A comparison of force curve profiles between the bench press and ballistic bench throws

The purpose of this study was to compare the peak force and force curve characteristics during a traditional bench press (BP) and a ballistic bench throw (BT). Eight (age = 21.0 +/- 2.3 years, height = 182.3 +/- 7.4 cm, body mass = 85.9 +/- 5.5 kg) semi-professional rugby league players with resistance and power training experience performed both BP and BT exercises at loads of 55 and 80% of their predicted one-repetition maximum. The force curves for each test were then divided into three intensity levels, set at low to moderate (0-75%), high (75-95%), and near-maximal force (95-100%). These values were obtained by determining the percentage of the range of motion (ROM) in which the force produced during each test was within these thresholds. The BT exercise produced significantly (p < 0.05) higher peak force than BP under both loading conditions. A significantly greater portion of the ROM during the 80% BT was at a high intensity in comparison with the BP. No significant differences were found between force intensity conditions at 55% loads. It can be concluded that performing the BT exercise results in a greater peak force output when compared with the traditional BP movement under both resistance training and maximal power loading conditions. Furthermore, performing the BT exercise with heavy loads results in a more efficient training method for maintaining high force levels throughout the ROM.     

Effect of movement velocity on the relationship between training load and the number of repetitions of bench press

This study investigated the effect of movement velocity on the relationship between loading intensity and the number of repetitions of bench press. Thirteen healthy men (age = 21.7 +/- 1.0 years; weight = 76.8 +/- 2.5 kg; 1 repetition maximum [1RM] = 99.5 +/- 6.0 kg), who were involved in regular weight training, voluntarily participated in the experiment. Subjects performed bench presses on a Smith machine at 5 different intensities (40-80% 1RM), repeated for 4 velocity conditions (slow: 0.15 +/- 0.03 m.s(-1); medium: 0.32 +/- 0.07 m.s(-1); fast: 0.52 +/- 0.12 m.s(-1); ballistic: maximum velocity), which were randomly assigned over 5 experimental sessions after a 1RM test. Velocity significantly changed the relationship between intensity (%1RM) and the number of reps performed (p < 0.001), with faster velocities producing a higher number of reps. A significant interaction between intensity and velocity meant that velocity had a much greater effect on repetitions at lower intensities. These results suggest that the benefits of using a stretch-shortening cycle during faster movements outweigh the associated disadvantages from the force-velocity relationship. The practical applications of this study are that, when trainees are assigned a resistance training with specific RM values, the lifted intensity (%1RM) or weights will not be consistent unless velocity is controlled during training.     

Kinematics and kinetics of the seated row and implications for conditioning

Optimizing transference of gym-based strength and power gains to sporting performance necessitates a physiological and biomechanical understanding of the weight-training exercise as well as the sporting activity. With this in mind, this paper describes the kinematics and kinetics associated with a seated row. The maximal strength and concentric power-load spectrum (30- 100% 1 repetition maximum [1RM]) for the cable seated row was assessed using Olympic rowers (n = 8). In terms of temporal characteristics, peak force across all loads occurred within the first 25% of movement time. Peak power across loads occurred within 35-45% of movement time. With regard to position, peak force occurred within 8.3% and peak power within 27-35% of the start of the concentric phase. To estimate the load that maximized mechanical power output, a quadratic was fitted to each subject's power output vs. 1RM. In terms of mean power, an estimated load of 81.4% (+/- 9.7%) 1RM was found to maximize power output. A 10 and 20% change in load each side of this maximum resulted in a 1.8 and 7.3% decrease in power output, respectively. The predilection of research to train all subjects at 1 load is fundamentally flawed due to interindividual maximum power differences (range in this study = 69-100% 1RM). Also, the importance of this measure would seem questionable, given that loads either side of the load that maximize power output do not change power output substantially.     

