Decoding the Contribution of Shoulder and Elbow Mechanics to Barbell Kinematics and the Sticking Region in Bench and Overhead Press Exercises: A Link-Chain Model
Evangelista P, Rum L, Picerno P, Biscarini A
Evidence is still limited and needs further study
Summary
A theoretical/mathematical link-chain biomechanical model incorporating single- and two-joint muscles, analyzing what causes the sticking region in the bench press and overhead press. The sticking region is explained as a local minimum in barbell velocity that emerges when shoulder torque drops below a critical threshold relative to the barbell's geometric constraints. Grip width (the horizontal distance between the shoulder joint and the barbell's vertical path) was found to shape this phenomenon more strongly than individual muscle architecture parameters.
Key findings
- 1
A link-chain model incorporating single- and two-joint muscles analyzed barbell kinematics in the bench press
- 2
The sticking region is explained as a local minimum in barbell velocity occurring when shoulder torque drops below a critical threshold
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Grip width (horizontal distance between shoulder joint and barbell path) strongly influences whether the sticking region occurs
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Grip width and barbell constraints shaped lift behavior more than individual muscle architecture parameters
Related research
A Biomechanical Analysis of the Sticking Region in the Bench Press (Elite Powerlifters)
Medicine & Science in Sports & Exercise, 1989
A classic study analyzing 10 elite powerlifters at approximately 80% 1RM, a maximal lift, and a failed lift using 3D cinematography and surface EMG. The 'sticking region' — a sharp deceleration mid-lift — could not be simply explained by an increased moment arm or reduced muscle activity at that point. The shoulder joint moment arm decreased consistently throughout the ascent, while the elbow joint moment arm reached its minimum near the sticking region before increasing again.
Effect of Grip Width on Bench Press Strength and Muscle Activation in Novice and Resistance-Trained Men
International Journal of Environmental Research and Public Health, 2021
A cross-sectional study in 15 resistance-trained and 13 novice men comparing 6-RM load and muscle activation (EMG) across narrow, medium, and wide grip widths. Pectoralis major activation was similar across grip widths, while in trained men the wide grip showed slightly lower triceps brachii activation and markedly higher biceps brachii (stabilizer) activation. The narrow grip produced 7-8% lower 6-RM loads than the other two conditions.
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