Squat Form Check, Drifitng Back Out of Hole

[quote]Haldor wrote:
I am thinking of doing pin squats with chains. What is your take on this?

My reasoning is that I’m weak within an angle of about 20Ã?° between parallel and 70Ã?°. So If I set the pins at parallel (or just below) I will start at my sticking point and that will help me solidify my position for when I drift backwards and the chains will help the weight get heavier specifically in that 20Ã?° angle. Thoughts?[/quote]
Better to do them as two separate exercises. With chains, the bottom range of motion is easier so that defeats the purpose of doing pin squats. You can’t overload the top and bottom of a movement at the same time.

FWIW, I would quit considering pin squats or chains etc. Your form needs tweaking. You are not weak at the top, so pin & chain work will only compound your issue. Peform the full squat with lighter weights till your form is perfect. Build the muscle via accessory movements. You PC is weak which is why your doing that “twitch” / stall or hatever you want to call it. Like I said before, work on your hip hinge / strength. Quit worrying about percentages and other irrelevant and distracting stuff. It’s all mental masturbation.

I don’t know squat…but you’re attempting a PR? -of course you’re going to “stall” there, the weight’s (too) heavy.

Check this guy out, he’s got great form, fantastic #s, and “stalls” at the same spot you do…except he grinds through it because he’s a very, very good powerlifter:

Like I said, I don’t know squat, but your bar path looks like it’s straight up and down, I don’t know why you think you’re doing anything “wrong”.

[quote]StrengthDawg wrote:
FWIW, I would quit considering pin squats or chains wtc. Your form needs tweaking. You are not weak at the top, so pin & chain work will only compund your issue. Peform the full squat with lighter weights till your form is perfect. Build the muscle via accessory movements. You PC is weak which is why your doing that “twitch” / stall or hatever you want to call it. Like I said before, work on your hip hinge / strength. Quit worrying about percentages and other irrelevant and distracting stuff. It’s all mental masturbation.
[/quote]
No disrespect, but I don’t completely agree with what you are saying. It’s true that working with lighter weights could help with technical errors in some cases, but for anyone except a complete beginner you would have to do very high volume and stay far from failure (like Sheiko programs). From personal experience, I would say that perfecting your technique with lighter weights doesn’t carryover to maximal lifts. My squats used to fall apart around 90%+, but they looked good with lighter weights. What helped me was two things: daily max squatting and special exercises like I mentioned above. In the case of Sheiko and similar programs, they work because you do so many repetitions of the same movement that your body learns to do it more efficiently. You still have to check your technique because if you are doing high volume with bad form then you will only make things worse, it only works if you can maintain proper form.

About pin squats, if you do them the way I was saying (reaching depth) then they will help the bottom end, not the top. I agree that chains won’t help, but I think bands might be useful because the force you to keep your balance. One way or another, the competition lift needs to be the basis of your training and not variations, they can help but they don’t replace it.

I realize that this is a bit of a controversial topic because everyone seems to have their own ideas of how to fix technical errors so I will start another thread where we can argue about that.

[quote]StrengthDawg wrote:
FWIW, I would quit considering pin squats or chains wtc. Your form needs tweaking. You are not weak at the top, so pin & chain work will only compund your issue. Peform the full squat with lighter weights till your form is perfect. Build the muscle via accessory movements. You PC is weak which is why your doing that “twitch” / stall or hatever you want to call it. Like I said before, work on your hip hinge / strength. Quit worrying about percentages and other irrelevant and distracting stuff. It’s all mental masturbation.
[/quote]

I know I’m overthinking it, it’s just that drifting backwards that’s bugging me because I haven’t stalled like that before. I know the weight is too heavy at this point so I’m adjusting accordingly and will add more hip work.

Thanks for all the input.

