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1.
Forty-eight volunteer males were randomly assigned to one of three groups. Group I trained with isokinetic exercises, Group II trained with plyometric exercises, and Group III was the control. Subjects in the training groups trained three times per week for 8 weeks. The isokinetic group performed three sets of 10 repetitions per set of leg presses each training session. The plyometric group performed three sets of 10 repetitions per set of depth jumps from a height of 34 inches, with added resistance beginning with weeks 3, 5, and 7 of 10, 15, and 20 pounds, respectively. Prior to and at the end of the training period, all subjects were given a vertical jump-and-reach test. Covariance analysis was used to compare posttest scores with the effect of pretest differences removed. Results showed both training groups improved significantly in vertical jump capacity; however, no significant difference existed between training groups.  相似文献   

2.
Plyometric training composed by unilateral exercises with horizontal jumping direction seems to be an effective way to improve physical performance in athletes. The present study aimed to compare the influence of a combined jumping direction and force application (horizontal-unilateral vs. vertical-bilateral) plyometric training on linear sprinting, jumping, change of direction (COD) and dynamic balance in young elite basketball players. Twenty young (U-13 to U-14) male basketball players (age: 13.2?±?0.7 years, body mass: 59.5?±?12.7?kg, height: 172.9?±?7.9?cm) were randomly assigned either to a unilateral-horizontal (UH, n?=?10) or bilateral-vertical (BV, n?=?10) plyometric group, twice a week for 6-wk. Both groups performed between 60 and 100 jumps/session. UH executed all jumps unilaterally with horizontal direction, while jumps in the BV were bilaterally with vertical direction. Performance was assessed by a linear sprinting test, vertical and horizontal jumping tests, COD tests (V-cut and 5+5?m with a 180°COD test), an ankle dorsiflexion test and dynamic balance tests (anterior and postero-lateral directions). Within-group differences showed substantial improvements (Effect size (ES):0.31–1.01) in unilateral vertical and horizontal jumping, V-cut test and postero-lateral direction with right leg after both training interventions. Furthermore, UH group also substantially improved (ES:0.33–0.78) all sprinting times and postero-lateral direction with left leg, while BV enhanced anterior direction with left leg (ES:0.25). Between-group analyses showed substantially greater improvements (ES:0.33) in 10-m and V-cut test in UH than in BV. The likely beneficial effect (small ES) achieved in sprinting abilities suggests the combination of unilateral-horizontal jumps to improve such abilities.  相似文献   

3.
Abstract

An increase in the period over which a muscle generates force can lead to the generation of greater force and, therefore, for example in jumping, to greater jump height. The aim of this study was to examine the effect of squat depth on maximum vertical jump performance. We hypothesized that jump height would increase with increasing depth of squat due to the greater time available for the generation of muscular force. Ten participants performed jumps from preferred and deep squat positions. A computer model simulated jumps from the different starting postures. The participants showed no difference in jump height in jumps from deep and preferred positions. Simulated jumps produced similar kinematics to the participants' jumps. The optimal squat depth for the simulated jumps was the lowest position the model was able to jump from. Because jumping from a deep squat is rarely practised, it is unlikely that these jumps were optimally coordinated by the participants. Differences in experimental vertical ground reaction force patterns also suggest that jumps from a deep squat are not optimally coordinated. These results suggest there is the potential for athletes to increase jump performance by exploiting a greater range of motion.  相似文献   

4.
An increase in the period over which a muscle generates force can lead to the generation of greater force and, therefore, for example in jumping, to greater jump height. The aim of this study was to examine the effect of squat depth on maximum vertical jump performance. We hypothesized that jump height would increase with increasing depth of squat due to the greater time available for the generation of muscular force. Ten participants performed jumps from preferred and deep squat positions. A computer model simulated jumps from the different starting postures. The participants showed no difference in jump height in jumps from deep and preferred positions. Simulated jumps produced similar kinematics to the participants' jumps. The optimal squat depth for the simulated jumps was the lowest position the model was able to jump from. Because jumping from a deep squat is rarely practised, it is unlikely that these jumps were optimally coordinated by the participants. Differences in experimental vertical ground reaction force patterns also suggest that jumps from a deep squat are not optimally coordinated. These results suggest there is the potential for athletes to increase jump performance by exploiting a greater range of motion.  相似文献   

