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Acute effects after maximal agonistic and antagonistic strength exercise on plyometric push up performance (CROSBI ID 552932)

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Gregov, Cvita ; Jukić, Igor ; Marković, Goran Acute effects after maximal agonistic and antagonistic strength exercise on plyometric push up performance // 6th International Conference on Strength Training : Abstracts / Fleck, Steven J. ; Kraemer, William J. ; Brown, Lee E. et al. (ur.). 2008. str. 91-92

Podaci o odgovornosti

Gregov, Cvita ; Jukić, Igor ; Marković, Goran

engleski

Acute effects after maximal agonistic and antagonistic strength exercise on plyometric push up performance

A certain group of researchers found significant improvements in explosive generation of muscle force due to postactivation potentiation (PAP) (Baker & Newton, 2005). Others have reported no significant improvements (but have not found any negative acute effects). Most of the researchers investigated acute effects of postactivation potentiation regarding lower body while few of them dealt with upper body. Besides, there is a single evidence of investigating acute effects of maximal antagonistic activation on explosive performance of the agonistic muscles. Although, the authors obtained positive acute effects in agonistic actions as a result of antagonistic activation, further research is necessary to confirm these outcomes. Therefore, the first purpose of the present study is to examine whether acute maximal dynamic contractions of upper body (primarily pectoral) musculature significantly improve the ability of explosive force generation in the same region. Second purpose of the study is to determine if maximal dynamic contractions of the antagonists (upper back musculature) significantly and acutely improve explosive performance of the upper body agonists. Twenty five male subjects (mean age 23), with at least one year resistance training experience participated in this study. Subjects were randomly assigned into 3 groups: experimental agonistic group (BP - bench press ; n = 8), experimental antagonistic group (TR - t-bar row ; n = 9), and control group (CON ; n = 8). Prior to experimental protocol, maximal dynamic power (1 RM ; 1 repetition maximum) performing bench press (agonistic experimental group) and T-bar row (antagonistic experimental group) was determined. 48 hours after the first session subjects performed plyometric push ups placing their palms on the force plate (Quattro jump ; Kistler, 9290AD). Each of the subjects was given directions to perform two trials before the initial testing. Ground reaction forces in the vertical direction were registered by the frequency of 500 Hz. Considering the registered vertical force, gravitational force and body mass all using Quattro jump ; Kistler software, following parameters were calculated: maximum push-off height (H), average relative mechanical power generated during concentric (propulsive) phase of the plyometric push-up (P) and the average rate of force development during the concentric phase (RFD). RFD was defined as the ratio between maximal generated force (concentric phase) and the time needed for its generation. Initial testing consisted of two plyometric push ups with 45 seconds passive rest between each. CON group performed two plyometric push ups immediately after the warm up and the trials, and after 10 minutes passive rest, again. Both experimental groups performed two plyometric push ups (initial testing). 5 minute rest interval followed the initial testing. After that, every subject from the agonistic group (BP) performed bench press and every subject from the antagonistic group (TR) performed T-bar row (two sets with 3RM for both groups). 3RM intensity stands for 90% of the maximum weight lifted (1RM). Sets were performed with 2 minute rest between each. The 2 minute rest followed the second set of bench press and t-bar row. Finally, both groups were tested by performing two plyometric push ups (final testing). Differences between the final and initial testing in average relative mechanical power, push-off height and rate of force development were estimated by ANOVA. In case of statistically significant F-ratio, Tukey post hoc test was used to determine which groups differ in treatment effects. T-test for dependent samples was used to determine the differences between initial and final testing for each of the groups in average relative mechanical power output, push-off height and rate of force development. The level of significant for all statistical analyses was p<0.05. Analyzed results of the CON and TR group showed no significant changes in mechanical power output between initial and final testing, but the results between initial and final testing in mechanical power output of the BP group significantly decreased (8.5 ; p < 0.05). Discussion: Unlike the authors’ hypothesis, agonistic preloading such as bench press exercise and antagonistic preloading such as T-bar row, didn’t improve power indices (average mechanical power, push-off height and RFD) of the plyometric push up performance. On the contrary, BP group significantly decreased its results in mechanical power (8.5 ; p < 0.05) after the experimental protocol. The RFD results for the same group also tended to the lower values compared to the initial testing. Altogether, the obtained results do not coincide completely with the previous research done. Several issues contributed to that fact. First one refers to residual fatigue which obviously exceeded effects of its concurrent phenomena – potentiation, in BP group. The 2 minute rest interval between the last BP set and the final plyometric push up testing didn’t provide enough time subjects to recover. Present literature review shows that various rest interval lengths may lead to significant potentiation effects (20 seconds to 10 minutes). Hence, Sale (2002) suggests the 'trial and error' method to determine appropriate interval for optimizing potentiation effects with different exercise protocols. Therefore, future research must be oriented at inclusion of several different time points at which the final testing will be done, after maximal preloading in order to determine appropriate rest interval. The obtained results may also be due to intensity magnitude at which the plyometric push up was performed. Research indicate that only explosive exercise performed at low to moderate intensities (20-50%1RM), i.e. the results primarily due to RFD, may be improved by PAP. Accordingly, PAP doesn’ t improve exercise performed at very low intensities (Sadibašić, 2005) which is mostly dependent on the speed of contraction, or exercise performed at maximal intensities, dependent mostly on maximal muscle force. In this study, subjects performed exercises at 55%1RM (2/3 of their body mass related to individual repetition maximum). These results only support the hypothesis by Sale (2002) that PAP contributes only to exercises performed at low to moderate intensities, i.e. weights. Acute effects of antagonistic preloading has so far been investigated only by Baker & Newton (2005) who have found that explosive performance at 50%1RM significantly (4, 7%) improves explosive weight throwing exercise. Those results do not coincide with the results of this study (no significant differences in TR group between initial and final testing). Unlike the present study (90%), Baker and Newton (2005) used significantly lower preloading (50%) which was performed explosively, and the rest interval length of 3 minutes leading to less fatigue effects. Also, the entire protocol differs from the present study making it difficult to compare two findings. Conclusions: No significant positive effects in any of the group were detected, but negative in BP agonistic group due mostly to fatigue. Results of the study support the hypothesis that PAP may significantly improve power performance only by explosive activities using low and moderate intensities (Sale, 2002). References: (1) Baker, D. & Newton, R.U. J. Strength Cond. Res., 19: 202-205, 2005. (2) Sadibašić, T. Diplomski rad. Zagreb: Kineziološki fakultet Sveučilišta u Zagrebu. 2005. (3) Sale, D.G. Exerc. Sport Sci. Rev., 30: 138-143, 2002.

postactivation potentiation (PAP); upper body; plyometrics; strength

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Podaci o prilogu

91-92.

2008.

objavljeno

Podaci o matičnoj publikaciji

6th International Conference on Strength Training : Abstracts

Fleck, Steven J. ; Kraemer, William J. ; Brown, Lee E. ; Antonio, Jose ; Weir, Joe ; Ebben, William P. ; Stout, Jeff

Podaci o skupu

International Conference on Strength Training (6 ; 2008)

poster

30.10.2008-02.11.2008

Colorado Springs (CO), Sjedinjene Američke Države

Povezanost rada

Pedagogija