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.     

The movement of the trunk and breast during front crawl and breaststroke swimming

Breast displacement has been investigated in various activities to inform bra design, with the goal of minimising movement; however, breast motion during swimming has yet to be considered. The aim was to investigate trunk and breast kinematics whilst wearing varying levels of breast support during two swimming strokes. Six larger-breasted females swam front crawl and breaststroke (in a swimming flume), in three breast support conditions while three video cameras recorded the motion of the trunk and right breast. Trunk and relative breast kinematics were calculated. Greater breast displacement occurred mediolaterally in the swimsuit condition (7.8, s = 1.5 cm) during front crawl and superioinferiorly in the bare-breasted condition (3.7, s = 1.6 cm) during breaststroke, with the sports bra significantly reducing breast displacements. During front crawl, the greatest trunk roll occurred in the sports bra condition (43.1, s = 8.3°) and during breaststroke greater trunk extension occurred in the swimsuit condition (55.4, s = 5.0°); however, no differences were found in trunk kinematics between the three breast support conditions. Results suggest that the swimsuit was ineffective as a means of additional support for larger-breasted women during swimming; incorporating design features of sports bras into swimsuits may improve the breast support provided.     

A quantitative evaluation of the high elbow technique in front crawl

Many coaches often instruct swimmers to keep the elbow in a high position (high elbow position) during early phase of the underwater stroke motion (pull phase) in front crawl, however, the high elbow position has never been quantitatively evaluated. The aims of this study were (1) to quantitatively evaluate the “high elbow” position, (2) to clarify the relationship between the high elbow position and required upper limb configuration and (3) to examine the efficacy of high elbow position on the resultant swimming velocity. Sixteen highly skilled and 6 novice male swimmers performed 25 m front crawl with maximal effort and their 3-dimensional arm stroke motion was captured at 60 Hz. An attempt was made to develop a new index to evaluate the high elbow position (I_he: high elbow index) using 3-dimensional coordinates of the shoulder, elbow and wrist joints. I_he of skilled swimmers moderately correlated with the average shoulder internal rotation angle (r = ?0.652, P < 0.01) and swimming velocity (r = ?0.683, P < 0.01) during the pull phase. These results indicate that I_he is a useful index for evaluating high elbow arm stroke technique during the pull phase in front crawl.     

A new device for estimating active drag in swimming at maximal velocity

A new device was designed to measure the active drag during maximal velocity swimming based on the assumption of equal useful power output in two cases: with and without a small additional drag. A gliding block was used to provide an adjustable drag, which was attached to the swimmer and measured by a force transducer. Six swimmers of national standard (3 males, 3 females) participated in the test. For the males, the mean active drag ranged from 48.57 to 105.88 N in the front crawl and from 54.14 to 76.37 N in the breaststroke. For the females, the mean active drag ranged from 36.31 to 50.27 N in the front crawl and from 36.25 to 77.01 N in the breaststroke. During testing, the swimmer's natural stroke and kick were not disturbed. We conclude that the device provides a useful method for measuring and studying active drag.     

Multiple modulation torque planning for a new golf-swing robot with a skilful wrist turn

A new golf-swing robot that included a feed-forward controller in the shoulder joint and a passive wrist joint was suggested in previous studies to more closely model a skilful golfer. In this study, multiple modulation torque planning for a new golf-swing robot that is capable of modelling a skilful golfer’s swing with a delayed wrist turn was analytically examined. The twostep modulation torque included the effects of whole-body motion on shoulder acceleration, which improved the efficiency index of the swing motion and the club head speed at impact with a correctly timed wrist turn. In addition, it was demonstrated that the optimum moment of inertia and optimum design of club shaft rigidity for several types of golfers could be determined by torque planning in a virtual performance test.     

Changes in kinematics and arm–leg coordination during a 100-m breaststroke swim

The purpose of this study was to compare arm–leg coordination and kinematics during 100 m breaststroke in 26 (8 female; 18 male) specialist breaststroke swimmers. Laps were recorded using three 50-Hz underwater cameras. Heart rate and blood lactate were measured pre- and post-swim. Arm–leg coordination was defined using coordination phases describing continuity between recovery and propulsive phases of upper and lower limbs: coordination phase 1 (time between end of leg kick and start of the arm pull phases); and coordination phase 2 (time between end of arm pull and start of leg kick phases). Duration of stroke phases, coordination phases, swim velocity, stroke length (SL), stroke rate (SR) and stroke index (SI) were analysed during the last three strokes of each lap that were unaffected by turning or finishing. Significant changes in velocity, SI and SL (P < 0.05) were found between laps. Both sexes showed significant increase (P < 0.05) in heart rate and blood lactate pre- to post-swim. Males had significantly (P < 0.01) faster swim velocities resulting from longer SLs (P = 0.016) with no difference in SR (P = 0.064). Sex differences in kinematic parameters can be explained by anthropometric differences providing males with increased propelling efficiency.     