Peak power, ground reaction forces, and velocity during the squat exercise performed at different loads

This study examined the changes in peak power, ground reaction force and velocity with different loads during the performance of the parallel squat movement. Twelve experienced male lifters (26.83 +/- 4.67 years of age) performed the standard parallel squat, using loads equal to 20, 30, 40, 50, 60, 70, 80, and 90% of 1 repetition maximum (1RM). Each subject performed all parallel squats with as much explosiveness as possible using his own technique. Peak power (PP), peak ground reaction force (PGRF), peak barbell velocity (PV), force at the time of PP (FPP), and velocity at the time of PP (VPP) were determined from force, velocity, and power curves calculated using barbell velocity and ground reaction force data. No significant differences were detected among loads for PP; however, the greatest PP values were associated with loads of 40 and 50% of 1RM. Higher loads produced greater PGRF and FPP values than lower loads (p < 0.05) in all cases except between loads equal to 60-50, 50-40, and 40-30% of 1RM for PGRF, and between loads equal to 70-60 and 60-50% of 1RM for FPP. Higher loads produced lower PV and VPP values than lower loads (p < 0.05) in all cases except between the 20-30, 70-80, and 80-90% of 1RM conditions. These results may be helpful in determining loads when prescribing need-specific training protocols targeting different areas of the load-velocity continuum.     

An examination of strength and concentric work ratios during variable range of motion training

Variable range of motion (ROM) training consists of partial ROM resistance training with the countermovement being performed at a different phase of the movement for each set. In this study, we assessed the effect of this method of training on peak force, load lifted, and concentric work performed. Six male subjects with resistance training backgrounds (age 20.2 +/- 1.3 years, height 179.4 +/- 4.6 cm, weight 89.6 +/- 9.9 kg, 6-repetition maximum [6RM] bench press 92.5 +/- 14.3 kg) participated in this study. Testing consisted of 6RM bench press strength tests during full (FULL), three quarter ((3/4)), one half ((1/2)), and one quarter ((1/4)) ROM from full elbow extension bench press performed on a Smith machine. The 6RM load, peak force (PF), and concentric work (W) performed during each ROM was examined using a one-way analysis of variance performed at an alpha level of p < 0.05. The 6RM load increased significantly as the ROM was decreased for all tests (FULL = 92.5 +/- 14.3 kg, (3/4) = 102.1 +/- 14.3 kg, (1/2) = 123.3 +/- 23.6 kg, (1/4) = 160.9 +/- 26.2 kg). PF during each test was significantly higher during the (1/4) (1924.8 +/- 557.9 N) and (1/2) (1859.4 +/- 317.1 N) ROM from full elbow extension bench press when compared with the (3/4) (1242.2 +/- 254.6 N) and FULL (1200.5 +/- 252.5 N) ROM exercise. Although higher force levels were evident, the restriction in barbell displacement resulted in a subsequent reduction in W as the lifting ROM was reduced. These results suggest that variable ROM resistance training results in increased force production as the ROM diminishes.     

Acute effects of augmented eccentric loading on jump squat performance

The purpose of this study was to determine the acute effects of a spectrum of eccentric loads on force, velocity, and power during the concentric portion of maximal-effort jump squats utilizing a repeated measures design. Thirteen resistance-trained men (age = 22.8 +/- 2.9 years, weight = 87.1 +/- 11.8 kg, 163.5 +/- 28.6 kg squat 1 repetition maximum [1RM]; mean +/- SD), who routinely incorporated back squats into their training, participated as subjects in this investigation. Jump squat performance was assessed using 4 experimental conditions. The first of these conditions consisted of an isoinertial load equal to 30% of back squat 1RM. The remaining conditions consisted of jump squats with a concentric load of 30% 1RM, subsequent to the application of experimental augmented eccentric loading (AEL) conditions of 20, 50, and 80% of back squat 1RM, respectively. All subjects performed 2 sets of 1RM of maximum-effort jump squats with all experimental conditions in a counter-balanced sequence. Forty-eight hours after completing the first testing session, subjects repeated the experimental testing protocol to establish stability reliability. Peak performance values for the reliable variables of force, velocity, and power, as well as force and power values obtained at 20-ms intervals during the initial 400 ms of the concentric jump squat range of motion, showed no statistical difference (p > 0.05) across the experimental AEL loads. These results suggest that load-spectrum AEL prior to a 30% 1RM jump squat fails to acutely enhance force, velocity, and power.     

