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# The Mechanics of the Pull-Up (and Why Women Can Absolutely Do Them)

As a former rock climbing instructor, I have seen many contorted struggles to raise a chin over a bar. The pull-up for many is a sort of “test piece” of fitness—an indicator of athletic prowess—that is a cornerstone of a good workout (or a good showing-off). Most either never try a pull-up after they leave high school gym class, or fail, but many succeed, especially women.

Long-time rock climber Sarah Brengosz pulls hard.

You can do yoga all day, you can run or bike or swim, but a pull-up will still be hard. It’s not that you have to be a juiced-up “lunk” to do one; it’s a matter of physics. In physics, as in a pull-up, you need to do work to affect one system or another. Work is described as the energy needed to move some mass over some distance. For a pull-up, the work that your arms and back need to do is a function of your mass and how far you need to move it upwards to get your chin over the bar.

The equation below describes the struggle:

A few things pop right out of the equation. If you have more mass fighting Earth’s gravity, or if you have further to move, the work you need to do quickly increases. But for its simplicity, the equation also reveals a few things about why pull-ups are so hard for so many people.

A lanky individual myself, I happen to have a decent balance between mass and arm length.

First, muscle men tend to flounder with the pull-up because of their mass. The heavier you are, the more work is required to move that bulk. I have seen many first-dates come to a screeching halt at the climbing gym after the would-be impresser fails to pull himself up six inches. Though rippled with muscle, they “have nothing to do with all their strength,” as the Joker would say.

Second, arm length matters. Take two people of the same mass, say 100 kilograms. If one person has to contract half a meter of arm to complete a pull-up, he or she is exerting 490 Joules of energy. If the other person, quite a lanky individual, has to pull through one full meter, he or she exerts 981 Joules of energy—the same amount released by a quarter gram of TNT. With just a moderate variability in arm length among us, pull-ups become harder or easier.

Lastly, gravity is important for the pull-up. I’d guess that no one will do a pull-up on another planet for at least a few decades, but suffice to say that a pull-up on Mars—with only 38% of Earth’s gravity—would be much easier.

So there is a trade-off. Especially in rock climbing, you want to be light enough to move gracefully yet powerful enough to handle the hard stuff. Being larger with shorter arms works, as does lanky and light. Both combinations fit most of the professional rock climbers that you will see, or the people at the local gym proud enough to pull-up.

Through this whole discussion, I’d bet that your mental image was of a man doing a pull-up; I want to change that.

Why Women Can Do Pull-Ups, A Lot of Them

Last year, in an article titled “Why Women Can’t Do Pull-Ups,” Tara Parker-Pope at the Well blog commented on a study which found that after training regular women three days a week for three months, almost none of the women could complete a pull-up. She then generalized the study out to all women, citing grade school fitness tests to keep would-be pull-uppers on the ground.

Tell Sarah that she can’t do a pull-up, I dare you.

Two immediate problems with the study are time and number. The study trained 17 women over three months to get the result reported in the Well. Any science writer will tell you that generalizing to half the world’s population from 17 individuals is a no-no. But more importantly, three months is simply not enough time for everyone. As I said before, and as the Well apparently knows, pull-ups are hard. In my experience as a rock climbing instructor, I have known men and women alike who couldn’t do a pull-up after a whole year of training who have eventually pulled one off.

So, the only thing that the study really says is that these women needed more than three months of training to do a pull-up. That is a perfectly reasonable conclusion, but I see no logical way to get from that to “women cannot do pull-ups.” And my guess is that if their sample included more athletic women, like Sarah featured in the photos above, their results would be different. Sarah isn’t a “freak” bucking the trend; she’s a dedicated woman climber (who has never specifically trained to do pull-ups) and the exception that disproves the rule. It’s not that women can’t do pull-ups, it’s that almost nobody can consistently do one without training, the required musculature, or that careful balance between mass and arm length.

Some will argue that women have lower centers of gravity (because women tend to store more fat around the buttocks and hips), and therefore are at some disadvantage. Again, physics tells us otherwise. Unless that woman has a significantly different mass or arm length to make a pull-up more difficult, her center of gravity moves the same distance vertically regardless of where it is. This is another attack on the female form that falls flat.