5.
Abstract

The purpose of this study was to determine the influence of lumbar spine extension and erector spinae muscle activation on vertical jump height during maximal squat jumping. Eight male athletes performed maximal squat jumps. Electromyograms of the erector spinae were recorded during these jumps. A simulation model of the musculoskeletal system was used to simulate maximal squat jumping with and without spine extension. The effect on vertical jump height of changing erector spinae strength was also tested through the simulated jumps. Concerning the participant jumps, the kinematics indicated a spine extension and erector spinae activation. Concerning the simulated jumps, vertical jump height was about 5.4 cm lower during squat jump without trunk extension compared to squat jump. These results were explained by greater total muscle work during squat jump, more especially by the erector spinae work (+119.5 J). The erector spinae may contribute to spine extension during maximal squat jumping. The simulated jumps confirmed this hypothesis showing that vertical jumping was decreased if this muscle was not taken into consideration in the model. Therefore it is concluded that the erector spinae should be considered as a trunk extensor, which enables to enhance total muscle work and consequently vertical jump height.  相似文献   

6.
Abstract

The aim of this study was to examine the effects of arm-swing and sporting activity on jump height and jump height variability of countermovement jumps in adolescent students to inform correct jumping technique in different settings. Altogether, 324 students (grades 5–11) performed three countermovement jumps with bilateral arm-swings and three countermovement jumps without arm-swings on a force platform. The participants were divided into three groups based on sporting activity. The groups with the most (“active group”; more than 6 h formal athletics in a sport club per week) and least active (“sedentary group”; less than 3 h formal athletics in a sport club per week) participants were compared. Jump height was calculated for all jumps, and the best trial of three was used for further analysis. Jump height variability was indicated by the coefficient of variation over three jumps. The reliability of jump height was determined using the intra-class correlation coefficient (ICC) over three trials of each jumping technique. The reliability of jump height was very high for all conditions (ICC: 0.90–0.96). Jump height was significantly higher for countermovement jumps with than without arm-swings for both groups. Jump height in the active group was significantly greater than in the sedentary group for both jumping techniques. A significant interaction between jumping technique and sporting activity indicates a greater benefit of arm-swing in the active than in the sedentary participants. No significant differences between groups were observed for jump height variability. Jump height can be measured reliably in active and sedentary adolescent individuals for both jumping techniques. The relevant jumping technique should be chosen with respect to the context of its application and based on its suitability for the individual and task of interest.  相似文献   

7.
Abstract

To determine the time course of performance responses after an acute bout of plyometric exercise combined with high and low intensity weight training, a 3-group (including a control group), repeated-measures design was employed. Changes in performance were monitored through jumping ability by measuring countermovement and squat jumping, and strength performance assessment through isometric and isokinetic testing of knee extensors (at two different velocities). Participants in both experimental groups performed a plyometric protocol consisting of 50 jumps over 50 cm hurdles and 50 drop jumps from a 50 cm plyometric box. Additionally, each group performed two basic weight exercises consisting of leg presses and leg extensions at 90–95% of maximum muscle strength for the high intensity group and 60% of maximum muscle strength for the low intensity group. The results of the study suggest that an acute bout of intense plyometric exercise combined with weight exercise induces time-dependent changes in performance, which are also dependent on the nature of exercise protocol and testing procedures. In conclusion, acute plyometric exercise with weight exercise may induce a substantial decline in jumping performance for as long as 72 hours but not in other forms of muscle strength.  相似文献   

8.
We present a method for quantifying sacral kinematics during countermovement jumping (CMJ) using an inertial measurement unit (IMU). The IMU-derived sacral kinematic trajectories reproduced motion capture acceleration, velocity, and displacement to within mean (standard deviation) differences of 0.024 (0.088) m/s2, 0.023 (0.026) m/s, and 0.003 (0.032) m, respectively, across 252 jumps performed by 14 subjects. The method also quantified differences in maximum sacral displacement to within 1 % and differences in maximum propulsive velocity to within 0.7 % of motion capture estimates. This builds upon existing IMU-based methods for quantifying jump performance, which do not provide sacral kinematic trajectories. The utility of this method is demonstrated by its ability to discriminate jump performance metrics across a diverse subject population. In particular, we found that 21 participants adopted multiple strategies to maximize jump height in unloaded and loaded fresh conditions, but converged to a common strategy when jumping fatigued and under load. Changes in kinematic parameters were evident across conditions, and several changes were significantly associated with changes in jump performance (i.e., height). These parameters include changes in the depth of the countermovement, duration of the propulsive phase and maximum propulsive velocity. Collectively, these results point toward the future use of this method in naturalistic environments and for multiple objectives including biomechanical performance assessment and tracking, fatigue assessment, and jump training.  相似文献   

