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Leg extensions and leg curls are bad for the knees.

UCSMiami

UCSMiami

Well-known member
So says an acquaintaince who is sports physical therapist. She advised me to discontinue and focus on squats, leg presses for the same muscle groups worked by the curls and extension.

I thought she was just being worried for me as I have a history of random knee cap dislocations going back to HS. My knee did actually pop out about three weeks ago for about 20 seconds.(It was not during an exercise set) I took a week off leg work and started back lightly after the convalescing period.

Once again the Internet provides conflicting advice.....do and do not do.

As always I come here for the good, the bad and the ugly.
 
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UCSMiami said:
So says an acquaintaince who is sports physical therapist. She advised me to discontinue and focus on squats, leg presses for the same muscle groups worked by the curls and extension.

I thought she was just being worried for me as I have a history of random knee cap dislocations going back to HS. My knee did actually pop out about three weeks ago for about 20 seconds.(It was not during an excercise set) I took a week off leg work and started back lightly after the convalescing period.

Once again the Internet provides conflicting advice.....do and do not do.

As always I come here for the good, the bad and the ugly.
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The good.....leg extension have their place and so do leg curls.

The bad...many people make the mistake of pausing and exploding up then slowly coming down. This will destroy your knees. A lot lift way to heavy on these aswell.

The good again ...they can be great if you leave your ego outa it and put some lighter weight on there while controlling the movement through the entire movement slowly.

The ugly ....continue using bad form/heavy weight and you may not be able to body build in the future...at least on your legs.

Yours truely:Guy who's learned the hard way
 
I can understand doctors and or therapist takes on this and or educational opinions.

Here are a few more I have heard over the years...

Flat and Incline BP's, bad for shoulders
Bent Rows, bad for low back
Squats, bad for knees/low back
SLDL's or BLDL's, bad for low back
BNP's, bad for shoulders
Upright Rows, bad for shoulders
Dips, bad for shoulders
Straight Bar Curls, bad for elbows
Tricep extens, bad for elbows
Any explosive/plyometric moves ie: cleans snatches etc. bad for the joints

That might leave me with Superslow wrist curls and a few chins, possibly, so I have been taking the gamble.

Motorcycles are kinda dangerous too and if you ride long enough, will most surly hit the ground at some point. But many guys still ride.
 
PaulBlack said:
I can understand doctors and or therapist takes on this and or educational opinions.

Here are a few more I have heard over the years...

Flat and Incline BP's, bad for shoulders
Bent Rows, bad for low back
Squats, bad for knees/low back
SLDL's or BLDL's, bad for low back
BNP's, bad for shoulders
Upright Rows, bad for shoulders
Dips, bad for shoulders
Straight Bar Curls, bad for elbows
Tricep extens, bad for elbows
Any explosive/plyometric moves ie: cleans snatches etc. bad for the joints

That might leave me with Superslow wrist curls and a few chins, possibly, so I have been taking the gamble.

Motorcycles are kinda dangerous too and if you ride long enough, will most surly hit the ground at some point. But many guys still ride.
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Don't forget leaving the house. The most deadly thing of all haha
 
Yeah, and I can see her/there point to at least bring the info out and let people decide for themselves. (It has been going on for absolute years) As you stated also, it depends on differing ways the exercises are used and or executed. How old or robust the trainee is etc. etc.
There are risks involved in most daily life. You just have to measure the trade offs and if the risks outweigh rewards.
IMO, there are way more risks to some of the meds some docs give you for the pain in those joints, than the exercises cause.
 
The distal loading on the knee is the reason for its detriment. When the femur is fixed and the tibia mobile the arthrokinematics at the knee are less than ideal. Ideally the femoral condyles roll and slide on the menisci superior to the tibial condyles. In addition there is a small degree of external and internal rotation during flexion and extension (screw home mechanism). When the femur is fixed, as in leg ext and curl, the dynamics of this relationship become altered and can increase risk of injury.
 
