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    Quicksilver

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    The strength difference between women and men

    Post by Quicksilver on Wed Mar 27, 2013 9:24 pm

    My question is primarily addressed to those with an academic background in areas related to the subject, just because of the nature of my questions and because I am primarily interested in a scientific & biomechanical point of view (though the answers to the obvious follow on questions from these ones with specific pertinence to Judo become a matter of experience and observation as well). It is an accepted empirical fact that all other non-gender related factors being equal your average man is physically stronger than your average woman. But what precisely is this difference- I'm not entirely sure what the appropriate unit or form of measurement for comparison would be- expressed perhaps as a percentage; and does this evolve linearly as training level increases (ie. is the proportional difference a constant)? And, what are the primary mechanism/s of/reasons for this? How much extra strength specific training would the woman have to do compared to the man to compensate for the biological difference? How big is the variation between individuals within genders within a given age group, and does the level of variation change between age groups, particularly between children as opposed to adolescents as opposed to adults?

    Any information anyone could provide me with (or, any resources on the subject anyone could direct me to, I understand that the information I ask for is quite a bit to write out) would be hugely appreciated. Thank you!

    Regards,

    -Q
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    JudoMojo

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    Re: The strength difference between women and men

    Post by JudoMojo on Wed Mar 27, 2013 10:46 pm

    As far as I can remember, I have heard with weight being equal, men are 10% stronger.

    I'm not any sort of expert on the subject, just what I have heard.
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    icb

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    Re: The strength difference between women and men

    Post by icb on Thu Mar 28, 2013 2:40 am

    The answer depends on how you are defining/measuring strength.

    If you are interested in the maximal contractile force that an individual muscle can produce for a brief isometric contraction, then all that basically matters is the muscle bulk, or more precisely the average cross-sectional area of the muscle. So if a female's muscle is the same size as a male's it will be able to produce the same maximal isometric force.

    For dynamic contractions and for longer contractions, the mix of fast twitch and slow twitch muscle fibers will come into play, but most of the evidence seems to suggest that there is not a large innate gender difference in the ratio of fast to slow twitch fibers.

    If you are referring to strength in a more applied sense, such as in the context of Olympic weight lifting or judo, then other factors need to be considered, such as the strength of the postural muscles and of the ligaments and tendons, which provide stability for the action of the main phasic (movement inducing) muscles. The different anatomy of males and females will be important in this case.
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    Cichorei Kano

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    Re: The strength difference between women and men

    Post by Cichorei Kano on Thu Mar 28, 2013 4:18 am

    icb wrote:The answer depends on how you are defining/measuring strength.

    If you are interested in the maximal contractile force that an individual muscle can produce for a brief isometric contraction, then all that basically matters is the muscle bulk, or more precisely the average cross-sectional area of the muscle. So if a female's muscle is the same size as a male's it will be able to produce the same maximal isometric force.

    That is not entirely true. While indeed muscle cross-sectional area is important, the maximal contractile force is not a passive process. You are describing anatomical differences, but muscle strength is not merely a function of anatomical structure or a passive process. Two muscles of the same size are definitely not able to produce the same strength. Muscle strength is a function of physiological, neurological and hormononal processes in addition to the anatomical processes.

    In fact, it is so that prepubertal children who do weightlifting increase strength without any gain in muscle size. Why, because that gain is achieved merely through neurological processes. If over many weeks you do extensive exercise with just a single arm and afterwards measure the strength in both arms, strength will have increased in both arms, though obviously by far not as much in the one you did not exercise. That is through neurological processes.

    In terms of size, hypertrophy of a muscle is just part of the picture, with hyperplasia (the increase in number of fibers) being the other half. The only thing is that hyperplasia is difficult to achieve after puberty, although through careful use of hormonal stimulants (popularly referred to as 'doping') if integrated into a scientifically crafted strength program satellite cells are sometimes produced which in some cases may lead to new fibers.

    Resulting strength moreover is also a function of the motor abilities, in particular the ability to simultaneously fire as many as possible motor units. While in the acute process of exerting strength rather than training or increasing strength, we are obviously not talking about anabolic steroids, but still acetylcholine as a neurotransmitter and the efficiency, promptness, and coordination of actin-myosin crossbridges plays a significant role. This certainly is not identical between two muscles of identical size.

