"The definitions of [the hamstrings'] functions are blurry, and are really significant only when we isolate joints on exercise machines. The complexities of normal movement do not lend themselves to such constructed distinctions." - Rip
>https://www.youtube.com/watch?v=QfOQWwEB3rI
While it's normal for people to instantly have a "this is stupid!" reaction when told the hamstrings can also help knee extension, probably due to how the isolation machines have dumbed complex muscular functions down for the masses, the truth is that the hamstrings also play a role in HELPING knee extension.
This is due to the muscles crossing two joints and acting on both joints at the same time.
When you are at the bottom of the low bar squat, your hamstrings are fully stretched and loaded. As your hips shoot upwards (hip drive), the hamstring's contraction creates a pulling force on the hips and the knees.
IF, and this is something often overlooked by people, your feet were not stuck to the ground, the hamstrings' pulling on the knee joint would cause knee flexion (what happens in the leg curl machines).
However, as your feet are a static point in the squat, the pulling force produced by the hamstrings actually pulls the knees BACK, while pulling your hips forward. This pulling force helps the quads to extend the knees.
This is due to the muscle fibers that run along the entire length of the muscle belly contracting 100% throughout the entire fiber. The hamstrings cannot "just extend the hip in case the feet are static", because their muscle fibers will always produce force on both joints.
This is the reason why you can lift heavier weights with the low bar squat. With the high bar and front squats, the hamstrings are shortened at the bottom, so their contribution to both knee and hip extension is highly diminished.
>>35386374
Well, its one reason you can lift more with lowbar. Comes at some costs though, minor that they are.
>>35386382
There's no cost to squatting low bar.
>>35386374
Yep, this is pretty accurate.
Many novices and shitposters on /fit/ will laugh about it, though. If something isn't on a wikipedia bulletpoint, those people don't think it an actual thing.
>>35386374
Mirin the paint picture for 5 years olds
... It does make it easier to understand it tho.
>>35386803
A weightlifter that trains lowbar will train movement patterns that will negatively affect the classic lifts. Thus, a cost of lowbar squatting.
>>35386803
It damages my elbow and puts my back at greater risk
>>35387096
You are not squatting correctly then.
Another video, this one is more about the running movement though. And a bit long.
https://www.youtube.com/watch?v=EGHd33S9oTo
And a small nice video about the knee joint.https://www.youtube.com/watch?v=nnIlz9CIYjI
Not very related to the squat per se but interesting nonetheless.
I wish I understood hipdrahve, whenever I try to do it I just raise my ass up too much and have to do a squat-morning, does anyone know how to fix that?
oh no not this shit again
it helps in the squat movement but it does not fucking pull the knee back. your picture is wrong. the violet arrow does not really exist. the force that the hamstrings pull on the tibia with is countered by the force on the other end of the hamstrings, at the ischial tuberosity. this changes things so that instead of "pulling the knee back", the actual force is pulling the tibia close to the ischial tuberosity which equals knee flexion. youre thinking the hamstrings are like a rope tied around the knee and something is pulling on it from behind of the figure. it doesnt work like that
What if you have very long flexible hamstrings that don't get loaded at parallel?
>>35390228
Then you just collapse
>>35390168
Holy fuck you have no idea what you're talking about.
>>35390228
You're supposed to go below parallel.
And it's humanly impossible not to load your hamstrings at the bottom of a well executed low bar squat. Your hamstrings would have to be mutant-level of length.
>>35390287
Holy fuck you have no idea what you're talking about.
Yes, the hamstrings (and glutes) aid in knee extension. The quads also aid in hip extension. And the muscles of the upper leg also help extend the muscles of the lower leg (the calves, which extend the ankle, this is part of why squats and such are not a good calf excercise, even though there's pretty significant movement at that joint).
I still don't think it's really significant, and the attachments of the hamstrings are at the hip and knee, and they're attached in a way that when they contract in isolation, they extend the hips and flex the knee. Bottom line.
In compound movements, yes, things can get more complex. The hamstrings are still primarily extending the hip in a squat, just as the quads are primarily extending the knee. Why do we have to overcomplicate this shit? Why do we have to have a wank over biomechanics? Just fucking squat however you want to, whichever on is better for your goals (my goals lead me to believe I should squat high bar ATG, as I want big quads/thighs and to do Oly lifting), if YOURS is to compete in powerlifting and move big weights on your back, have strong spinal erectors, a strong back, strong and big glute/hamstrings (good for movements that involve propelling your body horizontally), do a reasonable powerlifter low bar style squat.
I still think tiny trip is an idiot.
