Standard statistical methods were used to calculate means and standard deviations which were used to describe all performance data. A 2 × 2 repeated-measures analysis of variance was used to analyze all performance data. Subsequent Tukey's post hoc tests were used to determine pairwise differences when significant F ratios were obtained. For all statistical tests, a probability level of P ≤ 0.05 was established to denote statistical significance.
Lean body mass increased significantly in both groups with no differences observed between groups: HR = 69.5 ± 8.1 (pre) to 71.8 ± 8.4 (post) kg; COM = 69.3 ± 10.5 (pre) to 71.4 ± 9.9 (post) kg. In addition, percent body fat decreased significantly in both groups with no difference observed between groups: HR = 14.1 ± 5.3% (pre) to 12.8 ± 4.8% (post); COM = 15.5 ± 5.0% (pre) to 14.7 ± 3.5% (post).
The results of the present study indicated that the addition of ballistic exercises into a traditional heavy resistance training program can augment increases in 1RM bench press in recreationally trained men. Furthermore, average lower-body power also can be significantly enhanced with the addition of ballistic exercises to a traditional resistance training program. However, the hypothesis that the addition of ballistic exercises to heavy resistance training would augment 1RM squat was not supported in the present study.
The unique finding in the present study was that the addition of ballistic exercises to traditional heavy resistance training augmented 1RM bench press strength more than traditional resistance training alone. The COM group increased 1RM bench press by 12.1% whereas the HR group increased 1RM bench press by 7.4%. Although previous studies have examined strength increases in resistance-trained individuals who performed heavy resistance and power training (3), to our knowledge this was the first study to specifically quantify dynamic strength increases from the addition of ballistic training to heavy resistance training. It was hypothesized that improvements in power gained through the inclusion of ballistic exercises may enhance force production especially during the initiation of bar ascent. During initial ascent, a sufficient amount of power must be expressed in order to accelerate the bar through the “sticking point” of the exercise. Elliot et al. (10) defined the sticking region as a force-reduced transition phase between a strain energy-assisted acceleration phase and a mechanically advantageous maximum strength region. Additional power gained in this region could increase the likelihood of reaching the area of maximal strength thereby increasing 1RM strength to a greater extent. These results have important implications for those individuals who compete in maximal strength events (i.e., power lifting) as our data indicate maximal bench press performance can be enhanced by addition of ballistic exercises to traditional heavy resistance training.
Interestingly, the addition of ballistic training to heavy resistance training did not augment 1RM squat performance in the present study. Although both HR and COM groups increased 1RM squat by 17.3% and 15.2%, respectively, these improvements were not significantly different between groups. These data are in contrast to Hoffman et al. (15), who observed greater improvements in 1RM squat in an Olympic training group than those observed in a traditional power lifting group. The lack of augmentation observed in lower-body strength compared to upper-body strength in the COM group is unclear. However, a few explanations may be postulated. It is possible that the addition of upper-body ballistic training in the COM group led to augmentation of the bench press partially due to training status. Although our subjects were recreationally resistance-trained (and completed base resistance training prior to initiating the study), they had more experience with the bench press exercise than the squat. Thus, it is possible they may have still been in a learning phase for the squat which could have masked potential adaptations resulting from ballistic training. If this was the case, the changes observed in the bench press may have reflected greater familiarity which may indirectly suggest that the addition of ballistic training to heavy resistance training may have a greater potential effect when individuals have attained a threshold level of muscle strength and can be used as a technique to surpass training plateaus.
Another potential reason entails training specificity. The high pulls and jump squats performed in the present study may not have been specific enough to enhance 1RM squat strength. For safety reasons, jump squats were performed on specialized ballistic equipment (Cormax Squat/Overhead Press System 1000, Cormax Strength Power Systems, Valley City, ND) with a hydraulic braking system that limited loading during the eccentric phase. In addition, the range of motion (i.e., slightly above the parallel thigh position) of the jump squat and high pull exercises may not have been specific enough to the range of motion and motor patterns used in a free weight 1RM squat. If our original hypothesis was correct and the addition of ballistic training to enhance power at the sticking region was critical to augmenting 1RM performance, then the lack of specificity to the sticking region of a free weight barbell squat may have limited potential 1RM gains. Furthermore, the unloading of the eccentric phase could have played a role. This is consistent with the data of Hoffman et al. (16) who demonstrated the importance of the eccentric phase in developing maximal power.
Interestingly, no significant main effects in power improvements were observed in either group. However, a significant interaction was observed in jump squat average power where the decrease in power in HR (-397 W) and increase in COM (+478W) was statistically different. Although 6% to 13% mean improvements were observed in jump squat and ballistic push-up peak and mean power in COM, these values did not reach statistical significance. The lack of significant improvement in upper- and lower-body power in the COM group may be attributed to the relatively small sample size (n = 8 in the COM group) and the high degree of variance associated with power measurements. Due to the traditionally large numerical values associated with measuring power (4,5,20,23), the lack of a large sample size and subsequent low-to-moderate statistical power (0.30-0.63) observed in the power measurements may have masked the mean increases observed in the present study. Other studies have failed to denote statistical significance in power data despite substantial mean differences when N sizes of 17 or less were used (20,23). Thus, it is likely that a larger sample size would have been needed to denote significant main effects in power enhancement in the present study.
The significant interaction observed in average jump squat power demonstrated that combined heavy resistance and ballistic training has a beneficial effect on enhancing lower-body power. Interestingly, a slight insignificant reduction in average jump squat power was observed in HR. These results concur with research that has shown that heavy resistance strength training alone could potentially have a negative impact on lower-body power (6). Our results demonstrate the importance of inclusion of exercise-specific ballistic resistance exercises into a resistance training program in order to enhance lower-body muscular power.
In conclusion, the results of the present study provide evidence that the inclusion of ballistic exercises into a heavy resistance training program can enhance maximal upper-body strength and lower-body power. These results have positive implications for the inclusion of ballistic training for those athletes who are striving to increase 1RM maximal strength.
We would like to thank a dedicated group of subjects for their participation. In addition, we would like to thank the National Strength and Conditioning Association for funding this study.
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