Appreciate all the useful replies and chuckle at the ironic ones. You folks know what I meant. Must be nice to be 25 and feel indestructible. Things change later and risk-rewards is important.
 
As with most caution regarding an exercise, it is founded in some truth. The distal loading, as NYiron expounded on, combined with the fixed movement pattern can cause issues. I, personally, don't include either and think there are equal or better exercises for both hypertrophy and athletic performance.
 
UCSMiami said:
You folks know what I meant. Must be nice to be 25 and feel indestructible. Things change later and risk-rewards is important.
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I here you bud, since I am way over 25 myself and no longer feel immortal.
Personally, I do not or have not done much of either exercises myself, but I have done ones that were always touted as bad by some. Doctors told me long ago to quit deadlifting heavy and squats were going to be bad for me along with bent rowing. I do not white water raft, nor do I jump from planes or use recreational drugs, so some risks in my life, I feel are worth it.
That all said, I just lost another $6000 on Wall St.
 
I really need to complete my blog write up on this, but I find several issues with the leg curl machines.

First and foremost, too many people neglect the effect of the hamstrings at the hip joint in extension, which happens to be where functionally they are best suited to exert maximal force (think sprinting, dead lifting, etc.). So that is an issue.

Second, and perhaps most important, is how people use the curl machine. All too often too much weight is used such that to complete the repetition they leverage the HS by increasing lordosis and anterior pelvic tilt (thus basically "pulling up" at the knee from the hip, as the ishium is moved superiorly). The major issue with this is 1. most lifters already have too much APT, and 2. Any ground based athlete who uses APT to flex the knee during running is asking for a hamstring injury.

That said, there are ways to use leg curls to train knee flexion that require the athlete to maintain a level pelvis. These include swiss ball leg curls, single leg swiss ball leg curls, and hanging supine leg curls (video below).

[video=youtube;el-LVVUu6Ug]http://www.youtube.com/watch?v=el-LVVUu6Ug[/video]
 
ZiR RED said:
I really need to complete my blog write up on this, but I find several issues with the leg curl machines.

First and foremost, too many people neglect the effect of the hamstrings at the hip joint in extension, which happens to be where functionally they are best suited to exert maximal force (think sprinting, dead lifting, etc.). So that is an issue.

Second, and perhaps most important, is how people use the curl machine. All too often too much weight is used such that to complete the repetition they leverage the HS by increasing lordosis and anterior pelvic tilt (thus basically "pulling up" at the knee from the hip, as the ishium is moved superiorly). The major issue with this is 1. most lifters already have too much APT, and 2. Any ground based athlete who uses APT to flex the knee during running is asking for a hamstring injury.

That said, there are ways to use leg curls to train knee flexion that require the athlete to maintain a level pelvis. These include swiss ball leg curls, single leg swiss ball leg curls, and hanging supine leg curls (video below).
Click to expand...

What about plate drags? I know there's knee flexion but the ROM is reduced and even more when performed with some hip extension (in a glute bridge). Also, to play the devil's advocate, leg extesions and leg curls are far less detrimental when the shins are perpendicular to the ground. The reason people get hurt is because they're not used to putting their legs into hyper extension (leg curl starting spot) and hyper flexion (leg extension starting spot), whereas someone who does (olympic squaters) would be less prone to injury due to more strength in that given ROM.

Just some food for thought.
 
PROness said:
What about plate drags? I know there's knee flexion but the ROM is reduced and even more when performed with some hip extension (in a glute bridge). Also, to play the devil's advocate, leg extesions and leg curls are far less detrimental when the shins are perpendicular to the ground. The reason people get hurt is because they're not used to putting their legs into hyper extension (leg curl starting spot) and hyper flexion (leg extension starting spot), whereas someone who does (olympic squaters) would be less prone to injury due to more strength in that given ROM.

