Post by carruthersjam on Jul 29, 2008 9:42:14 GMT -8
A few notes from a Duncan McDougall presentation regarding hypertrophy. Krista Scott-Dixon wrote:
Anyway, McDougall began by explaining recent theories about what hypertrophy
entailed. The general conclusion seemed to be that it was a result of an
increase in myofibrils, and that the microdamage of training, with increase
in contractile proteins, eventually initiated a longitudinal splitting
process. He then turned to a discussion of what exactly was responsible for
causing hypertrophy.
(a) Testosterone. Although testosterone was shown to be elevated immediately
following a weights workout, he indicated that it was actually a transient
effect of the muscular contraction itself.
(b) Protein pool. The availability of a protein pool was the next explanation
discussed, and like supply-side economics where demand did not increase,
this was also shown to be incorrect. Additionally, because post-exercise
feeding studies were done with subjects in a fasted state, and thus the
results cannot necessarily be extrapolated to average trainees, he did not
feel that detailed attention to postworkout protein supplementation was
necessary.
(c) Stretch. Long term passive stretch was indeed shown to increase amino
acid uptake, and increase protein synthesis, but this was only demonstrated
in vitro, and not in any human studies. Studies of eccentric reps showed
that soreness was not indicative of the degree of damage, and neither was
the rate of protein synthesis.
• Resistance exercise causes increases in muscle protein synthesis that peak about 24 hours later and persist for about 36-48 hours.
• Although some people think the anabolic hormone response to exercise plays a role in muscle growth, this probably isn't true. Hormones peak immediately after exercise while protein synthesis peaks much later.
• Training induced increases in protein synthesis occur in starved animals, in the absence of anabolic hormones, and even in muscle with no nervous system innervation.
• Increased protein synthesis — manifested as new protein — is added to the outside of muscle cells, making the cells larger. Likewise, the splitting of the myofibrils creates a greater number of myofibrils, all of which are capable of growth.
• Evidence does not support the idea that muscle fiber hyperplasia occurs in humans.
• Genetics and training play the largest roles in determining how large a muscle can become.
Anyway, McDougall began by explaining recent theories about what hypertrophy
entailed. The general conclusion seemed to be that it was a result of an
increase in myofibrils, and that the microdamage of training, with increase
in contractile proteins, eventually initiated a longitudinal splitting
process. He then turned to a discussion of what exactly was responsible for
causing hypertrophy.
(a) Testosterone. Although testosterone was shown to be elevated immediately
following a weights workout, he indicated that it was actually a transient
effect of the muscular contraction itself.
(b) Protein pool. The availability of a protein pool was the next explanation
discussed, and like supply-side economics where demand did not increase,
this was also shown to be incorrect. Additionally, because post-exercise
feeding studies were done with subjects in a fasted state, and thus the
results cannot necessarily be extrapolated to average trainees, he did not
feel that detailed attention to postworkout protein supplementation was
necessary.
(c) Stretch. Long term passive stretch was indeed shown to increase amino
acid uptake, and increase protein synthesis, but this was only demonstrated
in vitro, and not in any human studies. Studies of eccentric reps showed
that soreness was not indicative of the degree of damage, and neither was
the rate of protein synthesis.
• Resistance exercise causes increases in muscle protein synthesis that peak about 24 hours later and persist for about 36-48 hours.
• Although some people think the anabolic hormone response to exercise plays a role in muscle growth, this probably isn't true. Hormones peak immediately after exercise while protein synthesis peaks much later.
• Training induced increases in protein synthesis occur in starved animals, in the absence of anabolic hormones, and even in muscle with no nervous system innervation.
• Increased protein synthesis — manifested as new protein — is added to the outside of muscle cells, making the cells larger. Likewise, the splitting of the myofibrils creates a greater number of myofibrils, all of which are capable of growth.
• Evidence does not support the idea that muscle fiber hyperplasia occurs in humans.
• Genetics and training play the largest roles in determining how large a muscle can become.