[b said:
Quote[/b] ]Why should a person do heavy isolation movements with a mechanical load if they are using the core compound lifts in their routines? During the compound lifts, the smaller muscle groups are being exposed to heavier loads than one could perform with isolation movements. Wouldn't it be ideal for hypertrophy if the person just focused on moving the heavy mechanical load during the core compound lifts
With respective to heavier vs. lighter weight, it's not directly applicable because we're talking about one body part vs. many. The key advantage to compound movement over isolation is that you have a much finer gradient of progressive load that can be indirectly applied to the muscle. In other words, it's easier to do progressive steps of military press during each session of HST than, say, lateral raises.
Also, about 75% of isolation movements people use -- pushdowns/kickbacks, normal flies/pec-dec, normal barbell curls, normal lateral raises, and so on -- only offers marginal value (if that) over their matching compound movement. The reasons are usually two-fold. The isolation movement doesn't work the muscle over anymore stretched ROM. Plus, with the notable exception of pulling/rowing compound movements (pullovers and DKM's lat press are legitimately superior excercises for lats than the chin/pulldown), the weak links of said isolation movement and matching compound movement are at the stretched portion of the muscle anyway. They are, however, excellent at generating metabolic stress.
The exceptions to the above are what are what the Position Of Flexion system calls the stretch-point movements. These do accelerate development by increasing the overall strain per relative maximal load. They work the muscle beyond the stretched ROM of the compound movements. These are your skullcrushers/overhead extensions, incline bench bicep curls, superlow DB flies, barbell pullovers, lateral raises across the body, and so on. BUT, they come with the caveat of limited choices with loads. Thus, you should schedule them later in your workout plan, and you may have to use various cheating or compound-iso techniques to get yourself a few extra increments.
From a pragmatic standpoint, your routine should be built around compound movements, and you should be looking at ways to safely increase strain with your compound movements through the post-5s. It's just easier that way. But you can use the stretch-point isolation movements to palpably speed up areas, understanding that they require more thought to implement.
As for metabolc work, because you're training 3x-a-week, a little bit does go a long way. The 15s set is a nice way to bring things up with little risk and headache to your program. And the pulses help bring things up further without wasting your time, albeit at higher risk. Remember to increase post-WO carbs if doing anything extra for metabolic work.
cheers,
Jules