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1.
Abstract

The objective of this study was to determine the relationship between different variables measured with a force plate during the swimming start push-off phase and start performance presented by times to 5, 10 and 15?m. Twenty-one women from the Slovenian national swimming team performed two different swim starts (freestyle and undulatory) on a portable force plate to a distance further than 15?m. Correlations between push-off variables and times to 5, 10 and 15?m were quantified through Pearson's product-moment correlation coefficient (r). The variables that significantly correlated (p?<?.05) to all times measured in the two starts performed were: average horizontal acceleration (freestyle: r?=??0.58 to ?0.71; and undulatory: r?=??0.55 to ?0.66), horizontal take-off velocity (freestyle: r?=??0.56 to ?0.69; and undulatory: r?=??0.53 to ?0.67) and resultant take-off velocity (freestyle: r?=??0.53 to ?0.65; and undulatory: r?=??0.52 to ?0.61). None of the variables derived from the vertical force were correlated to swimming start performance (p?>?.05). Based on the results of this study, we can conclude that horizontal take-off velocity and average horizontal acceleration (calculated as the average horizontal force divided by swimmer's body mass) are the variables most related to swimming start performance in experienced swimmers, and therefore could be the preferred measures to monitor swimmers’ efficiency during the push-off phase.  相似文献   

2.
This study investigated the effects of different reduced strength training (RST) frequencies on half-squat 1 RM and quadriceps cross-sectional area (QCSA). Thirty-three untrained males (24.7?±?3.9 years; 1.73?±?0.08?m; 74.6?±?8.4?kg) underwent a 16-week experimental period (i.e. eight weeks of strength training [ST] followed by additional eight weeks of RST). During the ST period, the participants performed 3–4 sets of 6–12 RM, three sessions/week in half-squat and knee extension exercises. Following ST, the participants were randomly allocated to one of three groups: reduced strength training with one (RST1) or two sessions per week (RST2), and ceased training (CT). Both RST1 and RST2 groups had their training frequency and total training volume-load (i.e. RST1?=?50.3% and RST2?=?57.1%) reduced, while the CT group stopped training completely. Half-squat 1 RM (RST1?=?27.9%; RST2?=?26.7%; and CT?=?28.4%) and QCSA (RST1?=?6.1%; RST2?=?6.9%; and CT?=?5.8%) increased significantly (p?<?.05) in all groups after eight weeks of ST. No significant changes were observed in 1 RM and QCSA for RST1 and RST2 groups after the RST period, while the CT group demonstrated a decrease in half-squat 1 RM (22.6%) and QCSA (5.4%) when compared to the ST period (p?<?.05). In conclusion, different RST frequencies applied were able to maintain muscle mass and strength performance obtained over the regular ST period. Thus, it appears that RST frequency does not affect the maintenance of muscle mass and strength in untrained males, as long as volume-load is equated between frequencies.  相似文献   

3.
The purpose of this study was to learn the interplay between dry-land strength and conditioning, and stroke biomechanics in young swimmers, during a 34-week training programme. Twenty-seven swimmers (overall: 13.33?±?0.85 years old; 11 boys: 13.5?±?0.75 years old; 16 girls: 13.2?±?0.92 years old) competing at regional- and national-level competitions were evaluated. The swimmers were submitted to a specific in-water and dry-land strength training over 34 weeks (and evaluated at three time points: pre-, mid-, and post-test; M1, M2, and M3, respectively). The 100-m freestyle performance was chosen as the main outcome (i.e. dependent variable). The arm span (AS; anthropometrics), throwing velocity (TV; strength), stroke length (SL), and stroke frequency (SF; kinematics) were selected as independent variables. There was a performance enhancement over time (M1 vs. M3: 68.72?±?5.57?s, 66.23?±?5.23?s; Δ?=??3.77%; 95% CI: ?3.98;?3.56) and an overall improvement of the remaining variables. At M1 and M2, all links between variables presented significant effects (p?p?≤?.05). Between M1 and M3, the direct effect of the TV to the stroke biomechanics parameters (SL and SF) increased. The model predicted 89%, 88%, and 92% of the performance at M1, M2, and M3, respectively, with a reasonable adjustment (i.e. goodness-of-fit M1: χ2/df?=?3.82; M2: χ2/df?=?3.08; M3: χ2/df?=?4.94). These findings show that strength and conditioning parameters have a direct effect on the stroke biomechanics, and the latter one on the swimming performance.  相似文献   

