Sex Differences in Physical Ability

The most obvious difference between men and women is their physique, which translates to very large differences in physical prowess. A 2010 review by anthropologist David Puts has captured these differences.[1]

Men are larger, stronger, faster, and more physically aggressive than women – and the degree of sexual dimorphism in these traits rivals that of species with intense male contests.

Sex differences in stature is relatively modest with men being about 10% bigger with 20% more body mass.[2] However, these seemingly modest figures greatly underestimate the magnitude of sex differences in strength and speed, partly because women are unique among primates in having copious fat stores.[3]

When fat-free mass is considered, men are 40% heavier and have 60% more total lean muscle mass than women. Men have 80% greater arm muscle mass and 50% more lower-body muscle mass. Men have about 90% greater upper-body strength and about 65% greater lower-body strength: the average man is stronger than 99.9% of women. In terms of anaerobic power, men have over 45% higher vertical leap and over 25% faster sprint times.[4][5][6] These differences in physique are in large part due to sex differences in muscle fiber distribution and muscle cross-sectional area.[7] Sex differences in anaerobic sprint speeds are not narrowing and some data suggest that the gap may have widened in the last decade.[8][9]

It should be noted that muscles are ‘organic armour’ reinforcing the integrity of the body frame as a whole: the male body frame is therefore more robust and resilient than the female body frame. The combined effects of greater strength and body frame resilience translates into a massive physical advantage in favour of males in military, industrial and other relevant domains.

The differential system demands contribute to differences in posture, gait, muscle activity and kinematics between men and women.


Psychomotor Ability


Sex differences in physical prowess extend into the realm of psychomotor abilities. Psychomotor abilities refer to skills that arise from brain–body coordination. These are generally classified into two categories: gross motor skills and fine motor skills.

Gross motor skills refer to large movements using large muscle groups like running, stretching, jumping and related secondary power components. The magnitude of differences in gross motor skills are as large as sex differences in physique. For example, in terms of hand-grip strength, 95% of males produce more force than 90% of females, with 75% of untrained males producing more force than 90% of heavily trained females.[10]

Fine motor skills refer to small movements using small muscle groups like the manipulation of objects and making quick, accurate movements. Psychologists Timothy Thorley and Michael McDaniel reviewed sex differences in fine motor abilities that are most relevant in industrial, medical and military domains.[11] Their review looked at studies that involved some type of arm, hand, leg, or foot movement, and in which real objects were being manipulated. The results of their meta-analysis by category of skills:

  • Speed of Limb Movement slightly favoured men (g=0.05)
  • Wrist-Finger Speed strongly favoured men (g=0.63)
  • Control Precision moderately favoured men (g=0.42)
  • Aiming strongly favoured men (g=0.74)
  • Steadiness moderately favoured women (g=0.48)
  • Multi-Limb Co-ordination very strongly favoured men (g=1.23)
  • Reaction Time moderately favoured men (g=0.30)
  • Motor Co-ordination slightly favoured women (g=0.25)
  • Finger Dexterity moderately favoured women (g=0.37)
  • Manual Dexterity slightly favoured women (g=0.19)

[The psychomotor measures, along with their descriptions, can be found at the end of this post.]

However, across all four categories which favoured women, the female advantage may be overestimated:

  1. All the measures that show a female advantage involve the manipulation of objects too small for the average male hands. For example, the female advantage appears in Pegboard tasks that use smaller pegs but disappears in the GATB-M and the Large Peg measures. Indeed, it has been found that when finger size is taken into account, the female advantage is nulled, or reversed.[12][13] However, data from more complex tests of dexterity where finger size does not confound, like the Kimura task, reveal a large male advantage.
  2. Age is an important variable which influences sex differences in some psychomotor measures because girls mature several years earlier than boys do. This is seen in some measures here, such as in Speed of Limb Movement and Motor Coordination, where the measured female advantage may be reduced or reversed among adult samples.[14]

There are several studies investigating sex differences in visuo-motor tracking and hand-eye coordination not included in the review. There is a large sex difference favouring males in pursuit precision.[15] Large sex differences favouring males are commonly reported on simulation trainers.[16] The male advantage in reaction time as well as in temporal processing are highly correlated with their greater cognitive capacity.