Difference in kinematics and kinetics between high- and low-velocity resistance loading equated by volume: implications for hypertrophy training

Although it is generally accepted that a high load is necessary for muscle hypertrophy, it is possible that a low load with a high velocity results in greater kinematics and kinetics than does a high load with a slow velocity. The purpose of this study was to determine if 2 training loads (35 and 70% 1 repetition maximum [1RM]) equated by volume, differed in terms of their session kinematic and kinetic characteristics. Twelve subjects were recruited in this acute randomized within-subject crossover design study. Two bouts of a half-squat exercise were performed 1 week apart, one with high load-low velocity (HLLV = 3 sets of 12 reps at 70% 1RM) and the other with low-load high-velocity (LLHV = 6 sets of 12 reps at 35% 1RM). Time under tension (TUT), average force, peak force (PF), average power (AP), peak power (PP), work (TW), and total impulse (TI) were calculated and compared between loads for the eccentric and concentric phases. For average eccentric and concentric single repetition values, significantly (p < 0.05) greater (～15-22%) PP outputs were associated with the LLHV loading, whereas significantly greater (～7-61%) values were associated with the HLLV condition for most other variables of interest. However, in terms of total session kinematics and kinetics, the LLHV protocol resulted in significantly greater (～16-61%) eccentric and concentric TUT, PF, AP, PP, and TW. The only variable that was significantly greater for the HLLV protocol than for the LLHV protocol was TI (～20-24%). From these results, it seems that the LLHV protocol may offer an equal if not better training stimulus for muscular adaptation than the HLLV protocol, because of the greater time under tension, power, force, and work output when the total volume of the exercise is equated.     

Mechanisms underlying the reduced performance measures from using equipment with a counterbalance weight system

Bench press throws are commonly used in the assessment of upper-body power and are often performed on a Smith machine that uses a counterbalance weight to reduce the net load on the barbell. The use of a counterbalanced Smith machine was recently shown to reduce performance measures, but the mechanisms for this reduction have not been established. The purpose of this study was to determine the underlying physiological and biomechanical causes of the reduced performance measures found when using a counterbalanced Smith machine. Twenty-four men (mean ± SE: age, 23 ± 1 years; weight, 91.0 ± 3.5 kg; height, 178.9 ± 1.2 cm) performed Smith machine bench press throws at 30% of 1-repetition maximum under 4 conditions: (a) rebound movement and counterbalance, (b) rebound movement and no counterbalance, (c) concentric-only movement and counterbalance, and (d) concentric-only movement and no counterbalance. Peak power, peak force, and peak concentric and eccentric velocities were measured using a linear accelerometer, and peak ground reaction force was measured using a force plate. The counterbalance condition produced significantly (p < 0.05) lower peak accelerometer-based force (-21.2 and -17.0% for rebound and concentric-only bench press throws, respectively) but increased peak ground reaction force (5.3 and 3.2%). The discrepancy between changes in peak accelerometer-based force and peak ground reaction force suggests that an increase in net external load occurred during the movement. For performance testing of explosive movements, the use of a counterbalance system results in an underestimation of performance capability, likely because of an increase in the net external load during the concentric phase. Therefore, a counterbalance system should not be used for explosive movement performance testing.     