4.
This investigation examined effects of two exercise modes (barbell, BB; bodyweight suspension, BWS) on muscle activation, resistance load, and fatigue. During session one, nine resistance-trained males completed an elbow flexion one-repetition maximum (1RM). During sessions two and three, subjects completed standing biceps curls to fatigue at 70% 1RM utilizing a randomized exercise mode. Surface electromyography (sEMG) recorded muscle activation of the biceps brachii, triceps brachii, anterior deltoid, posterior deltoid, rectus abdominis, and erector spinae. BWS resistance load was measured using a force transducer. Standing maximal voluntary isometric contractions of the elbow flexors recorded at 90° were used to determine the isometric force decrement and rate of fatigue (ROF) during exercise. sEMG and resistance load data were divided into 25% contraction duration bins throughout the concentric phase. BWS resulted in a 67.7?±?7.4% decline in resistance load throughout the concentric phase (p?≤?0.05). As a result, BB elicited higher mean resistance loads (31.4?±?4.0?kg) and biceps brachii sEMG (84.7?±?27.8% maximal voluntary isometric contractions, MVIC) compared with BWS (20.4?±?3.4?kg, 63.4?±?21.6% MVIC). No difference in rectus abdominis or erector spinae sEMG was detected between exercise modes. Isometric force decrement was greater during BWS (?21.7?±?7.0?kg) compared with BB (?14.9?±?4.7?kg); however, BB (?3.0?±?0.8?kg/set) resulted in a steeper decline in ROF compared with BWS (?1.7?±?0.6?kg/set). The variable resistance loading and greater isometric force decrement observed suggest that select BWS exercises may resemble variable resistance exercise more than previously considered.  相似文献   

5.
The purpose of this study was to compare one-repetition maximum (1-RM) and muscle activity in three chest-press exercises with different stability requirements (Smith machine, barbell, and dumbbells). Twelve healthy, resistance-trained males (age 22.7 ± 1.7 years, body mass 78.6 ± 7.6 kg, stature 1.80 ± 0.06 m) were tested for 1-RM of the three chest-press exercises in counterbalanced order with 3-5 days of rest between the exercises. One-repetition maximum and electromyographic activity of the pectoralis major, deltoid anterior, biceps, and triceps brachii were recorded in the exercises. The dumbbell load was 14% less than that for the Smith machine (P ≤ 0.001, effect size [ES] = 1.05) and 17% less than that for the barbell (P ≤ 0.001, ES = 1.11). The barbell load was ～3% higher than that for the Smith machine (P = 0.016, ES = 0.18). Electrical activity in the pectoralis major and anterior deltoid did not differ during the lifts. Electrical activity in the biceps brachii increased with stability requirements (i.e. Smith machine 相似文献   

6.
The aim of this study was to examine the influence of level of skill and swimming speed on inter-limb coordination of freestyle swimming movements. Five elite (2 males, 3 females; age 18.9?±?1.0 years, height 1.71?±?0.04?m, body mass 62.1?±?7.0?kg) and seven novice (age 22.0?±?2.0 years, height 1.77?±?0.04?m, body mass 74.8?±?9.0?kg) swimmers swam a sprint and a self-paced 25?m freestyle trial. The swimming trials were recorded by four digital cameras operating at 50 Hz. The digitized frames underwent a three-dimensional direct linear transformation to yield the three-dimensional endpoint kinematic trajectories. The spatio-temporal relationship between the upper limbs was quantified by means of the peak amplitude and time lag of the cross-correlation function between the right and left arm's endpoint trajectories. A strong anti-phase coupling between the two arms, as confirmed by peak amplitudes greater than 0.8, was noted for both groups and swimming speeds. Significantly higher (P <?0.05) peak amplitudes were observed for the sprint compared with self-paced swimming. No significant differences in the strength of inter-limb coupling were noted between the elite and novice swimmers (P >?0.05). Time lags were very close to 0?ms and did not differ between groups or swimming speeds. We conclude that in freestyle swimming, the intrinsic anti-phase (180° phase difference) inter-limb relationship is strongly preserved despite the physically powerful environmental influence of the water and this “preferred” pattern is not affected by level of skill. In contrast, increasing movement speed results in stronger inter-limb coupling that is closer to the anti-phase inter-limb relationship.  相似文献   

