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1.
This study examined the impact of load on lower body performance variables during the hang power clean. Fourteen men performed the hang power clean at loads of 30%, 45%, 65%, and 80% 1RM. Peak force, velocity, power, force at peak power, velocity at peak power, and rate of force development were compared at each load. The greatest peak force occurred at 80% 1RM. Peak force at 30% 1RM was statistically lower than peak force at 45% (p = 0.022), 65% (p = 0.010), and 80% 1RM (p = 0.018). Force at peak power at 65% and 80% 1RM was statistically greater than force at peak power at 30% (p < 0.01) and 45% 1RM (p < 0.01). The greatest rate of force development occurred at 30% 1RM, but was not statistically different from the rate of force development at 45%, 65%, and 80% 1RM. The rate of force development at 65% 1RM was statistically greater than the rate of force development at 80% 1RM (p = 0.035). No other statistical differences existed in any variable existed. Changes in load affected the peak force, force at peak power, and rate of force development, but not the peak velocity, power, or velocity at peak power.  相似文献   

2.
Understanding how loading affects power production in resistance training is a key step in identifying the most optimal way of training muscular power – an essential trait in most sporting movements. Twelve elite male sailors with extensive strength-training experience participated in a comparison of kinematics and kinetics from the upper body musculature, with upper body push (bench press) and pull (bench pull) movements performed across loads of 10–100% of one repetition maximum (1RM). 1RM strength and force were shown to be greater in the bench press, while velocity and power outputs were greater for the bench pull across the range of loads. While power output was at a similar level for the two movements at a low load (10% 1RM), significantly greater power outputs were observed for the bench pull in comparison to the bench press with increased load. Power output (P max) was maximized at higher relative loads for both mean and peak power in the bench pull (78.6 ± 5.7% and 70.4 ± 5.4% of 1RM) compared to the bench press (53.3 ± 1.7% and 49.7 ± 4.4% of 1RM). Findings can most likely be attributed to differences in muscle architecture, which may have training implications for these muscles.  相似文献   

3.
To investigate the effects of different loads on system and lower-body kinetics during jump squats, 12 resistance-trained men performed jumps under different loading conditions: 0%, 12%, 27%, 42%, 56%, 71%, and 85% of 1-repetition maximum (1-RM). System power output was calculated as the product of the vertical component of the ground reaction force and the vertical velocity of the bar during its ascent. Joint power output was calculated during bar ascent for the hip, knee, and ankle joints, and was also summed across the joints. System power output and joint power at knee and ankle joints were maximized at 0% 1-RM (p < 0.001) and followed the linear trends (p < 0.001) caused by power output decreasing as the load increased. Power output at the hip was maximized at 42% 1-RM (p = 0.016) and followed a quadratic trend (p = 0.030). Summed joint power could be predicted from system power (p < 0.05), while system power could predict power at the knee and ankle joints under some of the loading conditions. Power at the hip could not be predicted from system power. System power during loaded jumps reflects the power at the knee and ankle, while power at the hip does not correspond to system power.  相似文献   

4.
Whilst previous research has highlighted significant relationships between golfers’ clubhead velocity (CHV) and their vertical jump height and maximum strength, these field-based protocols were unable to measure the actual vertical ground reaction force (vGRF) variables that may correlate to performance. The aim of this study was to investigate relationships between isometric mid-thigh pull (IMTP), countermovement jump (CMJ), squat jump (SJ) and drop jump (DJ) vGRF variables and CHV in highly skilled golfers. Twenty-seven male category 1 golfers performed IMTP, CMJ, SJ and DJ on a dual force platform. The vertical jumps were used to measure positive impulse during different stretch-shortening cycle velocities, with the IMTP assessing peak force (PF) and rate of force development (RFD). Clubhead velocity was measured using a TrackMan launch monitor at a golf driving range. Pearsons correlation coefficient analyses revealed significant relationships between peak CHV and CMJ positive impulse (r = 0.788, p < 0.001), SJ positive impulse (r = 0.692; p < 0.001), DJ positive impulse (r = 0.561, p < 0.01), PF (r = 0.482, p < 0.01), RFD from 0–150 ms (r = 0.343, p < 0.05) and RFD from 0–200 ms (r = 0.398, p < 0.05). The findings from this investigation indicate strong relationships between vertical ground reaction force variables and clubhead velocity.  相似文献   