Just some food for thought.
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Are plate drags similar to hamstring curls on a slide board? If so, then go for it. I think training knee flexion is important; however, to make it effective the exercise should require a degree of active pelvic stabilization at the same time. Such as the video above, or leg curls on a swiss ball, or plate drags/slide board HS curls.
 
leg curls are good for your knees. they are the best thing in fact that you can do to keep your knee intact and tracking correctly. Whoever told you otherwise has no idea what they are talking about. I would place regular biking the second most important - especially for re-hab.
Leg curls work the hams (in this case the focus is on the lower hams) and the top of the calves. Their are tendons that cross the back of your knee through your hams and calves. Working the muscles that are attached to these tendons keep your knee tight so it does not move around easily and result in minor to major (ACL) tendon tears and slow (or fast in the case of an ACL tear) destruction of the meniscus and patella. The legs primary movement is to do a curling motion. The people that are most prone to acl and other knee related tendon tears are usually 1) female and or 2) tall. In both cases, these folks are likely to have less mass tied to the tendons that hold the knee in position. Check a sports injury centre and the highest percentage of folks with knee problems are the ones with the least mass. So, work your hams with curls! What is the first they do to to you before your even off the operating table and not yet awake - post knee surgery? They put your knee in a machine that performs a curling motion - albeit short range of motion due to the surgery. This range of motion gets increased more and more until you are ready to ride a bike and then you start to do curling motion exercises. Why would they do this if a curling motion was bad for your knees?

Leg extensions as noted above are great if you go light and high rep and use them to simply bring out the quads and tighten the knee from the front. They are by no means a mass builder. Not going light will chop up the meniscus at lock out and cause tracking issues etc..

Save the mass building for good form squats where your knees do not go in front of your toes at the bottom of the squat. High feet and close together leg press is also great for the hams - upper hams however.

This comes from going through knee surgeries and working with many people who have re-habbed from knee problems to be stronger than they ever were. With multiple knee surgeries under my belt, I still play hockey and can squat 500lbs ass to the ground.
 
The "curling" motion isn't poor and if you had read the other posts you would see other ways to perform loaded knee flexion. The issues we have described are the fixed pattern in which it occurs, the distal loading and thus long lever arm and the technical errors used when performing machine hamstring curls (apt and lordotic posture, in general). Knee flexion is just one of the two major functions of the hamstrings with the more important for athletes, in my opinion,, being hip extension. Also, women and ACL tears is pretty widely considered to be a result of the Q angle, which refers to the wider angle of the pelvis.

Edit: also, the have you do these exercises bc the load is easily controlled, they are isolated and after a major surgery getting Rom and some strength back is a very important goal. It doesn't inherently make them good for a healthy population. I'm sure one of our PT focus guys can chime in with much, much more
 
bakerwil said:
leg curls are good for your knees. they are the best thing in fact that you can do to keep your knee intact and tracking correctly. Whoever told you otherwise has no idea what they are talking about. I would place regular biking the second most important - especially for re-hab.
Leg curls work the hams (in this case the focus is on the lower hams) and the top of the calves. Their are tendons that cross the back of your knee through your hams and calves. Working the muscles that are attached to these tendons keep your knee tight so it does not move around easily and result in minor to major (ACL) tendon tears and slow (or fast in the case of an ACL tear) destruction of the meniscus and patella. The legs primary movement is to do a curling motion. The people that are most prone to acl and other knee related tendon tears are usually 1) female and or 2) tall. In both cases, these folks are likely to have less mass tied to the tendons that hold the knee in position. Check a sports injury centre and the highest percentage of folks with knee problems are the ones with the least mass. So, work your hams with curls! What is the first they do to to you before your even off the operating table and not yet awake - post knee surgery? They put your knee in a machine that performs a curling motion - albeit short range of motion due to the surgery. This range of motion gets increased more and more until you are ready to ride a bike and then you start to do curling motion exercises. Why would they do this if a curling motion was bad for your knees?