7.
The main objectives of the present research were (1) to examine the relationships between the distances travelled underwater during the start and turn segments with swimming race performance at the elite level and (2) to determine if the individualised-distance start and turn parameters affect the overall race performance. The race parameters of the 100 and 200?m events during 2013 World Championships were measured by an innovative image-processing system (InThePool® 2.0). Overall, 100?m race times were largely related to faster start velocities in men's breaststroke and freestyle events. Conversely, overall, 200?m race times were largely related to longer starting distances in the women's butterfly events, to longer turn distances in men's and women's backstroke and women's butterfly events and to shorter turn distances in women's freestyle events. Changes on the start or turn velocities could represent moderate time improvements in most of the 100?m events, whereas modifications on the start or turn distances (especially in the last turn) could provide elite swimmers with time improvements of practical importance on the 200?m events. The evaluation of races by individualised-distance parameters should be provided to elite swimmers in order to decide the most appropriate race segment configuration for each event.  相似文献   

8.
目的:研究我国优秀男子拳击运动员后手直拳出拳击打环节相关肌群的sEMG特征及其相应的运动学变化,为拳击专项力量训练提供参考.方法:通过表面肌电和三维红外高速摄像系统同步测试方法,采集6名高水平男子拳击运动员后手直拳出拳击打环节表面肌电和运动学的相关数据.结果:1)出拳击打环节,肌肉活动顺序为:腓肠肌→股二头肌→三角肌前束→肱三头肌→肱二头肌长头→肱桡肌.2)击打过程中三角肌前束、肱二头肌和肱三头肌肉在相应时间位置上出现明显的预激活和共收缩现象.3)肌肉做功百分比排序为:三角肌前束＞肱三头肌＞股二头肌＞腓肠肌＞肱桡肌＞肱二头肌长头,aEMG计算结果与肌肉做功百分比保持相一致的趋势.4)肩关节、上臂环节质心和拳心速度的峰值在击打过程中呈现次序性.结论:拳击后直拳出拳击打环节所选肌肉活动呈现从下肢向上肢激活的次序性.击打过程中三角肌前束、肱二头肌和肱三头肌肉在相应时间位置上出现的预激活和共收缩现象可能是反映运动员技术水平和特点的指标.在肌肉做功百分比和aEMG方面,三角肌前束、肱三头肌和股二头肌在动作过程中表现出相对重要的地位.上肢相关肌群的活动次序与肩关节、上臂环节质心和拳心速度变化的时序性有着合理的解剖学相关,是产生上肢开放链鞭打动作的根本原因.  相似文献   

9.
目的：为游泳运动员在水槽中进行水感表型强化训练提供参考和建议。方法：将上海市14名一级男性游泳运动员随机分为两组，A组为实验组，B组为对照组。A组每周安排3次水槽中的水感训练课，B组采用常规的泳池训练，保证两组的训练量一致，实验周期为20周。运用上海市游泳水槽系统的三线运动分析系统对运动员训练前后的技术动作进行分析与诊断，运用Tritonwear游泳运动表现分析系统对运动员训练前后50m自由泳成绩和游效指数进行分析。结果：A组与B组运动员经过一段时间的训练后，50 m自由泳成绩和游效指数都较实验前有了一定的提高；而且A组的50 m自由泳成绩和游效指数相比较B组都得到了明显的提高，实验后A组和B组队员的50 m自由泳成绩和游效指数存在显著性差异。结论：通过水槽中水感表型的多种训练方法，运动员的技术动作得到了改进，划水效果得到了提高，运动成绩也得到了提高。对水感的定量研究是我们未来的研究方向，后期还需要更加深入的研究。  相似文献   

