Although full range of motion (ROM) resistance training requires the movement of a load throughout the entire ROM of an exercise, the actual intensity of the movement varies dramatically. These fluctuations have been previously broken down into three main sections, which are, in concentric order, the acceleration, oscillation, and deceleration phases of the exercise (7).
For example, a previous study performed by Lander et al. (7) has reported that during 75% of one-repetition maximum (1RM) full ROM free weight bench press, peak force occurred at 1.78% of the ROM. This corresponded to a barbell position of 0.82 cm from the chest. However, by the time the bar had moved through 25% of the full ROM, the force value was almost halved. This position of the movement was labeled the end of the acceleration and the start of the oscillation phase. During the subsequent oscillation phase, the force level remained relatively stable before a further dramatic drop-off in the final 26.47% of the movement. This final drop-off stage was termed the deceleration phase of the lift, with negative acceleration occurring as the elbow joint reaches terminal extension. Similar deceleration phases of between 24 and 40% of the concentric ROM have also been reported in previous literature (5,11).
This dramatic reduction in force after the initial peak, along with the deceleration phase, limits the specificity of traditional full ROM resistance training exercises to sporting performance. The problem is that the maximal force and acceleration phase of the lift does not occur in the ROM in which many sporting movements may occur (14). This suggests that, in some cases, full ROM resistance training produces peak force and acceleration in phases of the ROM that are not used during sporting movements. For example, in tennis, the server might lower him- or herself into a deep squat position before performing a countermovement and exploding upward to hit the ball. In contrast, when a player is pursuing the tennis ball around the court, which may consist of numerous sprinting and cutting movements, his or her knee flexion angle during the countermovement may vary between near-full knee extension and deep flexion. Therefore, the specificity to athletic performance of an exercise such as full ROM squats seems to be somewhat limited.
Furthermore, velocity-specific, nonballistic resistance training exercises using low loads seem to result in an even greater ROM spent in the deceleration phase (2). Although potentially providing enhanced velocity specificity, this large deceleration phase during terminal extension may hinder the application of velocity-specific resistance training exercises to any sport where explosive movements are necessary.
One method of overcoming this limitation is ballistic power training. This popular method of training athletes has been shown to increase power levels more dramatically than traditional, nonballistic resistance training alone (13). Previous research suggests that one of the primary benefits of ballistic power training is an increase in velocity during the concentric phase of the movement (13). However, although the effectiveness of ballistic training has been previously examined (13,8,10), along with some aspects of its effects on the force curve (3,12), at present no studies have attempted to quantify the percentage of the ROM spent at maximal, high, and moderate to low force levels between ballistic and nonballistic resistance training. Therefore, the aim of this study was to evaluate the peak force and force curve characteristics during a traditional bench press (BP) and ballistic bench throw (BT). These tests will be performed under loading conditions representing both maximal power and normal resistance training conditions, in an attempt to determine the influence of the intention to throw the barbell on force production.
Experimental Approach to the Problem
This study examined the concentric peak force and concentric force intensity levels during BP and BT at loads of 55 and 80% of predicted 1RM in subjects with resistance training experience.
Eight male rugby league players (age = 21.0 ± 2.3 years, height = 182.3 ± 7.4 cm, body mass = 85.9 ± 5.5 kg) participated in the present study. These subjects possessed a minimum of 1 year of resistance, plyometric, and speed and agility training experience. They had performed both ballistic and nonballistic resistance training in the 6 months leading up to the study, which included a number of training sessions involving the equipment used in the present study. The subjects were tested in the early stages of the competitive season and were required to have no upper-body injuries that may have affected the results of the study. The subjects signed an informed consent document and were required to complete a preactivity readiness questionnaire. The testing methodologies were approved by a human research ethics committee (Central Queensland University).
Warm-Up and Preparation
The testing session consisted of a 5-minute warm-up on a rowing ergometer (Concept2, Morrisville, Vt) performed at a speed of 150 m·min−1. Each subject's concentric BP ROM was then determined by having the subject position his hands in a natural lifting position. This hand spacing position was then marked to allow for replication during each subsequent test. The distance between the countermovement position (at the chest) and terminal elbow extension was then measured using a digital position transducer (IDM Instruments, Hallam, Australia) interfaced with custom-written Labview software (National Instruments, Austin, Tex) on a Pentium III computer, which acquired data at a sampling frequency of 1000 Hz. This measurement was deemed the subject's concentric ROM and was used during analysis of the exercises. Once this measurement was taken, the subject commenced the isometric strength test, from which the predicted BP 1RM was derived.