Role of concentric force in limiting improvement in muscular strength

We hypothesized that resistance training with combined eccentric and concentric actions, and concentric action only, should yield similar changes in muscular strength. Subjects in a free weight group trained three times a week for 12 wk with eccentric and concentric actions (FW, n = 16), a second group trained with concentric-only contractions using hydraulic resistance (HY; n = 12), and a control group did not train (n = 11). Training for FW and HY included five sets of supine bench press and upright squat at an intensity of 1-6 repetition maximum (RM) plus five supplementary exercises at 5-10 RM for a total of 20 sets per session for approximately 50 min. Testing at pre-, mid-, and posttraining included 1) 1 RM bench press and squat with and 2) without prestretch using free weights; 3)isokinetic peak force and power for bench press and squat at 5 degrees/s, and isotonic peak velocity and power for bench press with 20-kg load and squat with 70-kg load; 4) hydraulic peak bench press force and power, and peak knee extension torque and power at fast and slow speeds; and 5) surface anthropometry (fatfolds and girths to estimate upper arm and thigh volume and muscle area). Changes in overall fatness, muscularity, and muscle + bone cross-sectional area of the limbs did not differ between groups (P greater than 0.05). Improvements in free weight bench press and squat were similar (P greater than 0.05) in FW (approximately 24%) and HY (approximately 22%, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Peak power, force, and velocity during jump squats in professional rugby players

Training at the optimal load for peak power output (PPO) has been proposed as a method for enhancing power output, although others argue that the force, velocity, and PPO are of interest across the full range of loads. The aim of this study was to examine the influence of load on PPO, peak barbell velocity (BV), and peak vertical ground reaction force (VGRF) during the jump squat (JS) in a group of professional rugby players. Eleven male professional rugby players (age, 26 ± 3 years; height, 1.83 ± 6.12 m; mass, 97.3 ± 11.6 kg) performed loaded JS at loads of 20-100% of 1 repetition maximum (1RM) JS. A force plate and linear position transducer, with a mechanical braking unit, were used to measure PPO, VGRF, and BV. Load had very large significant effects on PPO (p < 0.001, partial η2 = 0.915); peak VGRF (p < 0.001, partial η2 = 0.854); and peak BV (p < 0.001, partial η2 = 0.973). The PPO and peak BV were the highest at 20% 1RM, though PPO was not significantly greater than that at 30% 1RM. The peak VGRF was significantly greater at 1RM than all other loads, with no significant difference between 20 and 60% 1RM. In resistance trained professional rugby players, the optimal load for eliciting PPO during the loaded JS in the range measured occurs at 20% 1RM JS, with decreases in PPO and BV, and increases in VGRF, as the load is increased, although greater PPO likely occurs without any additional load.     

Muscular outputs during dynamic bench press under stable versus unstable conditions

Previous studies have suggested that resistance training exercise under unstable conditions decreases the isometric force output, yet little is known about its influence on muscular outputs during dynamic movement. The objective of this study was to investigate the effect of an unstable condition on power, force, and velocity outputs during the bench press. Twenty male collegiate athletes (mean age, 21.3 +/- 1.5 years; mean height, 167.7 +/- 7.7 cm; mean weight, 75.9 +/- 17.5 kg) participated in this study. Each subject attempted 3 sets of single bench presses with 50% of 1 repetition maximum (1RM) under a stable condition with a flat bench and an unstable condition with a Swiss ball. Acceleration data were obtained with an accelerometer attached to the center of a barbell shaft, and peak outputs of power, force, and velocity were computed. Although significant loss of the peak outputs was found under the unstable condition (p < 0.017), their reduction rates remained relatively low, approximately 6% for force and 10% for power and velocity outputs, compared with previous findings. Such small reduction rates of muscular outputs may not compromise the training effect. Prospective studies are necessary to confirm whether the resistance training under an unstable condition permits the improvement of dynamic performance and trunk stability.     

