The Effects Of Ballistic And Non-ballistic Bench Press On Mechanical Variables And EMG

Abstract

PURPOSE:To investigate the effects of ballistic and non-ballistic bench press performed with loads equivalent to 30 and 90% 1-repetition maximum (1-RM) on mechanical variables and EMG. METHODS: In a counterbalanced cross-over design, 12 resistance-trained men (age: 23.6 ± 2.1 years; height: 1.83 ± 0.10 m; mass: 97.8 ± 13.9 kg; 1-RM: 149.3 ± 20.5 kg) attended four testing sessions during a three week period where they performed one of the following sessions: 1) three sets of five non-ballistic repetitions performed with a load equivalent to 30% 1-RM (30T), 2) three sets of five ballistic repetitions performed with a load equivalent to 30% 1-RM (30B), 3) three sets of four non-ballistic repetitions with a load equivalent to 90% 1-RM (90T), 4) three sets of four ballistic repetitions with a load equivalent to 90% 1-RM (90B). Force plates and a 3-D motion analysis system were used to determine the mean vertical velocity, mean vertical force, and mean power output during each repetition. The mean activation of the anterior deltoid, pectoralis major, and triceps brachii muscles were determined from the EMG signals recorded during each set. RESULTS:The mean power output during 30B was significantly greater than during 30T (mean difference: 319 W; p < 0.001), 90T (mean difference: 474 W; p < 0.001), and 90B (mean difference: 435 W; p < 0.001). Significantly greater vertical velocity (mean difference: 0.32 m/s; p < 0.001) and vertical force (mean difference: 262 N; p < 0.001) were attained during 30B compared to 30T. Significantly greater vertical velocities were attained during 30B compared to 90T (mean difference: 1.19 m/s; p < 0.001) and 90B (mean difference: 1.17 m/s; p < 0.001), although the vertical forces were significantly lower (mean differences: 459 - 516 N; p 0.05). Mean muscle activation was significantly greater during the 90T and 90B conditions compared to the 30T and 30B conditions (mean differences: 480 - 682 μV; p < 0.001). CONCLUSIONS:Ballistic exercises may be an effective method for developing power output, although the benefits may be negated at higher percentages of 1-RM.