[quote]chris_ottawa wrote:

[quote]StrengthDawg wrote:
FWIW, I would quit considering pin squats or chains wtc. Your form needs tweaking. You are not weak at the top, so pin & chain work will only compund your issue. Peform the full squat with lighter weights till your form is perfect. Build the muscle via accessory movements. You PC is weak which is why your doing that “twitch” / stall or hatever you want to call it. Like I said before, work on your hip hinge / strength. Quit worrying about percentages and other irrelevant and distracting stuff. It’s all mental masturbation.
[/quote]
No disrespect, but I don’t completely agree with what you are saying. It’s true that working with lighter weights could help with technical errors in some cases, but for anyone except a complete beginner you would have to do very high volume and stay far from failure (like Sheiko programs). From personal experience, I would say that perfecting your technique with lighter weights doesn’t carryover to maximal lifts. My squats used to fall apart around 90%+, but they looked good with lighter weights. What helped me was two things: daily max squatting and special exercises like I mentioned above. In the case of Sheiko and similar programs, they work because you do so many repetitions of the same movement that your body learns to do it more efficiently. You still have to check your technique because if you are doing high volume with bad form then you will only make things worse, it only works if you can maintain proper form.

About pin squats, if you do them the way I was saying (reaching depth) then they will help the bottom end, not the top. I agree that chains won’t help, but I think bands might be useful because the force you to keep your balance. One way or another, the competition lift needs to be the basis of your training and not variations, they can help but they don’t replace it.

I realize that this is a bit of a controversial topic because everyone seems to have their own ideas of how to fix technical errors so I will start another thread where we can argue about that.[/quote]

I agree with what you’re saying, but the weight IS just too damn heavy. I’m only making a 20 lb adjustment so I’m not dropping down to “light weights”. The maximal work will still be there except it’ll be from a weight I can actually hit for a max.

I’ll give the band squats a try to see what they do for my balance.

[quote]punnyguy wrote:
I don’t know squat…but you’re attempting a PR? -of course you’re going to “stall” there, the weight’s (too) heavy.

Check this guy out, he’s got great form, fantastic #s, and “stalls” at the same spot you do…except he grinds through it because he’s a very, very good powerlifter:

Like I said, I don’t know squat, but your bar path looks like it’s straight up and down, I don’t know why you think you’re doing anything “wrong”.[/quote]

That fella’s 3rd squat was ridiculous. Very impressive, inspiring too.

[quote]chris_ottawa wrote:

[quote]StrengthDawg wrote:
FWIW, I would quit considering pin squats or chains wtc. Your form needs tweaking. You are not weak at the top, so pin & chain work will only compound your issue. Peform the full squat with lighter weights till your form is perfect. Build the muscle via accessory movements. You PC is weak which is why your doing that “twitch” / stall or hatever you want to call it. Like I said before, work on your hip hinge / strength. Quit worrying about percentages and other irrelevant and distracting stuff. It’s all mental masturbation.
[/quote]
No disrespect, but I don’t completely agree with what you are saying. It’s true that working with lighter weights could help with technical errors in some cases, but for anyone except a complete beginner you would have to do very high volume and stay far from failure (like Sheiko programs). From personal experience, I would say that perfecting your technique with lighter weights doesn’t carryover to maximal lifts. My squats used to fall apart around 90%+, but they looked good with lighter weights. What helped me was two things: daily max squatting and special exercises like I mentioned above. In the case of Sheiko and similar programs, they work because you do so many repetitions of the same movement that your body learns to do it more efficiently. You still have to check your technique because if you are doing high volume with bad form then you will only make things worse, it only works if you can maintain proper form.

About pin squats, if you do them the way I was saying (reaching depth) then they will help the bottom end, not the top. I agree that chains won’t help, but I think bands might be useful because the force you to keep your balance. One way or another, the competition lift needs to be the basis of your training and not variations, they can help but they don’t replace it.

I realize that this is a bit of a controversial topic because everyone seems to have their own ideas of how to fix technical errors so I will start another thread where we can argue about that.[/quote]

So your advice to the OP is that you don’t agree with what I’m tossing out there?

May I ask how long you have been seriously lifting? By what you wrote, I’m going to guess that you are new to this game. Few who have been lifting for years do daily max effort squats. It’s nonsense.
You are also recommending that one do Max effort Anderson squats off of pins? So a guy is supposed to take a 1m for a ride only from the bottom up? Looks like spine injury time to me. How many times did you do any of this personally and what was the results? Your writing “I think” this does that makes me believe you have little practical experience of this stuff you are spewing. Honestly dude, you sound like a guy who been lifting for 6 months. I may be totally wrong, whatever. I just think your comments are unfounded and not grounded in sound lifting priciples.

Anyways, Haldor man. Good luck with your squat. I hope you fix your issue and get back to kicking ass.

