David Eberhards "Det stora könsexperimentet"

Hand-grip strength has been identified as one limiting factor for manual lifting and carrying loads. To obtain epidemiologically relevant hand-grip strength data for pre-employment screening, we determined maximal isometric hand-grip strength in 1,654 healthy men and 533 healthy women aged 20–25 years. Moreover, to assess the potential margins for improvement in hand-grip strength of women by training, we studied 60 highly trained elite female athletes from sports known to require high hand-grip forces (judo, handball). Maximal isometric hand-grip force was recorded over 15 s using a handheld hand-grip ergometer. Biometric parameters included lean body mass (LBM) and hand dimensions. Mean maximal hand-grip strength showed the expected clear difference between men (541 N) and women (329 N). Less expected was the gender related distribution of hand-grip strength: 90% of females produced less force than 95% of males. Though female athletes were significantly stronger (444 N) than their untrained female counterparts, this value corresponded to only the 25th percentile of the male subjects. Hand-grip strength was linearly correlated with LBM. Furthermore, both relative hand-grip strength parameters (F max/body weight and F max/LBM) did not show any correlation to hand dimensions. The present findings show that the differences in hand-grip strength of men and women are larger than previously reported. An appreciable difference still remains when using lean body mass as reference. The results of female national elite athletes even indicate that the strength level attainable by extremely high training will rarely surpass the 50th percentile of untrained or not specifically trained men.

90% of females produced less force than 95% of males

Comparison of trunk muscle CSA at the peaks and troughs of the distribution curve shows a greater sex difference in the upper trunk region (in women it is about 56% of that in men)

On average, men have approximately 61% more total muscle mass than women (Illner, Brinkmann, Heller, Bosy-Westphal, & Müller, 2000; Kim et al., 2004; Phillips, 1995; Shen, Punyanitya, Wang, Gallagher, & St. Onge, 2004; Wetter & Economos, 2004). Relatively more of this muscle mass is allocated to the upper body, with men having about 75% more arm muscle mass than women (Abe, Kearns, & Fukunaga, 2003; Fuller, Laskey, & Elia, 1992; Gallagher, Visser, Meersman, & Sepulveda, 1997; Nindl, Scoville, Sheehan, Leone, & Mello, 2002). Not surprisingly, this latter difference translates into approximately 90% greater upper body strength in men (Bohannon, 1997; Murray, Gore, Gardner, & Mollinger, 1985; Stoll et al., 2000). The mean effect size for these sex differences in total and upper body muscle mass and strength is about 3, which indicates less than 10% overlap between the male and female distributions, with 99.9% of females falling below the male mean. An effect size of this magnitude also means that sex— a single dichotomous variable—explains roughly 70% of the variance in muscle mass and upper body strength in humans. The sex difference in upper-body muscle mass in humans is similar in magnitude to the sex difference in lean body mass in gorillas, the most sexually dimorphic primate (Zihlman & McFarland, 2000).

Sex differences in lower-body muscularity are nearly as large. In the legs, men's muscle mass is about 50% greater than that of women with a mean effect size of approximately 2 (Fuller et al., 1992; Lawler, Halliwill, Summer, Joyner, & Mulvagh, 1998; Shih, Wang, Heo, Wang, & Heymsfield, 2000), and lower body strength is about 65% greater with an effect size of about 3 (Bishop, Cureton, & Collins, 1987; Falkel, Sawka, Levine, & Pandolf, 1985; Wilmore, 1978).

90% of females produced less force than 95% of males

The results of female national elite athletes even indicate that the strength level attainable by extremely high training will rarely surpass the 50th percentile of untrained or not specifically trained men.