Prediction of One-Repetition Maximum Bench Press
Predicted 1RM BP strength in this study was based on the peak force levels recorded during an isometric BP test. The isometric strength test was performed using a modified Smith machine (Calgym, Ashmore, Australia) with high-tensile adjustable cables to restrict movement of the barbell. A 500-lb load cell (Scale Components, Brisbane, Australia) was attached between the cable and the barbell to provide isometric force data. This load cell outputted data to a custom-written, calibrated Labview software program sampling at 1000 Hz.
With the subject lying in the BP position, the barbell was set at 2% of the concentric ROM from the chest. This position corresponded with the position of peak force from the Lander et al. (7) BP study. The subject was then instructed to push as hard as possible against the barbell, which could not progress past this position, for 5 seconds. After completing this test, the subjects were assigned a 5-minute rest interval before commencing the BP and BT tests.
Bench Press and Bench Throw Tests
Using the results of the isometric test, loads of 55 and 80% of peak isometric force were determined. These loads were chosen because they corresponded to the percentages of peak 1RM strength used during training to enhance ballistic power and strength, respectively (6,11). Although these percentages were based on isometric peak force, and not isoinertial 1RM strength, a previous study (9) has shown that these two different tests result in similar strength values for the BP exercise in trained subjects (isometric BP maximal voluntary contraction = 101.7 kg, 1RM BP = 102.2 kg). Furthermore, this method of loading prescription allowed for all testing to be performed in a single session, which was important because of the subjects' training commitments.
The Smith machine was used for both the BP and BT tests. During the BT tests, a Plyopower braking system (Fitness Technologies, Skye, Australia) was used to ensure the safety of the subjects. This system allows for a reduction in the descending mass of the barbell during ballistic movements, reducing the impact force while catching the barbell after the throw.
During this experiment, the Plyopower braking system was set to remove half of the mass of the barbell during the eccentric phase of the BTs. This allowed for a reduction in the potential for injury while still maintaining some of the eccentric loading necessary for elastic energy contribution to the movement. Furthermore, this eccentric braking scheme replicated the BT training exercises the subjects often performed as part of their strength and conditioning program. During these tests, barbell displacement was assessed using the equipment incorporated in the ROM assessment.
A total of four testing sets consisting of three repetitions each were performed. One set was performed at each load for both the full ROM BP and BT. These two exercises were performed in a randomized order for each subject, with a 5-minute rest interval between tests.
The subject began the test with the barbell held at full elbow extension, and they were instructed to perform three full ROM repetitions with the countermovement position at the chest. The BP exercise was performed by instructing the subject to lift the barbell as they would during normal training, with minimal rest between repetitions. There was no attempt made to control the speed of movement, because the subjects were familiar with the exercise, and a natural lifting movement was desired.
The subject commenced this test in the same position as they performed the BP test. The subject was instructed to lower the barbell, perform a countermovement at the chest, and throw the barbell for maximal height. This test was identical to the BP, except for the intention to throw the barbell at the end of the lift. No rest interval was given between repetitions.
The assessment of kinetic data from the BT movement has been previously shown to be highly reliable using methods similar to the ones employed in the present study (4). The repetitions with the highest peak force value for the BP and BT were used for data analysis. The custom-written Labview software program (National Instruments, Austin, Tex) was used to split the concentric force curve (which corresponded to the distance between the countermovement position and terminal elbow extension) into three sections. These were near maximal (between 95 and 100% of peak force), high (between 75 and 95% of peak force), and low to moderate (between 0 and 75% of peak force) force. The total displacement during each phase of the movement was then used to determine the percentage of the ROM (%ROM) spent at each intensity level. An example of the intensity levels throughout the force/ROM curve is provided in Figure 1.
Repeated-measures analyses of variance (ANOVAs) were performed comparing the %ROM at each intensity level for the BP and BT exercises at the 55 and 80% loads. The peak force during each test was also assessed using this statistical method. Therefore, each ANOVA design included one within- (loading condition) and one between-factors (test type) variable. Fisher least significant difference post hoc analysis was performed in the event of a significant main effect or interaction, with the alpha level set at p ≤ 0.05.
The mean isometric peak force was 106.4 ± 12.6 kg, resulting in mean 55% loading of 58.5 ± 7.3 kg and 80% loading of 85.1 ± 9.9 kg. A comparison of peak force data for each test is provided in Figure 2. As expected, peak force significantly increased under the higher loading condition for both groups. In addition, peak force was significantly higher for the BT than the BP under both loading conditions.
Results for the percentages of the ROM spent at each intensity level are provided in Table 1. The 80% of 1RM BT resulted in a significantly greater proportion of the movement occurring at high intensities in comparison with the identical-load BP.