[quote]StrengthDawg wrote:

[quote]chris_ottawa wrote:

[quote]StrengthDawg wrote:
FWIW, I would quit considering pin squats or chains wtc. Your form needs tweaking. You are not weak at the top, so pin & chain work will only compound your issue. Peform the full squat with lighter weights till your form is perfect. Build the muscle via accessory movements. You PC is weak which is why your doing that “twitch” / stall or hatever you want to call it. Like I said before, work on your hip hinge / strength. Quit worrying about percentages and other irrelevant and distracting stuff. It’s all mental masturbation.
[/quote]
No disrespect, but I don’t completely agree with what you are saying. It’s true that working with lighter weights could help with technical errors in some cases, but for anyone except a complete beginner you would have to do very high volume and stay far from failure (like Sheiko programs). From personal experience, I would say that perfecting your technique with lighter weights doesn’t carryover to maximal lifts. My squats used to fall apart around 90%+, but they looked good with lighter weights. What helped me was two things: daily max squatting and special exercises like I mentioned above. In the case of Sheiko and similar programs, they work because you do so many repetitions of the same movement that your body learns to do it more efficiently. You still have to check your technique because if you are doing high volume with bad form then you will only make things worse, it only works if you can maintain proper form.

About pin squats, if you do them the way I was saying (reaching depth) then they will help the bottom end, not the top. I agree that chains won’t help, but I think bands might be useful because the force you to keep your balance. One way or another, the competition lift needs to be the basis of your training and not variations, they can help but they don’t replace it.

I realize that this is a bit of a controversial topic because everyone seems to have their own ideas of how to fix technical errors so I will start another thread where we can argue about that.[/quote]

So your advice to the OP is that you don’t agree with what I’m tossing out there?

May I ask how long you have been seriously lifting? By what you wrote, I’m going to guess that you are new to this game. Few who have been lifting for years do daily max effort squats. It’s nonsense.
You are also recommending that one do Max effort Anderson squats off of pins? So a guy is supposed to take a 1m for a ride only from the bottom up? Looks like spine injury time to me. How many times did you do any of this personally and what was the results? Your writing “I think” this does that makes me believe you have little practical experience of this stuff you are spewing. Honestly dude, you sound like a guy who been lifting for 6 months. I may be totally wrong, whatever. I just think your comments are unfounded and not grounded in sound lifting priciples.

Anyways, Haldor man. Good luck with your squat. I hope you fix your issue and get back to kicking ass. [/quote]
Sorry if you took offence to my comment, I just think that he could do more than just comp. squats with light weight. It looks like you missed one of my previous posts, I never said that he should do max effort squats off the pins. You’re right, that is a stupid idea. The pin squats I’m talking about involve squatting down to the pins - below parallel- pausing for a moment and coming back up. I advised him to work up to a set of 3-5 - not to failure - and repeat. I use these in my own training, I learned this from Mike Tuchscherer. And I don’t know for sure that squatting with bands will help him stop falling backwards because I don’t have that problem myself, but considering that it helped to fix my forward lean, I THINK it could help him as well. It’s not worth a try?

[quote]punnyguy wrote:
I don’t know squat…but you’re attempting a PR? -of course you’re going to “stall” there, the weight’s (too) heavy.

Check this guy out, he’s got great form, fantastic #s, and “stalls” at the same spot you do…except he grinds through it because he’s a very, very good powerlifter:

Like I said, I don’t know squat, but your bar path looks like it’s straight up and down, I don’t know why you think you’re doing anything “wrong”.[/quote]

I also thought the rep looked fine since the bar path was straight and the torso angle was relatively constant. That sticking point is common for most raw lifters.

OP: IMO, you just need to work on getting stronger again and don’t over analyze that weak point because it is a common one.

^It looks like the edit didn’t work earlier. If you’re dying to make a change, you can either sit back to use more hip strength like StrengthDawg suggested or use Oly shoes to get more quad drive out of the hole. I had the same problem of getting stuck at that point and feeling like I had no drive when I used chucks in the past. It helped to either sit back more or use Oly shoes and have my knees more forward. I’m sticking with the latter for the time being. It’s just preference and as long as you feel like you have a fighting chance to get the weight up then you’re probably fine. I had zero horsepower in that position in the past, lol.

