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• 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
glycolytic Kohn, T. A. et al. 2007 J Appl Physiol 103: 932-940 Muscle size- effects of exercise
• Training increases muscle
• Muscles increase in size via
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.
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.
has been shown
some cases but
usually only in
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.
- Fall '13