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1.
The goal of this randomized, double-blind, cross-over study was to assess the acute effects of caffeine ingestion on muscular strength and power, muscular endurance, rate of perceived exertion (RPE), and pain perception (PP) in resistance-trained men. Seventeen volunteers (mean?±?SD: age?=?26?±?6 years, stature?=?182?±?9?cm, body mass?=?84?±?9?kg, resistance training experience?=?7?±?3 years) consumed placebo or 6?mg?kg?1 of anhydrous caffeine 1?h before testing. Muscular power was assessed with seated medicine ball throw and vertical jump exercises, muscular strength with one-repetition maximum (1RM) barbell back squat and bench press exercises, and muscular endurance with repetitions of back squat and bench press exercises (load corresponding to 60% of 1RM) to momentary muscular failure. RPE and PP were assessed immediately after the completion of the back squat and bench press exercises. Compared to placebo, caffeine intake enhanced 1RM back squat performance (+2.8%; effect size [ES]?=?0.19; p?=?.016), which was accompanied by a reduced RPE (+7%; ES?=?0.53; p?=?.037), and seated medicine ball throw performance (+4.3%, ES?=?0.32; p?=?.009). Improvements in 1RM bench press were not noted although there were significant (p?=?.029) decreases in PP related to this exercise when participants ingested caffeine. The results point to an acute benefit of caffeine intake in enhancing lower-body strength, likely due to a decrease in RPE; upper-, but not lower-body power; and no effects on muscular endurance, in resistance-trained men. Individuals competing in events in which strength and power are important performance-related factors may consider taking 6?mg?kg?1 of caffeine pre-training/competition for performance enhancement.  相似文献   

2.
Comparison of 1 and 2 days per week of strength training in children   总被引：1，自引：0，他引：1  
The purpose of this study was to compare the effects of 1 and 2 days per week of strength training on upper body strength, lower body strength, and motor performance ability in children. Twenty-one girls and 34 boys between the ages of 7.1 and 12.3 years volunteered to participate in this study. Participants strength trained either once per week (n = 22) or twice per week (n = 20) for 8 weeks at a community-based youth fitness center. Each training session consisted of a single set of 10-15 repetitions on 12 exercises using child-size weight machines. Thirteen children who did not strength train served as age-matched controls. One repetition maximum (1RM) strength on the chest press and leg press, handgrip strength, long jump, vertical jump, and flexibility were assessed at baseline and posttraining. Only participants who strength trained twice per week made significantly greater gains in 1RM chest press strength, compared to the control group (11.5 and 4.4% respectively, p < .05). Participants who trained once and twice per week made gains in 1RM leg press strength (14.2 and 24.7%, respectively) that were significantly greater than control group gains (2.4%). On average, participants who strength trained once per week achieved 67% of the 1RM strength gains. No significant differences between groups were observed on other outcome measures. These findings support the concept that muscular strength can be improved during the childhood years and favor a training frequency of twice per week for children participating in an introductory strength training program.  相似文献   

3.
The aim of the study was to assess the relationship between performance-based and laboratory tests for muscular strength and power assessment in older women. Thirty-two women aged 68.8 +/- 2.8 years were recruited. All participants were asessed for: (a) two performance-based tests--the box-stepping test (mean 296 +/- 51 J) and two-revolution maximum test (mean 7.1 +/- 2 kg) performed while pedalling on a cycle ergometer; and (b) muscular function tests--maximal instantaneous peak power jumping on a force platform (mean 1528 +/- 279 W); maximal voluntary contraction (MVC) during knee extension (mean 601 +/- 571 N) and leg press (mean 626 +/- 126 N), and leg press power (mean 483 +/- 98 W) on a dynamometer. Using univariate analysis, performance-based tests were compared with laboratory muscle strength and power measurements. Muscle power correlated most strongly with the performance-based tests for both jumping and leg press power (r-values between 0.67 and 0.75; P < 0.01). The correlation with muscle strength measures ranged between 0.48 and 0.61 (P < 0.01). The proposed tests may have particular relevance in geriatric and rehabilitation environments as they represent an easy, practical, and inexpensive alternative for the assessment of muscular strength and power.  相似文献   

