Stimulating Reps

[Mike Dillon]

I just finished reading Chris Beardsley's Hypertrophy book. In the book he discusses the idea of a stimulating rep being that which results in high motor unit recruitment with slow contractile velocity. He explains that a 5RM load is the threshold of full motor unit recruitment. If you perform a 5 rep max then you have effectively done 5 stimulating reps. If you do a 10 rep max then only the last 5 reps are stimulating. If you do a set of 10 with 1 RIR then you've only done 4 stimulating reps. So basically, the lower the RPE the more sets you will have to do to accumulate enough volume of stimulating reps; he alludes to the idea that 15 stimulating reps in a session as being a good target. He also states that loads as light as 30% 1RM can be just as effective as heavier loads so long as you perform sets to or near failure. There's other contributing factors that he discusses, especially the influence of peripheral and central fatigue on subsequent sets.

This makes a lot of sense to me. I'm interested in your thoughts. Also, it makes me wonder if volume (of stimulating reps) is a variable that needs to be progressed or if it should just be fixed at a specific number (e.g. 15) or range.

Thanks!

[Alex Kovaleski]

Speaking generally of the theory: it appears to be sound and is supported by some evidence, so I think it is worth examining more closely on an individual basis. I would just caution individuals against living by the ideas that anything over than 5 repetitions can't be effective, and that 15 total stimulating repetitions are always what we need to aim for in a session (per exercise). My judgment of the available information is that it would be unreasonable to view these numbers as invariable - rather, they will probably differ from person to person. But operating around the takeaway of "muscular work requiring more effort will most often yield more of an effect than the same quantity of work that requires less effort" is, in my opinion, the best practice at this time. You could try seeing how this theory applies to your own training by monitoring training outcomes (for barbell trainees: e1RMs on the main movements) and seeing if these correlate at all with a stimulating repetitions count per movement per time interval of choice (I'd recommend a weekly basis, tracking two stimulating repetition counts: main movement only, and main movement + close variations).

However, I do think that this theory has its most interesting influence on the structure of training in time crunch situations. Being able to recognize that not all programmed volume is "stimulating" can help refine programming recommendations so that only maximally-stimulating work is programmed for times when a trainee does not have ample time to train.

[MSupply]

Wouldnt your warm-up sets be considered your "Stimulating" sets? Therefore negating the whole concept? Warm up and do your FAYHVES or something close.

[Alex Kovaleski]

Can you explain how you arrived at the idea that warm-up sets would be stimulating sets?

[Mike Dillon]

Thanks for the reply, Alex. It has made me think about being more efficient with my workout time. Beardsley discussed the usefulness of drop-sets where you do a set to failure then take off 20% and immediately do another set to failure and repeat once more. If all sets are done with at least 5 reps then you've effectively done 5 stimulating reps. I tried this a couple weeks ago with bench. Started with 300# for 12, dropped to 240, and finished with 190 for 8 (I think?). From warm-up to finish I was done in about 10 minutes.

MSupply, a stimulating rep is considered a rep that provides a mechanical stimulus to the fibers of high-threshold motor units with slow contraction velocity. This can only be done with heavy loads (>5RM) or light loads at a minimum of 4 reps in reserve (which would only provide 1 stimulating rep for the set). If you do a set of 25 reps at RPE 10 then reps 21-25 are stimulating reps, reps 1-20 simply served to fatigue your lower-threshold motor units.

[Mike Dillon]

I meant to type, "you've effectively done 15 stimulating reps" when discussing the drop-set method.

[MSupply]

MSupply, a stimulating rep is considered a rep that provides a mechanical stimulus to the fibers of high-threshold motor units with slow contraction velocity. This can only be done with heavy loads (>5RM) or light loads at a minimum of 4 reps in reserve (which would only provide 1 stimulating rep for the set). If you do a set of 25 reps at RPE 10 then reps 21-25 are stimulating reps, reps 1-20 simply served to fatigue your lower-threshold motor units.
I was confusing stimulating reps for "pre-fatiguing". Thank you for the clarification.

[John Hanley]

FWIW, I think the general theory is compelling, but I think the details are probably quite wrong.

I don't think Beardsley properly accounts for the peripheral fatigue in the fiber of high threshold motor units. If I'm doing high effort reps with submax loads (say 65%-80%), I'm pretty damned sure I'm recruiting most of my motor units early in the set (NOTHING in my lifting experience suggests there's some untapped reserve of exponentially more muscle fiber on early reps with 65%). A build up inorganic phosphate from ATP hydrolysis will likely compromise the cross-bridging in the fiber of high threshold motor units that have been recruited early in submax sets.

