Abstract
This study aimed to analyze between-shoulder kinematics symmetry at different load intensities considering full range of movement (ROM), mean and maximum velocities (VMEAN, VMAX), and accelerations (AMEAN, AMAX) of shoulders during phases 2 (characterized by positive acceleration and negative velocity, eccentric) and 3 (characterized by positive acceleration and velocity, concentric) of bench press exercise (BP); as well as to compare unilateral kinematics variables between the different load intensity intervals. Twenty-seven participants were evaluated during phases 2 and 3 of BP at different load intervals: interval 1 (55–75% 1-repetition maximum: 1RM), interval 2 (75–85% 1RM) and interval 3 (85–100% 1RM). Kinematics variables were determined using the Xsens MVN Link System. Results showed that full ROM was higher in left than right shoulder at all intensities (p = 0.008–0.035). VMEAN, VMAX, AMEAN, and AMAX were different in both shoulders for interval 3 during phase 2 and were lower as load intensity increased in both shoulders (p = 0.001–0.029). During phase 3, only VMAX on interval 2 was different between shoulders. Moreover, VMEAN, VMAX, AMEAN, and AMAX were greater during interval 1 compared with the others in both shoulders (p = 0.001–0.029). Therefore, there exists a kinematics asymmetry between both shoulders during phases 2 and 3 of bench press, although the acceleration was similar during both phases at all load intensities. Moreover, kinematic parameters differ between loads of 55–75% RM compared to 75–100% RM loads.
Highlights
Bench press (BP) is one of the most popular overload training exercises in different disciplines
The following parameters were computed for phases 2 and 3 under different load conditions: (1) full range of movement (ROM); (2) VMAX ; (3) VMEAN ; (4) AMAX ; (5) AMEAN
Pairwise comparisons showed a significantly greater ROM of left shoulder compared to right shoulder at all load intensity intervals (Interval 1: p = 0.008, g = 0.52; Interval 2: p = 0.035, g = 0.46; Interval 3: p = 0.015, g = 0.46)
Summary
Bench press (BP) is one of the most popular overload training exercises in different disciplines (e.g., weightlifting, powerlifting, etc.). In powerlifters, it is the main exercise for measuring maximal upper body strength during a competition, just as happens with squat and deadlift for lower body [1]. The BP exercise is usually used to induce hypertrophy and enhance muscle power [2,3]. Measuring how the peak load descends to the chest and ascends to full elbow extension is important to understand the kinematic parameters and performance factors of the BP exercise [4]. Krzysztofik et al (2020) [5] compared the electromyographic activity between the standard and cambered bar during BP, observing that a superior ROM due to the use of cambered bar increased anterior deltoid muscle activation compared to the standard bar, which showed higher pectoralis major and triceps brachii long head activation during BP
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