An analysis of selected kinematic variables in national and elite male and female 100-m and 200-m breaststroke swimmers

The kinematic analysis of competition breaststroke swimming has tended to focus on the mean values of swimming speed, stroke rate and stroke length; values in individual lengths, as well as the start, turns and finish, have largely been ignored. This study includes all such variables and aims to improve the coach's holistic understanding of breaststroke racing by determining the relationships and differences between and within these selected kinematic variables. We also compare 100-m events with 200-m events to determine if there are characteristic differences between them. Competitive breaststroke swimming performances in 100-m events (males: n = 159, finishing time = 65.05 +/- 2.62 s; females: n = 158, finishing time = 74.04 +/- 3.66 s) and 200-m events (males: n = 159, finishing time = 141.47 +/- 6.15 s; females: n = 158, finishing time = 158.66 +/- 7.87 s) were collected and analysed from 12 world, international and national championships. The better 100-m and 200-m breaststroke swimmers were found to demonstrate greater competency in the kinematic variables measured, except stroke kinematics, which were unique to each individual. These findings suggest that coaches should place emphasis on all of the kinematic components in training and that they should attempt to identify the stroke rate to stroke length ratio most appropriate for the individual. Finally, characteristic differences do exist between the 100-m and 200-m events, which has implications for how swimmers might train for each event.     

An analysis of selected kinematic variables in national and elite male and female 100-m and 200-m breaststroke swimmers

The kinematic analysis of competition breaststroke swimming has tended to focus on the mean values of swimming speed, stroke rate and stroke length; values in individual lengths, as well as the start, turns and finish, have largely been ignored. This study includes all such variables and aims to improve the coach's holistic understanding of breaststroke racing by determining the relationships and diff erences between and within these selected kinematic variables. We also compare 100-m events with 200-m events to determine if there are characteristic diff erences between them. Competitive breaststroke swimming performances in 100-m events (males: n = 159, finishing time = 65.05 - 2.62 s; females: n = 158, finishing time = 74.04 - 3.66 s) and 200-m events (males: n = 159, finishing time = 141.47 - 6.15 s; females: n = 158, finishing time = 158.66 - 7.87 s) were collected and analysed from 12 world, international and national championships. The better 100-m and 200-m breaststroke swimmers were found to demonstrate greater competency in the kinematic variables measured, except stroke kinematics, which were unique to each individual. These findings suggest that coaches should place emphasis on all of the kinematic components in training and that they should attempt to identify the stroke rate to stroke length ratio most appropriate for the individual. Finally, characteristic diff erences do exist between the 100-m and 200-m events, which has implications for how swimmers might train for each event.     

一些训练手段和技术对国家游泳队运动员肩痛影响的调查与分析

采用问卷调查法和访问调查法调查访问了81名国家游泳队运动员和15名国家游泳队教练。结果发现：国家游泳队运动员肩痛患病率为39．5%,男女之间无显著性差异。肩痛患病率最高的是蝶泳运动员(63．6%),其次是自由泳和仰泳运动员,蛙泳运动员肩痛患病率最低(31．3%)：水上训练手段中,短距离高强度戴划手掌训练、长距离中低强度戴划手掌训练和水上铁片牵引训练对肩痛的影响程度列前3位(明显影响率分别为46．7%、25%和18．2%)；陆上训练手段中,铁片拉力训练、卧推练习和等动拉力训练对肩痛的影响程度列前3位(明显影响率分别为43：8%、36．7%和19．4%)。陆上铁片拉力训练时采用高肘技术、抓水时早发力早加速后划技术和陆上铁片拉力训练时后划到底技术是前3位对国家游泳队运动员肩痛有影响的技术动作(明显影响率分别为60%、40%和33．3%)。     

The Construct and Concurrent Validity of a 12-Minute Crawl Stroke Swim as a Field Test of Swimming Endurance