I asked Big B about this ^, and he suggested that the peripheral fatigue won't compromise high threshold MUs until very late in a set. I find that implausible. Am I really to accept that - on high effort sets over ~65% my fatigue resistant fibers fatigue quickly but the fiber in my largest MUs doesn't fatigue until late in the set? That's crazy.

Also...he suggests "threshold velocity" for effective hypertrophy is the speed of the first rep of a 5RM. I think the logic for that threshold is...dubious. So....a .45 meters per second rep is fine and stimulating, but .6 meters per second rep compromises cross-bridging? Is this a binary? What would a "velocity-hypertrophy" graph look like? Even extremely fast barbell reps are slow-as-hell compared to max contraction velocities of a muscle (like 10-15% of a max contraction velocity).

Because I'm a contrarian asshole, I tried bench pressing with almost NO "stimulating reps" over the past 3 months. Things went extremely well. I highly recommend the zero stimulating reps [edit: okay, not "zero" but "minimal"] approach. Try it. Do a hell of a lot of reps with RPE 5-6 for a couple of months.

[Mike Dillon]

John,

Thanks for that reply. Coincidentally, I read the thread about stimulating reps on the Exodus forum yesterday and thought your explanation was a step or two closer to the truth. My exact thought was, "That John Hanley seems like a smart dude." I plan on re-reading that thread because I don't think I fully understand what you're trying to say. Is the approach you describe (7's @ 65%, 5's @ 70%, 1's or 2's @ 85%) an attempt to reach the point where velocity begins to make a linear decline and stop at that point or shortly after? In other words, do you try to reach the starting point for full MU recruitment and stop? Is this done for the purpose of controlling fatigue/soreness? If you push past an RPE 6/7 are you saying that the high threshold MU's are fatiguing which requires the low threshold fibers to change their firing frequency in order to maintain the effort?

I actually did 65% for 8 sets of 7 with about 2.5 min. rest yesterday for my bench. I do not have a bar speed device so I made sure to try and pay close attention to my perceived speed. What I noticed is that starting on about the 6th rep of each set my speed begin to noticeably drop. After 3 sets I could see how this was keeping my fatigue in check. So much so that I went ahead and began doing my pullups in-between sets. I had to add an extra minute of rest at that point. I probably need to fine-tune my numbers. I was working off an e1RM of 365 lbs but it does seem like this strategy leaves a little room for error.

Please correct any misunderstandings I might have. Again, thanks for the reply.

[Jordan Feigenbaum]

FWIW, I think the general theory is compelling, but I think the details are probably quite wrong.

I don't think Beardsley properly accounts for the peripheral fatigue in the fiber of high threshold motor units. If I'm doing high effort reps with submax loads (say 65%-80%), I'm pretty damned sure I'm recruiting most of my motor units early in the set (NOTHING in my lifting experience suggests there's some untapped reserve of exponentially more muscle fiber on early reps with 65%). A build up inorganic phosphate from ATP hydrolysis will likely compromise the cross-bridging in the fiber of high threshold motor units that have been recruited early in submax sets.

What do you mean by high effort reps? And depending on rest periods and previous training definitely influence peripheral fatigue, plus the multitude of inputs into central fatigue.

I agree though, the idea of stimulating reps is useful for describing reps that contribute to the desired outcomes, but I don't think Beardsley's description adequately defines what they are and probably overstates the difference in outcomes between stimulating and non stimulating reps- suggesting that the phrase "stimulating reps" needs to be expanded.

Also...he suggests "threshold velocity" for effective hypertrophy is the speed of the first rep of a 5RM. I think the logic for that threshold is...dubious. So....a .45 meters per second rep is fine and stimulating, but .6 meters per second rep compromises cross-bridging? Is this a binary? What would a "velocity-hypertrophy" graph look like? Even extremely fast barbell reps are slow-as-hell compared to max contraction velocities of a muscle (like 10-15% of a max contraction velocity).

Yea I think his take on this is that if the velocity is too high the force exerted by each muscle fiber is decreased to a point of it being a less effective mechanical stimulus compared to a slower contraction, which has to (in his view) be evoked by a heavy enough load or enough fatigue built up to cause the volitional decrease in velocity.

If he's taking in relative terms, I'd probably agree with him in that slower velocity reps 2/2 to loading or fatigue probably are better for hypertrophy than very fast reps, though there is obviously a non-zero hypertrophy stimulus exerted by your Westside -Style training (I kid).

I suppose if we just tell everyone to Grind it Out™ they will get the biggest hypertrophy results, right?

[John Hanley]

What do you mean by high effort reps?