4.
Abstract

The relationship between the ability to develop leg torque and performance in the vertical jump was investigated in 29 female athletes. Each subject's leg flexion, leg extension, and foot plantar flexion peak torque was determined isokinetically on a Cybex at angular velocities of 30 degrees/second and 180 degrees/second. The vertical jump was determined for each subject and correlations among the measures of torque and the vertical jump were calculated. Although the ability to produce leg power as exemplified by the vertical jump was significantly correlated with peak torque at the fast angular velocity but was not significantly correlated with peak torque at the slow angular velocity, the correlations were so low it was concluded that there was little if any relationship between torque at a fast or slow angular velocity and the ability to vertically jump.  相似文献   

5.
Abstract

In this study, we compared the effectiveness of ratio and allometric scaling for normalizing power and strength in elite male rugby union players. Rugby union forwards (n = 18) and backs (n = 20) were assessed for squat jump and bench throw peak power, and box squat and bench press one-repetition maximum strength. The performance data for the forwards and backs were compared using ratio (P/BM) and allometric scaling (P/BMb ), where P represents performance, BM is body mass in kilograms, and b is a power exponent. A proposed allometric exponent (0.67) and exponents (±95% confidence intervals) derived for the box squat (0.33 ± 0.31), bench press (0.45 ± 0.30), bench throw (0.46 ± 0.36), and squat jump (0.64 ± 0.31) exercises were used. In general, the absolute expression of power and strength was superior for the heavier forwards, but after ratio scaling these performance measures then favoured the lighter backs. There were no performance differences between the forwards and backs after allometric scaling using either the proposed or the derived exponents. Thus, allometric scaling may provide a more effective method for normalizing power and strength in elite athletes when body size is a confounding variable.  相似文献   

6.
Abstract

The objective of this study was to examine the chronic effects on strength and power of performing complex versus traditional set training over eight weeks. Fifteen trained males were assessed for throw height, peak velocity, and peak power in the bench press throw and one-repetition maximum (1-RM) in the bench press and bench pull exercises, before and after the eight-week programme. The traditional set group performed the pulling before the pushing exercise sets, whereas the complex set group alternated pulling and pushing sets. The complex set training sessions were completed in approximately half the time. Electromyographic (EMG) activity was monitored during both test sessions in an attempt to determine if it was affected as a result of the training programme. Although there were no differences in the dependent variables between the two conditions, bench pull and bench press 1-RM increased significantly under the complex set condition and peak power increased significantly under the traditional set condition. Effect size statistics suggested that the complex set was more time-efficient than the traditional set condition with respect to development of 1-RM bench pull and bench press, peak velocity and peak power. The EMG activity was not affected. Complex set training would appear to be an effective method of exercise with respect to efficiency and strength development.  相似文献   

7.
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.  相似文献   

8.
For activities such as squash, badminton and fencing, the ability to quickly complete a lunge and return to the start or move off in another direction is critical for success. Determining which strength qualities are important predictors of lunge performance was the focus of this study. Thirty-one male athletes performed: (1) a unilateral maximal squat (one-repetition maximum, 1-RM) and unilateral jump squat (50% 1-RM) on an instrumented supine squat machine, and (2) a forward lunge while attached to a linear transducer. We performed stepwise multiple regression analysis with lunge performance as the dependent variable and various strength, flexibility and anthropometric measures as the independent variables. From the many strength and power measures calculated, time to peak force was the best single predictor of lunge performance, which accounted for 55% of the explained variance. The best three-variable model for predicting lunge performance accounted for 76-85% of the explained variance. The models differed, however, according to whether lunge performance was expressed relative to body mass (time to peak force, mean power and relative strength = 76%) or taken as an absolute value (time to peak force, leg length and flexibility = 85%). We conclude that one to two trials were reliable for strength diagnosis and that one strength measure cannot accurately explain functional performance because other factors, such as body mass, flexibility and leg length, have diverse effects on the statistical models.  相似文献   