9.
The purpose of this study was to examine the effects of a 10 week contrast training (CT) programme (isometric + plyometric) on jumping, sprinting abilities and agility performance in prepubertal basketball players. Fifty-eight children from a basketball academy (age: 8.72 ± 0.97 years; body mass index: 17.22 ± 2.48 kg/m2) successfully completed the study. Participants were randomly assigned to experimental groups (EG, n = 30) and control groups (CG, n = 28). The CT programme was included in the experimental group’s training sessions – twice a week – as part of their usual weekly training regime. This programme included 3 exercises: 1 isometric and 2 plyometric. Jumping, sprinting and agility performance were assessed before and after the training programme. Significant differences were found in posttest between EG and CG in sprint and T-test: EG showed better results than CG. Furthermore, there were significant differences in posttest-pretest between EG and CG in squat jump, countermovement jump, drop jump, sprint and T-test with the EG showing better results than CG. The CT programme led to increases in vertical jump, sprint and agility levels, so that the authors suggest that prepubertal children exhibit high muscular strength trainability.  相似文献   

10.
The purpose of this study was to determine the effect of oral contraceptive use on bone serum markers following a 3-week jumping protocol. Twenty-three females (18–25 years) were grouped as oral contraceptive users (OC+) or non-users (OC?). Following a 3-week observation period, participants completed a 3-week (15-day) jump protocol. Jump sessions consisting of ten 42 cm drop jumps with a 30 s rest interval between jumps were completed each day, 5 days per week. Peak vertical ground reaction force and loading rate were measured and the osteogenic index was calculated. Serum markers for bone formation, bone alkaline phosphatase (BAP) and bone resorption, C-terminal telopeptides of type I collagen (CTX) were measured at three time points (pre-, mid-, post-jump). BAP and CTX increased significantly (P = 0.0017, 0.0488) in both groups post-jump; however, bone metabolic markers were not different between the OC+ and OC? groups. Osteogenic index, ground reaction force and vertical jump height were similar between groups. Correlations between markers of bone metabolism and participants’ age at menarche, weight, loading rate and years on OC were not significant. A 3-week jumping protocol was found to be effective in stimulating bone metabolism in both OC+ and OC? groups.  相似文献   

11.
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.  相似文献   

12.
Abstract

The aims of this study were to: (1) assess the reliability of various kinetic and temporal variables for unilateral vertical, horizontal, and lateral countermovement jumps; (2) determine whether there are differences in vertical ground reaction force production between the three types of jumps; (3) quantify the magnitude of asymmetry between limbs for variables that were established as reliable in a healthy population and whether asymmetries were consistent across jumps of different direction; and (4) establish the best kinetic predictor(s) of jump performance in the vertical, horizontal, and lateral planes of motion. Thirty team sport athletes performed three trials of the various countermovement jumps on both legs on two separate occasions. Eccentric and concentric peak force and concentric peak power were the only variables with acceptable reliability (coefficient of variation = 3.3–15.1%; intra-class correlation coefficient = 0.70–0.96). Eccentric and concentric peak vertical ground reaction force (14–16%) and concentric peak power (45–51%) were significantly (P < 0.01) greater in the vertical countermovement jump than in the horizontal countermovement jump and lateral countermovement jump, but no significant difference was found between the latter two jumps. No significant leg asymmetries (–2.1% to 9.3%) were found in any of the kinetic variables but significant differences were observed in jump height and distance. The best single predictors of vertical countermovement jump, horizontal countermovement jump, and lateral countermovement jump performance were concentric peak vertical power/body weight (79%), horizontal concentric peak power/body weight (42.6%), and eccentric peak vertical ground reaction force/body weight (14.9%) respectively. These findings are discussed in relation to monitoring and developing direction-specific jump performance.  相似文献   

13.
The purpose of this study was to determine the effects of training on the force-, velocity-, and displacement-time curves using principal component analysis (PCA) to examine the pre to post intervention changes. Thirty-four trained women basketball players were randomly divided into training and control groups. The training intervention consisted of full squats combined with repeated jumps. The effects of the intervention were analysed before and after the training period of 6 weeks by comparing the principal component scores. The magnitude of differences within-/between-group were calculated and expressed as standardised differences. After the intervention period, clear changes in principal components were observed in the training group compared to the control group. These were related to the execution of a vertical jump with a faster and deeper countermovement that was stopped with greater force. This resulted in greater force from the start of the upward movement phase which was maintained for a longer time. This increase in force throughout a greater range of motion increased the take-off velocity and consequently jumping height.  相似文献   

