I thought I'd read somewhere recently that the whole thing regarding GH response to heavy compounds had been debunked... couldn't tell you where I read that though... i might even have imaginied it!
There is little evidence examining the relationship of isolation/compound exercises to the amount of test generated. What there IS plenty of is research (and evidence) supporting 'significant increases' in test, GH, IGF arising from compound exercises (the ones I've read include squat, bench, leg press).
Now there are two kickers here:
Hormone response to different exercises:
The only study I've found that analyses different exercise types and resulting hormonal responses compare bilateral to unilateral (i.e. regular leg press to single leg press... or two limbs vs. one) which shows that both stimulated the same level of test despite the total work done via unilateral exercise being lower (caveat: I don't know if they did both legs individually as part of the investigation).
This may suggest that test may reach a certain level beyond which it doesn't increase, irrespective of the exercise performed. There could be a couple of factors to this:
1) A hard bicep workout is just as test-worthy as a hard leg workout;
2) The study was rubbish and they did perform unilateral exercises on both legs;
3) A by-product of exercise stimulates the test, meaning the whole thing is not rate-limited (i.e. test will only go to a certain level).
4) It's not worth testing this for isolation because they don't produce enough test.
Hormone response during rest periods:
Another study looked at the test:cortisol ratio induced through different rest periods (30, 60, 90, 120) and found that 120s was a much higher (better) ratio than 30s (with no real difference between 60 and 90s). The issue here being cortisol's action as a catabolic. This suggests that - unbelievably - the lifter would get knackered faster and feel worse doing short rests, but that this sort of exercise is potentially more damaging (and, therefore, better for hypertrophyz?) than longer rest periods. There was also a comparative study showing that longer rest periods result in bigger strength gains over time, but that's another matter.
So what?
Now there are two kickers here:
Hormone response to different exercises:
The only study I've found that analyses different exercise types and resulting hormonal responses compare bilateral to unilateral (i.e. regular leg press to single leg press... or two limbs vs. one) which shows that both stimulated the same level of test despite the total work done via unilateral exercise being lower (caveat: I don't know if they did both legs individually as part of the investigation).
This may suggest that test may reach a certain level beyond which it doesn't increase, irrespective of the exercise performed. There could be a couple of factors to this:
1) A hard bicep workout is just as test-worthy as a hard leg workout;
2) The study was rubbish and they did perform unilateral exercises on both legs;
3) A by-product of exercise stimulates the test, meaning the whole thing is not rate-limited (i.e. test will only go to a certain level).
4) It's not worth testing this for isolation because they don't produce enough test.
Hormone response during rest periods:
Another study looked at the test:cortisol ratio induced through different rest periods (30, 60, 90, 120) and found that 120s was a much higher (better) ratio than 30s (with no real difference between 60 and 90s). The issue here being cortisol's action as a catabolic. This suggests that - unbelievably - the lifter would get knackered faster and feel worse doing short rests, but that this sort of exercise is potentially more damaging (and, therefore, better for hypertrophyz?) than longer rest periods. There was also a comparative study showing that longer rest periods result in bigger strength gains over time, but that's another matter.
So what?
1) If a lifter is using PEDs, the whole discussion on compoounds and hormones is meaningless.
2) There is no quantitative comparative evidence to indicate that test is better from compounds as opposed to isolation exercises.
3) Shorter rest periods will limit your rest gainz;
4) Nobody seems to bother testing hormone response to isolation exercises. Whatever that means. My guess is it's related to exercise intensity and resulting bi-products/stimulation/whatever.
Now... does the debate on hormone levels matter to the unassisted lifter? More test is no doubt better than less, but is the difference between compound vs. isolation significant enough to adapt a routine around it for maximal gainz? No data available.
So... I'd suggest:
1) Hypertrophy: lower rest periods;
2) Strength: longer rest periods;