Despite the criticisms, it does seem like it is easier for men to do pull-ups than it is for women. Indeed, if we put the average heights and weights of American men and women into our equation, women have less physical work to do than men. So if it’s not because of center of gravity or arm length or weight, what is it?

It comes down to musculature. Men do in fact tend to have more muscle in their upper bodies ripe for the bulging. More muscle makes the work easier. But this advantage over women is fleeting. It may take a woman more time to develop the musculature required, but once developed, those muscles function like any males’. Overcoming this steep curve is no easy task. I suspect that because few among us have the time or effort available to significantly change our musculature, our bias against women doing pull-ups is not because they actually can’t do them, but because of men’s fortunate physiology.

Concluding that women can’t do pull-ups has a more sinister effect. I have trained many women who outright refuse to even try one. Women already believe that a pull-up is out of reach before their hands touch the bar. How many able women are discriminated against by this cultural truism?

Pealing back the bias, to me it’s obvious: if a woman isn’t culturally dissuaded from trying, she is absolutely able to pull up and hit her head against the glass ceiling, smashing through it.

It is easy to buy into the cultural stereotype of “the gentle sex,” but it simply isn’t true. If you put a woman in a situation where she has to effectively do pull-ups all the time, as in rock climbing, she will learn to do one. Of course I am biased here, but rock climbing is the perfect counterpoint to the “women can’t do pull-ups” truism. The same kind of glass ceiling is present in the sciences, where a significant bias against women festers. Imagine how many women could excel in science if not for the pernicious myth that science and math are a man’s game. Likewise, fitness isn’t defined by the Arnold Schwarzeneggers of the world. If you give women a chance to pull past the bias and the bullshit, they often do.

Images: All images provided by author

About the Author: Kyle Hill is a freelance science writer and communicator who specializes in finding the secret science in your favorite fandom. Follow on Twitter @Sci_Phile.

The views expressed are those of the author and are not necessarily those of Scientific American.

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1. 1. NicholasTesla 11:09 am 03/14/2013

I am not ashamed to admit that despite my bench of 350#, my dead-lift of 300#, and my squat of 250#…I cannot do a single pull up. I’ve got long arms and lots of mass.

2. 2. phalaris 12:48 pm 03/14/2013

I’m not sure that seeing energy as the limiting factor is the correct way to look at it. After all, the energy expended in a pull-up can’t be that different from the energy used to go up a couple of stairs.

I’d guess it’s more a question of the maximum force which can be exerted by the relevant muscles at a certain limb angle.

And by the way, the fact that some (or even many) women can be trained to do this, doesn’t mean that the average woman has the same potentiality as the average man in this discipline. You seem to admit that yourself higher up, before you get into the fashionable “we’re all completely the same mode”.

3. 3. K.Hill 1:14 pm 03/14/2013

Phalaris,

I see your point with the energy argument, which is why I stated in the article that required work doesn’t differ all that much for the average man and woman. It comes down to musculature.

The article that I am taking issue with stated that “women can’t do pull ups.” Whether or not men and women have the same potential (I mention this above), I believe I make the case that “can’t” is the wrong word (whether is it “fashionable” or not).

4. 4. phalaris 2:02 pm 03/14/2013

K.Hill
Thanks for the clarification. This particular man can’t get anywhere near doing a pull-up, and I’m full of admiration and envy for the women (and men) who can.

Since posting I can’t help ruminating on the forces and muscles involved, but it’s a complicated physiological question, I guess. I do wonder if it’s easier for the muscles to exert force when pushing than pulling – after all push-ups are quite a bit easier.

5. 5. thedavster 2:57 pm 03/14/2013

It has nothing to do with energy. Anyone can lift low weights repetitively exerting a fairly consistent amount of force with their muscles (in this case the ones use to do pull ups) and use much more energy as I think someone mentioned on the website comments. It is to do with the maximum force your muscles can exert to maintain enough torque to counteract gravity at your elbow joint therefore longer arms make it harder, nothing to do with the vertical height.

I think COM does make a difference – Lemme draw up a shitty paint diagram of why http://i.imgur.com/MmuzRRb.jpg , as you can see lower COM increases the distance D, (cba to derive this whilst defining additional lengths etc. this paint drawing took me like 10 minutes).

