How to Do the JM Press
The JM press is a barbell triceps exercise that sits between a close-grip bench press and a skull crusher. Lie on a bench with a close grip and lower the bar toward your chin, bending your elbows as they drop toward your feet, then press it back up. It mainly trains the triceps, with the chest and front delts helping. It is named after powerlifter JM Blakley. Most lifters do 3 sets of 8 to 12 reps.
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How to do a JM press
- Set the safety arms of a rack just above the height of your chin when you lie on the bench. Lie down with your eyes under the bar and your feet flat.
- Grip the bar about shoulder-width apart, thumbs wrapped. Unrack it and hold it over your shoulders with your arms straight and your shoulder blades pulled together.
- Lower the bar by bending your elbows and letting them drop down and slightly toward your feet. Keep your elbows pointing toward your feet, not flared out. The bar travels toward your chin, not your chest.
- Stop a few inches above your chin, or when your forearms meet your upper arms.
- Press the bar back up along the same path by straightening your elbows, and finish with your arms straight over your shoulders.
Barbell, EZ bar or Smith machine
No study has compared these versions. The Smith machine is the easiest to set up safely, and you can rack it at any point by turning your wrists. Weights on a Smith machine do not match a free bar, so log it as its own exercise.
How much weight should you JM press?
On Gravitus, the median man lifts 90 lb (40 kg) for 10 reps on the JM press.
- Most lift
- 65 to 115 lb
- Top 10% lift
- 145 lb or more
- Starting out
- under 65 lb
- Most lift
- 30 to 52.5 kg
- Top 10% lift
- 65 kg or more
- Starting out
- under 30 kg
What the research says about the JM press
No published study has measured the JM press. The closest evidence comes from the two lifts it combines. In a 10-week study, 43 young men trained with the bench press, the lying barbell triceps press (a skull crusher) or both. The triceps grew significantly only in the groups that did the skull crusher. The skull crusher grew the long head more, and the bench press grew the lateral head more (Brandão 2020). The JM press mixes a press and an extension, but whether it sits between them for growth has not been tested.
Arm position matters for the long head of the triceps, the only head that crosses the shoulder. In a 12-week study, overhead cable extensions grew the long head 1.5 times as much as extensions with the arms at the sides (Maeo 2023). In a JM press your upper arms stay in front of you, never overhead, so add an overhead extension if long-head size is your goal.
Three common claims the research does not back:
- The JM press is easier on the elbows than skull crushers. No study has measured elbow stress in either lift. Some lifters find one easier than the other, so let your elbows decide.
- It is just a close-grip bench with bad form. The elbow action is different. Your elbows bend much more, and the bar ends near your chin instead of on your chest.
- It targets one head of the triceps. No study has measured any head in the JM press. All three heads straighten the elbow.
Muscles worked
JM press vs close-grip bench vs skull crusher
| Attribute | JM press | Close-grip bench | Skull crusher |
|---|---|---|---|
| Bar goes to | Just above your chin | Your lower chest | Your forehead or behind your head |
| Elbows | Bend deeply and drop toward your feet | Bend less, travel down beside your body | Bend, upper arms stay still |
| Shoulders | Help some | Help a lot | Barely move |
| Load | In between | Heaviest | Lightest |
| Research | Not studied | Grip-width studies | Grew the long head (Brandão 2020) |
No study has compared them. Use the close-grip bench for the heaviest press, the skull crusher for long-head growth, and the JM press when you want heavy elbow extension with more weight than a skull crusher. If one bothers your elbows, use another.
Sets, reps and progression
Do the JM press after your main press on push or upper-body day. Stop each set 1 to 2 reps short of failure, since form breaks down fast near the chin. Sets taken close to failure build muscle across a wide range of reps (Schoenfeld 2021).
Add reps first. When every set reaches 12 clean reps, add 5 lb (2.5 kg) and drop back to 8.
Common mistakes
-
No safetiesThe bar comes down over your throat. Set the safety arms just above your chin, use a Smith machine with stops, or have a spotter.
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Turning it into a close-grip benchIf the bar drifts down to your chest, your elbows are not bending enough. Aim the bar at your chin.
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Turning it into a skull crusherIf your upper arms stay still and the bar heads for your forehead, let your elbows drop toward your feet as you lower.
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Flaring the elbowsKeep your elbows pointing toward your feet. Go lighter if they drift out.
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Hands too closeA grip with your hands touching bends your wrists. Shoulder-width is close enough.
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Bouncing at the bottomLower under control and stop a few inches above your chin before you press.
JM press variations and alternatives
Questions people ask
What is a JM press?
A lying barbell triceps exercise that mixes a close-grip bench press and a skull crusher. You lower the bar toward your chin while your elbows bend and drop toward your feet. It is named after powerlifter JM Blakley.
What muscles does the JM press work?
Mainly the triceps, with the chest and front delts helping as you press. No study has measured how the work is shared.
What are the benefits of the JM press?
It trains the triceps through a deep elbow bend with more weight than a skull crusher allows. Powerlifters use it for bench press lockout, though no study has tested whether it raises your bench.
JM press vs close grip bench, which is better?
They do different jobs. The close-grip bench moves the most weight, with the chest and shoulders doing more. The JM press bends your elbows much further, so it works more like a triceps extension. No study has compared them.
JM press vs skull crusher, which is better?
Not proven either way. The skull crusher keeps your upper arms still and grew the long head in a 10-week study (Brandão 2020). The JM press lets your elbows travel, so you can use more weight. Pick the one your elbows tolerate, or rotate both.
How do you do a Smith machine JM press?
Set a flat bench so the bar comes straight down to just above your chin, and set the stops there. Grip shoulder-width, unrack, and lower by bending your elbows as they drop toward your feet. Press back up and rack it by turning your wrists.
Is the JM press bad for your elbows?
No study has linked it to elbow injury or measured elbow stress in it. Warm up with light sets, stop a few inches above your chin, and switch to a close-grip bench if your elbows complain.
How much weight should I JM press?
For 10 reps, the median on Gravitus is 90 lb (40 kg) for men. The strongest quarter lifts 115 lb (52.5 kg) or more.
Log every set and see your percentile on every lift, JM press included.
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