When bench pressing, at max extension, should I lock my elbows or keep them loose? What about my knees when squatting?

UPDATE: Here are some links from the Mayo Clinic warning against locking joints while lifting:

2nd UPDATE: Also, must admit, a major concern of mine is that in military, always told us "Don't lock your knees, you'll pass out". This is when standing at inspection.

  • It's entirely possible that locking your knees could cause you to pass out in inspection. That has little or no connection to fully extending your limbs when lifting. May 9, 2012 at 13:44
  • As for the Mayo clinic, they give no reasons and so their only argument is pure assertion. If they gave reasons we could disagree, but as is we can simply give our reasons and note that their exercises are much more oriented towards rehabilitation than actual strength training. May 9, 2012 at 13:49
  • About locking knees during inspection, that's for like 10s of minutes at a time. During a lift, it will be for less than a second as you grab a breath for the next rep.
    – user3085
    May 9, 2012 at 17:52
  • 2
    Regarding the mayo links, they refer to the leg extension, an exercise that places much more stress on the ACL than a squat. When the knee is locked in extension during leg extensions, the skeleton is not able to help you support the weight. This is not the case in the squat. Regarding the chest press, the form they describe is completely different than the bench press (feet up on the bench, back not arched, scapulas not retracted, not bringing elbows below bench surface); I don't think their advice about elbow position at lock-out is any more reliable.
    – user3085
    May 9, 2012 at 17:59
  • Olympic lifters lock their arms with substantially more compression force than would be possible with a bench press. Here's an example of 533 lbs.
    – Daniel
    Feb 15, 2015 at 18:37

4 Answers 4


Yes, you should lock your elbows at full extension for each completion of a bench press repetition and also the knees at the top of the squat.

This is supported by text from Starting Strength, 3rd Edition:

Regarding the bench: "...push up on the bar, locking out your elbows."

"At the top [of the squat], all the skeletal components that support the bar - the knees, hips, and spine - will be locked in extension so that the muscular components have to exert only enough force to maintain this position."

I will speculate as to some reasons for this:

  • allows you to release your valsalva maneuver and take a breath of air while the weight is supported by skeletal components
  • allows you to train through the full range of motion
  • I can't find the video, but I've seen/heard him say (on the topic of unracking on BP) that the main reason for locking your elbows is that it is the most stable position your arms can be in and you want them stable while unracking so you are least likely to drop the bar on your throat.
    – Tyler
    Nov 10, 2014 at 2:54

The only reason not to do the full range of motion is if you're cheating in order to get more reps or use more weight than you could with proper form. Repetitively shorting weightlifting movements can cause joint problems.

Move your body through the whole movement. There's no good reason not to.

Further, what happens if you don't extend your joints fully? Use it or lose it--your body will stop being capable of going to full extension. Then you'll have to start shorting the movement more and more over time, until you are decrepit and immobile.

  • Isn't locking joints harmful? I remember always being told not to do that, and I believe the Mayo Clinic also advises against it (I believe). May 7, 2012 at 15:35
  • @S.RobertJames I'd be surprised if the Mayo Clinic believes that extending your arm fully is harmful. Hyperextending the arm, sure, that's no bueno, but nobody's espousing that. Without an actual claim that lifting weights through the whole ROM is bad, we can't disagree more substantively than that. May 7, 2012 at 15:50
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    Added links from Mayo Clinic warning not to lock May 9, 2012 at 7:55

I don't think there is an issue with locking our elbows(at a safe speed obviously) but in lifting, locking the knees is usually a no-no, especially with things like power (olympic) lifts.

  • Why? Do you mean when receiving the bar, or when completing the lift? May 9, 2012 at 16:01

Seriously depends on what your looking to do. I personally been lifting for over twenty six years, from my research and what works for me, everyone's body is different. Medium and light weight is safe to use full motion and softly lock out, heavier weight is a big no no. I prefer lifting just short of lock out on medium to heavy days. If I am benching I don't want to lock out fully and take away the tension in my chest muscles. Training the muscles to grow need constant tension to cause hypertrophy, place the most maximum load possible will increase muscle mass faster. Each time if I locked out years ago it would take the tension off my chest and move it to my deltoids, and triceps. If your competing get use to both I would recommend. (Short of lockout keeps tension on the concentrated muscles) that's what works for me

  • You could separate an objective answer from your personal preference by paring it down to "Locking out fully on the bench press moves the tension from your chest muscles to your deltoids and triceps, taking away the constant tension needed for hypertrophy. So I recommend not going to lockout on your medium to heavy days."
    – Noumenon
    Feb 16, 2015 at 7:44

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