    At the end of the day, very much as Quicksilver comprehends, indeed a woman with muscle the same size as a man, will typically not be able to produce as much strength as man, and no woman will be able to run as fast as a man either. Why ? Because apart from what is described above, there are many other things that women cannot overcome. Women biomechanically run less efficient than males because the transfer of force is less efficient due to the much larger angle of femur to tibia and the width of their pelvis. Once in blue moon, you will have some freak of nature when coupled to "optimal scientific guidance ..." you can develop something to the extreme, like in the case of Flo Jo, who was both extremely muscular and had unusually straight legs for a woman. In the end though even though she eclipsed everything that women previously had done, she would still have not been party for a male at the same level.

    Moreover, as much as you have such a "freak of nature" in women, they also happen at the male side, as for example, with Usain Bolt or Michael Phelps. Their size, leg length, arm length, relative body mass for such height, proportion of fast twitch fibers in Bolt due to ethnicity, etc. There are anatomical differences in terms of levers used which play out in the difference males/females, but also between ethnicities. That is also why an Olympic 100 m final will virtually always consist of African Americans, every so many years an exception when a similar "freak of nature" allows someone of other ethnicity to transgress the anatomo-physiological differences that are average in terms of specificity for that ethnicity. It is not only a matter of proportion of a certain type of fiber, but on the average the attachment of the tendon of the gastrocnemius muscle on the calcaneus is further in an African American than in a Caucasian hence creating a more powerful lever. We are not talking half a meter difference, but the difference becomes significant when push comes to shove and we are talking people who have pushed everything else to the maximum.

    A woman is also not trainable to that extent no matter what she does, even if you give her as much doping as you want. Why is that ? Because muscle response to hormones is not solely determined by the amount of anabolic hormone, but by the free faction and the amount of available receptor for that hormone to bind to. In women saturation of receptors will occur much earlier than in males, and even between members of the same sex number of receptors is genetically determined. Upregulation of number of receptors is very difficult to achieve. It is also difficult to research and measure due to current ethical restrictions. Most of our knowledge in this area dates from the late 1960s and early 1970s when no such stringent ethics rules were in place and it was still much easier to conduct certain scientific experiments. Specifically, what I am talking about is that to measure these things you have to infuse hormones which you first radioactively label, which today is almost impossible to get through any ethics committee when you want to do this in health people for the mere interest of science rather than in a patient to improve his health.

    As much as the strength gap male to female is unbridgeable for a woman, the reverse exists too depending on what we are talking about. When it comes to ultra-endurance which no longer is a matter of strength, but of other physiological parameters, males cannot bridge the gap with females. Virtually all endurance swimming records are health by women.

    Such gender differences exist in many more disciplines. Deep sea diving without scuba gear is another one. Women have desperately attempted to match males there with as a result several fatalities. The ama or female pearl divers in Japan stay under water for many minutes without oxygen, thus it was tempting to try and match depth records set by males. Only it isn't that simple. The reason that those pearl divers are female and not male has more to do with anthropo-cultural history than with physiological qualities. However, in setting depth record it is a different matters. The maximal ventilation of a male is much larger than of a female, because VEmax is strongly determined by size of lungs and males are taller than females and size of lungs is linked to body height. In diving, the issue is more complex the maximal depth someone can dive is also determined by the relationship between the non-expirable air in the lungs and the expirable, and how the factor of compression resulting from increased pressure.

    From personal and anecdotal memory, I did randori numerous times with one the most successful female elite judoka, who was the physically strongest woman I have met on a tatami and an Olympic gold and 6-fold judo world champion combination of -72kg and open classes. If you think you got your match there, forget it. When it comes to explosive force, speed, using that force optimally, breadth of techniques not a single male in the team or any male good enough for a national medal would have been threatened. This was not just one person, as over the years we had several female world and continental champions, and I can't imagine any of them ever being able to throw me or most male team members in randori. Now, I also vividly remember when I was a 2nd kyu and for the first time visited my club, I was like 14 years old or something, there was a female black belt and multiple national champion and European silver medalist -56 kg who made me see every corner of the dojo. By the time I had gained my 1st kyu though that had changed quite a bit. In other words, what was different and how did that female apparently bridge the gap ?