The female person mentioned in the article is irrelevant anecdotal evidence, I’ll forgive this as it’s an article which is supposed to be entertaining and not a factual journal entry or something.

She’s not a “freak” I agree but ITO if you plotted the bell curve of female pull up ability she is definitely in the shallow end of the curve.

Saying they could have added more females with better pull up ability to the study is pretty stupid, what they should have done is increased their sample sized, picked girls randomly and used a control group.

6. 6. K.Hill 3:14 pm 03/14/2013

thedavster,

I disagree that it has nothing to do with energy. Someone who can row 200 pounds (using similar muscles), is at a disadvantage if they are heavy or have longer arms. Your example of low weights is considering the work done to do an exercise repetitively, but you can’t add all of that together and say that therefore more work is done. If you consider one rep with a low weight and one rep of a pull-up, the work equation above still describes a pull-up as more strenuous.

Also, I explain why your COM argument doesn’t hold. As long as women and men don’t have significantly different average arm lengths (they don’t), it doesn’t matter where the COM is, it will move the same distance regardless of its position.

I used Sarah as an anecdote because the article needed a face, and I would be remiss if I didn’t refute the idea of “women can’t do pull-ups” with at least one example.

But the other side of your argument about me using an anecdote means that you can’t reasonably assume Sarah’s pull-up ability (her position in the bell curve), without knowing her personally.

Lastly, of course I was not suggesting that using only a bunch of women who can do pull-ups should constitute a study. I merely pointed out that the study’s conclusion that I had a problem with went far beyond the data. I argued that the variability of women’s ability was not captured. In other words, if musculature really is the problem, then even if you pick girls randomly (with a control group), you still won’t get accurate results if your study includes too few women for too short a time period.

7. 7. hanmeng 3:53 pm 03/14/2013

“Any science writer will tell you that generalizing to half the world’s population from 17 individuals is a no-no. But more importantly, three months is simply not enough time for everyone.” And yet that’s the kind of “science” that usually gets reported.

8. 8. KipHansen 5:02 pm 03/14/2013

There are always exceptions to a generality-a general rule of thumb.

Providing the exception does not refute the generality, but that is the type of “debunking” that is usually done.

TPP was providing general information for a mass market readership — so that the majority of women who find they can’t do something “as simple as a pull up” don’t freak out and think they’re hopeless. Instead, they find that this inability is not unusual at all – and their boyfriend, who gloats over it, is an idiot.

9. 9. OBoud 5:04 pm 03/14/2013

Your friend Sarah puts a fine face on the fact that women can do push-ups. Tell me though; can she do as many as you can? Does it matter that she can do any? Despite the title, the Times piece clearly cites that, “4 of the 17 women succeeded in performing a single pull-up.” So was this blog post necessary?

My gym has a weekly competition to see who can do the longest plank or wall-sit or, yes, the most pull-ups. The “challenge” is separated by sex and so the chalk board has the top competitors for men and women. During the week of pull-ups the men’s side was breaking the mid-forties while the woman’s side had a goose-egg. Anecdotes don’t matter except to disprove something that’s taken as a statement of fact. A headline isn’t a statement of fact; it is something an editor throws on an article to entice a reader. I’m willing to bet you didn’t bother to track down the actual paper before tearing down their methodology. Unfortunately this is typical of a science writer.

10. 10. castelle 5:12 pm 03/14/2013

I’m a female engineer and climber who can certainly do a pull-up. Thanks for writing this article. If I lived in Milwaukee, I’d buy you a beer.

11. 11. larkalt 5:33 pm 03/14/2013

I’m a woman, and I have over and over trained until I could do a chinup. Similar to pullups, altho I’ve heard that pullups are harder.
I train to do a chinup by doing it in stages at first. I do it in stages by having the bar low so I can rest between stages.
I’ve even done chinups with weights on my ankles.
I weigh about 120 pounds, it helps of course to not have much body fat. I’m not particularly athletically talented, and I’m in my 50s.
But I do like being strong. I’d love to be able to brachiate on those bars that are like horizontal ladders that are in children’s playgrounds. But my hands aren’t strong enough for that.
A lot of it is social expectations of women. I’ve lifted weights a lot, and it’s amazing how many women don’t lift big weights because they don’t want to get big muscles! They think having big muscles will make them unattractive to guys, I guess. So they lift little weights many times, to get “toned up”. Not me, I lift for strength!