10.
通过对18名北京体育大学中国游泳运动学院的一级游泳运动员进行陆上瑞士球核心训练和水中瑞士球核心训练，探讨水中瑞士球训练对优秀游泳运动员核心稳定性和运动表现的影响。结果表明，8周陆上和水中瑞士球训练均能显著提高优秀游泳运动员躯干力量、背肌耐力和身体平衡性，改善运动员陆上身体控制和平衡能力，进而改善游泳运动员力量传导的效率，促进躯干和上下肢之间力量的有效转移，提升打腿和划手的效果，提高50 m自由泳运动表现；两种训练对运动员柔韧性和功能性表现无显著影响；水中瑞士球训练对各测试的提升幅度和RPE强度上均高于陆上瑞士球训练，且水中瑞士球训练手段可以更有效提高游泳运动员的50 m自由泳运动表现。  相似文献   

11.
The aim of this study was to determine whether triceps brachii muscle volume can be adequately estimated from a single anatomical cross-sectional area (ACSA) and can the same model be used for prediction after training. Thirty-five healthy male non-athletes (age 21.6 ± 2.5 years, body mass index 24.8 ± 3.5 kg · m(-2)) volunteered for this study. The volumes of the upper arm extensors were calculated from magnetic resonance imaging (MRI) sequence scans and regression models were developed, which were used to predict muscle volumes from single MRI cross-sectional scans taken at different points along the humerus length. The same procedure was repeated after 12 weeks of maximal resistance training of the elbow extensors. Correlation coefficients were calculated for Model A with CSA(max), humerus length (HL), and body mass index (r = 0.919), a model with CSA(50%) and HL (r = 0.922), and a model with CSA(60%) and HL (r = 0.920) (P < 0.001). The standard error of estimate for Model A, Model CSA(50%), and Model CSA(60%) was 8.0%, 7.7%, and 7.8% respectively. Thesame prediction formula can be used for the left arm (r = 0.904). If a single ACSA is used for triceps brachii volume prediction, the best fit is with Model CSA(60%) and HL, both before and after training (r = 0.941). By introducing humerus length into the calculation, we simplify the procedure for volume measurement, since it can be obtained during MRI scanning.  相似文献   

12.
The aim of the present study was to compare the effect of an increasing-distance, interval-training programme and a decreasing-distance, interval-training programme, matched for total distance, on aerobic and anaerobic physiological indices. Forty physical education students were randomly assigned to either the increasing- or decreasing-distance, interval-training group (ITG and DTG), and completed two similar relevant sets of tests before and after six weeks of training. One training programme consisted of increasing-distance interval-training (100–200–300–400–500?m) and the other decreasing-distance interval training (500–400–300–200–100?m). While both training programmes led to a significant improvement in VO2 max (ES?=?0.83–1.25), the improvement in the DTG was significantly greater than in the ITG (14.5?±?3.6 vs. 7.8?±?3.2%, p?<?.05). In addition, while both training programmes led to a significant improvement in all anaerobic indices (ES?=?0.83–1.63), the improvements in peak power (15.7?±?7.8 vs. 8.9?±?4.7), mean power (10.6?±?5.4 vs. 6.8?±?4.4), and fatigue index (18.2?±?10.9 vs. 7.0?±?14.2) were significantly greater in the DTG compared to the ITG (p?<?.05). The main finding of the present study was that beyond the significant positive effects of both training programmes on aerobic and anaerobic fitness, the DTG showed significant superiority over the ITG in improving aerobic and anaerobic performance capabilities. Coaches and athletes should therefore be aware that, in spite of identical total work, an interval-training programme might induce different physiological impacts if the order of intervals is not identical.  相似文献   

13.
The aim of this study was to compute a swimming performance confirmatory model based on biomechanical parameters. The sample included 100 young swimmers (overall: 12.3?±?0.74 years; 49 boys: 12.5?±?0.76 years; 51 girls: 12.2?±?0.71 years; both genders in Tanner stages 1–2 by self-report) participating on a regular basis in regional and national-level events. The 100?m freestyle event was chosen as the performance indicator. Anthropometric (arm span), strength (throwing velocity), power output (power to overcome drag), kinematic (swimming velocity) and efficiency (propelling efficiency) parameters were measured and included in the model. The path-flow analysis procedure was used to design and compute the model. The anthropometric parameter (arm span) was excluded in the final model, increasing its goodness-of-fit. The final model included the throw velocity, power output, swimming velocity and propelling efficiency. All links were significant between the parameters included, but the throw velocity–power output. The final model was explained by 69% presenting a reasonable adjustment (model's goodness-of-fit; x2/df?=?3.89). This model shows that strength and power output parameters do play a mediator and meaningful role in the young swimmers’ performance.  相似文献   

