How is it different from the barbell JM press?

The elbow action and the muscles doing the work are the same. On the Smith machine the track sets the bar path and you can set stops to catch the bar above your throat, while on a free bar you steer the bar toward your chin and balance it yourself, which takes more skill but lets the path fit your elbows. Loads are not directly comparable between the two, so log them separately.

Where should I set the bench?

Set it so that, lying down with your arms straight over your shoulders, the bar sits above the top of your chest, just below your throat. Check it with an empty bar: at the bottom your forearms should meet your biceps with the bar still above your upper chest, not over your face.

Is it the same as a skull crusher?

No. In a Barbell Skull Crusher the upper arms stay still and the bar travels toward your forehead, while in the JM press the elbows drift forward and the bar comes down toward your chin, so it sits between a skull crusher and a close-grip bench press.

How heavy should I go?

Start well below your close-grip bench press weight and leave a couple of reps in reserve, usually for 6 to 12 reps. Add weight slowly, since the elbow tendons need longer to adapt than the triceps do.

How much does the Smith machine bar weigh?

It varies from machine to machine, and many Smith bars are counterbalanced so they feel lighter than a standard barbell. Check the label on the machine or the manufacturer's listing, and log your loads on the same machine each time.

Smith Machine JM Press

What Is the Smith Machine JM Press?

Smith Machine JM Press is a compound exercise that primarily targets the triceps and also engages the front shoulders and chest. It is an intermediate-level movement in which you lie on a flat bench inside a Smith machine, hold the bar with a close overhand grip and lower it toward your chin and throat by bending your elbows while they drift forward, then press it back to straight arms.

Like the Barbell JM Press, it sits between the Barbell Bench Press (Close Grip) and the Barbell Skull Crusher. The elbows bend much more than in a close-grip press, but unlike in a skull crusher the upper arms are allowed to travel forward a little, and the bar comes down toward the chin rather than the forehead. That keeps most of the work on the triceps while letting you handle more weight than a pure extension allows. The lift was devised by a powerlifter as a bench press accessory, and it is still used mainly to build triceps strength for the lockout.

The Smith machine changes how the bar travels, not the job of the triceps. On a free bar you steer the bar toward your chin and balance it yourself. On a Smith machine the bar rides a fixed track, so where you place the bench decides the path, and your elbows have to travel forward just enough to keep the bar on that line. With the bench set well, the track removes the balancing and leaves you free to focus on the elbows. With it set badly, the track forces the rep toward a close-grip press or toward your face. The hooks and safety stops are the other change: you can rerack the bar at any point, and the stops can be set to catch it above your throat, which matters on a lift that lowers the bar toward your neck and is often done without a spotter.

It is an accessory, usually done for moderate reps after the main pressing work in a session or early in an arm-focused one. It suits lifters who already press with sound form and want heavy triceps work, and lifters learning the JM press pattern who want the bar path and the stops taken care of. Elbow tendons adapt more slowly than muscle, so loads start well below your close-grip bench press weight. If the movement is too hard or bothers your elbows, build up with the Smith Machine Bench Press (Close Grip) and the Cable Triceps Pushdown (Straight Bar) first.

Muscles Worked

MuscleActivation

Triceps Brachii (Lateral Head): Primary
Triceps Brachii (Medial Head): Primary
Triceps Brachii (Long Head): High
Deltoid: Medium
Pectoralis Major: Medium
Flexor Carpi Radialis: Low
Flexor Carpi Ulnaris: Low
Serratus Anterior: Low

Instructions

Place a flat bench inside the Smith machine so that, when you lie down, the bar sits above the top of your chest, just below your throat.
Set the safety stops just below the lowest point of your rep, so they would catch the bar above your throat.
Lie back with your head, upper back and hips on the bench and your feet flat on the floor.
Grip the bar overhand, slightly narrower than shoulder width, with your wrists straight over your forearms.
Pull your shoulder blades back and down, rotate the bar to unhook it and hold it at arm's length over your shoulders.
Bend your elbows to lower the bar, letting them travel forward toward your feet and keep pointing up, with your upper arms about 45 degrees out from your torso.
Lower under control until your forearms meet your biceps, with the bar just above your upper chest. Do not let your elbows drop toward your sides.
Press the bar back up along the track until your elbows are straight.
Repeat for the planned reps, then rotate the bar to hook it back on the rack.

