Why You Should Not Lock Your Joints During Exercise
“Don’t lock your arms out!” If you have ever trained with me this is something I bark at my clients quite a lot. That command and another reference along similar lines about people’s knees. It is not just a pet hate of mine there is some actual training benefit to not locking your joints out during exercise.
What is meant by locking out?
Locking out is where you take a joint like the elbow and open it out as far as it will go, sometimes to the extreme where the arm goes beyond being straight and starts to go back on itself. Where the arm reaches its furthest point it has ‘locked out’, which you are about to find out is wrong.
Why shouldn’t you lock your joints out?
There are two main reasons why you shouldn’t lock your joints out during your exercise. The first is for safety and the second is that you are cheating by doing so and therefore not getting the most out of your training.
Why is it unsafe to lock your joints during exercise?
When performing an exercise, especially ones with large weights, you are putting yourself at great risk of injury if you lock out your joints. An example is always helpful so let’s take the overhead press as a perfect reason why you should not lock out your elbows.
From the video you can see the bar going up and down with perfect technique, however you probably can’t see that Nicky is stopping just before her elbows lock out. Let’s say though that she hasn’t been trained properly and she does not listen to the advice of her trainer. So at the top of the position she has locked her elbows out as in the diagram below.
From the diagram you can see that the weight is travelling straight down and through the elbow joint inserting huge pressure on just that point. Now it is very unlikely that her arms will snap backwards but it can cause damage to the elbow joint. If you try this movement yourself (with no weights please – Beeble) then you should be able to see that there is no benefit to the shoulder muscles (deltoids – Beeble), the primary muscles of this exercise, when you lock your elbows out compared to just stopping beforehand. There is no extra movement and therefore no extra work for the shoulder muscle. So play it safe and avoid locking your joints out!
Why is the body cheating when locking the joints?
When a joint is locked in some exercises it allows the muscle to stop working and rest as the weight is travelling through the bones. The overhead press is not the best example of this but the leg press is.
As you can see from the leg press video Nicky is again using perfect technique (you shouldn’t expect anything less! – Beeble) and again it will be difficult to see, but she is not locking out her knee joint. Of course for safety it is important to not lock out the knee joint so the weight doesn’t force your leg backwards the wrong way like an Ostrich’s leg, but if you lock your leg out on this exercise the weight will travel down the leg bones allowing the muscle to completely relax. Now I know for a fact that this happens a lot in the gym and more often than people will like to admit to. If the muscle is allowed to relax then it should be very obvious that your muscles won’t get the same workout and benefits as someone who doesn’t rest. So keep the movement going and change direction before you can lock your knee out.
Summary
If you are unsure about where you need to change direction in the movement then please ask a gym instructor or trainer. If their response is that it doesn’t matter or something to a similar effect, then may I suggest you ask someone else as you have probably just come across an unqualified instructor, the scourge of gyms around the world.
It is only a small difference to your training but can keep the injuries at bay and make the most of your exercise sessions.
Good luck with your exercise, be safe and have fun!
November 14th, 2008 at 9:40 am
The leg press is a classic for this. Almost everytime I go to the gym I see someone doing the exercise far too fast and locking out their joints with each rep – kind of like they’re bouncing up and down. I think part of the reason is that some people don’t know not to lock out their joints BUT also a lot of people like to kid themselves into thinking they are stronger than they actually are. If they slowed down and performed the proper technique they would have to drop the weight. Anyway, thanks for sharing. Hopefully, a lot of people who have been doing the wrong technique will learn from this post.
November 24th, 2008 at 11:54 am
That’s a fantastic … and interesting post.
I have been training and instructing martial arts for the past 25+ years. As in the nature of our program, we create huge forces through our arms and legs … and the rule is simple – never lock out your joints.
For legs, we focus a lot on the ’snap’ or the return motion, making both the extension as well as the retraction equal in motion, smoothness and speed. At no time should the joint be held in a hyperextended position, but should be allowed to recoil naturally.
For arms, we make sure that the arm is ’straightened’ only to the way it is as it hangs by your side. So a straight punch is really when the bones come into alignment, not anywhere close to the joint being fully opened and ‘locked’ as you say.
We do have a position of ‘kime’ or focused lock out. This happens when we try to transmit force into a particular target. The lockout however never occurs at the joint (whichever joint in the limb), but is done using muscle tension, body structure, and the right tool to transmit force into the opponent. This means that the force flows out of your body rather than stopping at any single ‘point of leverage’ or ‘joint’ in your body.
Good post!
Colin
August 15th, 2009 at 7:28 pm
Thank you for the post. I have always wondered what "elbow lock" means. Now I understand what it means. As a beginner, this will help me a lot.