    1. I was a 14-year old child and she was an adult in her prime, more than 10 years older than me.
    2. She was technically far more skilled than me, as she was a celebrated champion and blackbelt.

    Today, some of my male students sometimes visit places and work out with a few international female elite and getting their butts kicked. How is that possible ? It is possible because none of my current male students, black belt or other, has a noteworthy national or regional competitive career or has any exceptional judo talent. In other words, yes, in judo, women can bridge the gap female/male but not on strength but on technique, IF that technical gap between the woman and the man is sufficiently large and significant. This was exactly what happened to me when I had my butt kicked so many years ago, or what happened to my less experienced male students.


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    genetic judoka

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    Re: The strength difference between women and men

    Post by genetic judoka on Thu Mar 28, 2013 5:03 am

    sadly, there's a reason why in track & field and weight lifting, there's separate records for men & women. I'd be interested to learn if in any of those events the womens record surpasses the mens records.

    that's not a misogynist comment, just an observation


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    icb

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    Re: The strength difference between women and men

    Post by icb on Thu Mar 28, 2013 8:11 am

    Cichorei Kano wrote:
    icb wrote:The answer depends on how you are defining/measuring strength.

    If you are interested in the maximal contractile force that an individual muscle can produce for a brief isometric contraction, then all that basically matters is the muscle bulk, or more precisely the average cross-sectional area of the muscle. So if a female's muscle is the same size as a male's it will be able to produce the same maximal isometric force.

    That is not entirely true. While indeed muscle cross-sectional area is important, the maximal contractile force is not a passive process. You are describing anatomical differences, but muscle strength is not merely a function of anatomical structure or a passive process. Two muscles of the same size are definitely not able to produce the same strength. Muscle strength is a function of physiological, neurological and hormononal processes in addition to the anatomical processes.

    ....


    By maximal force I did only mean to refer to the mechanical constraint of the anatomy, i.e., the number of myofibrils that the muscle has. Certainly the effective maximum contractile strength that the person will normally produce will be less than this and dependent on the other factors you described.

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    Re: The strength difference between women and men

    Post by hedgehogey on Thu Mar 28, 2013 4:41 pm

    proportion of fast twitch fibers in Bolt due to ethnicity, etc.

    Dot. Dot. Dot.
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    Quicksilver

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    Re: The strength difference between women and men

    Post by Quicksilver on Fri Mar 29, 2013 3:33 pm

    Thanks, guys. Interesting discussion.

    Cichorei Kano wrote:
    (...)

    Today, some of my male students sometimes visit places and work out with a few international female elite and getting their butts kicked. How is that possible ? It is possible because none of my current male students, black belt or other, has a noteworthy national or regional competitive career or has any exceptional judo talent. In other words, yes, in judo, women can bridge the gap female/male but not on strength but on technique, IF that technical gap between the woman and the man is sufficiently large and significant. This was exactly what happened to me when I had my butt kicked so many years ago, or what happened to my less experienced male students.

    As something of a digression regarding bridging gaps in strength with technique- and if I may make what I recognize is a significant oversimplification of far more complex phenomena, but speaking in general terms- what in your experience is the nature of the correspondence between physical strength, size etc. and technical skill in an overall comparison of the abilities of two Judoka? For a given gap in size/strength what sort of gap in technical skill the other way is necessary for them to be evenly matched, assuming other variables are controlled?

    Regards,

    -Q
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    Re: The strength difference between women and men

    Post by finarashi on Fri Mar 29, 2013 5:35 pm

    Another factor for elite athletes is that males can function and be healthy with far less body fat than females. So for equal weight you have easily several kg more muscle in males than females.


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    Re: The strength difference between women and men

    Post by Cichorei Kano on Sat Mar 30, 2013 1:18 am

    finarashi wrote:Another factor for elite athletes is that males can function and be healthy with far less body fat than females. So for equal weight you have easily several kg more muscle in males than females.

    Indeed, lean body mass is much higher in males. Several male elte jûdôka (except for heavy-weights) have body fat percentages of less than 2%. Female elite jûdôka have at least 5-6 times that amount. In other words, females have much more 'useless' weight they have to carry and which energetically does not much contribute during short jûdô bouts. On the other hand there larger fat mass and body surface becomes a critical advantage in ultra-endurance swimming and the like then providing useful energy and insulation.