[quote]StrengthDawg wrote:

[quote]chris_ottawa wrote:

[quote]StrengthDawg wrote:
FWIW, I would quit considering pin squats or chains wtc. Your form needs tweaking. You are not weak at the top, so pin & chain work will only compound your issue. Peform the full squat with lighter weights till your form is perfect. Build the muscle via accessory movements. You PC is weak which is why your doing that “twitch” / stall or hatever you want to call it. Like I said before, work on your hip hinge / strength. Quit worrying about percentages and other irrelevant and distracting stuff. It’s all mental masturbation.
[/quote]
No disrespect, but I don’t completely agree with what you are saying. It’s true that working with lighter weights could help with technical errors in some cases, but for anyone except a complete beginner you would have to do very high volume and stay far from failure (like Sheiko programs). From personal experience, I would say that perfecting your technique with lighter weights doesn’t carryover to maximal lifts. My squats used to fall apart around 90%+, but they looked good with lighter weights. What helped me was two things: daily max squatting and special exercises like I mentioned above. In the case of Sheiko and similar programs, they work because you do so many repetitions of the same movement that your body learns to do it more efficiently. You still have to check your technique because if you are doing high volume with bad form then you will only make things worse, it only works if you can maintain proper form.

About pin squats, if you do them the way I was saying (reaching depth) then they will help the bottom end, not the top. I agree that chains won’t help, but I think bands might be useful because the force you to keep your balance. One way or another, the competition lift needs to be the basis of your training and not variations, they can help but they don’t replace it.

I realize that this is a bit of a controversial topic because everyone seems to have their own ideas of how to fix technical errors so I will start another thread where we can argue about that.[/quote]

So your advice to the OP is that you don’t agree with what I’m tossing out there?

May I ask how long you have been seriously lifting? By what you wrote, I’m going to guess that you are new to this game. Few who have been lifting for years do daily max effort squats. It’s nonsense.
You are also recommending that one do Max effort Anderson squats off of pins? So a guy is supposed to take a 1m for a ride only from the bottom up? Looks like spine injury time to me. How many times did you do any of this personally and what was the results? Your writing “I think” this does that makes me believe you have little practical experience of this stuff you are spewing. Honestly dude, you sound like a guy who been lifting for 6 months. I may be totally wrong, whatever. I just think your comments are unfounded and not grounded in sound lifting priciples.

Anyways, Haldor man. Good luck with your squat. I hope you fix your issue and get back to kicking ass. [/quote]

You mean the way you did to my comments? I don’t usually get involved in internet arguments anymore but if you’re going to go around telling people their opinion is wrong, than don’t get all pissed when other people do the same to you. There are more than one way to do things, and rather than having people explain why they suggested it; you just say they are flat out wrong. Shit like this is why it takes new ideas so long to come out. The second something different is suggested, it’s shot down under the premise “How long have you been lifting”. Maybe you should let the OP decide what he does and does not want to try, and learn what actually helps him correct his problems.

For instance when I said chain squats, it wasn’t to address an upper back weakness, it was picked to help him both develop the correct positional strength as well as the ability to apply explode out of the hole in the correct position without falling forward. I know because I have done them. I did everything I suggested and you know what, It worked for me and that is why I was comfortable enough to recommend them.

More over, you have no idea what the OP’s learning curve to technique fixes are and what exercises will end up helping him the most.That’s why guys swear by different “money” exercises that they usually admit they overlooked.

[quote]kjmont wrote:
You mean the way you did to my comments?

For instance when I said chain squats, it wasn’t to address an upper back weakness, it was picked to help him both develop the correct positional strength as well as the ability to apply explode out of the hole in the correct position without falling forward. I know because I have done them. I did everything I suggested and you know what, It worked for me and that is why I was comfortable enough to recommend them.

More over, you have no idea what the OP’s learning curve to technique fixes are and what exercises will end up helping him the most.That’s why guys swear by different “money” exercises that they usually admit they overlooked.
[/quote]

UMMMM, WTF are you talking about homie? My reply was to Haldor.

[quote]Haldor wrote:
I am thinking of doing pin squats with chains. What is your take on this?

