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Muscle Fiber Distribution

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Discuss the relationship between distribution of muscle fiber type and performance.
In a study from the US National Library of Medicine National Institutes of Health (1991), the relationship between muscle fiber and performance they tested two different groups of athletic boys between the ages of 11-13. The subjects were divided into two groups according their fiber distribution. The fast group comprised 10 subjects with more than 50% fast-twitch fibers and the slow group comprised 8 subjects with more than 50% slow-twitch fibers in their lateralis muscle (Mero, 1990). The 'fast' group had 59.2 +/- 6.3% and the 'slow' group had 39.4 +/- 9.8% type II fibers. Other clear differences (P less than 0.05-0.01) between the groups were observed as …show more content…

The heart is one of the strongest muscles in the body. According to Henry Gray's “Anatomy of the Human Body” (2015), the heart is roughly the size of a large fist and weighs between about 10 to 12 ounces (280 to 340 grams) in men and 8 to 10 ounces (230 to 280 grams) in women (Lewis, 2015). The human heart has four chambers: two upper chambers (the atria) and two lower ones (the ventricles). The heart's outer wall consists of three layers; epicardium (outermost wall), myocardium (middle wall), endocardium (inner layer). The tricuspid valve and the mitral valve make up the atrioventricular (AV) valves, which connect the atria and the ventricles (Lewis, 2015). The function of the heart is divided into two pathways: the pulmonary circuit and the systemic circuit. In the pulmonary circuit, deoxygenated blood travels to the lungs by way of the pulmonary artery, then returns as oxygenated blood to the left atrium of the heart via the pulmonary vein. The systemic circuit, delivers oxygenated blood to the body from the left ventricle to the aorta, and from there enters the arteries and capillaries where it supplies the body's tissues with oxygen. Then, deoxygenated blood returns through the veins to the venae cavae, re-entering the heart's right atrium to restart the

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