12. 12. Molecule 8:20 pm 03/14/2013

We got to take into account the lever ratios too :
http://en.wikipedia.org/wiki/Lever
+ other things like : muscle section, type of fibers, nerves power + arm length does not count for the strength, but only for the work [joule].

But the lever ratios resulting from joins, bones and tendons is the less studied part, it certainly change between people and can certainly change during childhood depending on the environment and may depend on sex too!

13. 13. Bobobo 12:13 am 03/15/2013

I think the writer has good intentions, but I’m appalled that this is considered science in any way. No citations anywhere about muscle growth, and the physics concepts are somewhat misguided. Can anyone submit an article?

If his definition of Work were correct, he’d have wound up showing that the total force of your two arms pulling upward must equal/exceed your weight pulling downward. And wow, that makes perfect sense! Work = FORCE x distance. Work does not equal mass x distance.

Considering Energy with regard to pull-ups is perfectly valid, but the author stopped just short of the punch line, and this is what thedavster was probably thinking in his/her comment. What’s critical for most feats of strength is the amount of energy your muscles can deliver per time or say one repetition. In physics this is called Power. If your arms can supply, in one go, the energy required to raise your center of mass the necessary height, then you’ll do a pull-up! If it’s less, you’ll come short. So pull-ups are easiest for people with high arm power to mass ratio.

In short, women who yearn to do pull-ups should aim for strong arms and low weight (obvious, right?), and they should dismiss the myth that women can’t do pull-ups altogether.

14. 14. mbraynard 1:41 am 03/15/2013

The author doesn’t know what he’s talking about.

Training to do pull-ups for men or women is about synaptic facilitation. It’s the same reason 150 lbs guy can squat 450 lbs.

It’s about conditioning muscle more than just building it or losing body fat, and developing motor neurons.

I went from being able to do zero pull-ups to doing 20 in a relatively short time, and I did it by… doing pull-ups.

Here is how to do a pull-up.

Most gyms have an assisted pull-up device. Using these are key. Start with enough ‘assistance’ so you can do 20 pull-ups. It may be just 10 lbs less than your body weight. Wait 2 minutes. Then drop the assistance slightly so you can do 15. Then drop it again and do 10. Finally 5.

Do this three-four times a week and each week try to reduce the amount of assistance slightly.

This way, you are getting closer to doing a pullup and can SEE that you are getting closer as the weights gradually drop.

Finally, when you can do 10 with only 50% body weight assistance, try doing just one pullup, and you probably will.

How do do Multiple pull-ups:
Follow the above regime, but add one body-weight pull-up at the beginning of the routine, and gradually add another every two weeks (if you can).

When you can do 5 unassisted, get a pull-up bar in your house (those portable ones are pretty good; they require no installation) and do a sub-maximal number (less than your maximum) every day and every one or two weeks add another.

Again, it’s about conditioning/synaptic facilitation. Women will have a harder time because that’s just how they are built, but if they keep this program up, they’ll be able to do more than most men can, which is zero.

15. 15. Geopelia 7:54 am 03/15/2013

Are any women capable of doing those Gymnastic exercises on the Rings? Only men seem to do them at the Olympics.

16. 16. amplify 9:28 am 03/15/2013

As a man I can do a pull up, just not a lot of them. I agree with Kyle that the pull up is viewed as the pinacle fitness test.

As for women being able to do pull ups, I think it’s the same reason that men don’t/ can’t do them. It has the perception of being hard but like anything, train for it and you can do it. After reading this article, I’m think of re-evaluating my ability to do pull ups. Might be fun goal to go after.