It should be noted that studying mental abilities in isolation underestimates their real world impact. In real world settings, small measured effects may translate to very large performance advantages, especially when compounded with other domain-specific abilities and general mental ability. This is especially true for men because their brain is organized for holistic ‘global’ processing.’ For example, temporal processing ability, psychomotor ability and Dynamic Spatial Ability may manifest in the male advantage for throwing and intercepting.[17][18][19]


Conclusion


Measurable sex differences in strength, speed, resilience and endurance as well as in motor control, precision and complexity can largely explain male dominance in relevant occupational settings.


Psychomotor Taxonomy, Thorley and McDaniel 2013, Table 1
Measures Description
Speed of Limb Movement Two-Plate Tapping Subject alternately strikes two plates as quickly as possible.
Forearm Tapping Subject taps a sensor as quickly as possible, using the forearm, with only the elbow moving.
Wrist-Finger Speed Finger Tapping Subject taps a sensor as quickly as possible, using a finger while the arm and hand are at rest.
Hand Tapping Subject taps a sensor as quickly as possible, using the hand, with only the wrist moving.
Control Precision Time Sharing While a tracking a moving target, the subject must respond to a random number flashed on the screen.
Rotary Pursuit The subject must keep a stylus in contact with a moving target on a turntable.
Tracking Subject uses a joystick or a stylus to track a moving target.
Aiming Marksmanship Subjects fired real weapons at targets in a range.
Target Shoot Distance Score represents accuracy of shots compared with targets on a screen.
Steadiness Arm-Hand Subject is required to keep a metal stylus from touching the sides of a small hole or the walls of a narrow maze or path.
Gardner Same as above.
Multi-Limb Co-ordination Two-Hand Co-ordination Subject uses a control stick in each hand, one for horizontal movements and the other for vertical movements, to keep a gun-sight on a target.
NASA Langley Complex Co-ordination Subject uses hand sticks and foot pedals to activate lights in order to match a pattern of lights given as a cue.
Reaction Time Simple Subject responds as quickly as possible to a signal (auditory or visual).
Choice Similar to Simple Reaction Time, but in Choice there are two or more signals, and the subject must quickly respond to just one of them.
Psychomotor Vigilance Task Similar to, if not the same as, simple RT. Subject presses a button as soon as a stimulus is activated.
Target Detection Time Similar to Target Shoot Time-to-Fire. Score is derived from the time it takes a subject to press the fire key after a target appears.
Dynavision Using a wall mounted board with 64 light-up buttons, subjects must press a button after it lights up and quickly respond to the next button to light up. The score is the number of correct hits in 60 seconds.
Target Shoot Time-to-Fire While controlling a cursor on a screen, the subject must quickly fire on a target that will appear randomly on the screen. Score on this measure reflects the time it takes for the subject to shoot after the target appears.
Motor Co-ordination Marking Subject draws, letters, symbols, or marks of some kind in a series of spaces or boxes on a piece of paper as quickly as possible.
GATB K Same as above.
Gibson Spiral Maze Subject traces a line through a maze on a piece of paper, as quickly as possible, without touching the walls or any obstacles.
Finger Dexterity Transfer Small nails or pegs are quickly moved from 1 hole to another or from a basin to a hole using the fingers of one hand.
Assembled Parts Includes multiple measures with similar descriptions, all of which includes simple assembly of small parts, using both hands.
GATB F Similar to assembled parts, the subject puts a washer on a rivet, or removes a washer from a rivet, and repeats this process with more parts, as quickly as possible.
Tweezers Peg Placement Small Pegs are moved from 1hole to another or from a small basin to a hole, using tweezers.
Beads Subject is required to string small beads as quickly as possible.
Manual Dexterity Hand Tool Dexterity
Grooved Pegboard Similar to the Purdue Pegboard, but in this measure the pegs or holes have grooves that force subjects to turn and accurately insert the pegs, with the pattern lined up.
Large Peg Placement Similar to other pegboard measures, but in this measure the peg has a thicker, easier to grasp top, to eliminate any advantage smaller hands might have.
Purdue Pegboard Subject is required to place pegs in holes as quickly as possible.
GATB M Subject moves pegs from one part of a board with holes in it to another.
Tactual Performance While blindfolded, the subject must quickly place blocks into a form board.
Kimura Task The subject completes a series of motions, including pushing a button, pulling a lever and turning a switch, as quickly as possible.
Product Assembly The measure was a timed simulation of a pharmacy order, including small containers and beads. The subject had to accurately fill the containers, with the correct type and quantity of beads.
Cattell Pegboard Subjects placed six pegs into corresponding holes on a board. This seems different from the other pegboards in that it is designed specifically for children.