5.
For simplicity of biomechanical analyses, the weightlifting barbell is typically modelled as a rigid, non-deformable object. Most coaches and weightlifters, however, are aware of the elastic nature of the barbell, and its influence on the successful completion of lifting attempts. Variables such as velocity, work performed, and power output are indicators of the quality of performance during the snatch, clean, and related weightlifting pulling movements. The aim of this study was to establish whether differences exist in determining these biomechanical parameters when the centre of the barbell is analysed compared with each end of the barbell. Nine men performed three maximal-effort repetitions in the clean pull exercise at 85% of their self-reported single repetition maximum (1-RM) clean (90–155 kg) using a barbell instrumented for mechanical analysis. Results indicated that peak barbell speed was 5–30% (P < 0.05) lower for the centre of the barbell than the ends. Although differences (P < 0.05) in kinetic and potential energy were found between the centre and ends of the bar, differences between total work performed were small ( < 6%; P < 0.05) and no differences were observed for average power (P > 0.05). Although approximately the same work and power occur for the centre and ends of the barbell, they manifest as different kinematics as a result of the elastic nature of the equipment. The elastic characteristics should be considered when selecting instrumentation and variables for research involving barbells. Coaches should be aware of the elasticity of barbells, including selecting appropriate viewing angles as well as understanding how deformation may affect the ends of the barbell relative to the centre.  相似文献   

6.
The aim of this study was to examine the effects of barbell load on countermovement vertical jump (CMJ) power and net impulse within a theoretically valid framework, cognisant of the underpinning force, temporal, and spatial components. A total of 24 resistance-trained rugby union athletes (average ± SD: age: 23.1 ± 3.4 years; height: 1.83 ± 0.05 m; body mass (BM): 91.3 ± 10.5 kg) performed maximal CMJ under 5 experimental conditions in a randomised, counterbalanced order: unloaded, and with additional loads of 25%, 50%, 75%, and 100% of BM. Peak power and average power were maximised during the unloaded condition, both decreasing significantly (P < 0.05) as load increased. Net impulse was maximised with 75% of BM, which was significantly greater (P < 0.05) than the unloaded and 100% of BM conditions. Net mean force and mean velocity were maximised during the unloaded condition and decreased significantly (P < 0.05) as load increased, whereas phase duration increased significantly (P < 0.05) as load increased. As such, the interaction between barbell load and the underpinning force, time, and displacement components should be considered by strength and conditioning coaches when prescribing barbell loads.  相似文献   

7.
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8.
A popular method to improve athletic performance and lower body power is to train with wearable resistance (WR), for example, weighted vests. However, it is currently unknown what training effect this loading method has on full-body explosive movements such as the power clean. The purpose of this study was to determine what effects WR equivalent to 12% body mass (BM) had on the power clean and countermovement jump (CMJ) performance. Sixteen male subjects (age: 23.2?±?2.7 years; BM: 90.5?±?10.3?kg) were randomly assigned to five weeks of traditional (TR) power clean training or training with 12% BM redistributed from the bar to the body using WR. Variables of interest included pre and post CMJ height, power clean one repetition maximum (1RM), peak ground reaction force, power output (PO), and several bar path kinematic variables across loads at 50%, 70%, and 90% of 1RM. The main findings were that WR training: (1) increased CMJ height (8.7%; ES?=?0.53) and 1RM power clean (4.2%; ES?=?0.2) as compared to the TR group (CMJ height?=??1.4%; 1RM power clean?=?1.8%); (2) increased PO across all 1RM loads (ES?=?0.33–0.62); (3) increased barbell velocity at 90% 1RM (3.5%; ES?=?0.74) as compared to the TR group (?4.3%); and (4) several bar path kinematic variables improved at 70% and 90% 1RM loads. WR power clean training with 12% BM can positively influence power clean ability and CMJ performance, as well as improve technique factors.  相似文献   

9.
This study aimed to evaluate the within- and between-session reliability of force, velocity and power performances and to assess the force-velocity relationship during the deadlift high pull (DHP). Nine participants performed two identical sessions of DHP with loads ranging from 30 to 70% of body mass. The force was measured by a force plate under the participants’ feet. The velocity of the ‘body + lifted mass’ system was calculated by integrating the acceleration and the power was calculated as the product of force and velocity. The force-velocity relationships were obtained from linear regression of both mean and peak values of force and velocity. The within- and between-session reliability was evaluated by using coefficients of variation (CV) and intraclass correlation coefficients (ICC). Results showed that DHP force-velocity relationships were significantly linear (R² > 0.90, p < 0.05). Within sessions and between sessions, mean and peak forces during DHP showed a strong agreement (CV < 3%, ICC > 0.94), mean and peak velocities showed a good agreement (CV < 9%, 0.78 < ICC < 0.92). It was concluded that DHP performance and its force-velocity relationships are highly reliable and can therefore be utilised as a tool to characterise individuals’ muscular profiles.  相似文献   