Effects of stretching on upper-body muscular performance

The purpose of this investigation was to examine the influence of upper-body static stretching and dynamic stretching on upper-body muscular performance. Eleven healthy men, who were National Collegiate Athletic Association Division I track and field athletes (age, 19.6 +/- 1.7 years; body mass, 93.7 +/- 13.8 kg; height, 183.6 +/- 4.6 cm; bench press 1 repetition maximum [1RM], 106.2 +/- 23.0 kg), participated in this study. Over 4 sessions, subjects participated in 4 different stretching protocols (i.e., no stretching, static stretching, dynamic stretching, and combined static and dynamic stretching) in a balanced randomized order followed by 4 tests: 30% of 1 RM bench throw, isometric bench press, overhead medicine ball throw, and lateral medicine ball throw. Depending on the exercise, test peak power (Pmax), peak force (Fmax), peak acceleration (Amax), peak velocity (Vmax), and peak displacement (Dmax) were measured. There were no differences among stretch trials for Pmax, Fmax, Amax, Vmax, or Dmax for the bench throw or for Fmax for the isometric bench press. For the overhead medicine ball throw, there were no differences among stretch trials for Vmax or Dmax. For the lateral medicine ball throw, there was no difference in Vmax among stretch trials; however, Dmax was significantly larger (p 相似文献   

Maximal power at different percentages of one repetition maximum: influence of resistance and gender

National Collegiate Athletic Association Division I athletes were tested to determine the load at which maximal mechanical output is achieved. Athletes performed power testing at 30, 40, 50, 60, and 70% of individual 1 repetition maximum (1RM) in the squat jump, bench press, and hang pull exercises. Additionally, hang pull power testing was performed using free-form (i.e., barbell) and fixed-form (i.e., Smith machine) techniques. There were differences between genders in optimal power output during the squat jump (30-40% of 1RM for men; 30-50% of 1RM for women) and bench throw (30% of 1RM for men; 30-50% of 1RM for women) exercises. There were no gender or form interactions during the hang pull exercise; maximal power output during the hang pull occurred at 30-60% of 1RM. In conclusion, these results indicate that (a) gender differences exist in the load at which maximal power output occurs during the squat jump and bench throw; and (b) although no gender or form interactions occurred during the hang pull exercise, greater power could be generated during fixed-form exercise. In general, 30% of 1RM will elicit peak power outputs for both genders and all exercises used in this study, allowing this standard percentage to be used as a starting point in order to train maximal mechanical power output capabilities in these lifts in strength trained athletes.     

Increased number of forced repetitions does not enhance strength development with resistance training

Some research suggests that strength improvements are greater when resistance training continues to the point at which the individual cannot perform additional repetitions (i.e., repetition failure). Performing additional forced repetitions after the point of repetition failure and thus further increasing the set volume is a common resistance training practice. However, whether short-term use of this practice increases the magnitude of strength development with resistance training is unknown and was investigated here. Twelve basketball and 10 volleyball players trained 3 sessions per week for 6 weeks, completing either 4 x 6, 8 x 3, or 12 x 3 (sets x repetitions) of bench press per training session. Compared with the 8 x 3 group, the 4 x 6 protocol involved a longer work interval and the 12 x 3 protocol involved higher training volume, so each group was purposefully designed to elicit a different number of forced repetitions per training session. Subjects were tested on 3- and 6-repetition maximum (RM) bench press (81.5 +/- 9.8 and 75.9 +/- 9.0 kg, respectively, mean +/- SD), and 40-kg Smith Machine bench press throw power (589 +/- 100 W). The 4 x 6 and 12 x 3 groups had more forced repetitions per session (p < 0.01) than did the 8 x 3 group (4.1 +/- 2.6, 3.1 +/- 3.5, and 1.2 +/- 1.8 repetitions, respectively), whereas the 12 x 3 group performed approximately 40% greater work and had 30% greater concentric time. As expected, all groups improved 3RM (4.5 kg, 95% confidence limits, 3.1- 6.0), 6RM (4.7 kg, 3.1-6.3), bench press throw peak power (57 W, 22-92), and mean power (23 W, 4-42) (all p < or = 0.02). There were no significant differences in strength or power gains between groups. In conclusion, when repetition failure was reached, neither additional forced repetitions nor additional set volume further improved the magnitude of strength gains. This finding questions the efficacy of adding additional volume by use of forced repetitions in young athletes with moderate strength training experience.     

