Q: I am totally onboard with a high-rep set first to fatigue slow-twitch fibers first. I’ve noticed visible size gains in only one week using the Anabolic Reload program. What do you think about an isometric hold (iso-bolic hold) in the contracted position, like the top of a leg extension, for over a minute to accomplish that same slow-twitch fatigue first?
A: That’s an interesting question. Most people believe that a bundle of fibers fire on a rep, then more bundles engage on the next rep, and so on as the set progresses. However…
If you’ve ever been lean enough to watch your quads fire during a set of leg extensions, you see fibers switching on and off throughout the range–like a fireworks show…
And if you hold at the top, you see the same thing–twitching as the multiple fibers engage and disengage.
So while we don’t have any research to back the assumption, it would appear that a long contracted-position hold can provide loads of slow-twitch exhaustion, so that the heavy full-range sets that follow activate many more fast-twitch growth fibers…
In other words, a static hold, or “iso-bolic hold,” should replicate the laser-focused warmup of a single high-rep set, producing more growth in both the slow-twitch and fast-twitch fibers if followed by heavy sets.
Keep in mind that this iso-bolic hold is much like blocking blood flow to the muscle. That’s because when the target is in full contraction, blood cannot enter or escape. That explains the pain.
And as far as blocking blood flow, there is a relevant study that we discuss in 3D Muscle Building, the official Positions-of-Flexion mass-building manual (Chapter 12, Warmup: Prelude to Mass, page 60). Here’s an excerpt:
Researchers placed a blood-pressure cuff on subjects’ upper arms for two minutes. The cuff was then removed and the subjects did wrist curls. Results: Those who had their blood flow impaired prior to exercise showed a 20 percent strength increase over the subjects who didn’t use the cuff. That indicates significantly better [fast-twitch] fiber recruitment.
Bottom line: A preliminary a high-reps set or a contracted-position static hold (iso-bolic hold)–either is an anabolic primer for freaky muscle growth.
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–Steve Holman and Jonathan Lawson
www.X-Rep.com