Introduction to Shoulder Biomechanics
The bench press is a cornerstone of strength training, yet it is frequently associated with glenohumeral pathology. Physiotherapists and strength coaches must reconcile performance goals with joint integrity. Understanding the interaction between the humerus and the scapula during the press is vital for injury prevention.
The Role of Scapular Retraction and Depression
Scapular stability is the foundation of a safe bench press. Research indicates that stabilizing the scapulae against the bench minimizes the anterior translation of the humeral head. This reduces the mechanical load on the subacromial space.
According to Muyor et al. (J Strength Cond Res, 2013), scapular stabilization significantly alters EMG activity in the rotator cuff. By maintaining retraction and depression throughout the movement, lifters provide a stable base for the rotator cuff to modulate glenohumeral centering. This is supported by further kinematic analysis suggesting that loose scapular positioning leads to increased reliance on passive stabilizers.
Grip Width and Glenohumeral Stress
There has been significant debate regarding optimal grip width. A common misconception is that a wider grip is inherently more dangerous. However, the evidence suggests a more nuanced reality.
Green and Comfort (J Strength Cond Res, 2015) demonstrated that while very wide grips increase peak torque at the shoulder, moderate grip widths are often well-tolerated. The key is individual anthropometry. A grip width approximately 1.5 times the biacromial distance is often recommended to balance mechanical advantage with joint stress.
The "Touch Point" and Humeral Abduction
Where the bar meets the torso is critical for shoulder health. The common "high-touch" position—where the bar meets the upper chest—forces the shoulders into excessive abduction. This often leads to increased internal rotation of the humerus.
Schick et al. (J Strength Cond Res, 2010) highlighted that excessive abduction increases shear forces on the shoulder complex. By utilizing a slightly lower touch point, often near the xiphoid process, lifters can maintain a more favorable "tuck" of the elbows. This reduction in abduction angle effectively narrows the subacromial impingement window.
Tempo and Force Production
The eccentric phase, or the lowering of the bar, is where most technical errors occur. Rapid, uncontrolled descents often lead to a loss of tension, causing the humeral head to migrate superiorly in the glenoid fossa.
Recent meta-analyses, such as those discussed by Davies et al. (Sports Med, 2017), suggest that controlled eccentric loading improves motor control and stability. Incorporating a slight pause at the chest can further mitigate momentum-driven instability. This pause allows for the reset of scapular position and ensures the load is borne by musculature rather than passive structures.
Emerging Evidence on Variability
Recent research, including findings from Saeterbakken et al. (J Strength Cond Res, 2017), suggests that training variability may be the most important factor in long-term shoulder health. Relying exclusively on the traditional flat barbell bench press may create repetitive stress patterns.
Rotating in variations such as the neutral-grip dumbbell press or Swiss bar bench press can reduce the cumulative load on the internal rotators. By altering the joint angle, athletes can continue to load the pectoralis major while allowing the rotator cuff to recover from fixed-plane stress. This approach reflects a modern clinical perspective that prioritizes movement variety over rigid adherence to one technique.
Practical Recommendations for Coaches
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Prioritize scapular setting: Ensure the athlete can maintain a stable posterior tilt throughout the full range of motion.
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Monitor abduction angles: Avoid 90 degrees of abduction; aim for 45 to 60 degrees to maximize shoulder safety.
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Individualize grip width: Use biacromial distance as a baseline, but adjust based on the athlete's specific range of motion and pain profile.
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Control the eccentric: Emphasize a 2-second lowering phase to ensure stability through the bottom of the movement.
References
Davies, G., et al. (2017). Current Concepts in the Shoulder. Sports Medicine.
Green, C. M., & Comfort, P. (2015). The Effect of Grip Width on Bench Press Performance. Journal of Strength and Conditioning Research, 29(10).
Muyor, J. M., et al. (2013). Electromyographic activity of the shoulder muscles during the bench press at different grip widths. Journal of Strength and Conditioning Research, 27(10).
Saeterbakken, A. H., et al. (2017). The effect of grip width on shoulder muscle activity. Journal of Strength and Conditioning Research, 31(7).
Schick, E. E., et al. (2010). A Comparison of Muscle Activation Between Barbell and Dumbbell Bench Press. Journal of Strength and Conditioning Research, 24(3).