17. 17. jbairddo 10:40 am 03/15/2013

No where does this talk about the attachment of the muscle tendon. The size of the tendon, the presence of muscle dysfunction and most important is training the correct muscles for the task. Oh and since the muscle most important for this is the Latissimus dorsi the per cent of slow vs fast twitch muscle fibers and whether or not you train them correctly for the fiber types is critical. narrow vs wide grip is also a critical aspect of this.
this shit is only easy if you aren’t bright enough to know all the other aspects of the problem (why is it these guys get all the grants)

18. 18. betainverse 4:25 pm 03/15/2013

As a woman who can do pullups, I would like to point out that a lot of the pullup bars at gyms have grips that are spaced so that a man would be doing a standard-width pullup, but it’s practically a wide-grip pullup for women with narrower shoulders. This honestly makes it even more difficult for women to get started doing pullups.

I also think the abs might be more involved in a pullup than we realize, and doing planks might be beneficial, especially for the transition from machine-assisted pullups to real pullups.

19. 19. K.Hill 4:27 pm 03/15/2013

Bobobo,

The other biophysical concepts you feel that I should have included I did not think were relevant to the article.

You say: “Work does not equal mass x distance.” And I agree with you. If you read the equation in the picture I provided, you will see that I have work=mass*gravity*distance. Mass*gravity is the force of gravity pulling down on you (i.e., weight). Perhaps you would consider this less “misguided”?

I did not consider power because it only muddies the waters. A weight lifter may be able to generate a large amount of power lifting a massive weight in a short amount of time. But unless that weight lifter can do the physical work I am considering in the piece (basically lifting his/her own weight up a distance), it does not matter how much energy they can generate over time. Work is the barrier here. If you can do the work to lift yourself, that’s good. If your muscles can generate enough power to do that work over a long period of time, that’s great. But the initial barrier to lifting yourself off the ground is work.

You say “power to mass ratio” is the key, but again I think you are confusing things. Power in physics is defined differently than “muscle power” that is used colloquially. You still have to do work over time to get power.

Yes, to do a pull-up, having upper-body musculature will help, I agree. But muscle size is less important than weight and arm length (as you can see in the best women rock climbers, for example).

20. 20. Bobobo 9:04 pm 03/15/2013

K. Hill, sorry, but your understanding of physics is fundamentally flawed. Run your article past any competent high school physics teacher and they will agree with me.

In your article you state “Work is described as the energy needed to move some mass over some distance.” This is NOT what work means. Mass moves distances by itself because of inertia (Newton’s first law). Your potential energy equation (m x g x d) is flawed because it replaces height with distance. Doing a pull-up sideways would be much easier than a pull-up in the normal direction, right? So it’s not simply distance that matters, but distance in the vertical direction (i.e. height). And you need a force applied over a certain distance (aka work) in order to raise your center of mass and pull your chin over the bar.

But anyone’s arms can do any amount of work. Did you know your arms are capable of doing as much work as the energy involved in the blast of an atomic bomb??? Truly, they are. But it takes a lifetime for them to do that much work. They’re not as POWERFUL as the atomic bomb, which releases a tremendous amount of energy in the blink of an eye. Your arms are comparatively weak, and lucky for the rest of us they don’t explode every time you do a pull-up.

I’m calling your bluff. You seriously ought to research more before your write articles like this for the general public to read. Your physics analysis is worse than garbage because it has the guise of science when it’s mostly made up of opinions and poorly remembered ideas from your education in engineering. And frankly, your magna cum laude in engineering must be a joke, because your article and comments show you ought to have received a B or C in physics 101.

21. 21. leecris 1:59 am 03/16/2013

Growing up, I attended a rural one-room country school with very little playground equipment: one small A-frame support with one swing and one trapeze bar, and a slide. We improvised; most of us could ‘skin a cat’ by hanging by our hands from the trapeze and then raising the feet and pushing them through the arm opening to touch the ground backward. My arms were too short. I couldn’t do that, but I could, and did, climb to the bar of the A and swing by my hands across the entire top support to the other side. My arms were strong. I could do multiple pull-ups easily, because my muscles had been accustomed to supporting and lifting my entire weight. If active girls do exercise that involves supporting and moving their entire body with their arms, pull-ups come with it. It’s a matter of opportunity and training.

22. 22. OBoud 7:31 am 03/16/2013

Bobobo, you could also point out that no net work is done when you finish a pull-up but I don’t think it would do any good.

23. 23. mamalisa 11:47 am 03/17/2013

Since a large number of female Marines will shortly be doing pull-ups to pass the PFT, I think the argument over women doing them will shortly become moot.