14.
ABSTRACT

We aimed to determine key biomechanical parameters explaining age-related jumping performance differences in youth elite female soccer players. Multiple biomechanical parameters from countermovement (CMJ) squat (SJ) and drop (DJ) jump testing of elite female soccer players (n = 60) within the same national training centre were analysed across ages 9-11y, 12-14y and 15-19y. Effects of age group and jump type on jump height were found, with the older jumping higher than the younger groups in all jumps (P < 0.05). For DJ, higher reactive strength index was found for older, compared to each younger group (P < 0.001). For CMJ and SJ, peak power was the most decisive characteristic, with significant differences between each group for absolute peak power (P < 0.0001) and body-weight-normalised peak power in CMJ (57 ± 7W/kg, 50 ± 7W/kg, 44.7 ± 5.5W/kg; P < 0.05) and between the older and each younger group in SJ (56.7 ± 7.1W/kg, 48.9 ± 7.1W/kg, 44.6 ± 6W/kg; P < 0.01). Age-related differences in jumping performance in youth elite female soccer players appear to be due to power production during standing jumps and by the ability to jump with shorter ground contact times during reactive jumps.  相似文献   

15.
Much of the training of competitive telemark skiers is performed as dry-land exercises. The specificity of these exercises is important for optimizing the training effect. Our aim here was to study the activation of the knee extensor musculature and knee angular displacement during competitive telemark skiing and during dry-land strength training exercises to determine the specificity of the latter. Specificity was analysed with respect to angular amplitude, angular velocity, muscle action and electromyographic (EMG) activity. Five male telemark skiers of national and international standard volunteered to participate in the study, which consisted of two parts: (1) skiing a telemark ski course and (2) specific dry-land strength training exercises for telemark skiing (telemark jumps and barbell squats). The angular displacement of the right knee joint was recorded with an electrogoniometer. A tape pressure sensor was used to measure pressure between the sole of the foot and the bottom of the right ski boot. Electromyographic activity in the right vastus lateralis was recorded with surface electrodes. The EMG activity recorded during maximum countermovement jumps was used to normalize the EMG activity during telemark skiing, telemark jumps and barbell squats. The results showed that knee angular displacement during telemark skiing and dry-land telemark jumps had four distinct phases: a flexion (F1) and extension (E1) phase during the thrust phase of the outside ski/leg in the turn/jump and a flexion (F2) and extension (E2) phase when the leg was on the inside of the turn/jump. The vastus lateralis muscle was activated during F1 and E1 in the thrust phase during telemark skiing and telemark jumps. The overall net knee angular amplitude was significantly greater (P<0.05) for telemark jumps than for telemark skiing. Barbell squats showed a knee angular amplitude significantly greater than that in telemark skiing (P<0.05). The mean knee angular velocity of the F1 and E1 phases during telemark skiing was about 0.47 rad?·?s?1; during barbell squats, it was about 1.22 rad?·?s?1. The angular velocity during telemark jumps was 2.34 and 1.59 rad?·?s?1 in the F1 and E1 phase, respectively. The normalized activation level of the EMG bursts during telemark skiing, telemark jumps and barbell squats was 70–80%. In conclusion, the muscle action and level of activation in the vastus lateralis during the F1 and E1 phases were similar during telemark skiing and dry-land exercises. However, the dry-land exercises showed a larger knee extension and flexion amplitude and angular velocity compared with telemark skiing. It appears that an adjustment of knee angular velocity during barbell squats and an adjustment of knee angle amplitude during both telemark jumps and barbell squats will improve specificity during training.  相似文献   

