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Leg press VS Bench press

  1. Apr 18, 2012 #1
    I heard peoples such as powerlifters and bodybuilders, are always can leg press more than they can bench press and other forms of exercises. For example the record for the leg press is 2300 pounds by bodybuilder Ronnie Coleman, compared to the bench press record at 1250 pound. Here is the link showed Ronnie Coleman doing the 2300 pound leg press. http://www.youtube.com/watch?v=TSWbeWJyPcQ

    So that's mean that his legs are stronger than his arms? I don't think so. From what I've read from most websites, people can press heavier weights on leg press comparing to other exercises because the leg press stabilizes the lifter and moves weights in a direction that is not vertical. If we are going to using some physics, actually the angle determines how much each of these is. If the angle is 0 and the weight is sitting on a flat surface, the surface is providing all the force to keep it there when you disengage the locks holding the weight (how much force you need to push it across the surface depends on other stuff like friction which I won't get into here). If the angle is 90, that means the weight is hanging vertically, and that when you disengage the locks, you are going to be the only thing providing force to keep the weight off the ground.

    Therefore, using some formulas, leg pressing 2300 pounds at 45 degrees really means that you're only pushing:

    2300*sin45= ~1626 pounds

    But I'm not sure if the angle of the leg press sled that Ronnie Coleman using is 45 degree, it's look like 40-30. And it seems that his range of motion is limited. Can someone give a more detailed explanation about this?
     
    Last edited: Apr 18, 2012
  2. jcsd
  3. Apr 18, 2012 #2
    You are correct in thinking that using a machine such as a leg press to lift 2300 pounds, doesn't necessarily mean he's actually exerting 2300 pounds of force. With a leg press probably simple trigonometry gives you most of the story, but also other factors are involved, such as not having to worry about stability and such compared to when you use free-weights (as you stated).

    That said, I'm pretty sure that legs are nevertheless stronger than arms.

    But...yeah, seems that you have it pretty much figured out. What detailed explanation are you looking for? Or you just want confirmation?
     
  4. Apr 18, 2012 #3
    So actually Ronnie Coleman doesn't push 2300 pound right? If you compared leg press to squat, instead of bench press, actually squat is a more suitable exercises to test your leg strength. Because when you squat you have to move a portion of your own body weight. If you squat 275, and weigh 175 , then you are actually lifting 450 lbs. (no, you can't claim you squat 450, however). On a 45 degree seated leg press, you are not lifting the entire weight you have loaded, nor are you lifting your body weight. Also, in order to compare the leg muscle and arm muscle groups, we should think of a way to measure their ability to do work, in this case, an exercise that is similar to each other. Standing shoulder press (aka military press) are analogous to squats. They are each exercises that move weight away from the middle of the body in each direction (upward and downward). An average male who doesn't workout at all, weighing 150 lbs, 6' tall, could probably shoulder press 40 lbs maybe once, whereas he could probably do a squat (with no weights) maybe 10-30 times.

    Btw, I got this comment from an other forum. Do you think that this guy is true?
    'THAT driveway your talking about is 45 degree steep. Honda (like every other car) have wheels, thus rolling. That machine has NO inertia.'
    How can the leg press machine have no inertia?
     
    Last edited: Apr 18, 2012
  5. Apr 18, 2012 #4

    russ_watters

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    A quick google puts the squat record at 1260 lb and the bench press at 1075. Two other factors further widen the disparity:

    -With a squat you are also lifting your torso.
    -Your legs are longer than your arms, so you generate more energy with the squat. If that matters depends on the precise focus of the question.
     
  6. Apr 18, 2012 #5

    sophiecentaur

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    It seems to me that there is not a lot of point in trying to 'compare' one form of exercise with another. If you are training for some kind of activity then you would presumably choose the Gym exercise that mostly replicates that activity so as to develop the appropriate improved and relevant strength or power.
    I have to ask just how relevant it is to say that one guy can produce one force on one exercise whilst another guy can produce another force on another exercise. Is a concert pianist 'better' than a concert violinist? Some people are just 'really strong' and can score well in 'strongest man' competitions which examine a whole range of strengths and toughness. They would often do worse in a particular exercise than someone who is notionally not as strong overall.
    This idea of relating physical exercise to Physics keeps being raised but it is a much more tenuous link than the 'believers' in this notion realise. If it's not studied in extreme depth, it runs the risk of becoming pseudo Science. And, for some people, it really is just that.
     
  7. Apr 18, 2012 #6
    FInally, an area I have knowledge. First,

    SIZE.

    Starting Strength, 2nd Edition by Mark Rippetoe on page 83 explains the notion of cross-sectional area. He elaborates, "a third class lever exhibits greater efficiency the more closely the force is perpendicular to the resistance, no matter what the exercise."

    He then presents diagams further explaining the process in both the squat and the bench press. In short, "[the efficiency] of levers is the primary source of the advantages to be obtained by increased bodyweight."

    We all know (at least barbell enthusiasts) legs are much more massive, or at the very least have greater cross-sectional area than the arms/chest system.

    Here is a primer on the most common barbell sports for perspective. The link will also make obvious legs are bigger than arms. http://www.t-nation.com/free_online...ng_versus_powerlifting_which_is_right_for_you

    Please note: These barbell sports (powerlifting and weightlifting) are NOT Bodybuilding. Bodybuilding is a different pursuit all together and very successfully alters the standard person's idea of barbells.