9.
Abstract

The aim of the study was to assess the relationship between performance-based and laboratory tests for muscular strength and power assessment in older women. Thirty-two women aged 68.8 ± 2.8 years were recruited. All participants were asessed for: (a) two performance-based tests – the box-stepping test (mean 296 ± 51 J) and two-revolution maximum test (mean 7.1 ± 2 kg) performed while pedalling on a cycle ergometer; and (b) muscular function tests – maximal instantaneous peak power jumping on a force platform (mean 1528 ± 279 W); maximal voluntary contraction (MVC) during knee extension (mean 601 ± 571 N) and leg press (mean 626 ± 126 N), and leg press power (mean 483 ± 98 W) on a dynamometer. Using univariate analysis, performance-based tests were compared with laboratory muscle strength and power measurements. Muscle power correlated most strongly with the performance-based tests for both jumping and leg press power (r-values between 0.67 and 0.75; P < 0.01). The correlation with muscle strength measures ranged between 0.48 and 0.61 (P < 0.01). The proposed tests may have particular relevance in geriatric and rehabilitation environments as they represent an easy, practical, and inexpensive alternative for the assessment of muscular strength and power.  相似文献   

10.
The aim of this study was to evaluate the effect of varying knee angle (120° and 90°) on the external validity of an isometric leg press test with reference to vertical jump performance. Isometric peak force (PF 120 and PF 90 ), rate of force development (RFD 120 and RFD 90 ), and maximum height reached with a squat jump and counter-movement jump were measured in 14 males. Although RFD 120 was significantly correlated with squat jump and counter-movement jump performance ( r = 0.71 and 0.69), and the correlations with PF 120 approached statistical significance ( r = 0.53 and 0.50), neither PF 90 nor RFD 90 was significantly related to vertical jump performance. Furthermore, although both RFD 120 and PF 120 were significantly different between the best five and the worst five jumpers, RFD 90 and PF 90 did not differentiate between individuals' vertical jump performance. We conclude that the choice of joint angle affects the external validity of isometric strength testing. Based on our results, we recommend accurate control of biomechanical specificity and assessment at different angles to find the position at which isometric strength testing is most comfortable.  相似文献   

11.
The aim of this study was to evaluate the effect of varying knee angle (120 degrees and 90 degrees) on the external validity of an isometric leg press test with reference to vertical jump performance. Isometric peak force (PF120 and PF90), rate of force development (RFD120 and RFD90), and maximum height reached with a squat jump and counter-movement jump were measured in 14 males. Although RFD120 was significantly correlated with squat jump and counter-movement jump performance (r = 0.71 and 0.69), and the correlations with PF120 approached statistical significance (r = 0.53 and 0.50), neither PF90 nor RFD90 was significantly related to vertical jump performance. Furthermore, although both RFD120 and PF120 were significantly different between the best five and the worst five jumpers, RFD90 and PF90 did not differentiate between individuals' vertical jump performance. We conclude that the choice of joint angle affects the external validity of isometric strength testing. Based on our results, we recommend accurate control of biomechanical specificity and assessment at different angles to find the position at which isometric strength testing is most comfortable.  相似文献   