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    afulldeck

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    Re: The strength difference between women and men

    Post by afulldeck on Sat Mar 30, 2013 12:22 pm

    [quote="Cichorei Kano"]
    icb wrote:
    Moreover, as much as you have such a "freak of nature" in women, they also happen at the male side, as for example, with Usain Bolt or Michael Phelps. Their size, leg length, arm length, relative body mass for such height, proportion of fast twitch fibers in Bolt due to ethnicity, etc. There are anatomical differences in terms of levers used which play out in the difference males/females, but also between ethnicities.

    Just as a side note, I think you will find that women supercede men (or give them a run for their money) in open water swimming. Yes the sprint swimming events the men still win....


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    Cichorei Kano

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    Re: The strength difference between women and men

    Post by Cichorei Kano on Sat Mar 30, 2013 12:48 pm

    [quote="afulldeck"]
    Cichorei Kano wrote:
    icb wrote:
    Moreover, as much as you have such a "freak of nature" in women, they also happen at the male side, as for example, with Usain Bolt or Michael Phelps. Their size, leg length, arm length, relative body mass for such height, proportion of fast twitch fibers in Bolt due to ethnicity, etc. There are anatomical differences in terms of levers used which play out in the difference males/females, but also between ethnicities.

    Just as a side note, I think you will find that women supercede men (or give them a run for their money) in open water swimming. Yes the sprint swimming events the men still win....

    If you read my entire post you will see that I have explicitly already said that twice:

    "Virtually all endurance swimming records are health by women." (...) (first post)

    "On the other hand there larger fat mass and body surface becomes a critical advantage in ultra-endurance swimming and the like then providing useful energy and insulation." (...) (second post)

    Aussie ex-ultra-swimmer Susie Maroney comes to mind, and I have talked about her on several occasions on the old forum.


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    Re: The strength difference between women and men

    Post by finarashi on Sun Mar 31, 2013 2:53 am

    When in doubt look at believable source. There is a series of Sports books by VK-Kustannus many of them featuring Antti Mero as one of the authors. The book I'm referring is "Naisten ja tyttöjen urheiluvalmennus." (Sports coaching of women and girls) In Finnish, 2012, 383 p.

    p. 18 "The difference in weightlifting world records is about 20 %" at 69 kg women 128+158=286 kg and men 165+198=358kg.
    p. 54 "Women have about 36 % of weight as muscle and men about 45 %, but there are large variations depending on the sport"
    p. 64 "For lower legs the strength difference of 25 to 30 % is about zero if we look at strenght vs fatless body weight. For upper body the strength difference of 40 to 60 % is less than 10 % if we look at strenght vs fatless body weight. The difference is believed to be caused mainly from differences in training.
    p. 114 "Maximum strength per muscle cross section is about the same for men and women athletes (Häkinen 1990)"
    p. 123 "Men and women benefit from strenght training the same way and gains in strength are equal. However in the long run men acquire more muscle from similar training."
    Translations mine
    References as pdf


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    cuivien

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    Re: The strength difference between women and men

    Post by cuivien on Sun Mar 31, 2013 5:33 am

    Cichorei Kano wrote:
    finarashi wrote:Another factor for elite athletes is that males can function and be healthy with far less body fat than females. So for equal weight you have easily several kg more muscle in males than females.

    Indeed, lean body mass is much higher in males. Several male elte jûdôka (except for heavy-weights) have body fat percentages of less than 2%. Female elite jûdôka have at least 5-6 times that amount. In other words, females have much more 'useless' weight they have to carry and which energetically does not much contribute during short jûdô bouts. On the other hand there larger fat mass and body surface becomes a critical advantage in ultra-endurance swimming and the like then providing useful energy and insulation.

    Less than 2% BF seems dangerously low as typically bodybuilders tend to aim for 2-4% for competition day...

    Also, since Friedl, Moore et.al. (1994) concludes that "Our results suggest that 4-6% BF or approximately 2.5 kg fat represents the lower limit for healthy men", is there much to be gained from having that low BF?