This study investigated the construct and concurrent validity of a 12-minute crawl stroke swim as a field test of swimming endurance. A sample of 42 male college students who ranged from certified life savers to competitive swimmers were administered three tests. The first, a multistage swimming endurance test, required that a tethered subject swim to exhaustion under a linear progressive increase in workload. The second measure was the crawl stroke count for two lengths of a 25-yard pool. The third test was a 12-minute crawl stroke swim for distance with total distance and distance covered each minute recorded for each subject. Alpha factor analysis of the 12 minute intervals of the crawl stroke swim produced one factor which demonstrated that swimming performance was internally consistent during the 12-minute swim. There was a correlation of .898 (p < .01) between the 12-minute swim and the tethered swim test. Cross validity procedures demonstrated a high degree of stability for the correlation between the 12-minute swim and the tethered swim and for resulting regression statistics. The construct validity was established for both the multistage test and the 12-minute swim using the known groups approach. On the basis of the data the 12-minute swim is a valid field test for swimming endurance for the population studied.     

The influence of the hand’s acceleration and the relative contribution of drag and lift forces in front crawl swimming

The aim of this study was to assess the effect of the hand’s acceleration on the propulsive forces and the relative contribution of the drag and lift on their resultant force in the separate phases of the front crawl underwater arm stroke. Ten female swimmers swam one trial of all-out 25-m front crawl. The underwater motion of each swimmer’s right hand was recorded using four camcorders and four periscope systems. Anatomical landmarks were digitised, and the propulsive forces generated by the swimmer’s hand were estimated from the kinematic data in conjunction with hydrodynamic coefficients. When the hand’s acceleration was taken into account, the magnitude of the propulsive forces was greater, with the exception of the mean drag force during the final part of the underwater arm stroke. The mean drag force was greater than the mean lift force in the middle part, while the mean lift force was greater than the mean drag force in the final part of the underwater arm stroke. Thus, swimmers should accelerate their hands from the beginning of their backward motion, press the water with large pitch angles during the middle part and sweep with small pitch angles during the final part of their underwater arm stroke.     

Muscle coordination,activation and kinematics of world-class and elite breaststroke swimmers during submaximal and maximal efforts

The aims of this study were to describe muscular activation patterns and kinematic variables during the complete stroke cycle (SC) and the different phases of breaststroke swimming at submaximal and maximal efforts. Surface electromyography (sEMG) was collected from eight muscles in nine elite swimmers; five females (age 20.3 ± 5.4 years; Fédération Internationale de Natation [FINA] points 815 ± 160) and four males (27.7 ± 7.1 years; FINA points 879 ± 151). Underwater cameras were used for 3D kinematic analysis with automatic motion tracking. The participants swam 25 m of breaststroke at 60%, 80% and 100% effort and each SC was divided into three phases: knee extension, knee extended and knee flexion. With increasing effort, the swimmers decreased their SC distance and increased their velocity and stroke rate. A decrease during the different phases was found for duration during knee extended and knee flexion, distance during knee extended and knee angle at the beginning of knee extension with increasing effort. Velocity increased for all phases. The mean activation pattern remained similar across the different effort levels, but the muscles showed longer activation periods relative to the SC and increased integrated sEMG (except trapezius) with increasing effort. The muscle activation patterns, muscular participation and kinematics assessed in this study with elite breaststroke swimmers contribute to a better understanding of the stroke and what occurs at different effort levels. This could be used as a reference for optimising breaststroke training to improve performance.     

Influence of short-term inertial training on swimming performance in young swimmers

The aim of this study was to evaluate the influence of dry-land inertial training (IT) on muscle force, muscle power, and swimming performance. Fourteen young, national-level, competitive swimmers were randomly divided into IT and control (C) groups. The experiment lasted four weeks, during which time both groups underwent their regular swimming training. In addition, the IT group underwent IT using the Inertial Training Measurement System (ITMS) three times per week. The muscle groups involved during the upsweep phase of the arm stroke in front crawl and butterfly stroke were trained. Before and after training, muscle force and power were measured under IT conditions. Simultaneously with the biomechanical measurements on the ITMS, the electrical activity of the triceps brachii was registered. After four weeks of training, a 12.8% increase in the muscle force and 14.2% increase in the muscle power (p?<?.05) were noted in the IT group. Moreover, electromyography amplitude of triceps brachii recorded during strength measurements increased by 22.7% in the IT group. Moreover, swimming velocity in the 100?m butterfly and 50?m freestyle improved significantly following the four weeks of dry-land IT (?1.86% and ?0.76%, respectively). Changes in the C group were trivial. Moreover, values of force and power registered during the ITMS test correlated negatively with the 100?m butterfly and 50?m freestyle swimming times (r value ranged from ?.80 to ?.91). These results suggest that IT can be useful in swimming practice.     