The results of this study suggest that ballistic resistance training at high loads may result in a greater percentage of the ROM spent at higher force levels. At 80% of peak isometric force, the BT exercise resulted in a significant (p < 0.05) increase in the percentage of ROM spent at high intensity (27.6 vs. 17.4%). Although no significant differences were evident in the 55% loading condition, nonsignificant trends (p < 0.10) revealed that less ROM was spent at low to moderate intensity (56.2 vs. 65.1%), and more of the ROM consisted of near-maximal force intensity (19.9 vs. 14.3%) during the BTs in comparison with the BP.
Whereas the analysis of force intensity as a function of peak force between exercises seemed to favor the use of BTs, this method of training was reinforced by the findings pertaining to the peak force levels. The BT exercise resulted in significantly higher peak force production at both 55% (1010.5 ± 132.2 vs. 866.9 ± 189.1 N) and 85% (1187.3 ± 106.8 vs. 1037.4 ± 137.2 N) of peak isometric force. These findings provide evidence of the benefits of the intention to propel the barbell at the end of the movement, regardless of the loading condition. In comparison with the 55% loading condition, during the 80% of 1RM BT the barbell only left the subjects' hands for a relatively small distance. Despite this, the peak force values were significantly higher. This suggests that although the actual vertical displacement of the barbell was only minimally increased under heavy loads, the intention to propel the barbell required the subject to produce a far greater amount of force.
This refutes the previous findings of the study by Cronin et al. (2), who found that peak force did not differ between the two exercises at a set load. However, the untrained and relatively low strength levels of the subjects in that study suggest that the application of their findings to trained athletes is limited. In addition, the BP movement in the current study was performed using the subjects' natural lifting movement, in an attempt to replicate the performance of a resistance training session. In contrast, the Cronin et al. (2) study required the subjects to perform the BP movement in an identical manner to the BT, only without the barbell leaving the hands at the end of the movement.
The difference in peak force values between the testing conditions also skewed the intensity calculations, resulting in the BP percentage thresholds being lower than the BT thresholds under the same loading condition. For example, during the 55% tests, the mean cutoff thresholds for the BP compared with the BT were 650.2 vs. 757.9 and 823.5 vs. 960.0 N for 75 and 95% of peak force, respectively. Therefore, this resulted in the need to produce higher force levels throughout the ROM during the BTs, even though the loading condition was identical, just to remain equal with the BP exercise in terms of force intensity. For example, on the basis of these mean values, a force value of 700 N would fall within the high force intensity region for the BP. In contrast, this same force value would fall in the low to moderate intensity region for the BT, because of the higher cutoff thresholds.
The significant differences and nonsignificant trends suggest that the BT exercise actually exceeded the %ROM intensity of the BP exercise despite the higher cutoff thresholds. If identical absolute cutoff thresholds-for example based on peak force of the BP only-were applied between exercise conditions, the superiority of the BT movement would have become even more obvious.
The potential mechanisms behind the advantages of the BT exercise are most likely related to the intention of the movement. Although the concentric ROM of the exercise is identical between the exercises, the intention of the movement is vastly different. During the BP, the primary goal of the exercise is to lift the barbell to full elbow extension for a certain number of repetitions, usually until momentary muscular failure. For inexperienced lifters, this may present an optimal stimulus during each repetition; however, for experienced lifters, this may result in the lifter performing the movement as economically as possible. By performing each repetition with optimal efficiency, it would ensure that the maximum number of repetitions could be performed with the set load, which is often the goal of the resistance training program. In contrast, during ballistic BTs, the goal of the program is the opposite. Instead of the quantity of repetitions, ballistic training focuses on the quality of each repetition. Simply, the aim of each throw is to propel the barbell as high as possible. Therefore, optimal efficiency during the ballistic BTs consists of the movement that will result in the most powerful movement. In relation to maximal force production, this increases because of a higher peak acceleration. In relation to the force curve, it takes on a more plateaued shape. This is because the aim of the exercise is to maintain as close to maximal acceleration as possible throughout the movement, ensuring the highest possible terminal velocity as the barbell leaves the hands and, subsequently, the greatest vertical displacement.
When the findings for peak force and force intensity throughout the ROM are examined together, it is evident that ballistic BTs, even under loading conditions that would severely hamper the ability to propel the barbell, are a superior exercise to the traditional BP in terms of force production. In addition to the ability to produce a higher peak force, a greater proportion of the ROM is also spent at higher percentages of peak force levels. Whereas performing the traditional BP is an effective method of increasing strength levels, because of factors such as time under tension, the performance of ballistic BTs under both maximal power and high loading conditions should be included in an athlete's training program to optimize performance.
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