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Web Resources. Human Kinetics Coach Education. The angle between the two pelvic bones is also much wider. In general, the female limb bones are thinner and shorter with less calcium deposition.
The skull bone of females has a less pronounced external occipital protuberance and the jaw bone is more rounded and pointed in females. Similar to males, in females, the bone development is influenced by the female sex hormone oestrogen which in turn determines the shape of these bones. Male bones include bones of different shape and morphology specifically designed for male functions whereas female bones include bones of different shape and morphology specifically designed for female functions.
The pelvic bone in males is narrower with a heart-shaped pelvic inlet while that of females is wider with a circular shaped pelvic inlet. Moreover, the limb bones in males are longer and thicker than females. Male bones also have more calcium depositions than female bones. The skull of males has a more pronounced external occipital protuberance while the skull of females has a less pronounced external occipital protuberance.
Furthermore, males have a square shaped jaw bone while females have a round and pointed jaw bone. Simultaneous to the age-specific subperiosteal bone apposition, a complex activity characterized by resorption and apposition occurs at the endosteal surface of the bone. Whereas subperiosteal activity determines the width of the bone, endosteal activity determines the width of the medullary canal. The combination of the relative activities at the two modeling surfaces over a period of time determines the thickness of the cortex.
On the other hand, endochondral ossification determines the cross-sectional area of the vertebrae. Endochondral ossification commences in the central area of the cartilage anlage in the vertebrae and, from this region, expands and progresses toward the periphery in all directions. It is generally assumed that normal development and growth of the diaphysis of the femur is mainly dependent upon mechanical loading, whereas endochondral growth and ossification may occur without mechanical stress The findings of this study corroborate previous studies indicating that females and males have identical cancellous and cortical bone density, emphasizing that gender differences in bone mass in children are related to variations in bone size 3 , 4 , 32 , Values for cancellous bone were, however, 8 times lower than those for cortical bone, reflecting its greater porosity Because of the relatively small size of the spicules of cancellous bone compared to that of the voxel CT unit of measurement , some degree of area averaging is always incorporated, and values for cancellous bone density reflect the amount of bone and marrow per unit of tissue In contrast, the femoral cortex is sufficiently thick to circumvent area-averaging errors, and CT measurements reflect the true density of the bone In the present study, the values for cancellous and cortical bone densities remained unchanged, whereas, simultaneously, the cross-sectional areas of the vertebrae and femur increased with age and body size, underscoring the importance of bone size to meet increasing loads.
The discrepant effect of gender in the appendicular and axial skeleton may account for the sex difference in the incidence of fractures in elderly subjects with osteoporosis. Because variations in the dimensions of the vertebrae and femurs in adults reflect differences in bone growth that evolve during early skeletal development, changes in bone size during childhood have important biomechanical implications with respect to the loading capacity of the skeleton in adulthood 2 , Recent studies have shown that vertebral size is a major determinant of vertebral fractures, and theoretically, the smaller cross-sectional area in women could explain their 4- to 8-fold higher incidence of vertebral fractures compared to that in men In contrast, the lack of gender differences in the size of the femur between girls and boys may partially account for the less discrepant ratio of hip fractures between women and men Nevertheless, future studies are needed to establish whether the differential effect of gender on the size of the bones in the appendicular and axial skeletons during childhood is related to the disparity in fracture incidence in elderly women and men.
In conclusion, the cross-sectional dimensions of the appendicular and axial skeletons are influenced by separate determinants during childhood. Changes in cortical bone area and cross-sectional area in the midshaft of the femur correspond to a number of anthropometric indexes of body size and body mass, findings consistent with the view that weight-bearing or mechanical stresses applied to the skeleton are important regulators of appendicular bone mass.
Changes in the cross-sectional area of the vertebral body during growth are not only associated with increases in body size, but they are also strongly influenced by gender.
The results suggest that although increases in mechanical loading are the main determinant of cross-sectional properties in the appendicular skeleton, other factors related to gender play an important role in the regulation of the size of the axial skeleton. The authors thank Dr. Dennis Carter for his insightful comments, and Cara L. Beck for her technical assistance and comments on the manuscript for this article. Epidemiol Rev.
Google Scholar. J Clin Endocrinol Metab. Mechanical implications and relationship to fractures. J Clin Invest. J Bone Miner Res. Tanner JM. Textbook of pediatrics, 2nd ed. Edinburgh : Churchill Livingstone; — Nelson textbook of pediatrics, 13th ed. Philadelphia : Saunders; 24— Stanford : Stanford University Press.
Cann CE. J Comput Assist Tomogr. Expanding the role of medical physics in nuclear medicine. Kalender WA. Osteopor Int. New York : McGraw Hill; — Morrison DF. Trotter M , Peterson RR. Am J Phys Anthropol. Clin Orthop. Am J Anthropol. Am J Dis Child. Bone Miner. New York : Academic Press; — J Pediatr. Mosekilde L , Mosekilde L. Advanced radiologic assessment using quantiative computed tomography. Any averagely healthy person can build more muscle by exercising and, to an extent, change the composition of their muscles.
Hormone doping scandals continue to shake the sporting world, along with confusion over natural variations in biological sex and transgender medications. Hand grip is one of the most widely-used markers for strength. These were large samples that included plenty of fit, young sportswomen with good upper body strength. Taking the 60 elite women separately, they were still only as good as an average to weak man. You have to go down to men under 62kg to find a champion Zhou Lulu could beat, and under 56kg for a male champion Tatiana Kashirina could beat in the Snatch.
This type of muscle fibre contains a lot of protein but not much blood. Because of this, Type 2 muscle fibres get tired more quickly. Type 1 slow-twitch fibres are more loosely packed and have their own capillaries. This means they can keep going for a long time. They interact with other metabolic processes , which helps to protect against insulin resistance and heart disease, supports the immune system and promotes hormonal functions.
This is the secret of our famed endurance: not the slow-twitch fibres themselves, but neuromuscular activity which uses all the fibres. Around the mucosal lining is a folded layer of smooth muscle. As it goes, women have evolved compensatory strategies some on this page, more in later posts!
It is the biological sex of our bodies that is at the root of the sexism women have to deal with throughout life. It is why we are at risk of sexual and physical violence from males.
It is why women are expected to take on caring roles throughout life.
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