Effect of swimming velocity on arm coordination in the front crawl: a dynamic analysis

We examined the preferred mode of arm coordination in 14 elite male front-crawl swimmers. Each swimmer performed eight successive swim trials in which target velocity increased from the swimmer's usual 3000-m velocity to his maximal velocity. Actual swim velocity, stroke rate, stroke length and the different arm stroke phases were then calculated from video analysis. Arm coordination was quantified by an index of coordination based on the lag time between the propulsive phases of each arm. The index expressed the three coordination modes in the front crawl: opposition, catch-up and superposition. First, in line with the dynamic approach to movement coordination, the index of coordination could be considered as an order parameter that qualitatively captured arm coordination. Second, two coordination modes were observed: a catch-up pattern (index of coordination?=??8.43%) consisting of a lag time between the propulsive phases of each arm, and a relative opposition pattern (index of coordination?=?0.89%) in which the propulsive phase of one arm ended when the propulsive phase of the other arm began. An abrupt change in the coordination pattern occurred at the critical velocity of 1.8?m?·?s^?1, which corresponded to the 100-m pace: the swimmers switched from catch-up to relative opposition. This change in coordination resulted in a reorganization of the arm phases: the duration of the entry and catch phase decreased, while the duration of the pull and push phases increased in relation to the whole stroke. Third, these changes were coupled to increased stroke rate and decreased stroke length, indicating that stroke rate, stroke length, the stroke rate/stroke length ratio, as well as velocity, could be considered as control parameters. The control parameters can be manipulated to facilitate the emergence of specific coordination modes, which is highly relevant to training and learning. By adjusting the control and order parameters within the context of a specific race distance, both coach and swimmer will be able to detect the best adapted pattern for a given race pace and follow how arm coordination changes over the course of training.     

The effect of wet suit use by triathletes: an analysis of the different phases of arm movement

We analysed stroke phases and arm and leg coordination during front crawl swimming with and without a wet suit. Twelve nationally and internationally ranked French male triathletes performed three swim trials in randomized order using the front crawl stroke with and without a wet suit. All triathletes swam at three different swim velocities, corresponding to the paces appropriate for the 800?m (V800), 100?m (V100) and 50?m (V50) events. The different stroke phases and arm and leg coordination were identified by video analysis. Arm coordination was quantified using a new index of coordination, which expresses the three major modalities of opposition, catch-up and superposition in swimming. At all swim velocities, no significant differences in leg movements with or without the wet suit were noted. However, the wearing of the wet suit was associated with a significantly greater stroke length at the paces appropriate for the 100 and 50?m events (+3.46% and +3.10% at V100 and V50, respectively; P?<0.01); a significantly greater stroke index at all three velocities (+5.18%, +5.21% and +5.91% at V800, V100 and V50, respectively; P?<0.01); a significantly shorter pulling phase (?10.97%; P?<0.05) and lower index of coordination (?21.87%; P?<0.01) at the pace appropriate for the 800?m; and a significantly greater entry and catch phase (+9.81%; P?<0.05) at the pace appropriate for the 100?m. We conclude that the wet suit amplified the coordination mode of the triathletes (i.e. catch-up coordination) without modifying stroke rate, recovery phase or leg movements.     

Quantitative understanding of the fly casting stroke through measurements and robotic casting

A stumbling point for many learning to fly fish is being able to fly cast well enough to ‘present’ a fly to a feeding fish. Even among more skilled fly fishers, learning to fly cast better is often a bottleneck towards advancement in the sport. Fly casting instruction today relies on the visual inspection of the fly casting stroke and the resulting ‘loop’ of fly line. These qualitative visual cues help fly casting instructors spot the strengths and weakness in a student’s casting stroke. We introduce two novel technologies for fly casting instruction that result in aquantitative understanding of the fly casting stroke. In particular, we describe a novel robot that is able to replicate standard overhead casts. This achievement is made possible by measuring the casting stroke using a small (MEMS) rate gyro to record the angular velocity of the fly rod in the casting plane. The robot is then programmed to replicate this angular velocity history. Potential uses of this robot include an objective means to assess fly rod, fly line and leader designs, as well as new methods for fly casting instruction.     