10.
ABSTRACT

We assessed the intraocular pressure (IOP) behaviour during a 1-minute period of isometric physical effort and the immediate 1-minute of recovery in the mid-thigh clean pull and squat exercises at three different intensities. Twenty physically active individuals performed the isometric mid-thigh clean pull and squat exercises at three intensities (0% [low-intensity], 25% [medium-intensity] and 50% [high-intensity] of the maximum isometric force). IOP was semi-continuously measured by rebound tonometry. There was a statistically significant effect of exercise intensity on IOP (p < 0.001, ?p² = 0.416), observing that IOP increments were positively associated with exercise intensity. The mid-thigh clean pull and squat exercises did not demonstrate differences (p = 0.510), and also, no differences were observed between men and women (p = 0.683). The IOP changes during the isometric physical effort showed a positive linear behaviour in all conditions (r = 0.70 to 0.96). IOP returned to baseline levels after 8 seconds of recovery. Our data showed a progressive and instantaneous IOP increment during isometric exercise, which was positively associated with exercise intensity. IOP changes were independent on the type of exercise and participant´s sex. After exercise, IOP rapidly (≈ 8 seconds) returned to baseline levels.  相似文献   

11.
The aim of the present study was to investigate loading effects on kinematic and kinetic variables among elite-weightlifters in order to identify an optimal training load to maximize power production for clean-movement. Nine elite-weightlifter (age: 24 ± 4years, body-mass: 77 ± 6.5kg, height: 176 ± 6.1cm and 1RM clean: 170 ± 5kg) performed 2 separate repetitions of the clean using 85, 90, 95% and 100%, in a randomized order, while standing on a force platform and being recorded using 3D-capture-system. Differences in kinematics (barbell displacement, velocity and acceleration) and kinetics (power, vertical ground reaction force (vGRF), rate of force development (RFD), and work) across the loads were statistically assessed. Results revealed significant load effects for the majority of the studied parameters (p < 0.01) and showed that typical bar-displacement, greatest bar-velocity and peak-power were achieved at 85 and 90% 1RM (p < 0.001). Additionally greater average power was shown for 90 and 95% (p < 0.01) and greater work and vGRF were shown for 90, 95 and 100% than 85% 1RM (p < 0.05). Load had no significant effect on peak-vGRF and peak-RFD (p > 0.05). The results of this study, suggest 90% 1RM to be the most advantageous load to train explosive-force and to enhance power-outputs while maintaining technical efficiency in elite-weightlifters.  相似文献   

12.
This study determined whether backward grinding performance in America's Cup sailing could be improved using a training intervention to increase power capability in the upper-body pull movement. Fourteen elite male sailors (34.9 ± 5.9 years; 98.1 ± 14.4 kg; 186.6 ± 7.7 cm) were allocated into experimental (speed-focussed) and control groups. Grinding performance was assessed using a grinding ergometer and an instrumented Smith machine measured force, velocity and power during the bench pull exercise. Conventional training produced significant improvements in bench pull 1 RM (5.2 ± 4.0%; p = 0.016) and maximum force production (5.4 ± 4.0%; p = 0.014). Speed-focussed training improved maximum power (7.8 ± 4.9%; p = 0.009), power at 1RM (10.3 ± 8.9%; p = 0.019) and maximum velocity (8.4 ± 2.6%; p = 0.0002). Backward grinding performance showed greater improvements in the experimental group than the control group for moderate (+1.8%) and heavy load (+6.0%) grinding. Changes in maximum power output and power at 1 RM had large correlations (r = 0.56–0.61) with changes in both moderate and heavy load grinding performance. Time to peak force had the strongest relationship, explaining 70% of the change in heavy load grinding performance. Although the performance benefit was not entirely clear the likelihood of a detrimental effect was low ( < 5%) and therefore implementation could be recommended.  相似文献   

13.
The strength and technical competence of junior female lifters play a decisive role not only for their current but also adulthood performance. The objective of this study was to investigate the three-dimensional kinematics of the snatch technique in junior female weightlifters. Ten elite junior female weightlifters participated in the study. Two cameras operating at 50 fields per second were used to record the lifts. The heaviest successful lifts were selected for the kinematic analysis. The kinematical data were obtained using a motion analysis system. The duration of the first pull was significantly longer than that of the other phases (P < 0.05). Maximum extension angle and velocity of the lower limb joints were significantly greater in the second pull (P < 0.05). The greatest extension angle was found in the knee joint during the first pull, while the greatest extension angle was observed in the hip joint during the second pull (P < 0.05). Maximum extension velocity of the knee and hip joints was significantly greater than that of the ankle in both phases (P < 0.05). In addition, the vertical velocity of the barbell and the absolute and relative power outputs was significantly higher in the second pull than in the first pull (P < 0.05). In the snatch lifting of junior female weightlifters, the angular kinematics of lower limb joints, the linear kinematics and trajectory of the barbell and other energy characteristics are similar to and consistent with the values reported in literature for adult female weightlifters.  相似文献   

