Shoulder Muscle Activation of Novice and Experienced Weightlifters During Dumbbell Bench Press Exercises

Bench press exercises are commonly used for development of chest and shoulders muscles. Altering the trunk inclination angle changes the angle of the resistive force relative to the body and therefore changes the resistive force line of action. Whether the effects occur similarly for both experienced and novice weightlifters remains unknown. PURPOSE: To compare muscle activity of the anterior deltoid (AD), clavicular (CPM) and sternal (SPM) portions pectoralis major, and upper trapezius (UT) by surface electromyography (sEMG) between horizontal (HBP), incline (IBP), and military (MBP) bench press in experienced and novice women weightlifters. METHODS: sEMG data were recorded at the dominate arm UT, AD, CPM and SPM for 12 experienced female weightlifters (64.33±10.08kg, 1.69±0.07m, 23.0±2.8yrs) and 12 novice (64.58±8.02kg, 1.69±0.04m, 22.6±1.7yrs) female weightlifters. Five repetitions each were performed at horizontal (0°), incline (45°), and military (85°) bench presses. Exercise order was randomized between participants. Average sEMG amplitude for each repetition phase (concentric, eccentric) was computed and averaged across the five repetitions. Separate group by exercise by phase analyses of variance were conducted. RESULTS: No significant differences were found between experienced and novice weightlifters. For both UT and AD, within both phases, the MBP was significantly greater than IBP which in turn was significantly greater than the HBP. For SPM during both phases HBP and IBP were significantly greater than MBP. For CPM, during the concentric phase HBP was significantly greater than IBP which in turn was significantly greater than MBP, however, during the eccentric phase IBP was significantly greater than both the HBP and MBP. CONCLUSIONS: While there were no differences related to lifting experience, as expected there were differences revealed between the three bench presses. Of the three bench presses, the MBP targeted the UT and AD during both the concentric and eccentric phases. For the pectoralis major, the HBP and IBP equally worked the sternal part during both phases, whereas the CPM was targeted during the concentric phase by the HBP and the IBP during the eccentric phase. These results provide evidence for selecting exercises in resistance and rehabilitation programs