JM Press: Biomechanics & Clinical Form | VisualBody Lab

JM Press

Triceps Focus Compound Movement Horizontal Press Free Weights
✍️ Written by Visual Body Lab Team ⚕️ Medically Reviewed by Visual Body Lab Team
Medical Disclaimer: The JM Press requires exceptional elbow and wrist mobility. Avoid utilizing maximal loads if you have a history of medial or lateral epicondylitis. Always perform adequate dynamic warm-ups of the elbow flexors and extensors prior to loading.

TL;DR

The JM Press is a highly effective hybrid movement bridging the gap between a close-grip bench press and a lying triceps extension. By keeping the load closely aligned over the neck and chest, it allows for heavy mechanical loading of the Triceps Brachii while minimizing strain on the anterior deltoids and pectorals.

Biomechanics Profile

Primary Mover ● Triceps Brachii (All Heads)
Secondary Synergists ○ Anterior Deltoid, Pectoralis Major
Joint Actions Elbow Extension, Glenohumeral Flexion
Resistance Profile Ascending Resistance (Free Weight)

Programming Parameters

Optimal Volume 3-4 Sets × 6-10 Reps
Intensity Target 1-2 RIR (Near Failure)
Rest Interval 120-180 Seconds
Execution Tempo 3-1-1-1 (Eccentric-Pause-Concentric-Squeeze)

Execution Protocol

  • Setup & Alignment Lie supine on a flat bench. Unrack a barbell using a close, pronated grip (shoulder-width or slightly narrower). Retract your scapulae, plant your feet firmly on the floor, and position the barbell directly over your upper chest to establish a solid base of support.
  • The Descent (Eccentric Phase) Lower the bar in a highly controlled motion (3-4 seconds) while inhaling deeply. Allow your elbows to track forward and slightly outward (roughly 45 degrees relative to the torso) while simultaneously flexing the elbow joint. The barbell should travel toward your upper chest or lower neck region until your forearm touches your bicep.
  • The Press (Concentric Phase) Drive the barbell straight back up in a vertical line while exhaling forcefully. Focus entirely on extending the elbows to move the weight, minimizing shoulder flexion. Squeeze the triceps hard at lockout without hyperextending the elbow joint.

Clinical Red Flags

  • Flaring Elbows Excessively: Allowing the elbows to flare out to 90 degrees places immense sheer stress on the elbow capsule and limits triceps leverage, shifting the tension negatively to the shoulder joint.
  • Dropping Bar to Lower Chest: Lowering the bar to the mid/lower chest turns the movement into a standard close-grip bench press, effectively shifting the hypertrophic stimulus away from the triceps and onto the anterior deltoids and pectorals.

Clinical Troubleshooting

Wrist Pain at the Bottom Position
The Fix: Shift to a false (thumbless) grip or cock your wrists slightly backward. This modification aligns the heavy mechanical load directly over the radius and ulna bones, eliminating unwanted wrist extension torque.
Elbow Discomfort During Transition
The Fix: Ensure a highly controlled, smooth eccentric phase (3-4 seconds) and implement a brief pause at the bottom to dissipate kinetic energy. Never bounce the bar off your forearms or chest to generate momentum.

Biomechanically Similar Alternatives

Close-Grip Bench Press

More chest and anterior deltoid engagement.

Skull Crushers

Higher triceps isolation, lower absolute loading.

Frequently Asked Questions

What is the difference between a JM Press and a Close-Grip Bench Press?

The JM Press is a hybrid movement blending the close-grip bench press and the skull crusher. Unlike the close-grip bench where elbows tuck to the sides to target the chest and anterior delts, the JM Press allows the elbows to track forward, shifting the mechanical load heavily onto the triceps brachii.

Is the JM Press safe for the elbow joints?

Yes, provided it is executed with controlled eccentric tempos. Bouncing the barbell or using excessive loads before the connective tissue has adapted can strain the triceps tendon. A 3-4 second negative prevents sheer stress and builds robust tendon integrity.

Should I use a Smith machine or free weights for the JM Press?

The Smith machine offers a fixed plane of motion, eliminating stability requirements and allowing for maximum triceps isolation. Free weights demand higher synergist stabilization. Both are highly effective, but the Smith machine is often preferred by bodybuilders for pure hypertrophy and joint safety.

Evidence-Based Citations

  1. Kholinne, E., Zulkarnain, R. F., Sun, Y. C., Lim, S., Chun, J. M., & Jeon, I. H. (2018). The different role of each head of the triceps brachii muscle in elbow extension. Acta Orthopaedica et Traumatologica Turcica, 52(3), 201-205. PMID: 29848600
  2. Lehman, G. J. (2005). The influence of grip width and forearm pronation/supination on upper-body myoelectric activity during the flat bench press. Journal of Strength and Conditioning Research, 19(3), 587-591. PMID: 16095407