yeah, traps/abs/calves are the classic slow twitch muscles. slow twitch tend to recover faster, need more reps(TUT), and don't grow as fast as fast twitch muscles.
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Arthur Jones has a neat little slow/fast twitch test out there, I need to find the link sometime. If one buys into the whole slow twitch "higher reps, more volume and frequency" and fast twitch "lower reps, less volume and frequency" in conjuction with fast/slow twitch testing one could derive a workout program based on some sort of scientific workout program, although I don't know how scientific it really is, that is catered to one's muscle fiber makeup.
I have been doing this for a few monthes now, I tested and found that the only fast twitch I have were delts and quads (both of which are my biggest muscles, delts too big really in comparison to my chest); and slow twich were traps/abs/calves and sadly, biceps. The rest were of mixed type. So far my results are very good, nothing to call up MuscleMag over but I have been making gains after I had been at a plateau for a while..
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Ok. Anyway, yeah training traps/abs/calves more often makes sense to me...