    (link: PubMed)


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    finarashi

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    Re: The strength difference between women and men

    Post by finarashi on Sun Mar 31, 2013 7:37 am

    The point is AFAIU that many elite Judoka drop weight before the competition and being very lean with no fat is advantageous. Yes, I know of various healt probelms associated with loosing weight. Females typically have more than males. Yes it is not healthy. A good book about this is
    Ma diététique de judoka by Bellard, Franck (1976 - ), Paris, France, Amphora, 2003, 207p, ISBN 2851806297



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    Cichorei Kano

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    Re: The strength difference between women and men

    Post by Cichorei Kano on Sun Mar 31, 2013 7:53 am

    cuivien wrote:
    Cichorei Kano wrote:
    finarashi wrote:Another factor for elite athletes is that males can function and be healthy with far less body fat than females. So for equal weight you have easily several kg more muscle in males than females.

    Indeed, lean body mass is much higher in males. Several male elte jûdôka (except for heavy-weights) have body fat percentages of less than 2%. Female elite jûdôka have at least 5-6 times that amount. In other words, females have much more 'useless' weight they have to carry and which energetically does not much contribute during short jûdô bouts. On the other hand there larger fat mass and body surface becomes a critical advantage in ultra-endurance swimming and the like then providing useful energy and insulation.

    Less than 2% BF seems dangerously low as typically bodybuilders tend to aim for 2-4% for competition day...

    Also, since Friedl, Moore et.al. (1994) concludes that "Our results suggest that 4-6% BF or approximately 2.5 kg fat represents the lower limit for healthy men", is there much to be gained from having that low BF?

    (link: PubMed)

    Why did you insert the adjective 'dangerously' ? In other words, what prompts you to label something below a certain threshold as 'dangerous' unless you are thinking of any specific health impairment ?

    There is no known negative impact of low body fat in healthy males, unless that low body fat is a accompanied with a complete body wasting that also includes muscle and bone, as may be seen due to cachexia in cancer, aids, Third-World malnutrition or for advanced geriatric conditions. This is entirely different from females were body fat below certain percentiles is associated with increased incidence of menstrual irregularities, stress fractures, and temporary subfertility. These are not direct effects, however, but caused through decreases in estrogen production, anovulation and disappearance of the cyclic high-estrogen levels during the second phase of the menstrual cycle. Because female need estrogen to sufficiently absorb calcium in bone, their situation is thoroughly different from men.

    You will see that as a man, if your body mass increases this will be reflected in a ... "more female-like" sex-steroid profile, thus higher estrogens, lower testosterone. But since males do not require estrogens for absorption of calcium in their bones, the reverse ... i.e. very low estrogens and low body fat has no relevant impact on bone health. Moreover, when we are talking athletes, lean body mass is much higher than in average males. Because testosterone does not only originate in the testicles, but also from peripheral conversion in muscle tissue (which is higher in athletes) there is no negative effect of low body fat on hormonal function in males. In other words, while the reproductive function of females benefits from "well-rounded, well-fed", and other similar adjectives, the opposite is true in males. To be blunt, fatness makes women a fertile acre, whereas fatness in men increases impotence, and diseases such as diabetes which induce impotence and reduced male ferility.

    The study you quote used as subjects 55 normal young men during an 8-wk Army combat leadership training course. As much as they exercised, they are not elite athletes. In army courses, you typically just want to get through the whole thing. As a topathlete it is different, with various short- and long-term plans; top athletes may even have a certain vanity towards their body, insisting on eating healthy, or certain foods, whereas in the army, one might want to get through things like that on a combination of cigarettes, junk food and the like. In other words, the low fat level in a jûdôka (on the condition that that jûdôka is male) is a result of genetics, diet and hard training. This also entitles the jûdôka at minimal age to generate maximal performance, whereas someone who has low body fat as a result of starvation and disease clearly can't. So low body fat must always seen in the context of how it has been achieved.

    The classical studies on antropometry in jûdôka are:

    Claessens A, et al.: Somatotype and body structure of world top judoists. J Sports Med Phys Fitness. 27, 1: 105-113, 1987.