Leg extensions as noted above are great if you go light and high rep and use them to simply bring out the quads and tighten the knee from the front. They are by no means a mass builder. Not going light will chop up the meniscus at lock out and cause tracking issues etc..

Save the mass building for good form squats where your knees do not go in front of your toes at the bottom of the squat. High feet and close together leg press is also great for the hams - upper hams however.

This comes from going through knee surgeries and working with many people who have re-habbed from knee problems to be stronger than they ever were. With multiple knee surgeries under my belt, I still play hockey and can squat 500lbs ass to the ground.
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As was stated the arthrokinematics associated with a distally loaded knee and fixed femur are less than ideal. There are much better ways to train with a focus of joint integrity, which is where you are basing your opinion. Also, Stating the primary movement of the legs as a curl motion is very short sighted. Additionally pertaining to knee flexion the gastroc will exhibit a small amount of biarticular influence but it is minimal at best.

Yes strengthening the quads and hamstrings will reduce risk of injury but muscular balance and proprioception are higher on the priority list then mass with regards to pre/re-hab. There is a synergy of ligament and muscular action that provide the stability you are touching on the acl is not a tendon and the hamstrings are not anatomically divided into upper or lower only semitendinosus, semimembranosus and biceps femoris just FYI. In addition the reason why females are at high risk for ligament injuries is largely hormonal relating to relaxin secretion around the menstrual cycle. It is also accepted that as a whole women tend to more often carry their mass below the waist as compared to men. With regards to the CPM it does not fix the femur in flexion and extension in the same way a leg curl or leg ext will, which lends itself to more natural osteokinematics and ensuing arthrokinematics. No one said knee flexion was bad but rather distal loading of the knee in flexion and extension. Also the point Zir has raised regarding pelvic tilt comes into play as well. Lastly TKE is usually the recommended use of a leg ext in a therapy based setting. It is not the end range of extension that will give rise to the most problems (chopping of the meniscus as you have stated) it's the end range of flexion working through to TKE and tracking issues come as a result of flawed muscular balance.
 
tigerdb2 said:
The "curling" motion isn't poor and if you had read the other posts you would see other ways to perform loaded knee flexion. The issues we have described are the fixed pattern in which it occurs, the distal loading and thus long lever arm and the technical errors used when performing machine hamstring curls (apt and lordotic posture, in general). Knee flexion is just one of the two major functions of the hamstrings with the more important for athletes, in my opinion,, being hip extension. Also, women and ACL tears is pretty widely considered to be a result of the Q angle, which refers to the wider angle of the pelvis.

Edit: also, the have you do these exercises bc the load is easily controlled, they are isolated and after a major surgery getting Rom and some strength back is a very important goal. It doesn't inherently make them good for a healthy population. I'm sure one of our PT focus guys can chime in with much, much more
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Beat me to it. He was asking for it with the statement saying we have no idea what were talking about.
 
NYiron said:
Beat me to it. He was asking for it with the statement saying we have no idea what were talking about.
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Hey, I am not a Doctor, just going by many, years of experience with Professional sports teams. People (not just Woman as I stated) that have less mass around the back of the knee are most likely to have knee problems. Yes, I was short sited in stating the primary movement of the leg. Anyhow, I will ask you as you seem well educated on the subject. What is more effective than a curling motion or biking for working the lower part of the hams? Many sports professionals I know would like to also know Bud....
 
bakerwil said:
Hey, I am not a Doctor, just going by many, years of experience with Professional sports teams. People (not just Woman as I stated) that have less mass around the back of the knee are most likely to have knee problems. Yes, I was short sited in stating the primary movement of the leg. Anyhow, I will ask you as you seem well educated on the subject. What is more effective than a curling motion or biking for working the lower part of the hams? Many sports professionals I know would like to also know Bud....
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What professional sports teams are you working with? My assumption is that they would understand the flawed arthrokinematics, I have discussed, associated with fixing the femur and distally loading especially with respect to sports performance.
 
