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Hello Ron,
Re your question about the mismatch between greater damage but not
greater protein synthesis after eccentric vs. concentric exercise, and
that repair from damage seems to last longer than elevated protein
synthesis. The authors (Gibala et al. 2000) themselves suggested that
their results and those of another group (Phillips et al. 1997)
indicate that the amount of mechanical work done rather than the type
of contraction (and consequent damage) determined protein synthesis.
In both studies, the weight lifted in the concentric and eccentric
phases was the same. However, a factor to consider was that protein
synthesis was measured only at 24 h post-exercise. It is possible that
at 48 h (or later), when signs of damage are usually greatest, there
may have been a difference between eccentric and concentric exercise.
Another factor to consider is that exercise can elevate both protein
synthesis and degradation, so what really needs to be known is the net
protein synthesis. In the first day or two after eccentric exercise,
protein degradation may be elevated at least as much as synthesis.
<u> Finally, protein synthesis and degradation may fluctuate at different
times of the day and from day to day, so it is a bit of a ?crap shoot?
when you make a measurement at a given time.</u>
So the discrepancies you noted may be mainly the result of limitations
in experimental methods.