>>35390359
>The quads also aid in hip extension
funny since the rectus femoris is the stronger hip FLEXOR
the quads do work in squats. hip extension also happens in squats. this does not mean quads assist hip extension.
>And the muscles of the upper leg also help extend the muscles of the lower leg
u wot m8
>>35390168
>it does not fucking pull the knee back
Stopped reading there. Go learn some anatomy before trying to broscience biomechanics.
>>35390168
It's time.
Someone with no knowledge has come to argue.
The thread is now gonna become a shitfest.
Enjoy everyone.
>>35390398
>funny since the rectus femoris is the stronger hip FLEXOR
You mean the Iliopsoas.
>>35390407
pulling the knee back =/= knee flexion
>>35390433
someone who has trouble with reading comprehension has come to shitpost
>>35390443
smaller muscle with weaker leverages
My theory is that as your hips drive upwards, it causes your hips to act as a fulcrum. Since your hams are tight, it pulls your hips into extension.
>>35390398
It's true.
The tendon of the hamstrings at the knee is longer than it is at the hip. The tendon at the quad is shorter at the knee than it is at the hip. Which is why the quads and hamstrings can both contract hard and NOT cancel eachother out. The hamstrings are a stronger hip extensor than they are knee flexor, and the opposite applies to the quads (stronger knee extensor, weak hip flexor).
There's an article on strength theory by Greg Knuckles talking about how the glutes assist in knee extension and the quads assist in hip extension.
It still really doesn't matter though.
>>35390446
>sees hamstrings attaching to the knee
>can't understand what happens when the hamstrings contract when you are in a parallel squat stance
Sorry but I'm not gonna bother m8, you're just straight up retarded.
>>35390467
https://en.wikipedia.org/wiki/Iliopsoas
>>35390485
>The hamstrings are a stronger hip extensor than they are knee flexor, and the opposite applies to the quads (stronger knee extensor, weak hip flexor).
I know, how does that counter anything I said?
>There's an article on strength theory by Greg Knuckles talking about how the glutes assist in knee extension and the quads assist in hip extension.
in squats, yes. but squatting does not equal "hip extension".
>>35390503
oh youre posting an image of rippetoe
then let me quote the holy bible for you
"If your knees move forward at the bottom of the squat, you may have relaxed your quads, which hold the knees open; the closed knee angle in turn shortens the hamstrings, which then are slacked distally and therefore cannot be used effectively for proximal hip extension. Quads maintain the knee angle, which in turn anchors the hamstrings as they tighten with greater squat depth and a more closed hip angle so that they can extend the hips on the way up. Or you may have relaxed the hamstrings’ tension on the tibias, dorsiflexed your ankles, and shifted forward to your toes from the bottom. The soleus anchors the knee angle from the distal end, and the gastrocnemius adds to this effect by crossing the knee joint to the distal femur, to anchor the knee to the ankle. The squat is essentially an interaction with the ground and your balance point over the mid-foot. All these muscles, if relaxed at the bottom of the squat, have to be retightened to be used effectively, and this is hard to do from what are now terribly inefficient skeletal
positions."
knee angle closes = hamstrings tighten
hamstrings tighten = knee angle closes
>https://en.wikipedia.org/wiki/Iliopsoas
gee if wikipedia says so it must be true. the rectus femoris has more leverage to flex the hip than the iliopsoas, look at the attachments yourself
>>35390446
The muscular contraction of a muscle fibre exerts force that pulls both ends of the muscle fibre towards the centre.
When the hamstrings contracts, they pull both the knee and the hip attachments, as the muscle fibres span the entire length (excluding non-spanning muscle fibres, but those are not innervated by motoneurons and depend on the spanning muscle fibre contractions in order to activate). If you are in a parallel squat stance, this means the hamstrings are in a position to pull your knee back.
As you ascend during the squat, the hip and knee angles maintain that equivalence, and the hamstrings continue to pull the hip and the knee closer.
>>35390588
The Rippetoe quote you are pasting is talking about a completely different thing. He is talking about the DESCENT, not the ascent.
>>35390398
>funny since the rectus femoris is the stronger hip FLEXOR
You are utterly wrong.
http://lmgtfy.com/?q=strongest+hip+flexor
>>35386374
Don't do this. I've had a hamstring tendon strain for 2 months now and it hurts most when doing this
>>35390675
>don't squat
>>35390606
>If you are in a parallel squat stance, this means the hamstrings are in a position to pull your knee back.
what? how the hell did you jump in to that conclusion?
hamstring contraction will pull the attachments closer together. that is, the head of the tibia and the ischial tuberosity. i dont understand how you can see that as anything else but the tibia moving closer to the femur as in knee flexion.
the hamstring does not know if youre descending or ascending in a squat. the function does not change.
