Other/Mixed Why partial reps for ST fibers

[North Coast Miller]

Thanks Mike, nice article. In practical day to day hypertrophy training my body adapts quickly to specific stimulus, drop sets for instance work for 2-3 sessions the I have to switch modes.
Higher rep training tends to give me a muscle ache feeling and dullness in contractile intensity during follow up work. I've used many different strategies but always seem to gravitate back to 10 reps while varying loads, TUT, intensity, exercises etc.
Same but different using the above strategy enabled me to build muscle consistently.

This exactly what I've found as well. Or maybe it is TUT roughly equivalent to 10 reps of an average lift as I speculated above.
I've improved endurance/work capacity best by doing interval work, but recently getting good results with restricted/limited ROM.
Have used Duck Walks in the past to help with squat endurance.

 

[Anna C]

An interesting footnote is to do the "to refusal" in the first option. In the second option your would only do the last one in the set "to refusal." "In Russian literature, when all-out sets of bodybuilding exercises are prescribed, one is instructed to do the lift "to refusal." Contemplate the difference between refusal and failure."

But Mr Miller, you make me wonder; how does starving a slow twitch muscle fiber of oxygen while using it cause growth? You would think (as you alluded to) it would grow better being used under more aerobic conditions. 30-60 seconds of partial reps is very anaerobic still.

I'm wondering the same thing as @rickyw. I'm thinking it's something like this -- the contraction is not forceful enough to recruit fast twitch fiber, it's moderate and sustained enough that slow-twitch can do the job. But, that fiber does suffer from lack of blood flow and eventually needs to stop contracting. The growth then comes from that stress and the resulting adaptation -- the body realizing it needs a new capability that is being demanded of it, and then building it for the next episode. More slow twitch fiber would do that job better than less.

And as for the suffering from lack of blood flow, maybe this is the difference between "refusal" and "failure" referenced in the quote above. When slow twitch fiber runs out of oxygen and everything else supplied by blood flow, as with a sustained hold with very little movement in the middle of the push-up position, it eventually "refuses" to continue. When fast twitch fiber fatigues to the point where cannot sustain a forceful enough contraction to complete a movement, as with a max set of full ROM explosive push-ups, this is failure. It does feel a little different...

 

[Anna C]

The widely available research literature has not really nailed down the specifics yet. What is commonly practiced is 1-3 sets of 20ish repetitions to failure, with short rest periods after the normal heavy training. This is what seems to work with natural bodybuilders currently.

This talk of bodybuilding has me wondering.... what type of muscle fibers are they building? Some of both, I'm sure (fast and slow twitch), but is there something about their training that actually builds a higher ratio of slow-twitch fiber, compared to a powerlifter for example? Does the muscle look different, is it easier to keep, or some other advantage?

 

[mprevost]

This talk of bodybuilding has me wondering.... what type of muscle fibers are they building? Some of both, I'm sure (fast and slow twitch), but is there something about their training that actually builds a higher ratio of slow-twitch fiber, compared to a powerlifter for example? Does the muscle look different, is it easier to keep, or some other advantage?

No doubt it is mostly fast twitch muscle fibers. They have a much higher potential for hypertrophy. But, to get the maximum development, training the slow twitch fibers also makes sense. Therefore the 1-3 sets of high reps after the heavy work is done. As far as detraining, I don't know of any data looking at detraining rates of fast vs slow twitch fibers. However, it is clear that muscle disuse causes a shift towards fast twitch fibers and more use causes the opposite. With age there is also a selective loss of fast twitch fibers.

 

[rickyw]

But, that fiber does suffer from lack of blood flow and eventually needs to stop contracting. The growth then comes from that stress and the resulting adaptation -- the body realizing it needs a new capability that is being demanded of it, and then building it for the next episode

This is a plausible explanation

 

[North Coast Miller]

With most resistance training the ratio is going to build fairly equally and not far from the general population. Slow twitch generate nearly the same amount of force per cross section as fast twitch, but generate it at slower rate - also don't grow as large. This effect cannot be as pronounced as commonly believed or the average ratio of fast to slow would skew way to the type 2, that's not what is observed.

The problem with preferential resistance training slow twitch, is the loads tend not to be great enough to stimulate hypertrophy. Greatest improvements to slow twitch endurance tend to come from training at higher intensity to promote better throughput of pyruvate.

Slow twitch are always getting a workout - first in, last out. But this does not address specificity and ROM, which is where I believe the real benefit comes from with this strategy.