JM Press: Technique, Benefits, Muscles Worked, and Variations

How to perform a JM press?

The JM press is a hybrid strength exercise that combines elements of a close-grip bench press and a skullcrusher, primarily targeting the triceps brachii for enhanced lockout strength and hypertrophy, particularly beneficial for powerlifters and strength athletes.

What is the JM Press?

The JM press is a highly effective, specialized upper body exercise invented by powerlifter JM Blakley. It is a unique movement that bridges the gap between a close-grip bench press and a triceps skullcrusher, offering a distinct stimulus to the triceps and contributing significantly to lockout strength in pressing movements. Unlike a standard skullcrusher where the bar typically moves towards the forehead, or a close-grip bench where the bar touches the chest, the JM press involves lowering the bar to a point just above the neck/upper chest, with the elbows tucked and driving forward, then pressing it back up in a specific arc.

Muscles Worked

The JM press is a compound exercise that primarily isolates the triceps while engaging supporting muscle groups.

• Primary Movers:
  • Triceps Brachii (all three heads: long, lateral, medial): These are the primary muscles responsible for elbow extension and are heavily recruited throughout the movement, especially during the lockout phase.
• Synergists and Stabilizers:
  • Anterior Deltoid: Assists in shoulder flexion and stabilization.
  • Pectoralis Major (Clavicular Head): Provides minor assistance, especially at the top portion of the press.
  • Serratus Anterior: Helps stabilize the scapula.
  • Rotator Cuff Muscles: Provide shoulder joint stability.

Benefits of the JM Press

Integrating the JM press into your training regimen can yield several significant benefits, particularly for those focused on strength and power development.

• Exceptional Triceps Development: The unique bar path and elbow position place the triceps under immense tension, promoting both strength and hypertrophy across all three heads.
• Enhanced Lockout Strength: For bench pressers, the JM press directly translates to improved lockout ability, which is often a sticking point in heavy presses.
• Reduced Shoulder Stress: Compared to some skullcrusher variations that can place stress on the elbow or shoulder joints, the JM press, when performed correctly, can be more shoulder-friendly due to the tucked elbow position and slightly different bar path.
• Specificity for Powerlifting: Its unique mechanics closely mimic the top portion of a heavy bench press, making it an excellent accessory exercise for competitive powerlifters.
• Improved Pressing Mechanics: It teaches control and a strong triceps drive, which can carry over to overhead pressing and other pushing movements.

Proper JM Press Technique

Executing the JM press correctly is crucial for maximizing its benefits and minimizing injury risk.

• Setup:

  • Bench Position: Lie supine on a flat bench, ensuring your head, upper back, and glutes are firmly pressed into the bench. Your feet should be flat on the floor, creating a stable base.
  • Barbell Placement: Position yourself under a barbell in a power rack. Set the J-hooks or safety pins at a height that allows you to unrack the bar with extended arms, similar to a bench press.
  • Grip: Use a close grip, typically shoulder-width or slightly narrower, with a pronated (overhand) grip. Your thumbs should be wrapped around the bar for safety. Some lifters prefer a thumbless grip, but this increases risk.

• Execution:

  1. Unrack the Bar: With arms fully extended, unrack the bar and hold it directly above your chest, establishing a stable starting position.
  2. Initiate Descent: Begin the descent by simultaneously bending your elbows and driving them forward towards your feet. The key is to keep your elbows tucked tightly to your sides, not flared out.
  3. Bar Path: The bar should descend in an arc that brings it towards your upper chest/neck area, not your forehead or lower chest. Your forearms should be perpendicular to the floor at the bottom of the movement.
  4. Bottom Position: Unlike a skullcrusher where the bar might hover or lightly touch the head, or a close-grip bench where it touches the chest, the JM press involves the bar making contact (or coming very close) with the upper chest/neck area while your elbows are still significantly tucked and forward. This creates a tight, compressed position.
  5. Ascent: From the bottom position, powerfully extend your elbows, driving the bar back up along the same arc to the starting position. Focus on squeezing your triceps at the top.
  6. Breathing: Inhale during the eccentric (lowering) phase and exhale forcefully during the concentric (lifting) phase.

• Key Cues for Success:

  • Elbows Tucked and Forward: This is the defining characteristic of the JM press. Think about driving your elbows towards your feet.
  • Forearms Perpendicular: At the bottom of the movement, your forearms should be vertical to the floor.
  • Controlled Descent: Do not let gravity do the work. Control the bar throughout the entire range of motion.
  • Explosive Drive: Focus on a powerful, triceps-driven extension on the way up.
  • Maintain Full Body Tension: Keep your core braced, glutes squeezed, and feet firmly planted.

Common Mistakes to Avoid

Proper form is paramount in the JM press to prevent injury and maximize effectiveness.

• Flared Elbows: Letting your elbows flare out turns the exercise into more of a close-grip bench press or places undue stress on the shoulders. Keep them tucked tight.
• Incorrect Bar Path: Bringing the bar to the forehead (skullcrusher) or too low on the chest (close-grip bench) negates the unique benefits of the JM press. The target area is the upper chest/neck.
• Excessive Weight: Starting with too much weight compromises form and increases injury risk. Master the technique with lighter loads first.
• Lack of Control: Dropping the weight quickly or bouncing it off the chest can lead to injury and reduces muscle activation.
• Not Fully Extending: Failing to fully lockout at the top reduces the triceps work and the benefit for lockout strength.

Variations and Progressions

Once you've mastered the basic JM press, you can explore variations to keep your training fresh and challenge your muscles in new ways.

• Dumbbell JM Press: Allows for a greater range of motion and addresses potential muscular imbalances, as each arm works independently.
• Smith Machine JM Press: Provides a fixed bar path, which can be useful for learning the movement pattern or for pushing heavier loads with less need for stabilization.
• Tempo JM Press: Performing the eccentric (lowering) or concentric (lifting) phase slowly (e.g., 3-0-1-0 tempo) increases time under tension, promoting hypertrophy.
• Banded/Chained JM Press: Adding bands or chains provides accommodating resistance, making the top portion of the lift harder and further improving lockout strength.
• JM Press with Pause: Pausing at the bottom of the movement increases time under tension and eliminates any stretch reflex.

Integrating the JM Press into Your Program

The JM press is typically used as an accessory exercise after primary compound movements like the bench press.

• Rep Ranges:
  • Strength: 3-5 sets of 3-6 repetitions.
  • Hypertrophy: 3-4 sets of 8-12 repetitions.
• Placement: It's best performed after your main pressing movement (e.g., bench press, overhead press) but before other isolation exercises for the triceps.
• Frequency: 1-2 times per week, depending on your training split and recovery capacity.
• Who Can Benefit: While highly beneficial for powerlifters and strength athletes, anyone looking to build stronger, more defined triceps and improve pressing power can incorporate the JM press.

Safety Considerations

As with any strength exercise, safety should be your top priority.

• Use a Spotter: Especially when attempting heavier loads, a spotter can help you maintain form and assist with reracking or failed lifts.
• Utilize Safety Pins: If training alone, always set the safety pins in a power rack to a height that would catch the bar if you fail a lift.
• Warm-Up Thoroughly: Perform a general warm-up followed by specific warm-up sets with light weight to prepare your elbows, shoulders, and triceps for the movement.
• Listen to Your Body: If you experience sharp pain, stop the exercise immediately. Do not push through pain.
• Prioritize Form Over Weight: Never sacrifice proper technique for the sake of lifting heavier weight. Good form ensures muscle activation and reduces injury risk.