Common Mistakes

Setting the bench in the wrong spot
The track cannot follow you, so a bar lined up over your face pushes the rep toward a skull crusher and a bar lined up over your mid chest turns it into a close-grip bench press.
Dropping the elbows to the sides
Letting the elbows sink toward your ribs turns the lift into a narrow press to the neck and takes work off the triceps.
Flaring the elbows wide
Letting the elbows drift far out to the sides shifts work to the chest and front shoulders and stresses the shoulder joint.
Letting the wrists fold back
Letting the bar roll toward your fingers bends the wrists back under load and moves the bar off the line of your forearms.
Adding weight too quickly
The fixed track makes heavier loads feel manageable, but the elbow tendons adapt far more slowly than the triceps get stronger.
Skipping the safety stops
Lowering a loaded bar toward your throat with the stops set too low, or not set at all, leaves nothing to catch a missed rep.

Injuries

Smith Machine JM Press is a medium risk exercise when performed with proper technique. The elbows take most of the strain, because the bottom of each rep loads the triceps tendon with the elbows deeply bent, and the wrists come next when they fold back under the bar. The fixed track adds its own risk: if the bench is in the wrong spot, the bar cannot drift to where your elbows want it, so the rep is forced over your face or down to your chest and the elbows and shoulders take the difference.

Set the bench and the safety stops with an empty bar before you load it, so the stops sit just below the bottom of your rep and catch a missed rep above your throat. Warm up with light sets, start well below the weight you use on a close-grip bench press and add load slowly, because the elbow tendons adapt more slowly than the triceps get stronger. If your elbows feel hot during a set or stay sore the next day, reduce the load. Lifters with existing elbow tendon pain or shoulder impingement are better served by another triceps exercise.

If the movement irritates your elbows, the Cable Triceps Pushdown (Straight Bar) trains the triceps with far less load on the joint, and the Smith Machine Bench Press (Close Grip) keeps the fixed track with less elbow bend. Once the pattern feels solid, the Barbell JM Press lets you steer the bar yourself.

Stop the set if you feel sharp pain at the elbow, wrist or front of the shoulder, or numbness or tingling in your hands.

Overview

Primary Focus: Triceps
Equipment: Smith machine and bench
Modality: Strength
Difficulty: Intermediate

Alternative Exercises

Frequently Asked Questions

Q: How is it different from the barbell JM press?: The elbow action and the muscles doing the work are the same. On the Smith machine the track sets the bar path and you can set stops to catch the bar above your throat, while on a free bar you steer the bar toward your chin and balance it yourself, which takes more skill but lets the path fit your elbows. Loads are not directly comparable between the two, so log them separately.
Q: Where should I set the bench?: Set it so that, lying down with your arms straight over your shoulders, the bar sits above the top of your chest, just below your throat. Check it with an empty bar: at the bottom your forearms should meet your biceps with the bar still above your upper chest, not over your face.
Q: Is it the same as a skull crusher?: No. In a Barbell Skull Crusher the upper arms stay still and the bar travels toward your forehead, while in the JM press the elbows drift forward and the bar comes down toward your chin, so it sits between a skull crusher and a close-grip bench press.
Q: How heavy should I go?: Start well below your close-grip bench press weight and leave a couple of reps in reserve, usually for 6 to 12 reps. Add weight slowly, since the elbow tendons need longer to adapt than the triceps do.
Q: How much does the Smith machine bar weigh?: It varies from machine to machine, and many Smith bars are counterbalanced so they feel lighter than a standard barbell. Check the label on the machine or the manufacturer's listing, and log your loads on the same machine each time.