12.
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   

13.
The insulin response following carbohydrate ingestion enhances creatine transport into muscle. Cinnamon extract is promoted to have insulin-like effects, therefore this study examined if creatine co-ingestion with carbohydrates or cinnamon extract improved anaerobic capacity, muscular strength, and muscular endurance. Active young males (n?=?25; 23.7?±?2.5?y) were stratified into 3 groups: (1) creatine only (CRE); (2) creatine+ 70?g carbohydrate (CHO); or (3) creatine+ 500?mg cinnamon extract (CIN), based on anaerobic capacity (peak power·kg?1) and muscular strength at baseline. Three weeks of supplementation consisted of a 5?d loading phase (20?g/d) and a 16?d maintenance phase (5?g/d). Pre- and post-supplementation measures included a 30-s Wingate and a 30-s maximal running test (on a self-propelled treadmill) for anaerobic capacity. Muscular strength was measured as the one-repetition maximum 1-RM for chest, back, quadriceps, hamstrings, and leg press. Additional sets of the number of repetitions performed at 60% 1-RM until fatigue measured muscular endurance. All three groups significantly improved Wingate relative peak power (CRE: 15.4% P?=?.004; CHO: 14.6% P?=?.004; CIN: 15.7%, P?=?.003), and muscular strength for chest (CRE: 6.6% P?P?P?P?P?P?P?=?.013; CHO: 10.0% P?=?.007; CIN: 17.3% P?P?=?.021) and CIN (15.5%, P?相似文献   

14.
Abstract

Although vertical jumping is often incorporated into physical activity tests for both adults and children, normative data for children and adolescents are lacking in the literature. The objectives of this study were to provide normative data of jump height and predicted peak leg power for males and females aged 10.0–15.9 years. Altogether, 1845 children from 12 state primary and secondary schools in the East of England participated in the study. Each child performed two countermovement jumps, and jump height was calculated using a NewTest jump mat. The highest jump was used for analysis and in the calculation of predicted peak power. Jump height and predicted peak leg power were significantly higher for males than females from the age of 11 years. Jump height and peak power increased significantly year on year for males. For females, jump height and predicted peak leg power reached a plateau after age 12 and 13 years respectively. This study provides normative data that can be used as a tool to classify jumping performance in children aged 10–15 years.  相似文献   

15.
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 (νball), 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.  相似文献   

16.
The purpose of this investigation was to compare valgus/varus knee angles during various jumps and lower body strength between males and females relative to body mass. Seventeen recreationally active females (age: 21.94 ± 2.59 years; height: 1.67 ± 0.05 m; mass: 64.42 ± 8.39 kg; percent body fat: 26.89 ± 6.26%; squat one-repetition maximum: 66.18 ± 19.47 kg; squat to body mass ratio: 1.03 ± 0.28) and 13 recreationally active males (age: 21.69 ± 1.65 years; height: 1.77 ± 0.07 m; mass: 72.39 ± 9.23 kg; percent body fat: 13.15 ± 5.18%; squat one-repetition maximum: 115.77 ± 30.40 kg; squat to body mass ratio: 1.59 ± 0.31) performed a one-repetition maximum in the squat and three of each of the following jumps: countermovement jump, 30 cm drop jump, 45 cm drop jump, and 60 cm drop jump. Knee angles were analysed using videography and body composition was analysed by dual-energy X-ray absorptiometry to allow for squat to body mass ratio and squat to fat free mass ratio to be calculated. Significant differences (P ≤ 0.05) were found between male and female one-repetition maximum, male and female squat to body mass ratio, and male and female squat to fat free mass ratio. Significant differences were found between male and female varus/valgus knee positions during maximum flexion of the right and left leg in the countermovement jump, drop jump from 30 cm, drop jump from 45 cm, and drop jump from 60 cm. Correlations between varus/valgus knee angles and squat to body mass ratio for all jumps displayed moderate, non-significant relationships (countermovement jump: r = 0.445; drop jump from 30 cm: r = 0.448; drop jump from 45 cm: r = 0.449; drop jump from 60 cm: r = 0.439). In conclusion, males and females have significantly different lower body strength and varus/valgus knee position when landing from jumps.  相似文献   