14.
Abstract

The purpose of this study was to compare one-repetition maximum (1-RM) and muscle activity in three chest-press exercises with different stability requirements (Smith machine, barbell, and dumbbells). Twelve healthy, resistance-trained males (age 22.7 ± 1.7 years, body mass 78.6 ± 7.6 kg, stature 1.80 ± 0.06 m) were tested for 1-RM of the three chest-press exercises in counterbalanced order with 3–5 days of rest between the exercises. One-repetition maximum and electromyographic activity of the pectoralis major, deltoid anterior, biceps, and triceps brachii were recorded in the exercises. The dumbbell load was 14% less than that for the Smith machine (P ≤ 0.001, effect size [ES] = 1.05) and 17% less than that for the barbell (P ≤ 0.001, ES = 1.11). The barbell load was ～3% higher than that for the Smith machine (P = 0.016, ES = 0.18). Electrical activity in the pectoralis major and anterior deltoid did not differ during the lifts. Electrical activity in the biceps brachii increased with stability requirements (i.e. Smith machine <barbell <dumbbells; P ≤ 0.005; ES = 0.57, 1.46, and 2.00, respectively), while triceps brachii activity was reduced using dumbbells versus barbell (P = 0.007, ES = 0.73) and dumbbells versus Smith machine (P = 0.003, ES = 0.62). In conclusion, high stability requirements in the chest press (dumbbells) result in similar (pectoralis major and anterior deltoid), lower (triceps brachii) or higher (biceps brachii) muscle activity. These findings have implications for athletic training and rehabilitation.  相似文献   

15.
Abstract

The present investigation verified that strength is improved by a training programme consisting of repetitions of maximal isometric voluntary co-contractions without increasing co-activations during contractions against external resistances. Ten participants performed 12 training sessions (four sets of 6 × 4 second maximal isometric co-contraction of the elbow flexor and extensors, 3 days a week for 4 weeks). Surface electromyograms of triceps and biceps brachii were collected during maximal voluntary isometric elbow flexion and extension against a force transducer. Maximal voluntary isometric force increased significantly after training, by 13.8 ± 6.0% (extension) and 9.6 ± 9.5% (flexion), but the observed increases in EMG of agonist muscles during maximal voluntary contraction were not significant. No significant changes in the levels of co-activation of the elbow flexors and extensors were observed. No significant change was observed for all the parameters in a control group of ten participants. These results indicated that the strength improvements after co-contraction training occur without increases in co-activation level.  相似文献   

16.
Abstract

This study aimed to analyse whether increasing the eccentric overload (EO) during resistance training, in terms of range of motion and/or velocity using an electric-motor device, would induce different muscle adaptations than conventional flywheel-EO resistance training. Forty physically active university students (21.7?±?3.4 years) were randomly placed into one of the three training groups (EX1, EX2, FW) and a control group without training (n?=?10 per group). Participants in the training groups completed 12 sessions (4 sets of 7 repetitions) of iso-inertial single-leg squat training over 6 weeks for the dominant leg. Resistance was generated either by an electric-motor device at two different velocities for the eccentric phase; 100% (EX1) or 150% (EX2) of concentric speed, or by a conventional flywheel device (FW). Thigh lean tissue mass, unilateral leg press one-repetition maximum (1-RM), unilateral muscle power at different percentages of the 1-RM and bilateral/unilateral vertical jump were assessed before and after the 6-week training. There were significant (p?<?0.05–0.001) main effects of time in the 3 training groups, indicating increased thigh lean tissue mass (2.5–5.8%), 1-RM load (22.4–30.2%), vertical jump performance (9.1–32.9%) and muscle power (8.8–21.7%), without differences across experimental groups. Participants in the control group did not improve any of the variables measured. In addition, EX2 showed greater gains in eccentric average peak power during training than EX1 and FW (p?<?0.001). Despite the different EO offered, 6 weeks of resistance training using flywheel or electric-motor devices induced similar significant gains in muscle mass, strength, muscle power and vertical jump.  相似文献   

