 4 split time method proposed in the current study to assess several key race variables that describe a sprinter’s performance capacities,which can be subsequently used to further inform training.     

Selected Mechanical Factors Associated with Acceleration in Ice Skating

Abstract

The purpose of this study was to explore the techniques of ice skating acceleration through analysis of specific characteristics of the movement pattern during a “front start” skating task. Two Locam 16 mm cameras operating at 100 frames per second were used to record side and overhead views of the first 6.0m of the skating starts of 69 male subjects. Data were collected on three skating start criteria, three structural variables, and twelve performance variables measured over the first three strides of the start. Summary statistics were generated and Pearson product moment correlation analysis was used to assess relationships between the criteria and performance variables. In addition, stepwise multiple regression analysis was used to predict time to skate 6.0m from a combination of the structural and performance variables. Results revealed that the mean time taken to skate 6.0m was 1.95 sec; the mean instantaneous velocity at the 6.0 mark was 5.75 m/s; and the mean average acceleration over 6.0m was 2.96m/s². Evaluation of correlation coefficients, the regression model and summary statistics resulted in several conclusions: (1) There is a statistically significant positive relationship between velocity attained and the average rate of acceleration over a 6.0m distance in a front style skating start. (2) There are statistically significant negative relationships between both mean acceleration and final instantaneous velocity, and the time taken to skate 6.0m in a front style skating start. (3) In general, the stride pattern associated with a high rate of acceleration and a minimal skating time in a front style skating start includes: a high stride rate, significant forward lean at the point of touchdown of the recovery skate, short single support periods, and placement of the recovery foot below the hip of the recovery leg at the end of the single support period.