It is harder for women to learn to do pull-ups because, in general, women have less upper body muscle. It is certainly possible to do so: I am a 51 year old grandmother of 3 who can do 5 in a row after working a 12 hour night shift lifting and caring for patients. Could I do this a year ago? No. The hardest part of learning was not, in fact, acquiring the necessary muscle, as I could do a lat pull-down with my body weight long before I could actually pull myself up unassisted. Figuring out *how* to engage which muscle was the hard part.

24. 24. foreigngirl 4:31 pm 03/17/2013

Thank you very much Kyle for this thoroughly intelligent piece. I find it quite funny to read some of the male comments on here who sound quite chauvinistic despite trying not to be. The key problem to solve with any achievement is usually in the mind. And generalisations about women are the perfect tool for conditioning their mind so that they ‘know their place’. This has been done by men for centuries. Any woman can achieve whatever she wants to achieve – this is the main thing to remember. This is why men and women are the same. It is not a ‘fashionable’ statement. If one thinks it is a fashionable statement then one does not understand the meaning of it, one still wants to see women as slaves. I am using strong words here because people just don’t get it without strong words. The only way for men and women to be happy with each other is for both sexes to feel free and fulfilled. Despite so many changes in our societies to date we still have the ability to feel freedom and fulfillment skewed more towards men. Men who try to make women feel inferior are threatened by them, and this fear is totally irrational and unfounded (the same like any other fears that drive discrimination). Make love, not war. The true equality of sexes is in our hearts. Men will not lose out if women stop being bullied slaves, to the contrary there is a lot more for both sexes to gain from equal relationships.

25. 25. marclevesque 4:20 pm 03/18/2013

Excellent article. I enjoyed, and it’s explained very well for a general audience.

26. 26. TyInSD 11:14 am 03/19/2013

I am a female engineer. My first 31 years I could not perform a pullup. Less than a year of training, I’m up to 8. At first it felt impossible, and each rep is still difficult but somehow I get there. I’ve also gained 20 lbs, a mix of both fat and muscle, and my bf% is a few points higher than it was last year. My point being that my pullup improvements are outpacing my increasing mass, which shocks me every time I perform them. And yes I am sort of showing off when at the park and I mow them out “just for fun.” I work hard and I earned it.

27. 27. b2curious 3:26 pm 03/19/2013

I’m a 43 yr old female, just a few months past my birthday. A couple of weeks ago, I set a goal for myself that by my next birthday, I will be able to do at least one pull up. I’d been sort of working on pull ups for a year, but several months ago, my morning work outs got sacrificed in the name of sleep. About a month or so ago, I read a posting on a blog I frequent which suggested that for those of us who are chronically sleep (a stressor) deprived, rather than further stress our bodies by setting aside a chunk of time to work out (another stressor), we set a timer when we are at home, and every 10 minutes, knock out a few reps of something. Most days, I even remember to do so. I do my 2 leg assisted pull ups in one chunk, rather than a few here and there, because I have to pull out my 2-step step stool. I do them 4-6 days a week, depending on how I feel on a given day. After a month of this, I tested my ability to do a pull up and was impressed that in that short time, I’d gone from just hanging from the bar to being able to pull myself up about 3 inches.

28. 28. intelcurio 4:53 pm 03/20/2013

I am a 56 year old female and have been training for the past 15 months to do pull ups with a 57 year old female (breast cancer survivor, (masectomy and major armpit muscles missing) . After all that time I am able to do 7 pull ups, she can do 2 (amazing given that she is missing a whole muscle group under one of her arms that is key in performing a pull up) We are obsessed about pull up training, religiously training twice a week, we started our training using this web resource http://50pullups.com/ after 12 months we decided to change to this program on youtube go here http://www.youtube.com/watch?v=mRznU6pzez0
We continue to train using the youtube video menitoned above and add variation at the end of our training session by performing Arched back V Pullups go here http://www.bodybuilding.com/exercises/detail/view/name/v-bar-pullup
We continue to do our pullup training twice a week, we are not giving up, we are determined to get to 50 pull ups.
It is slow and painful, but there is nothing like that feeling when you are able to pull your self up. The pull up training has done wonders for posture and a sense of overall well being