16.
Much of the training of competitive telemark skiers is performed as dry-land exercises. The specificity of these exercises is important for optimizing the training effect. Our aim here was to study the activation of the knee extensor musculature and knee angular displacement during competitive telemark skiing and during dry-land strength training exercises to determine the specificity of the latter. Specificity was analysed with respect to angular amplitude, angular velocity, muscle action and electromyographic (EMG) activity. Five male telemark skiers of national and international standard volunteered to participate in the study, which consisted of two parts: (1) skiing a telemark ski course and (2) specific dry-land strength training exercises for telemark skiing (telemark jumps and barbell squats). The angular displacement of the right knee joint was recorded with an electrogoniometer. A tape pressure sensor was used to measure pressure between the sole of the foot and the bottom of the right ski boot. Electromyographic activity in the right vastus lateralis was recorded with surface electrodes. The EMG activity recorded during maximum countermovement jumps was used to normalize the EMG activity during telemark skiing, telemark jumps and barbell squats. The results showed that knee angular displacement during telemark skiing and dry-land telemark jumps had four distinct phases: a flexion (F1) and extension (E1) phase during the thrust phase of the outside ski/leg in the turn/jump and a flexion (F2) and extension (E2) phase when the leg was on the inside of the turn/jump. The vastus lateralis muscle was activated during F1 and E1 in the thrust phase during telemark skiing and telemark jumps. The overall net knee angular amplitude was significantly greater (P < 0.05) for telemark jumps than for telemark skiing. Barbell squats showed a knee angular amplitude significantly greater than that in telemark skiing (P < 0.05). The mean knee angular velocity of the F1 and E1 phases during telemark skiing was about 0.47 rad x s(-1); during barbell squats, it was about 1.22 rad x s(-1). The angular velocity during telemark jumps was 2.34 and 1.59 rad x s(-1) in the F1 and E1 phase, respectively. The normalized activation level of the EMG bursts during telemark skiing, telemark jumps and barbell squats was 70-80%. In conclusion, the muscle action and level of activation in the vastus lateralis during the F1 and E1 phases were similar during telemark skiing and dry-land exercises. However, the dry-land exercises showed a larger knee extension and flexion amplitude and angular velocity compared with telemark skiing. It appears that an adjustment of knee angular velocity during barbell squats and an adjustment of knee angle amplitude during both telemark jumps and barbell squats will improve specificity during training.  相似文献   

17.
Abstract

Six groups of subjects were tested to determine if various training programs affected performance in speed in swimming 30 yards. No evidence of improvement was found after one group of subjects had been exposed to absolutely no exercise for six weeks and, also, after a group of subjects had participated in various exercises with weights three times weekly for six weeks. Two groups of swimmers who participated in practicing starts, kicking, arm stroking, and sprinting 30 and 60 yards significantly improved their performances in speed in swimming; one group of subjects followed the preceding program three times weekly and another group used the same routine six times a week. Two other groups, one of which was exposed to weight training and swimming, and one of which was exposed only to 30-yard sprints and practicing starts, both showed statistically significant differences in performance.  相似文献   

18.
刘艳 《冰雪运动》2012,(1):22-24,28
力量素质是花样滑冰运动员在比赛中高质量的完成一套节目的保证。通过文献资料法、综合分析法,对花样滑冰运动员的专项力量训练方法进行研究。在花样滑冰力量训练中应遵循科学性、循序渐进、区别对待的训练原则,注意素质的全面发展,利用不同屈伸角度跳跃的组合练习、跳箱练习、变换方向跳障碍练习、跳绳练习、负重练习、滑行训练等方法进行力量素质的训练,双人滑选手尤其要特别注意进行托举力量及核心力量的练习。  相似文献   

19.
The two-handed dyno technique was studied in nine experienced climbers. According to textbooks, the preferred technique is to jump only as high as necessary and to grab the upper hold exactly at the dead point (highest position of the body centre of mass). Piezoelectric force transducers were connected to the right and left footholds and to the lower and upper handholds. From the forces, the vertical take-off velocity and the jump height were calculated. The results showed that in unsuccessful jumps, the vertical take-off velocity is too small. In successful jumps, however, the vertical take-off velocity is higher than required. In order to reach the same required minimal height, the successful jumper produced a higher force than the unsuccessful (including marginal fail) jumper did. The force produced by the feet was approximately 1.8 times higher than that of the hands. Unsuccessful jumps were significantly closer to the dead point than successful ones. The peak force at the fingers after touchdown at the upper hold ranged from 1.1 to 1.63 times body weight. Overshooting, i.e. jumping higher than required resulted in a smaller peak force and a greater chance of performing a successful jump. In successful jumps, the climber jumps higher than required and grabs the upper hold before and below the dead point. Furthermore, the closer to the dead point the climber grasps the upper hold, the higher is the peak reaction force at the fingers. The advice for the climber is to jump higher than necessary (at least 10 cm), and to grab the handhold before the dead point. This results in a high success rate and a minimal finger injury risk.  相似文献   

20.
Abstract

The relative effectiveness of six intensive training programs on the development of four selected skills was studied, with emphasis on limited time encountered within the semester organizational plan. One hundred and twenty college freshmen men volunteers were randomly assigned to training groups of 30 members each, which met for two sessions a week for 16 weeks.

Results indicated that: (a) direct practice jumping, alone or combined with repetitive sprinting or weight training, was significantly superior to weight training alone on standing broad jump development; (b) direct practice of a zigzag run was superior to both weight training and repetitive sprinting; and (c) when group acquisition of “adequate” skill is the objective, performance improvements educed over the first nine weeks were great enough to question the merits of persisting at an activity over a full semester. Only the zigzag run was adversely affected by the spring vacation cessation of training.  相似文献   

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