>>35390636
yeah i guess if google says so it must be then! keep ignoring my arguments
>>35390692
>yeah i guess if google says so it must be then! keep ignoring my arguments
Google doesn't say anything, it's a search engine.
Try looking at the links in the search result, and you might find out why and how you are completely wrong.
> i dont understand how you can see that as anything else but the tibia moving closer to the femur as in knee flexion.
Listen, the hamstrings do not simply "decide" to do knee flexion.
All they do is pull the attachments.
If your feet is fixed on the ground and you are in a ascending squat position, when the hamstrings pull the knee attachment they create a vector of force that is pulling the knee back, which aids knee extension.
>the hamstring does not know if youre descending or ascending in a squat. the function does not change.
Yes it does...
>>35390739
>Try looking at the links in the search result, and you might find out why and how you are completely wrong.
i looked and they all just say "psoas is the strongest hip flexor". thats not an argument. wikipedia cites a book but i cant read it to see how theyve ended up in such a result.
>All they do is pull the attachments.
no shit?
>If your feet is fixed on the ground and you are in a ascending squat position, when the hamstrings pull the knee attachment they create a vector of force that is pulling the knee back, which aids knee extension.
holy fuck youre stupid
if the knee extends, the hamstrings lengthens. therefore its not contracting.
the tibial end of the hamstrings pull the TIBIA back, not the knee. this is a completely different thing and since every force must be countered, this force is countered by pulling the ischial tuberosity to the tibia at the other end of the hamstring. this would result in knee flexion, but due to the nature of the squat it doesnt happen. in knee extension these two points would get further apart, meaning the muscle does not contract in that function.
>Yes it does...
what the fuck?
>>35390849
>if the knee extends, the hamstrings lengthens. therefore its not contracting.
Wrong.
The hamstrings crosses two joints. This is what you are not understanding.
If the hip extends faster than the knee, the hamstrings will be shortening during the knee extension. This is what happens during the squat.
Again, you are forgetting that the hamstrings crosses two joints. You are looking at it as if it only crosses the knee joint.
>the tibial end of the hamstrings pull the TIBIA back, not the knee
You know the tibia is part of the knee, right?
Or are you one of those people anatomically illiterate that don't know the humerus is part of the shoulder?
>this force is countered by pulling the ischial tuberosity to the tibia at the other end of the hamstring
No it's not. The hamstring contraction produces a vector of force that goes from the attachments towards the centre. If one of the forces countered the other, the hamstrings would also not be able to do hip extension.
>in knee extension these two points would get further apart, meaning the muscle does not contract in that function.
Wrong.
You aren't realising something incredibly obvious.
The hamstrings produce force from the ends towards the centre. It pulls BOTH ends towards the centre. Since they are attached to the knee, and the feet are in a fixed position, when you are ascending from the bottom of the low bar squat (where your hamstrings are at max length and fully loaded), their contraction causes the pulling of the hip joint and the knee joint. This causes hip extension and knee extension, as the vectors are pulling the hip forwards and the knee backwards, with the aim of locking them both out.
Check the picture in the OP again.
>what the fuck?
Your nervous system and neuromotor system know very well whether your are descending or ascending the squat, and thus control the hamstring contraction and function accordingly.
>>35391050
>If the hip extends faster than the knee, the hamstrings will be shortening during the knee extension. This is what happens during the squat.
only because the hip part has more leverage. the hamstrings contract as a whole, but close to the knee it extends.
>You know the tibia is part of the knee, right?
i know but this is just semantics. what i mean is that instead of the hamstrings pulling at some kind of thing that attaches the tibia and the femur together it pulls on the femur.
>No it's not. The hamstring contraction produces a vector of force that goes from the attachments towards the centre.
exactly what i said. the other vector is the tibial head pulling, the other is the ischial head pulling.
>If one of the forces countered the other, the hamstrings would also not be able to do hip extension.
countering each other does not mean nullifying each other.
>as the vectors are pulling the hip forwards and the knee backwards,
the vector isnt pulling the knee backwards. it is pulling the tibia closer to the femur which is the opposite of "pulling the knee backwards".
>Check the picture in the OP again.
the picture is WRONG. the vector you have does not exist. it is incorrect, it does not work like that. im going to make a video about this soon if you still keep being silly.
>nd thus control the hamstring contraction and function accordingly.
the cns cant change the attachments. the function stays the same.
>>35391223
>but close to the knee it extends
This doesn't exist.