14.
ABSTRACT

This project examined the interrelationships between power production and upper body kinematics during a series of medicine ball push-press (MBP-P) throws. Twenty-five regular weight trainers (body mass = 86 ± 10 kg) performed a series of ballistic vertical MBP-P throws at loads representing 5% and 10% of their assessed 5RM bench press. Throws were performed lying supine on a force platform (1 kHz) with upper body kinematics assessed using standard infra-red motion capture techniques (0.5 kHz). Gross measures of performance and power production such as peak vertical ball velocity (Velpeak), peak force (Fpeak) and power (Ppeak) were recorded during the propulsive phase of the movement. Comparative analyses indicated that despite significant reductions in Velpeak from the 5% to 10% loads (P < 0.001), Fpeak remained largely unchanged (P = 0.167). Analysis of inter-trial variability showed that the gross measures of performance and power were relatively stable (Coefficient of Variation [CV%] <13%), while most upper limb segmental kinematics varied considerably between trials (CV% up to 70%). This project highlights the complexity of the relationships between power production and upper body kinematics during light load ballistic MBP-P throwing. Additionally, it shows how trained athletes can achieve similar outcomes during ballistic movements using a variety of movement strategies.  相似文献   

15.
ABSTRACT

This study aimed to compare the reliability and magnitude of velocity variables between 3 variants of the bench press (BP) exercise in participants with and without BP training experience. Thirty males, 15 with and 15 without BP experience, randomly performed 3 variants of the BP on separate sessions: (I) concentric-only, (II) fast-eccentric and (III) controlled-eccentric. The mean velocity (MV) and maximum velocity (Vmax) of the concentric phase were collected against 3 loads (≈30%1RM, 50%1RM, and 75%1RM) with a linear velocity transducer. Reliability was high regardless of the variable, BP variant, and load (coefficient of variation [CV] ≤ 4.47%, intraclass correlation coefficient [ICC] ≥ 0.87). The comparison of the CVs suggested a higher reliability for the fast-eccentric BP (8 out of 12 comparisons), followed by the concentric-only BP (5 out of 12 comparisons), and finally the controlled-eccentric BP (never provided a higher reliability). No differences in reliability were observed between experienced (CV ≤ 4.71%; ICC ≥ 0.79) and non-experienced (CV ≤ 6.29%; ICC ≥ 0.76) participants. The fast-eccentric BP provided the highest MV (p < 0.05) and no differences were observed for Vmax. These results support the assessment of movement velocity during the fast-eccentric BP even in participants without experience.  相似文献   

16.
Abstract

Nine males (age 24.7 ± 2.1 years, height 175.3 ± 5.5 cm, body mass 80.8 ± 7.2 kg, power clean 1-RM 97.1 ± 6.36 kg, squat 1-RM = 138.3 ± 20.9 kg) participated in this study. On day 1, the participants performed a one-repetition maximum (1-RM) in the power clean and the squat. On days 2, 3, and 4, participants performed the power clean, squat or jump squat. Loading for the power clean ranged from 30% to 90% of the participant's power clean 1-RM and loading for the squat and jump squat ranged from 0% to 90% of the participant's squat 1-RM, all at 10% increments. Peak force, velocity, and power were calculated for the bar, body, and system (bar + body) for all power clean, squat, and jump squat trials. Results indicate that peak power for the bar, body, and system is differentially affected by load and movement pattern. When using the power clean, squat or jump squat for training, the optimal load in each exercise may vary. Throwing athletes or weightlifters may be most concerned with bar power, but jumpers or sprinters may be more concerned with body or system power. Thus, the exercise type and load vary according to the desired stimulus.  相似文献   