The effects of combined ballistic and heavy resistance training on maximal lower- and upper-body strength in recreationally trained men

The purpose of the present study was to investigate the additive effects of ballistic training to a traditional heavy resistance training program on upper- and lower-body maximal strength. Seventeen resistance-trained men were randomly assigned to 1 of 2 groups: (i) a combined ballistic and heavy resistance training group (COM; age = 21.4 +/- 1.7 years, body mass = 82.7 +/- 15.1 kg) or (ii) a heavy resistance training group (HR; age = 20.1 +/- 1.2 years, body mass = 81.0 +/- 9.2 kg) and subsequently participated in an 8-week periodized training program. Training was performed 3 days per week, that is, 6-8 exercises per workout (6-8 traditional exercises for HR; 4-6 traditional + 2 ballistic exercises in COM) for 3-8 repetitions. A significant increase in 1-repetition maximum (1RM) squat was shown in both groups (COM = 15.2%; HR = 17.3%) with no difference observed between groups. However, 1RM bench press increased to a significantly greater extent (P = 0.04) in COM than HR (11.6% vs. 7.1%, respectively). For peak power attained during the jump squat, an interaction (P = 0.02) was observed where the 5.4% increase in COM and -3.2% reduction in HR were statistically significant. Nonsignificant increases were observed in peak plyometric push-up power in COM (8.5%) and HR (3.4%). Lean body mass increased significantly in both groups, with no between-group differences observed. The results of this study support the inclusion of ballistic exercises into a heavy resistance training program for increasing 1RM bench press and enhancing lower-body power.     

Contraction mode shift in quadriceps femoris muscle activation during dynamic knee extensor exercise with increasing loads

The objective of the present study was to examine the superficial quadriceps femoris (QF) muscle electromyogram (EMG) during dynamic sub-maximal knee extension exercise between young adult men and women. Thirty subjects completed, in a random order, 2 sub-maximal repetitions of single-leg knee extensions at 20-90% of their one-repetition maximum (1RM). Vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF) muscle integrated EMG (IEMG) during each sub-maximal lift was normalized to the respective 1RM for concentric, isometric and eccentric modes. The EMG median frequency (f(med)) was determined over the isometric mode. Men attained a significantly (p<0.05) greater knee angular velocity than the women during the concentric mode (83.6+/-19.1 degrees /s and 67.4+/-19.8 degrees /s, respectively). RF IEMG was significantly lesser than the VM (p=0.014) and VL (p<0.001) muscles, when collapsed across all contraction modes, loads, and sex. Overall IEMG was significantly greater during the concentric (p<0.001) and isometric (p<0.001) modes, than the eccentric mode. Men generated significantly (p=0.03) greater VL muscle IEMG than the women, while the opposite pattern emerged for the RF muscle. VM f(med) (105.1+/-11.1Hz) was significantly lesser than the VL (180.3+/-19.5Hz) and RF (127.7+/-13.9Hz) muscles across all lifting intensities, while the men (137.7+/-10.7Hz) generated greater values than the women (129.0+/-11.4Hz). The findings demonstrate a reduction in QF muscle activation across the concentric to eccentric transition, which may be related to the mode-specific velocity pattern.     

Eccentric and concentric torque-velocity characteristics of the quadriceps femoris in man

The primary purpose of this investigation was to study the eccentric and concentric torque-velocity characteristics of the quadriceps femoris in man using a recently developed combined isometric, concentric and eccentric controlled velocity dynamometer (the SPARK System). A secondary purpose was to compare the method error associated with maximal voluntary concentric and eccentric torque output over a range of testing velocities. 21 males (21-32 years) performed on two separate days maximal voluntary isometric, concentric and eccentric contractions of the quadriceps femoris at 4 isokinetic lever arm velocities of 0 degree.s-1 (isometric), 30 degrees.s-1, 120 degrees.s-1 and 270 degrees.s-1. Eccentric peak torque and angle-specific torques (measured every 10 degrees from 30 degrees to 70 degrees) did not significantly change from 0 degrees.s-1 to 270 degrees.s-1 (p greater than 0.005) with the exception of angle-specific 40 degrees torque, which significantly increased; p less than 0.05). The mean method error was significantly higher for the eccentric tests (10.6% +/- 1.6%) than for the concentric tests (8.1% +/- 1.7%) (p less than 0.05). The mean method error decreased slightly with increasing concentric velocity (p greater than 0.05), and increased slightly with increasing eccentric velocity (p greater than 0.05). A tension restricting neural mechanism, if active during maximal eccentric contractions, could possibly account for the large difference seen between the present eccentric torque-velocity results and the classic results obtained from isolated animal muscle.     