The muscle doesn't lengthen in one part and shorten in another. The contraction is 100% and throughout the entire length of the fibre.
>what i mean is that instead of the hamstrings pulling at some kind of thing that attaches the tibia and the femur together it pulls on the femur.
I don't even get what you are trying to say here?
Did you mean tibia instead of femur at the end?
In which case, you have to realise that they pull the very top of the tibia, and this affects the knee joint. By pulling that part of the tibia back, it extends the knee because it IS connected to the femur.
>exactly what i said. the other vector is the tibial head pulling, the other is the ischial head pulling.
No, it's not what you said. You said their vectors cancel each other, and they DON'T because the hip and the knee joint are independent of each other.
>countering each other does not mean
They do not counter each other because the hip and knee joint are independent of each other. The hamstrings causes a certain movement on the hip, defined by the vector that pulls the hip forwards (hip extension), and causes another movement on the knee joing, defined by the vector that pulls the knee back (knee extension)
>the vector isnt pulling the knee backwards. it is pulling the tibia closer to the femur which is the opposite of "pulling the knee backwards".
No it's not.
Please check the anatomy of the hamstrings and where they attach in pic related.
When you are in the squat position, the hamstrings are pulling the knee back as the drawing in the OP shows
>the vector you have does not exist
The hamstrings are pulling both their attachments, and on each of those they produce a vector that independent of the vector on the other attachment. The contraction goes from the end to the centre of the fibre, which means the fibres that attach on the knee are pulled towards the centre of the hamstrings (aka pulling the knee back).
>>35391223
>im going to make a video about this soon if you still keep being silly.
Please do, I'm really curious on how you still can't understand this. I wonder what even goes through your thought process that it blocks the information from being processed by your brain.
I mean, you have a paint drawing clearly showing you how the vectors work and you still can't comprehend it...
>the cns cant change the attachments. the function stays the same.
The CNS and the PNS control the contraction, and control the functions.
If they do not want the knee to flex, they won't make the knee flex.
If they want a certain thing to happen, but not another thing, they will control the entire muscular system in order to tailor their functions so that, together, they achieve the objective.
>>35391223
Please draw on paint how you think the vectors work, I'm really really curious as to why this is being hard to understand.
>>35391651
http://draw.to/D1REK5s
>>35391666
wtf?
>>35391680
Hamstring goes up, knee comes in. Simple
>>35386374
>that paint image
Can you into physics?
>>35391666
>>35391710
Please draw on this.
Make a line that represents the hamstrings, make arrows following the line that represents the muscular contraction, and the make two arrows the represent the resulting vectors of the force produced by the contraction.
>>35391578
>The muscle doesn't lengthen in one part and shorten in another. The contraction is 100% and throughout the entire length of the fibre.
if you look at the knee, the close fibers "lengthen" in a way.
>Did you mean tibia instead of femur at the end?
yeah
>No, it's not what you said. You said their vectors cancel each other, and they DON'T because the hip and the knee joint are independent of each other.
i didnt say they cancel each other, i said they counter each other as per newtons law.
im going to make the fucking video soon...
>>35391985
>if you look at the knee, the close fibers "lengthen" in a way.
No they don't.
Muscular contraction is 100% throughout the entire fiber.
The only thing that lengthenens at the knee is the tendon, but that makes no difference to the direction of the movement, since the tendon produces no force by itself.
>i didnt say they cancel each other, i said they counter each other as per newtons law.
They don't. The hip and knee joint and independent of each other. The force being produce to move one joint does not directly affect the other joint, the vectors cannot "counter each other".
Stil waiting on the drawing >>35391739 or video so I can point out exactly how you are wrong and you can finally understand this.
>>35392105
>No they don't.
Muscular contraction is 100% throughout the entire fiber.
no shit, but the fibers near the knee joint move "forward" as if they hamstrings would be extended relative to the knee. ill make a video on this too
>The force being produce to move one joint does not directly affect the other joint, the vectors cannot "counter each other".
do you have any idea what the newtons law does? the force pulling on the tibia also creates force at the hip
the video will come but not anytime soon. i have to use my both hands and need to record my POV so ill have to be a bit creative and convert shit to webm and stuff
>>35387075
>playing football has its negatives because it has little carry over to basketball
basically how dumb you sound.
>>35387096
both of those happen with shit form - may as well not lift anything if your gonna do everything wrong.
>>35392148
Video or drawing please, tired of reading through your pseudo-knowledge of biomechanics and having to teach basic stuff.
>>35392148
this guy btfo left with his dick between his legs
>tfw people complaining finally realised the truth
Hammies bros UNITE
Still waiting on that video or drawing.
Still waiting.