29. 29. Diesel67 11:57 pm 03/20/2013

K. Hill -
As you said, the key is upper body muscle and men have more of it. Many women can develop the necessary muscle, and even more could if they were given a little androgen boost to correct nature’s mistake. But while chicks like Sarah give me a lift, most men find them ugly and some louts question their sexual preference out loud. Therefore, most women aren’t interested in growing the necessary muscle. Another problem is fat. Muscle lifts and fat needs to be lifted; the less of it an athlete has the better. But with food scarce for most of human history, women needed to put energy in the bank to sustain a pregnancy, hence their higher percent body fat. If a woman loses so much fat that her menses and fertility are impaired, she has a problem and so do we. You can’t have a civilization without people, and ours is not replacing itself.

30. 30. dangert4 4:37 pm 04/3/2013

Great article. I am a female in my 50′s and just got my first two pull ups ever! I have always been intrigued by chinups/pullups since I was 12 years old and my uncle brought all the nieces and nephews down to the basement to see who could do a chinup. I couldn’t do one but by the end of the summer had 7.
I had long let my chinups fade but never lost the interest and now am up to 6 chins and 2 pullups. My goal is 10 of each. It has not been easy to say the least. Patience, determination, and hard work. But especially patience.

31. 31. Shmick 11:20 pm 04/15/2013

I think you need to pull out your Physics textbook because you are making NO sense in discussing Work.

A simplified definition from Wikipedia:
“The work done by a constant force of magnitude F on a point that moves a distance d in the direction of the force is the product, W = F.d”

Now this is a simplification with respect to the forces within the body, but the total Work done ON the body against the direction of Gravity DOES equal the distance the mass has moved multiplied by the force against which it was moved, eg F(weight due to gravity)* d, or m(mass)* g(gravitational acceleration) * d

Think of it from another perspective and it becomes even more obvious, Potential Energy. By how much has the body’s PE changed? What would the Kinetic Energy be if the body where released from its “up” position and allowed to fall to its starting point (assuming no friction obviously)? PE (due to Gravity) = m.g.h

These are all just different ways of phrasing the same principles of energy/work. I can even see from your post where you started out kinda right but went off the deep end. You owe Kyle an apology.

I enjoyed the central thrust of your article, as I enjoy many of your pieces, but as a former athlete and Biomechanics student I would feel remiss about not pointing out one critical aspect of the analysis that was lacking.

At the outset I agree that it is stupid to state in a “Health & Fitness” column that women can’t do pull-ups. Even if the “study” had been of good quality it is obvious in gyms all around the world that many women can and do perform pull-ups! I have trained with many of them and despite the sexist ignorance earlier in the comments there is nothing unattractive about a woman who can “lift her own weight”.

Now it could be that you are using “musculature & arm-length” as a catch all for the total mechanical factors involved in the exercise but I don’t think you are, and even if you were it is an oversimplification all the same.

From an external perspective the analysis you present is correct, but even elementary Biomechanics shows that this does not hold within the body. We do not move by exerting linear forces on our whole mass, but by exerting torques around joints. As such “Levers” are critical.

More important than just “musculature” is the origins and insertions of said musculature, more important than just “arm length” is relative length of various bones to each other. These factors combine to define the lines of action of forces and of movement that we might sum up as giving “relative mechanical advantage”.

For example the broader the shoulder (distance of glenohumeral joint from body’s centerline) the greater the relative mechanical advantage with respect to the action of the major back muscle, Lat Dorsii. Also given that this joint is THE most mobile in the human body mechanical aspects become more important, as if the joint cannot be stabilised sufficiently for the prime movers to begin acting, precisely zero will happen except perhaps partial dislocation.

Relative mechanical advantage is why you so regularly see certain body-types in certain sporting roles rather than in others. Why do swimmers have long arms and sprinters long hamstrings? Relative mechanical advantage.

I didn’t mean for this to be a rant, as I say I’m a fan of your writing, but relative mechanical advantage is fundamental to relative athletic prowess. And this is true both inter- and intra- sex.

32. 32. MusicLV 3:09 am 05/6/2013

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33. 33. roboursa87 11:02 pm 05/16/2013

I’d just like to add I haven’t done a pull up in at least 7+ years. The last time I remember it being mandatory was maybe middle school. I do not rock climb, or do any other active sports or work.