NYiron said:
What professional sports teams are you working with? My assumption is that they would understand the flawed arthrokinematics, I have discussed, associated with fixing the femur and distally loading especially with respect to sports performance.
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Please just answer the question as to what you would recommend. What I am affiliated with has nothing to do with what you think is functionally best. Thanks for your help...
 
bakerwil said:
Hey, I am not a Doctor, just going by many, years of experience with Professional sports teams. People (not just Woman as I stated) that have less mass around the back of the knee are most likely to have knee problems. Yes, I was short sited in stating the primary movement of the leg. Anyhow, I will ask you as you seem well educated on the subject. What is more effective than a curling motion or biking for working the lower part of the hams? Many sports professionals I know would like to also know Bud....
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ACL injuries in sports most commonly occur upon landing or cutting when the knee tracks medially (inward, knock-kneed). The injury has a lot less to do with the mass of muscle around the knee, as it does the muscles of the hips and thighs that control femoral rotation and abduction/adduction. Generally, tight adductors and weak abductors and VMO, inconjunction with poor movement patterns, is what results in ACL injuries.

As for the hamstring, there is no upper vs. lower. The fibers of the muscle run longintudinally, and will either flex the knee or extend the hip (or both) depending on which joint is fixed or not. Perhaps you mean the short head of the biceps femoris, which only flexes the knee. Either way, when you work the hamstrings you are working the entire muscle, not the upper vs. lower.
 
ZiR RED said:
ACL injuries in sports most commonly occur upon landing or cutting when the knee tracks medially (inward, knock-kneed). The injury has a lot less to do with the mass of muscle around the knee, as it does the muscles of the hips and thighs that control femoral rotation and abduction/adduction. Generally, tight adductors and weak abductors and VMO, inconjunction with poor movement patterns, is what results in ACL injuries.

As for the hamstring, there is no upper vs. lower. The fibers of the muscle run longintudinally, and will either flex the knee or extend the hip (or both) depending on which joint is fixed or not. Perhaps you mean the short head of the biceps femoris, which only flexes the knee. Either way, when you work the hamstrings you are working the entire muscle, not the upper vs. lower.
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Yes, you are correct Bud - can anyone answer my question though?
What is more effective than a curling motion or biking for working the 'ham stings' which in my experience and opinion keeps the knee in place and tracking correctly when under the stress you speak of)?
 
bakerwil said:
Yes, you are correct Bud - can anyone answer my question though?
What is more effective than a curling motion or biking for working the 'ham stings' which in my experience and opinion keeps the knee in place and tracking correctly when under the stress you speak of)?
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Think critically on it the answers are there just not in neon lights.
 
bakerwil said:
Helpful response....
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No problem...
You having years of experience with professional sports teams and us not knowing anything figured you'd be able to find the answer.
 
There have been quite a few knee flexion exercises listed in this thread (maybe even a video? don't feel like going to check mid response) and the GHR is a favorite of mine, although not accessible for all.
 
bakerwil said:
Yes, you are correct Bud - can anyone answer my question though?
What is more effective than a curling motion or biking for working the 'ham stings' which in my experience and opinion keeps the knee in place and tracking correctly when under the stress you speak of)?
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You are party correctly regarding the hamstring action on preventing ACL injuries during landing: Invalid Link Removed

Finding pubmed studies of EMG activity difference during various HS exercises is not something I particularly feel like searching for right now (perhaps you, or someone else can). My guess though is that you will see a greater recruitment intensity with things like RDL's (hip extension) than biking or curling. Additionally, a good study is underway by Schoenfeld, Contreras and Wilson "investigating if regional differences in muscle activation exist by performing different hamstrings exercises", which will likely support my hypothesis of hip extension > knee flexion for HS strengthening.
 
And given that most have overactive lateral hamstrings, the use of hip extension based movements that target the media hamstrings are probably a good idea for most athletes. Invalid Link Removed
 
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