Slides 21 - Muscle systems

Public library of science august 24 2004 are there

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Unformatted text preview: of oxidative fibres • Show increased running endurance Wang et al. 2004. Regulation of Muscle Fiber Type and Running Endurance by PPARδ. Public Library of Science. August 24, 2004. Are there genetic differences in humans? • Kenyans and other East Africans dominate in middle and long distance running events Do East Africans have different fibre types? • The Xhosa are speakers of the Bantu language who live in south-east South Africa. • They have more fast oxidative fibres than caucasians Fig. 2. Fiber types (A; n = 9 pairs) and myosin heavy chain (MHC) isoform content (B; n = 13) in homogenate muscle samples of Caucasian and Xhosa athletes Slow oxidative Fast oxidative Fast glycolytic Kohn, T. A. et al. 2007 J Appl Physiol 103: 932-940 Muscle size- effects of exercise • Training increases muscle size. • Muscles increase in size via two mechanisms: 1.Hypertrophy = increase in size of muscle cells 2.Hyperplasia = increase in number of muscle cells • In humans, most growth is through hypertrophy, but hyperplasia may also occur. -controversial Hypertrophy Pre-training Post-training • Training leads to new contractile proteins being expressed and incorporated into existing myofibrils. • When the myofibrils grow to a certain point, they split into two. Hypertrophy - genetics • Hypertrophy can also arise through genetics. • The Myostatin gene normally inhibits muscle growth. • Knock outs of this gene according lead to hypertrophy • For example, the “Belgian Blue” cow. Dietary Supplements • There are many dietary supplements available but only a few have been tested. • Some supplements are dangerous. • Creatine supplementation has been shown increase performance in some cases but usually only in beginning stages of training. Volek, J.S. et al. 1999. Medicine and Science in Sports and Exercise 31, 1147-1156....
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This note was uploaded on 01/22/2014 for the course BIOL 361 taught by Professor Dougaltshuler during the Fall '13 term at University of British Columbia.

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