17.
This study investigated the acute fatigue pattern in neuromuscular activity after a simulated Boccia game and the effect of fatigue pattern on sport performance. Nine elite Boccia athletes were tested before, during, and after a simulated game. Maximum ball speed was captured with video, and the target hitting rate and rating of perceived exertion (RPE) score were collected and analyzed. Electromyography signals from the upper trapezius, anterior deltoid, posterior deltoid, biceps brachii, triceps brachii, and wrist extensor muscles were collected by surface electrode and were evaluated with mean power frequency (MPF). Only the upper trapezius muscle showed fatigue as demonstrated by a reduction of MPF of 8% (p = 0.027) when comparing the first and last throws in a simulated game. Subjective RPE score increased during the game (118%, p = 0.004), and sports performance in terms of maximum ball speed (-12%, p = 0.004) and target hitting rate (-25%, p = 0.004) also deteriorated. In conclusion, fatigue on the upper trapezius muscle was demonstrated in elite Boccia athletes following a prolonged Boccia game and may have affected Boccia performance. Preventative measures against upper trapezius muscle fatigue and endurance training for synergists of the upper trapezius muscle may be considered in future studies.  相似文献   

18.
本文通过对2008年美国、中国、澳大利亚三国游泳冠军赛1500米自由泳决赛运动员成绩进行分析，在揭示优秀1500米自由泳运动员体力分配特点的同时，找出中外运动员在该项目的差异并分析其原因所在，以此为我国1500米自由泳训练提供一定参考。  相似文献   

19.
[目的]：研究运动预适应对过度训练大鼠心肌缺血缺氧形态影响及血清MDA.[方法]：将鼠随机分为安静对照组、一般训练组、过度训练组、运动预适应组.安静对照组常规饲氧,不加干预;一般训练组第1-2w常规饲养,第3-4w进行无负重游泳运动,每次游泳1h/d,每周游泳6天.过度训练组第1-2w常规饲养,第3-4w每天进行一次尾部负重3％体重的负荷进行力竭性游泳,每周游泳6天.运动预适应组第1-2W大鼠每天尾部负重3％体重负荷进行间歇性游泳运动一次,每天游泳15 min,休息5 min,重复3次,6 d/周,周日休息,第3-4周运动与过度训练组的第3-4周训练一致.训练结束后取材,进行常规HE染色和HBEP染色并摄片,测血清MDA.[结果]：HE染色,过度训练组肌纤维排列紊乱,部分肌纤维界限模糊.运动预适应组肌纤维轮廓较清楚.HBEP染色过度训练组有若干片状的红色缺血缺氧部位;运动预适应组心肌缺血缺氧改变程度比过度训练组明显减轻.运动各组大鼠血清MDA均高于安静对照组;过度训练组高于一般训练组和运动预适应组.[结论]：运动预适应可以降低过度训练大鼠血清MDA的含量,对心肌缺血缺氧性损伤产生保护作用.  相似文献   

20.
Ratings of perceived exertion (RPE: 0–10) during resistance training with varying programming demands were examined. Blood lactate (BLa) and muscle activation (using surface electromyography: EMG) were measured as potential mediators of RPE responses. Participants performed three sets of single arm (preferred side) bicep curls at 70% of 1 repetition maximum over 4 trials: Trial (A) 3 sets?×?8 repetitions?×?120?s recovery between sets; (B) 3 sets?×?8 repetitions?×?240?s recovery; (C) 3 sets?×?maximum number of repetitions (MNR)?×?120?s recovery; (D) 3 sets?×?MNR?×?240?s recovery. Overall body (RPE-O) and active muscle (RPE-AM) perceptual responses were assessed following each set in each trial. Biceps brachii and brachioradialis muscle EMG was measured during each set for each trial. RPE-O and RPE-AM were not different between Trial A (3.5?±?1 and 6?±?1, respectively) and Trial B (3.5?±?1 and 5.5?±?1, respectively) (p?p?相似文献   

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