Q: I’m growing again with STX. But I was thinking that instead of 15 to 20 reps on set #1, how about getting to the fast-twitch fibers faster with a heavier 8-rep set instead? Then lighten the weight and do a Speed Set for even more fast-twitch stimulation.
A: The higher-rep initial set is more efficient, safer and better for hypertrophy—especially for older trainees—for a few reasons…
1) You must use a lighter weight, which reduces the risk of injury and joint trauma
2) You get more blood flow to the target muscle faster, creating a precision warmup that also has growth stimulation
3) You train more muscle-fiber types within a higher-rep set
Numbers 1 & 2 are self-explanatory. Let’s clarify #3 with a review of the Size Principle of Muscle-Fiber Recruitment (Hennemen)…
That basically states that muscle fibers are recruited by their size and force capacity. So in a given set, you recruit the slow-twitch first and gradually involve almost all fast-twitch toward the end of a set close to failure.
Scientists have identified seven muscle-fiber types, with four primary ones: 1 (endurance), 2a (endurance/power), 2b (power), and 2x (explosive)
So in a higher-rep set, you get an excellent fiber cascade: 1—> 2a —> 2b
ALL of those fiber types have growth capacity, with the 2b having the most. So what happens if you start with a heavier, lower-rep set?
You miss stimulating the 1 and 2a types to a great degree. That means you leave that layer of growth untapped.
Sure, most trainees do a couple of light warmup sets before hitting a heavier weight, but that doesn’t provide the efficient fiber cascade, with each type hitting the red zone before exhaustion and bringing in new fiber types.
Plus, warmups plus work sets takes three to four times longer.
That’s a simplified explanation, but all of the above is why ONE higher-rep set to failure first has such excellent growth activation.
But what about fatigue? What happens on the follow-up set? Do you even need a second set? What about the 2x fibers?
Answers tomorrow.
Till next time, train hard—and smart—for BIG results.
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