17.
姚卫 《体育科研》2012,33(1):97-100
主要采用实验法、访谈法,对上海市杨浦区小学生50 m快速跑、实心球掷远和立定跳远成绩进行统一测试并统计分析。结果显示：（1）杨浦区小学生50 m快速跑、实心球掷远和立定跳远等运动成绩的增长均符合身体素质自然增长规律。（2）小学生的运动能力有下降趋势,尤其是五年级的学生最为明显。（3）小学体育课堂教学要在教学内容和方法上遵循身体生长发育的自然规律,以提高学生的运动技能和身体素质以及发展学生团结合作的精神作为教学效果的评估标准。  相似文献   

18.
Abstract

The aim of the study was to estimate the influence of body size and pubertal status on variation in functional capacities and sport-specific skills of 59 youth basketball players aged 14.0–15.9 years. Height and mass were measured and stage of pubic hair was assessed at clinical examination. Six tests of functional capacity were evaluated: squat jump, countermovement jump, 60-s sit-ups, 2-kg standing medicine ball throw, hand grip strength, and 20-m multi-stage shuttle run. Four basketball skills were tested (shooting, passing, dribbling, and defensive movements). Comparisons between basketball players of different sexual maturity status were performed using analysis of covariance (controlling for chronological age). Functional capacities and basketball skills appeared to be largely independent of pubertal status especially after controlling for variation in body size. Results of multiple linear regressions indicated chronological age as a significant predictor for four items, while maturity status was a significant predictor for only one item. The influence of body mass was negative for two functional indicators (jumping, multi-stage shuttle run) and two basketball skills (dribbling, defensive movements), but positive for two functional tests of upper body strength (hand grip, ball throw). Height was positively correlated with two specific skills (passing, defensive movements), while a combination of tallness and heaviness was associated with a disadvantage on three functional capacities and two sport-specific skills.  相似文献   

19.
This study aimed to examine the reliability of different power and velocity variables during the Smith machine bench press (BP) and bench press throw (BPT) exercises. Twenty-two healthy men conducted four testing sessions after a preliminary BP one-repetition maximum (1RM) test. In a counterbalanced order, participants performed two sessions of BP in one week and two sessions of BPT in another week. Mean propulsive power, peak power, mean propulsive velocity, and peak velocity at each tenth percentile (20–70% of 1RM) were recorded by a linear transducer. The within-participants coefficient of variation (CV) was higher for the load–power relationship compared to the load–velocity relationship in both the BP (5.3% vs. 4.1%; CV ratio = 1.29) and BPT (4.7% vs. 3.4%; CV ratio = 1.38). Mean propulsive variables showed lower reliability than peak variables in both the BP (5.4% vs. 4.0%, CV ratio = 1.35) and BPT (4.8% vs. 3.3%, CV ratio = 1.45). All variables were deemed reliable, with the peak velocity demonstrating the lowest within-participants CV. Based upon these findings, the peak velocity should be chosen for the accurate assessment of BP and BPT performance.  相似文献   

20.
ABSTRACT

This study investigated the role of reactive and eccentric strength in stiffness regulation during maximum velocity sprinting (Vmax) in team sport athletes compared with highly trained sprinters. Thirteen team sport athletes and eleven highly trained sprinters were recruited. Vmax was measured using radar, and stiffness regulation was inferred from modelled vertical and leg spring stiffness. Reactive strength (RSI) was determined from a 0.50 m drop jump, and an eccentric back squat was used to assess maximum isoinertial eccentric force. Trained sprinters attained a higher Vmax than team sport athletes, partly due to a briefer contact time and higher vertical stiffness. Trained sprinters exhibited a moderately higher RSI via the attainment of a briefer and more forceful ground contact phase, while RSI also demonstrated large to very large associations with vertical stiffness and Vmax, respectively. Isoinertial eccentric force was largely correlated with Vmax, but only moderately correlated with vertical stiffness. Reactive and eccentric strength contribute to the ability to regulate leg spring stiffness at Vmax, and subsequently, the attainment of faster sprinting speeds in highly trained sprinters versus team sport athletes. However, stiffness regulation appears to be a task-specific neuromuscular skill, reinforcing the importance of specificity in the development of sprint performance.  相似文献   

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