References

  1. Puts DA. (2010) Beauty and the Beast: Mechanisms of sexual selection in humans. Evolution and Human Behavior, 31, 157–175. 

  2. Mayhew JL & Salm PC. (1990) Gender differences in anaerobic power tests. European Journal of Applied Physiology and Occupational Physiology, 60(2):133−138. 

  3. Pond CM & Mattacks CA. (1987) The anatomy of adipose tissue in captive macaca monkeys and its implications for human biology. Folia Primatologica, 48:164−185. 

  4. Lassek WD & Gaulin SJC. (2009) Costs and benefits of fat-free muscle mass in men: Relationship to mating success, dietary requirements, and natural immunity. Evolution and Human Behavior, 30, 322−328. 

  5. Abe T, et al. (2003) Sex differences in whole body skeletal muscle mass measured by magnetic resonance imaging and its distribution in young Japanese adults. British Journal of Sports Medicine, 37(5):436−440. 

  6. Mayhew & Salm, 1990. 

  7. Miller AE, et al. (1993) Gender differences in strength and muscle fiber characteristics. European Journal of Applied Physiology and Occupational Physiology, 66(3):254-262. 

  8. Seiler S et al. (2007) The fall and rise of the gender difference in elite anaerobic performance 1952-2006. Medicine and Science in Sports and Exercise, 39(3):534−540. 

  9. Cheuvront SN et al. (2005) Running performance differences between men and women: An update. Sports Medicine, 35(12):1017−1024. 

  10. Leyk D, et al. (2007) Hand-grip strength of young men, women and highly trained female athletes. European Journal of Applied Physiology, 99(4):415–421. 

  11. Thorley TE & McDaniel MA. (2013) Mean sex differences in Psychomotor Ability: A meta-analysis. Presented at the 28th Annual Conference of the Society for Industrial and Organizational Psychology, Houston. 

  12. Peters M & Campagnaro P. (1996) Do women really excel over men in manual dexterity? Journal of Experimental Psychology, 22(5):1107–1112. 

  13. Peters M, et al. (1990) Marked sex differences on a fine motor skill task disappear when finger size is used as covariate. The Journal of applied psychology, 75(1):87–90. 

  14. Piper BJ. (2011) Age, handedness, and sex contribute to fine motor behavior in children. Journal of Neuroscience Methods, 195(1):88–91. 

  15. Wilmer JB & Nakayama K. (2010) A large gender difference in smooth pursuit precision. Journal of Vision, 6(6):94–94. 

  16. Thorson CM, et al. (2011) Can we continue to ignore gender differences in performance on simulation trainers? Journal of Laparoendoscopic & Advanced Surgical Techniques, 21(4):329–333. 

  17. Kyllonen PC & Chaiken S. (2003) Dynamic spatial ability and psychomotor performance. International Journal of Testing. 3(3):233–249. 

  18. Watson NV & Kimura D. (1991) Nontrivial sex differences in throwing and intercepting: Relation to psychometrically-defined spatial functions. Personality and Individual Differences. 12(5):375–385. 