It's a little tricky to discuss "high effort" absent fatigue, especially given that -- in barbell work -- we're so used to using RPE scaled to failure (like...what's a single RPE 8 vertical jump?). That qualifier out the way, a high effort rep is something like RPE 8 for a single rep, though scaled not to failure but to max volitional effort.

depending on rest periods and previous training definitely influence peripheral fatigue, plus the multitude of inputs into central fatigue.

Honestly, I think it's a little ridiculous to speak about single factors of fatigue with anything like confidence. But I'm trying to work within the internal logic of Beardsley's argument.

His claim is that acute intraset peripheral fatigue in the fiber of smaller motor units leads to increased recruitment of type II motor units as a set progresses.

But what about acute intraset peripheral fatigue in the fiber of my big MUs?

His argument only works if large MUs aren't recruited early within a set. The burden of proof is on him that his is the case. So, I really don't have to do anything other than fold my arms and ask him to convince me that on sets using 15-8RM loads my large TYPE II MUs aren't recruited (and starting to acutely fatigue) within the first 50% of reps. He hasn't done that.

I find it implausible that --using a 15RM load -- I hit peak transient velocity, peak average velocity and peak force somewhere between reps 4 to 6 BUT, in Beardsley-World, this happens absent high type II recruitment? Really? Again, burden of proof on him. I think my concerns are warranted.

Yea I think his take on this is that if the velocity is too high the force exerted by each muscle fiber is decreased to a point of it being a less effective mechanical stimulus compared to a slower contraction, which has to (in his view) be evoked by a heavy enough load or enough fatigue built up to cause the volitional decrease in velocity.

If he's taking in relative terms,

Well, yeah, but in the sort of barbell work that we do (like ~18RM or heavier loads) everything is slow. He doesn't just get to DEDUCE that more slower is more better. Doing so can lead to bone-headed overly simplified conclusions like "only reps RPE @6+ are optimal stimulating". The solution for a range of "optimally stimulating velocities" is almost certainly a constrained optimization problem...and I'd guess that instraset fatigue of fiber in type II MUs will be a factor in that nasty optimization problem.

You know who else abused deductive logic to build horseshit models for "optimal" lifting?

I shan't utter the name.

[John Hanley]

I've never had a "replication crisis" running Greg's programs. They work. Therefore, I put his models in the "potentially valid" drawer.

How's your SRA cycle these days? Overload Event going well?

My SRA and Required Duration of Overload Event (RDOE for the cool kids) are shrinking! From a training age perspective, I've gotten younger! How about that?

[Jordan Feigenbaum]

It's a little tricky to discuss "high effort" absent fatigue, especially given that -- in barbell work -- we're so used to using RPE scaled to failure (like...what's a single RPE 8 vertical jump?). That qualifier out the way, a high effort rep is something like RPE 8 for a single rep, though scaled not to failure but to max volitional effort.

Hmm, that is interesting to consider. I think max volitional effort as an end point of the RPE scale is similar enough to a RIR scale (failure-based) to use them relatively interchangeably depending on what is being rated (the single vertical jump example is better suited to RPE than RIR, of course). I think that definition of high effort rep (HER?) is reasonable and has plenty of room for modification under different scenarios and as we learn more .

His claim is that acute intraset peripheral fatigue in the fiber of smaller motor units leads to increased recruitment of type II motor units as a set progresses.
But what about acute intraset peripheral fatigue in the fiber of my big MUs?

His argument only works if large MUs aren't recruited early within a set. The burden of proof is on him that his is the case. So, I really don't have to do anything other than fold my arms and ask him to convince me that on sets using 15-8RM loads my large TYPE II MUs aren't recruited (and starting to acutely fatigue) within the first 50% of reps. He hasn't done that.

Yea I think the data on running suggests they ARE recruited relatively early on and then, by definition, would be fatigued somewhat- though I cannot say with confidence that the level or type of fatigue is useful for generating outcomes like increased muscle CSA or force production.

Well, yeah, but in the sort of barbell work that we do (like ~18RM or heavier loads) everything is slow. He doesn't just get to DEDUCE that more slower is more better. Doing so can lead to bone-headed overly simplified conclusions like "only reps RPE @6+ are optimal stimulating". The solution for a range of "optimally stimulating velocities" is almost certainly a constrained optimization problem...and I'd guess that instraset fatigue of fiber in type II MUs will be a factor in that nasty optimization problem.

Yea I would agree with that. Probably a range of velocities work under various conditions to produce similar outcomes. Would be hard to simplify without additional constraints.

You know who else abused deductive logic to build horseshit models for "optimal" lifting?

I shan't utter the name.

Hah!