Optimal load maximizes the mean mechanical power output during upper extremity exercise in highly trained soccer players

The purpose of this study was to determine the optimal load for the maximal power output during the acceleration phase of a power movement in bench press (BP) exercises of highly trained soccer players at the beginning of a competition period. Fifteen professional male soccer players with an average age of 26.1 ± 3.9 years, an average height of 183.3 ± 6.7 cm, an average body mass of 78.8 ± 7.2 kg, and an average 1 repetition maximum (1RM) of 83.3 ± 11.2 kg were employed as subjects in this study. Maximal mean power output during a BP at 0, 10, 30, 50, 70, and 90% of their 1RM was measured to determine whether an optimal load exists that allows for the attainment of maximal power output. Three-dimensional upper extremity kinematic data were collected. Two force plates embedded in the floor and positioned below the bench were used to measure contact forces between the bench and ground during the lift. A repeated-measures analysis of variance was performed to determine power output differences at different percentages of the 1RM. The results of this study indicated that loads of 50% of the 1RM resulted in greater mean power output during the complete positive power movement. Loads at 30 and 50% of the 1RM resulted in greater mean power output computed from the acceleration phase of the lift than did all loads and were not statistically different from each other. However, individual soccer players did not reach the maximum power output with the same relative load. In conclusion, when soccer players develop muscular power toward the end of when the most important competitions are scheduled, dynamic effort strength training with the range of load from 30 to 50% of 1RM BP should be used. During the competition period, a load of 50% of a 1RM should be used in a BP to maintain muscular power over a wide load range.     

Effect of torso rotational strength on angular hip, angular shoulder, and linear bat velocities of high school baseball players

This investigation examined the effect of torso rotational strength on angular hip (AHV), angular shoulder (ASV), linear bat-end (BEV), and hand velocities (HV) and 3 repetition maximum (RM) torso rotational and sequential hip-torso-arm rotational strength (medicine ball hitter's throw) in high school baseball players (age 15.4 +/- 1.2 y). Participants were randomly assigned to 1 of 2 training groups. Group 1 (n = 24) and group 2 (n = 25) both performed a stepwise periodized resistance exercise program and took 100 swings a day, 3 days a week, for 12 weeks with their normal game bat. Group 2 performed additional rotational and full-body medicine ball exercises 3 days a week for 12 weeks. A 3RM parallel squat and bench press were measured at 0 and after 4, 8, and 12 weeks. Participants were pre- and posttested for 3RM dominant and nondominant torso rotational strength and medicine ball hitter's throw. Angular hip velocities, ASV, BEV, and HV were recorded pre- and posttraining by a motion capture system that identified and digitally processed reflective markers attached to each participant's bat and body. Groups 1 and 2 increased (p < or = 0.05) BEV (3.6 and 6.4%), HV (2.6 and 3.6%), 3RM dominant (10.5 and 17.1%) and nondominant (10.2 and 18.3%) torso rotational strength, and medicine ball hitter's throw (3.0 and 10.6%) after 12 weeks. Group 2 increased AHV (6.8%) and ASV (8.8%). Group 2 showed greater improvements in BEV, AHV, ASV, 3RM dominant and nondominant torso rotational strength, and medicine ball hitter's throw than group 1. Groups 1 and 2 increased predicted 1RM parallel squat (29.7 and 26.7%) and bench press (17.2 and 16.7%) strength after 12 weeks. These data indicate that performing additional rotational medicine ball exercises 2 days a week for 12 weeks statistically improves baseball performance variables.