    Ikai M, et al. Studies on body composition of judoists. In: Bulletin of the Association for the Scientific Studies on Judo – Report III. Tōkyō: Kōdōkan; 1969, pp 81-92.


    and some recent work:

    Muramatsu S, et al. Studies on weight reduction of judoist (II)—Examination of anthropometric measurements, body composition and chemical findings weight reduction in the jūdō participators of 31st Kantō-Kōshin’etsu district university sports match—. Research Journal of Budō 20, 1: 32-40, 1987 [in Japanese]

    There is also one specific about female jûdôka and thus with much higher percentages of body fat, thus less relevant here, but which I mention nevertheless because it is freely available online:

    Jagiełło W, Kalina RM, Korobielnikow G. Morphological diversification of female judo athletes. Arch Budo 3: 27-34, 2007 [downloadable from: http://www.archbudo.com/abstracted.php?level=4&id_issue=77676]


    The data about the very low body fat come from two studies at our place in the 1980s and from data that were not published as full papers. The two studies which were published unfortunately are not in English and the journals are not available online and have been discontinued.


    To conclude, a couple of random remarks. When discussing these issues, I am excluding the jûdôka who participate in the Open Class and Heavy-weights as their anthropometry is entirely different from other jûdôka because they have no weightclass limit and instead even gain a certain advantage from maximizing their body mass. Secondly, there are genetic limits. I know that for me personally 10% body fat is the limit. I can't go below it. At that point my risk of injury and feel of "dry muscles" is serious increasing and I am starting to suffer from severe weakness. Some of the jûdôka I have met with 1-2% body fat are not even on a diet. They were also all Caucasian males. In other words, genetics is critical. Also ... it is easier to achieve such "ideal values" through the use of "extra help". Growth hormone is lipolytic while strongly anabolic ...

    Also, note that I have not said that top-jûdôka all have 1-2% of body fat. Indeed, averages will be closer to 7-9%. In the 1980s though we were primarily interested in finding an answer to the question: "what kind of anthropometry is ideal for a world class jûdôka ?". The way forward to find this answer obviously was to "measure them". This was luckily still in a time that jûdô was more open in terms of attitudes hence there was great cooperation from top athletes including the Japanese and Soviet teams and thus even people like Yamashita, Rougé, Van De Walle, en many others were included to come to those conclusions. However, some of the very low body fat percentages were already found in national elite athletes.


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    Re: The strength difference between women and men

    Post by cuivien on Mon Apr 01, 2013 1:36 am

    Cichorei Kano wrote:
    Why did you insert the adjective 'dangerously' ? In other words, what prompts you to label something below a certain threshold as 'dangerous' unless you are thinking of any specific health impairment ?

    There is no known negative impact of low body fat in healthy males, unless that low body fat is a accompanied with a complete body wasting that also includes muscle and bone, as may be seen due to cachexia in cancer, aids, Third-World malnutrition or for advanced geriatric conditions. This is entirely different from females were body fat below certain percentiles is associated with increased incidence of menstrual irregularities, stress fractures, and temporary subfertility. These are not direct effects, however, but caused through decreases in estrogen production, anovulation and disappearance of the cyclic high-estrogen levels during the second phase of the menstrual cycle. Because female need estrogen to sufficiently absorb calcium in bone, their situation is thoroughly different from men.

    You will see that as a man, if your body mass increases this will be reflected in a ... "more female-like" sex-steroid profile, thus higher estrogens, lower testosterone. But since males do not require estrogens for absorption of calcium in their bones, the reverse ... i.e. very low estrogens and low body fat has no relevant impact on bone health. Moreover, when we are talking athletes, lean body mass is much higher than in average males. Because testosterone does not only originate in the testicles, but also from peripheral conversion in muscle tissue (which is higher in athletes) there is no negative effect of low body fat on hormonal function in males. In other words, while the reproductive function of females benefits from "well-rounded, well-fed", and other similar adjectives, the opposite is true in males. To be blunt, fatness makes women a fertile acre, whereas fatness in men increases impotence, and diseases such as diabetes which induce impotence and reduced male ferility.