My reasoning is that I’m weak within an angle of about 20Ã???Ã??Ã?° between parallel and 70Ã???Ã??Ã?°. So If I set the pins at parallel (or just below) I will start at my sticking point and that will help me solidify my position for when I drift backwards and the chains will help the weight get heavier specifically in that 20Ã???Ã??Ã?° angle. Thoughts?[/quote]

Chains are bad ass and I use them all the time because I lift geared. I don’t think it’ll fix the OPS specific issue with that drift back. That’s PC weakness and there are many better ways of improving that IMO You’ve given advice and so have I. Now Haldor has to try or decide what he thinks will help him. Why the fuck would I call you out? Come on dude…

FWIW, go ask Wendler or many of the other coaches about using chains, they usually recommend, for the raw lifter, not using them. They do not benefit the natural strength curve of ones lift.

Again, do chains help some folks, YES. Do they not work for others, YES. Again, I do not believe chains, that HE was considering using, will directly fix the OPS PC strength issue and I replied as such. This has nothing to do with you.

[quote]StrengthDawg wrote:

[quote]kjmont wrote:
You mean the way you did to my comments?

For instance when I said chain squats, it wasn’t to address an upper back weakness, it was picked to help him both develop the correct positional strength as well as the ability to apply explode out of the hole in the correct position without falling forward. I know because I have done them. I did everything I suggested and you know what, It worked for me and that is why I was comfortable enough to recommend them.

More over, you have no idea what the OP’s learning curve to technique fixes are and what exercises will end up helping him the most.That’s why guys swear by different “money” exercises that they usually admit they overlooked.
[/quote]

UMMMM, WTF are you talking about homie? My reply was to Haldor.

[quote]Haldor wrote:
I am thinking of doing pin squats with chains. What is your take on this?

My reasoning is that I’m weak within an angle of about 20Ã???Ã???Ã??Ã?° between parallel and 70Ã???Ã???Ã??Ã?°. So If I set the pins at parallel (or just below) I will start at my sticking point and that will help me solidify my position for when I drift backwards and the chains will help the weight get heavier specifically in that 20Ã???Ã???Ã??Ã?° angle. Thoughts?[/quote]

Chains are bad ass and I use them all the time because I lift geared. I don’t think it’ll fix the OPS specific issue with that drift back. That’s PC weakness and there are many better ways of improving that IMO You’ve given advice and so have I. Now Haldor has to try or decide what he thinks will help him. Why the fuck would I call you out? Come on dude…

FWIW, go ask Wendler or many of the other coaches about using chains, they usually recommend, for the raw lifter, not using them. They do not benefit the natural strength curve of ones lift.

Again, do chains help some folks, YES. Do they not work for others, YES. Again, I do not believe chains, that HE was considering using, will directly fix the OPS PC strength issue and I replied as such. This has nothing to do with you. [/quote]

I know your response wasn’t to me and to chris_ottawa, but you were discussing some of the things I said. Than attacked him saying what you said. I have no problem with people who disagree but do it in a respectful manner and don’t go siting coaches to prove you’re right, I can do that too.

Go look up Chris Duffin and Matt Wenning, two world record holders in BOTH raw and geared. Both have been competing in the first lately and STILL rely heavily on chain movements.

No problem with you or your advice, just respect other people enough to have theirs. Big AND small.

Look Kj, I hang out on forums that when a guy give BS advice they get fucking BANNED because the advice given has the potential to get fuckers killed. (Military & tactical shit) Folks better have real world experience and facts. Dudes who say shit like “I think” get shut the fuck down quick by some “hard pipe hittin niggaz”. Like I said, this ain’t got shit to do with you.

Do you think you are the first guy to talk about chains? NO. Maybe read the thread again. HE called ME out and countered with some bullshit but whatever. I dont know why you feel the need to butt into this convo. I’m done with this shit. Good luck in your lifting career in 20 years you’ll be where I’m at and have a different perspective on things and you’ll be the old fuck trying to keep the young guys on the path.

[quote]StrengthDawg wrote:
Look Kj, I hang out on forums that when a guy give BS advice they get fucking BANNED because the advice given has the potential to get fuckers killed. (Military & tactical shit) Folks better have real world experience and facts. Dudes who say shit like “I think” get shut the fuck down quick by some “hard pipe hittin niggaz”. Like I said, this ain’t got shit to do with you.