Relationship between shoulder roll and hand propulsion in the front crawl stroke

This study re-evaluated the magnitude of hand propulsion (HP) in the pull and push phases of the front crawl stroke and investigated the association between the angular velocity of shoulder roll (ω_SR) and hand propulsive lift (HP_L). ω_SR was computed in the plane normal to a forward direction for 16 skilled swimmers performing the front crawl stroke at a maximal sprinting pace. HP, hand propulsive drag (HP_D) and HP_L were determined by a dynamic pressure approach. HP and HP_D in the pull phase were greater than in the push phase (P < 0.05) while HP_L in the pull phase was similar to that in the push phase. Eleven swimmers out of the 16 swimmers had a significant within-swimmers correlation between ω_SR and HP_L in the push phase (P < 0.05). That is, HP_L increased in the push phase as the ω_SR of rolling back to the neutral position became faster. A swimmer should use more drag for hand propulsion in the pull phase and propulsion from drag and lift equally in the push phase. Based on the relationship between ω_SR and HP_L in the push phase, a possible stroke technique to enhance HP_L using ω_SR is discussed.     

Effect of swimming velocity on arm coordination in the front crawl: a dynamic analysis

We examined the preferred mode of arm coordination in 14 elite male front-crawl swimmers. Each swimmer performed eight successive swim trials in which target velocity increased from the swimmer's usual 3000-m velocity to his maximal velocity. Actual swim velocity, stroke rate, stroke length and the different arm stroke phases were then calculated from video analysis. Arm coordination was quantified by an index of coordination based on the lag time between the propulsive phases of each arm. The index expressed the three coordination modes in the front crawl: opposition, catch-up and superposition. First, in line with the dynamic approach to movement coordination, the index of coordination could be considered as an order parameter that qualitatively captured arm coordination. Second, two coordination modes were observed: a catch-up pattern (index of coordination= -8.43%) consisting of a lag time between the propulsive phases of each arm, and a relative opposition pattern (index of coordination= 0.89%) in which the propulsive phase of one arm ended when the propulsive phase of the other arm began. An abrupt change in the coordination pattern occurred at the critical velocity of 1.8 m. s(-1), which corresponded to the 100-m pace: the swimmers switched from catch-up to relative opposition. This change in coordination resulted in a reorganization of the arm phases: the duration of the entry and catch phase decreased, while the duration of the pull and push phases increased in relation to the whole stroke. Third, these changes were coupled to increased stroke rate and decreased stroke length, indicating that stroke rate, stroke length, the stroke rate/stroke length ratio, as well as velocity, could be considered as control parameters. The control parameters can be manipulated to facilitate the emergence of specific coordination modes, which is highly relevant to training and learning. By adjusting the control and order parameters within the context of a specific race distance, both coach and swimmer will be able to detect the best adapted pattern for a given race pace and follow how arm coordination changes over the course of training.     

Effect of swim speed on leg-to-arm coordination in unilateral arm amputee front crawl swimmers

The aim of this study was to examine the effect of swimming speed on leg-to-arm coordination in competitive unilateral arm amputee front crawl swimmers. Thirteen well-trained swimmers were videotaped underwater during three 25-m front crawl trials (400 m, 100 m and 50 m pace). The number, duration and timing of leg kicks in relation to arm stroke phases were identified by video analysis. Within the group, a six-beat kick was predominantly used (n = 10) although some swimmers used a four-beat (n = 2) or eight-beat kick (n = 1). Swimming speed had no significant effect on the relative duration of arm stroke and leg kick phases. At all speeds, arm stroke phases were significantly different (P < 0.05) between the affected and unaffected sides. In contrast, the kicking phases of both legs were not different. Consequently, leg-to-arm coordination was asymmetrical. The instant when the leg kicks ended on the affected side corresponded with particular positions of the unaffected arm, but not with the same positions of the affected arm. In conclusion, the ability to dissociate the movements of the arms from the legs demonstrates that, because of their physical impairment, unilateral arm amputee swimmers functionally adapt their motor organisation to swim front crawl.     

对我国男子蛙泳项目划频、划幅的分析

通过划频、划幅的技术数据与世界水平对比、分析,从中找出我国选手与外国选手间的差异,为我国选手在蛙泳训练中提供参考依据。