Recently I’ve been trying to lose a little weight and become more tone. I am 25 years old now, and just tried my first pull-up today. I did 4 total, not at the same time. My goal was to run back and forth and do a pull up, giving my arms a break in between. My right muscle is a bit sore now, but I figure that’s not a bad number.

So yeah, women can certainly do pull-ups. Even ones who don’t regularly workout. Perhaps it does have a lot to do with some fun body mechanics or genetic factors.

34. 34. Colenso 11:44 am 10/12/2013

Humans are animals. Animals are biomechanical. Animals, including humans, are machines. Torque is the vector product of force and displacement. In the real world of machines (systems that can do external work), the torques on a part of a system always matter more than forces per se on that part. Most school science teachers, many of whom don’t have even an undergrad degree or major in physics, don’t understand this because they have a hazy to poor understanding of classical mechanics. The writers of school textbooks often don’t fare much better. Hence, in many schools, especially in the USA, one ends up with the blind leading the blind. Science teachers teach school kids rectilinear mechanics before they try to tackle curvilinear mechanics because the concepts are easier – for the teachers as well as the kids. Often, rotational mechanics (a special case of curvilinear mechanics where objects move in a circle, a special case of an ellipse where the two foci coincide) is a tack-on, or not even tackled at all. Further, not using SI units makes rotational mechanics even harder than it already is.

I’m embarrassed to say that it took me a couple of years of teaching A-level physics before my own light bulb finally went on properly: rectilinear mechanics, ie in a straight line, is of course just a special case of curvilinear mechanics. In the real world, on earth, force may be thought of as special case of torque in the limiting case as the displacement of the torque from a given point in space-time approaches zero. Using this approach, torque is more fundamental than force. This is not the approach taken by Newton of course, probably because in the treatment of celestial bodies, treated as points, torques never or rarely occur.

In the real world in which we live, all the external forces acting upon a system rarely all pass through the centre of mass of the system. Nevertheless, it’s only when all the external forces pass through the centre of mass of the system, and there is a resultant net force acting upon the centre of mass, that the system will accelerate in a straight line only, that is without also acquiring any component of rotational acceleration. The rest of the time, which in the real world of life on earth is almost always, the net external force on a system almost always acts off-centre so that the system accelerates in a rotational fashion (spins faster or slower) as well as accelerating in a straight line or along a curve.

What does this mean for pull-ups? What it means is that neither the force per se acting on any part of the system, nor the energy state (potential or kinetic) of the system is what determines whether or not a person can execute one pull-up. At all points in space-time, we have to calculate, estimate or measure, and then almost immediately do it again, each of the torques acting on each of the relevant parts of the person’s body. If the person cannot apply sufficient torque on the critical body part at the critical moment, then they will not be able to lever their body past that point unless their curvilinear momentum immediately preceding that point is sufficient to carry them through the most torque demanding point of the execution.

This means that doing one very slow or even slow pull-up may be impossible for a person, but doing the pull-up as fast as they can may work for them.

Where does the person’s energy expenditure come into this? Answer, the total energy expenditure of the person, which in any case will be many times greater than the work they do because the human body is at best only about 22% mechanically efficient, becomes important because this will determine how many pull-ups in a single session the person can do. Usually, provided a person’s upper parts are ‘torquey’ enough to execute a single pull-up slowly and easily, with no sticking points, then unhurried pull-ups will result in the greatest number executed in total in a session. Too fast, and the rapid lactate build-up will soon put a stop to our pull-ups. Too slow, and the lactate, which is building up anyway, will bring our pull-ups to an end before we have executed the maximum possible.

As always, a picture is worth a thousand words. Take 50 fps or faster footage of a person executing easy pull-ups – or not. Using the individual frames as aids to accuracy, draw diagrams of the person at the various different stages of their pull-up, paying particular attention to their limb positions, limb lengths, joint angles and muscle attachment points. Draw on each diagram the directions of each of the external forces acting on each body part, and the distance of each force from the relevant pivot points. You will then begin to understand that what I have explained here is correct: it is the torques, not the forces alone, that matter.

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