  19. Watson NV & Kimura D. (1989) Right-hand superiority for throwing but not for intercepting. Neuropsychologia. 27(11-12):1399–1414. 


21 thoughts on “Sex Differences in Physical Ability

  1. I have always heard in the media that the only the upper body strenght difference is relevant, whereas such disparity in the lower body part is either non-existent or negligible. Here tho I see that it is argued otherwise, so I am quite confused. If I had to judge based on my own intuition and limited observations, I would say that men are also stronger in their legs.
    So, is there an important advantage favouring males in lower body strenght as well?

    1. Greater muscle mass in the lower body of men translate to greater lower body strength. Sex differences in upper- and lower-body strength are well established, and not particularly difficult to measure. Men and women have similar total mass, but different body composition. Much greater fat mass in women largely counterbalances the greater muscle mass in men to make the sexes appear similar. [The fat stores in women exist for the building of infant brains.]

  2. “”in terms of hand-grip strength, 90% of heavily trained female athletes produce less force than 95% of untrained males.[10]””

    I think you misinterpreted the result of this study

    95% of males produced more force than 90% of regular females
    ,not heavily trained female athletes.

    and “only” 75% of the males have greater force than 90% heavily trained females athletes

    There were two groups of females in that study.

    Still, it is a remarkable differences

  3. Typed a long comment, posted, captcha error due to time out. Can’t go back, comment deleted. Wow. Just wow.

  4. The results are kind of bias. For example, a point was made that when you account for finger thickness when testing dexterity, there may a slight male advantage. First, there is no reason to believe finger thickness has anything to do with dexterity and second, why does it matter anyway if the results say females are more dexterous than males? It is not as if males can suddenly reduce their finger size.
    If you want try to use data to make it sounds as if there is some male superiority, then couldn’t someone argue that female muscle per unit volume is way stronger than male muscle per unit volume?
    You see, the data is good but when you go above to make opinion based conclusions, it just sounds biased. Any who, I got the data I needed. I found this page because I started to notice that female dexterity was way better than male dexterity so I googled it and found your page, and the results say that is true.

    1. The peg tests are confounded because of finger length (large pegs = male advantage, small pegs = female advantage) so it’s hard to draw any conclusions from it. This is why I highlighted the male advantage in more complex tests of dexterity—these don’t rely on finger size/length—they are much more useful in assessing real world performance (for instance, training pilots).

  5. What happened to your original articles that talk about females being the genetic filters of the species as well as how males maintain their variance despite losses as a result of natural selection.

    You even referenced the size of the X and Y chromosomes.

    1. Unlisted it temporarily to add some new experimental research. I didn’t want to tag references without actually explaining the findings properly. Should be done in a week.

      (Btw, males—not females—are the genetic filters.)

  6. Good article and to the point! You have created a fair resource on the topic of sex differences in one place which is difficult to find these days. My main criticism with respect to this article is that you have reduced psychomotor g to a footnote.

  7. I return to this (excellent) website frequently but I always fail to understand why interesting and controversial articles like this don’t receive more conversation in the comments.

    1. Tbh, I haven’t come across a lot of controversy surrounding sex differences in physical ability. I think it may be too obvious a difference, even for extremist gender ideologues.

  8. Found this through a bodybuilding forum. Very informative article. I thought you would be interested to know that your blog is all over the place on reddit. Some guy even got banned for linking this on r/everythingscience. What bullshit. Anyway thanks.

    1. A bodybuilding forum? Unusual, but not entirely unexpected considering the topic in question. 🙂

      This has given me an idea. I think I’ll update this article soon with a section on sex differences in physical abilities that rely on brain-body coordination rather than strength and speed. EDIT: See: http://www.sciencevsfeminism.com/the-myth-of-equality/sex-differences-psychomotor-ability/

      I’m not active on these social networks but that probably explains why my ‘sex difference’ posts have received several thousands of views within a few days. If what you say is true, then it’s amusing and also pathetic that a channel which calls itself “Everything Science” should be so afraid of something so obvious, and resorts to banning users.

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