    The study you quote used as subjects 55 normal young men during an 8-wk Army combat leadership training course. As much as they exercised, they are not elite athletes. In army courses, you typically just want to get through the whole thing. As a topathlete it is different, with various short- and long-term plans; top athletes may even have a certain vanity towards their body, insisting on eating healthy, or certain foods, whereas in the army, one might want to get through things like that on a combination of cigarettes, junk food and the like. In other words, the low fat level in a jûdôka (on the condition that that jûdôka is male) is a result of genetics, diet and hard training. This also entitles the jûdôka at minimal age to generate maximal performance, whereas someone who has low body fat as a result of starvation and disease clearly can't. So low body fat must always seen in the context of how it has been achieved.

    The classical studies on antropometry in jûdôka are:

    Claessens A, et al.: Somatotype and body structure of world top judoists. J Sports Med Phys Fitness. 27, 1: 105-113, 1987.

    Ikai M, et al. Studies on body composition of judoists. In: Bulletin of the Association for the Scientific Studies on Judo – Report III. Tōkyō: Kōdōkan; 1969, pp 81-92.


    and some recent work:

    Muramatsu S, et al. Studies on weight reduction of judoist (II)—Examination of anthropometric measurements, body composition and chemical findings weight reduction in the jūdō participators of 31st Kantō-Kōshin’etsu district university sports match—. Research Journal of Budō 20, 1: 32-40, 1987 [in Japanese]

    There is also one specific about female jûdôka and thus with much higher percentages of body fat, thus less relevant here, but which I mention nevertheless because it is freely available online:

    Jagiełło W, Kalina RM, Korobielnikow G. Morphological diversification of female judo athletes. Arch Budo 3: 27-34, 2007 [downloadable from: http://www.archbudo.com/abstracted.php?level=4&id_issue=77676]


    The data about the very low body fat come from two studies at our place in the 1980s and from data that were not published as full papers. The two studies which were published unfortunately are not in English and the journals are not available online and have been discontinued.


    To conclude, a couple of random remarks. When discussing these issues, I am excluding the jûdôka who participate in the Open Class and Heavy-weights as their anthropometry is entirely different from other jûdôka because they have no weightclass limit and instead even gain a certain advantage from maximizing their body mass. Secondly, there are genetic limits. I know that for me personally 10% body fat is the limit. I can't go below it. At that point my risk of injury and feel of "dry muscles" is serious increasing and I am starting to suffer from severe weakness. Some of the jûdôka I have met with 1-2% body fat are not even on a diet. They were also all Caucasian males. In other words, genetics is critical. Also ... it is easier to achieve such "ideal values" through the use of "extra help". Growth hormone is lipolytic while strongly anabolic ...

    Also, note that I have not said that top-jûdôka all have 1-2% of body fat. Indeed, averages will be closer to 7-9%. In the 1980s though we were primarily interested in finding an answer to the question: "what kind of anthropometry is ideal for a world class jûdôka ?". The way forward to find this answer obviously was to "measure them". This was luckily still in a time that jûdô was more open in terms of attitudes hence there was great cooperation from top athletes including the Japanese and Soviet teams and thus even people like Yamashita, Rougé, Van De Walle, en many others were included to come to those conclusions. However, some of the very low body fat percentages were already found in national elite athletes.

    To be honest, most of my knowledge in this particular area stems from research done as a favor to a gym buddy of mine who was participating in amateur body-building competitions 2010-2012. The results of the investigations done at that time seemed to suggest that the "optimal" (if indeed such a word is suitable here) body fat percentage lay in the 2-4% area for males and somewhere around 5-8% for female, as several of the athletes I talked to who did such competitions (either straight body building or something called "athletic fitness" which focus more on functional strength) professionally and cut weight in preparation for an event stated that even being that low for more than 24-48 hours was "extremely uncomfortable" and "took too great of a toll on the body". One of the involved participants had his physician-brother monitor his body vitals during the cut, and was advised against going lower than appr. 5% BF.

    However, there is of course a significant difference between a body builder and a jûdôka (even though the difference seems to have been reduced in modern day competitions), both in their training regimes, and in terms of goals...

    Once, in winter 2011 during my stay in Seoul, I was down at ~8% before weigh-ins at the All-Korea University Championships. I felt horrible though, went directly to yaki-niku after getting an "OK" next to my entry from the officials, and must have stepped on to the mat a good 2 or 3 pounds heavier the next morning Razz


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    Re: The strength difference between women and men

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