Impact of the "Sling Shot" Supportive Device on Upper-Body Neuromuscular Activity during the Bench Press Exercise

The Effects of the "Sling Shot" Device on Bench Press Performance, Mechanical Properties of Muscle, and Movement Kinematics

ABSTRACT

Wojdała, G and Krzysztofik, M. The effects of the "sling shot" device on bench press performance, mechanical properties of muscle, and movement kinematics. J Strength Cond Res 37(4): 780-786, 2023-This study aimed to evaluate the influence of the sling shot support device at various external loads and intensities of effort, taking into account acute changes in power performance, mechanical muscle properties, and bench press kinematics. For this purpose, 12 resistance-trained men (age: 27.1 ± 4.2 years, body mass: 90.3 ± 16.9 kg, bench press [BP] 1 repetition maximum [1RM]: 112.7 ± 23.1 kg) (resistance training experience: 6.9 ± 3.8 years) participated in the study. Each subject completed 2 experimental sessions that differed in the use of the sling shot (SS) or nonuse (CONT) of the SS and an appropriate external load. The 2 experimental sessions consisted of the 1RM test, 3 sets of 2 repetitions of BP with the load increased in each set (50-70-90% 1RM), and a fourth set of the BP efforts to muscle failure with a 70% 1RM load. Before and after each set, the changes in triceps brachii oscillation frequency and stiffness were assessed by means of myotonometry. Results indicated a significant main effect of the SS to increase peak power ( p < 0.0001, η 2 = 0.733). Furthermore, a significantly higher 1RM (129 ± 26 vs. 113 ± 23 kg, p < 0.001, effect size [ES]: 0.63), number of repetitions (15 ± 3 vs. 13 ± 2, p = 0.013, ES: 0.76), and time under tension (34 ± 10 vs. 29 ± 6 seconds, p = 0.017, ES: 0.59) were found during the set to failure for SS in comparison to the CONT condition. Moreover, there was a significant main effect of time to increase oscillation frequency ( p = 0.001; η 2 = 0.666) and stiffness ( p = 0.002; η 2 = 0.613) from pre- to postset measure. In addition, the main effect of the side ( p = 0.034; η 2 = 0.348) was reported to show higher stiffness on the dominant than on the nondominant side in the CONT condition. The results suggest that an independent 1RM measurement and a correspondingly higher workload are required to take full advantage of the SS device. Moreover, the SS can also be used successfully to increase training volume and the involvement of nondominant limbs during a bench press.

Does relative strength influence bench press kinematics in resistance-trained men?

The aim of the present study was to examine whether relative strength influences lifting kinematics (e.g., lifting time, barbell velocity, vertical displacement) during the bench press (BP) exercise with healthy men. Loaded BP 6-repetition maximum normalized to body mass (i.e., relative strength) was examined in 110 resistance-trained men (age: 22.9 ± 2.5 years, height: 180.9 ± 6.9 cm, body mass: 80.3 ± 7.9 kg), by analysing lifting kinematics using a linear encoder. According to relative BP strength, subjects were classified as beginners, recreationally trained, intermediate, and advanced. Results showed that in the intermediate (p = 0.004, ES = 0.85) and advanced (p = 0.016, ES = 0.81) groups barbell velocity was lower in the sticking region of the BP action, compared with beginners, however there were no significant differences between groups for vertical displacement (p = 0.122-1.000) and lifting time (p = 0.052-1.000). These findings suggest that greater relative strength improves the capacity to perform the eccentric but not the concentric phase of BP. Enhanced barbell lowering indicates that the sticking region is caused by a high demand for eccentric force production during biomechanically disadvantageous conditions.

A Comparison of Electromyographic Inter-Limb Asymmetry During a Standard Versus a Sling Shot Assisted Bench Press Exercise

The objective of this study was to compare peak surface electromyography (sEMG) activity of selected muscles along with inter-limb asymmetries between a control (CONT) and a Sling shot assisted (SS) bench press exercise. Ten resistance-trained males with at least three-year experience in resistance training (22.2 ± 1.9 years, 88.7 ± 11.2 kg, 179.5 ± 4.1 cm, bench press one-repetition maximum (1RM) = 127.3 ± 25.9 kg) performed the flat bench press exercise under two conditions at selected loads (85% and 100% of 1RM assessed without the SS). Peak sEMG amplitude of triceps brachii, pectoralis major, and anterior deltoid was recorded for the dominant and the non-dominant side of the body during each attempt. The comparison between the dominant and the non-dominant side was carried out using the limb symmetry index (LSI(%) = (2*(XR - XL)/(XR + XL))*100%) where XR = values of the right side and XL = values of the left side. There was a main effect of condition (p = 0.004; η² = 0.64) and the load (p = 0.004; η² = 0.63) for the triceps brachii LSI in parallel with a main effect of condition (p = 0.003; η² = 0.42) for the anterior deltoid LSI. Post hoc analysis for the main effect of condition showed significant differences in the LSI between the CONT and SS conditions for the triceps brachii (p = 0.003; 1.10% vs. -8.78%) as well as for the anterior deltoid muscles (p = 0.03; 12.91% vs. 9.23%). The results indicate that the assistance of the Sling shot significantly affects the sEMG activity pattern on both the dominant and non-dominant sides of the body while influencing inter-limb asymmetries.