Do you think you are the first guy to talk about chains? NO. Maybe read the thread again. HE called ME out and countered with some bullshit but whatever. I dont know why you feel the need to butt into this convo. I’m done with this shit. Good luck in your lifting career in 20 years you’ll be where I’m at and have a different perspective on things and you’ll be the old fuck trying to keep the young guys on the path. [/quote]

Alright guy, have a good one.

[quote]StrengthDawg wrote:
Look Kj, I hang out on forums that when a guy give BS advice they get fucking BANNED because the advice given has the potential to get fuckers killed. (Military & tactical shit) Folks better have real world experience and facts. Dudes who say shit like “I think” get shut the fuck down quick by some “hard pipe hittin niggaz”. Like I said, this ain’t got shit to do with you.

Do you think you are the first guy to talk about chains? NO. Maybe read the thread again. HE called ME out and countered with some bullshit but whatever. I dont know why you feel the need to butt into this convo. I’m done with this shit. Good luck in your lifting career in 20 years you’ll be where I’m at and have a different perspective on things and you’ll be the old fuck trying to keep the young guys on the path. [/quote]

“hard pipe hittin niggaz” = crackheads.
“Hittin the pipe” means you are smoking crack.

If you don’t like me saying “I think” because YOU THINK I don’t know what I’m talking about, maybe you need to check yourself before you go and use lines from some old movie.
“Folks better have real world experience and facts.” So, how long have you been smoking crack?

I don’t see why you are so upset over my initial comment, I wasn’t “calling you out”, I was trying to respectfully disagree with your comment but you took things to another level. And you’re still talking about me. For an old school multi ply lifter who’s into “Military & tactical shit”, you’re very sensitive.

And since I didn’t answer all of your question earlier, I have been lifting weights for over 10 years. I was mostly into general strength and fitness training before but for the last year my focus has been strictly on powerlifting. I might not have as much experience as you but that doesn’t mean that I don’t know anything. I know enough to know that lifting light weights doesn’t help your technique with maximal attempts. Your advice was vague at best.

Maybe we should ask Jim Wendler what he thinks about guys who ask questions like “well how long have you been lifting, huh?” or “oh yeah, well how much can you lift?”. I think that’s what he calls a “pecker checker”!

Well then.

Um.

After doing pin squats:

First thing that happens off the pins? Hips drift up while the bar barely moves.

Well, that’s an exaggeration, but the hips definitely are going up and back before the bar goes up.

I really had to focus on keeping everything going up at the same time, 60% was kicking my ass.

I could really feel my sticking point off the pins, so keeping those in the program, hopefully they don’t effect my recovery, but I’ll only be doing them after my main squat sets so progress should be made.

Thanks again for the input!

[quote]chris_ottawa wrote:
“hard pipe hittin niggaz” = crackheads.
“Hittin the pipe” means you are smoking crack.[/quote]

umm, again you aren’t “in the know” but I won’t hold that against you.

[quote]chris_ottawa wrote:

For an old school multi ply lifter who’s into “Military & tactical shit”, you’re very sensitive…[/quote]

Negative. I took ZERO issue with what you wrote. You however came back quoting me and I rebutted. You keep carping on about “light weight”. I never said light I said lighter. One cannot perform very many near maximal lifts so they would not get much opportunity to get the reps in required to relearn the movement patters and to “unlearn” bad habits. You CAN do this with lighter weights. By “lighter” I Mean sets of 3-5 in the 80-90% 1RM range. Squat variations can sometimes correct technical deficiencies but performing the full squat generally is much better. I have given my 2 cents to HALDOR in regards to specific things that I have seen in his videos. He doesn’t need a total makeover. He has issue with driving the hips thru, which is a fuction of glute strength and I suggested accessory movements to help with that.
Look, I can appreciate that you have got the iron bug. It’s obvious that you are new to the PL game and this is may first forum discussing Pl and you want everyone to know how much you love this stuff. You’re a reformed gym rat all jazzed about it. Good for you, I love guys like you. Welcome to The Dark Side. I’ve seen your other posts and you’re trying to learn the game. Keep in mind there are those of us who have been in the game a long time and while some toss out theory and all that stuff what often works for 98% of the people is going back to basics. Your zeal is intoxicating and your name is all over this board. I’ve seen a thousand guys like you pop in and out of this forum and many like it. Give your advice and let the OP decide if it will work for him / her and don’t quote others and say you disagree with them. It ads nothing to the convo but starts shit.

Good luck with your lifting.

SD