17.
This study examined the influence of differing volume load and intensity (%1 repetition maximum[%1RM]) resistance exercise workouts on session rating of perceived exertion (sRPE) countermovement jump (CMJ) performance and endocrine responses. Twelve participants performed a workout comprising four exercises (bench press, back squat, deadlift and prone bench pull) in randomised order as either power (POW); 3 sets × 6 repetitions at 45%1RM × 3 min inter-set rest, strength (ST); 3 sets × 3 repetitions at 90%1RM × 3 min inter-set rest, or hypertrophy (HYP); 3 sets × 10 repetitions at 70%1RM × 1 min inter-set rest in a randomised-crossover design. CMJ performance and endocrine responses were measured immediately pre-, post-, 12, 24, 48 and 72 h post-exercise. POW sRPE (3.0 ± 1.0) was lower than ST (4.5 ± 1.0) (P = 0.01), and both were lower than HYP (8.5 ± 1.0) (P = 0.01). Duration of CMJ decrement was longer (P ≤ 0.05) for HYP (72 h) compared to POW (12 h) and ST (24 h). Testosterone concentration was greater (P ≤ 0.05) immediately post-exercise in HYP compared to POW and ST. In conclusion, less inter-set rest, greater volume load and intensity (%1RM) may increase sRPE, duration of CMJ performance decrement and testosterone responses in resistance exercise.  相似文献   

18.
This study examined the relationship between sit-to-stand (STS) power and physical function in adults with severe obesity. Thirty-eight adults (age: 44 ± 12 years; body mass index [BMI]: 45.2 ± 7.8 kg/m2) completed evaluations of STS power, strength and functional performance. STS power was measured with a wearable inertial sensor, strength was assessed with the isometric mid-thigh pull, and function was measured with the timed up-and-go (TUG), six-minute walk test (6MWT) and 30-s chair STS. Power and strength (normalised to body mass) entered regression models in addition to age, gender, BMI and physical activity (daily step count). Power displayed large univariate associations with TUG (r = 0.50) and 30-s chair STS (r = 0.67), and a moderate association with 6MWT (r = 0.49). Forward stepwise regression revealed that power independently contributed to TUG (β = ?0.40, p = 0.010), 30-s chair STS (β = 0.67, p < 0.001) and 6MWT performance (β = 0.27, p = 0.007). Power also appeared to be a superior determinant of function compared with strength. Power generated via the STS transfer largely underpins the ability to perform functional tasks in adults with severe obesity, although intervention studies are required to investigate a potentially causal relationship.  相似文献   

19.
The purpose of this study was to analyse the validity and reliability of a novel iPhone app (named: PowerLift) for the measurement of mean velocity on the bench-press exercise. Additionally, the accuracy of the estimation of the 1-Repetition maximum (1RM) using the load–velocity relationship was tested. To do this, 10 powerlifters (Mean (SD): age = 26.5 ± 6.5 years; bench press 1RM · kg?1 = 1.34 ± 0.25) completed an incremental test on the bench-press exercise with 5 different loads (75–100% 1RM), while the mean velocity of the barbell was registered using a linear transducer (LT) and Powerlift. Results showed a very high correlation between the LT and the app (r = 0.94, SEE = 0.028 m · s?1) for the measurement of mean velocity. Bland–Altman plots (R2 = 0.011) and intraclass correlation coefficient (ICC = 0.965) revealed a very high agreement between both devices. A systematic bias by which the app registered slightly higher values than the LT (P < 0.05; mean difference (SD) between instruments = 0.008 ± 0.03 m · s?1). Finally, actual and estimated 1RM using the app were highly correlated (r = 0.98, mean difference (SD) = 5.5 ± 9.6 kg, P < 0.05). The app was found to be highly valid and reliable in comparison with a LT. These findings could have valuable practical applications for strength and conditioning coaches who wish to measure barbell velocity in the bench-press exercise.  相似文献   

20.
The aim of this study was to identify how changes in the stability conditions of a back squat affect maximal loads lifted and erector spinae muscle activity. Fourteen male participants performed a Smith Machine (SM) squat, the most stable condition, a barbell back (BB) squat, and Tendo-destabilizing bar (TBB) squat, the least stable condition. A one repetition max (1-RM) was established in each squat condition, before electromyography (EMG) activity of the erector spinae was measured at 85% of 1-RM. Results indicated that the SM squat 1-RM load was significantly (p = 0.006) greater (10.9%) than the BB squat, but not greater than the TBB squat. EMG results indicated significantly greater (p < 0.05) muscle activation in the TBB condition compared to other conditions. The BB squat produced significantly greater (p = 0.036) EMG activity compared to the SM squat. A greater stability challenge applied to the torso seems to increase muscle activation. The maximum loads lifted in the most stable and unstable squats were similar. However, the lift with greater stability challenge required greatest muscle activation. The implications of this study may be important for training programmes; if coaches wish to challenge trunk stability, while their athletes lift maximal loads designed to increase strength.  相似文献   

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