    SPORT JARGON.

    As has been dully mentioned before this post, a better comparison will be the squat and the bench press. "But wait" you may say: "The bench press is still 1000s pounds and according to some sources is stronger heavier than a squat!"

    Well, here is a history lesson. The reason you found those numbers is they aren't the correct values for our comparison.

    This is CRITICAL. In the sport of powerlifting, there are 'geared' and 'raw' divisions. Most simply put, the gear division also for material assistance in the toughest part of the all lifts (the bottom). Consequently, competitors can push the easiest part (the lockout) much much much harder, due in part to a decreased range of 'difficult' motion.

    'Raw' divisons present a much better picture of reality. Here, the bench records range from 680-715 and the squat is around 950-990 lbs.

    In this sport, it is exceedingly difficult to pin down an exact number because nothing is publicized much due to a lack of general popularity and because the sport has MANY governing bodies, unlike weightlifting.

    What does this mean? There is an average 300 lbs disparity between lifts. This is absolutely massive in elite levels of lifting. In fact, even the 'geared' records 1000ish for bench and 1250ish for the squat still show something is a pretty big disparity.

    A another final point I'd like to mention is Russ_Walters mention of the torso. In all these lifts, the lifters are at least 275 lbs so their legs have to lift an addition 100+ lbs.

    FINALLY

    Thanks for showing interest in the sport! It is a great activity, hopefully I helped to clear somethings up. Many people have numerous misconceptions about weightlifting and powerlifting.
     
  8. Apr 18, 2012 #7
    Okay, but if someone can leg press more than they can bench press, is it mean that his legs are always stronger than his arms? I know leg muscles are generally larger than the muscles of the arms but sometime, I think that our arms can become stronger than the muscles of the lower body despite the legs always support our body. What if we compare the bench press to the leg press? What's the physics behind these?
     
  9. Apr 18, 2012 #8

    russ_watters

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    What, have you been lurking but not posting??!?!?! Uncool! :tongue:

    Welcome to PF!

    I had no idea. Thanks for the input/contribution. Don't be a stranger!
     
  10. Apr 18, 2012 #9

    russ_watters

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    Clearly, that piece of information is not on its own enough to determine the answer. But most humans are pretty much the same, so using other information, we can conclude that generally the legs are significantly stronger than the arms for lifting.
    Certainly. In particular, after suffering an injury (temporary or permanent), leg muscles can atrophy a shocking amount in a shockingly short time. In people who have had such injuries, I'm sure it is possible that their arms are stronger.
    Um....we just did that? Did you mean to say something else? In any case, why not try to compare the most similar types of exercises for clarity?
     
  11. Apr 18, 2012 #10
    Yeah you're right maybe there are no definite and convincing answers to these. But I know legs are supposed to be stronger than arms, only in general sense.

    Of course their arms are gonna be stronger because their legs are crippled. Actually I mean maybe is it possible for someone's arms become stronger than their legs without their legs being injured or crippled. Perhaps someone who have mutated gene will have stronger arms than their legs, but who knows?

    Sorry I didn't realised that we already discussed this earlier, hahaha :biggrin:
     
    Last edited: Apr 18, 2012
  12. Apr 18, 2012 #11
    Russ's answer pretty much answers your question Munyit. Legs can be weaker than arms.

    You say, "Actually I mean maybe is it possible for someone's arms become stronger than their legs without their legs being injured or crippled."

    The answer is yes. One simply trains their upper body and neglects their lower body. I've meet people with bench presses stronger than their squat. True, genetics could make you a bench press freak but they aren't out-lifting their squat if they trained both properly.

    I think I may be missing the point of your question. Do you want your arms to be stronger than your legs?

    -- Also thanks for the Greeting. Love the website, just didn't have anything to contribute until now.
     
  13. Apr 18, 2012 #12
    I don't want my arms to be stronger than my legs, certainly. I'm more interested if my upper body and lower body have the same strength. I think the muscles of the arms may have the same strength as the leg muscles, if someone trained their upper body and lower body properly. By the way, I recalled that there are no 'strongest' muscles in our body actually, because muscles never work individually. People always said that the leg muscles are the strongest, if not one of the strongest muscles in human body, but some said the masseter, some said heart and some said even tongue. I think arm muscles can be as strong as the all muscles in human body.
     
    Last edited: Apr 19, 2012
  14. Apr 19, 2012 #13
    Just my thought, but I am of the opinion that if you train yourself to have arms just as strong as legs, you will tend to look like a freak (especially if you wear shorts), as this is arguably not the "natural state" of a human being.
     
  15. Jul 15, 2012 #14
    AHH I know I am kind of late on this but it all goes down to what body part you train and for how long , in fact not just that but also which lift in particular. In my case , my upper body outperforms lower one , however my deadlift was doing terrific progress prior the injury yet my squat was pathetic.

    So the key is , yes legs are large muscles hence greater chance of creating hormonal imbalance BUT intensity matters . WL has many disciplines one of which is power-lifting.
    I wish to find scientific literature on these compound lifts mentioned but so far google has revealed nothing :(
    If anyone is aware of it , post the link or source please. I am interested into the physics of it , which I must admit is basic for an undergraduate , lol.
    Thanks !
     
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