To Pump or NOT to Pump? This is the Question.

23 comments written by Joshua Trentine

More of What We Want and Less of What We Don’t

I am unaware what role muscular “pumping” plays in either stimulation or ultimate growth.

What should be understood from the onset, is that while attempting to achieve the real objective of exercise,  we make demands on the musculature that require large amounts of  blood, oxygen and nutrition, as well as waste removal.

The pump is a consequence of this objective.  It is not our intent, but merely a side effect.  We do know that maximal pump is affected to a large extent by hydration, electrolyte balance, glycogen levels as well as amino acid concentrations.

Let’s discuss the origins of the “pump”.

The pump or engorgement of the musculature occurs secondarily to a negative feedback loop as a consequence of occlusion.

Exercise of this type necessitates that blood flow oscillates due to high intra-muscular pressure produced by muscular contractions.  However, said contractions create high pressures that occlude the aforementioned blood flow.

The degree of this occlusion appears to be directly proportional to the intensity or force of the muscular contraction.  It has been observed that efforts above 60% of maximal voluntary contraction (MVC) may entirely occlude blood flow.

The result of the negative feedback loop dramatically increases the blood flow to the affected muscles as a consequence of the fact that the muscular effort has dropped below the level which caused the occluded blood flow to initially occur (60% MVC).

The resulting phenomenon explains the pump.

My experience has led me to conclude that the most profound pump can be produced in the least amount of time through a combination of several factors.

They are high volitional effort exhibited by the subject, proper resistance provided by the machine and slightly longer set durations.  Where the largest degree of pump is concerned, I am opposed to short duration sets, performed with limited range of motion, that are often exhibited by many bodybuilders.

My personal experiments, as well as the training of thousands of clients, has led me to conclude,  that the modality of exercise that we promote,  produces a  superior, severe and predictable pump,  that is longer lasting than any other form of exercise.

On what do I base this conclusion?  Through the simple fact that the muscle remains occluded longer, with a more constant tension (provided by the accommodating resistance curve of the machine) and consequently produces a larger flush after the exercise is concluded.

Having been a professional bodybuilder I can probably predict, with a high degree of accuracy, your reaction.

Perhaps it goes something along the lines of “I’ve been performing fast, short, low weight, pumping repetitions for as many years as I’ve been competing-it works”.

My answer – yes it does work, sometimes.

This action does produce a pump during the performance of the set, but the results remain unpredictable.

Have you ever attempted to pump your muscles and no matter how hard you tried or how many sets you perform you just can’t achieve a satisfactory result?

Knowing the answer to this problem is probably worth the entire time investment you have in reading this article.

The answer is “instant gratification”.

Every repetition you perform adds to the engorgement of the muscle.  More blood volume, more engorgement.  The repetitions are short, brief and usually partial.  They provide very little negative work (back pressure) that allows the muscle to rest with every repetition you perform.  This respite produces reduced occlusion and poor fatiguing characteristics.  Simply stated, sometimes it works and other times it doesn’t.

Be advised that this type of performance can result in significant fatiguing of the involved muscles. However I have an altogether different theory on way this occurs. This theory that I will explain latter, partially explains why I perform my exercises in a manner opposite to the behavior I have just described.

First…Which is better?

Is it one big predictable profound flush after the set, or many mini pumps during the set?

It depends what you are trying to do, if you are about to step on stage to pose for the next thirty minutes or take some vanity pictures, I strongly recommend that you do not exhaust (inroad) the muscle too much. In this case I would recommend “pumping” reps.

If I wanted to produce the greatest exercise effect I recommend prolonged occlusion (Renaissance Exercise type reps). It will provide a more consistent, predictable and sustained effect and it will allow for Random failure as opposed to a metabolic back up. Meaning the set ends because the available fibers have been tapped out, not due to congestion and or mechanical constraints of the machine, such as friction or poor resistance curves.

Therefore, more stimulation and as a side effect more occlusion followed by more blood, oxygen and nutrition.  More of what we want and less of what we don’t….congestion and interruption of the Real Objective of Exercise.

Why does the body produce congestion?

Why do we experience edema?

A theory I have proposed is that the system is attempting to shut down.

Biological self-preservation and system redundancy is circumvented by the atypical act of slow repetition speed.

In a sense we “fly under the radar.”

The stimulus is presented in a manner so foreign to the body that we stay beneath its protective margins, at least for a longer period of time.  This may also account for the protective nature some have expressed when we encounter “harsh” resistance.  “A bracing affect if you will.” – Negative Thoughts

Most of us have trained on conventional exercise equipment, machines designed for more ballistic type training. Let’s talk about one exercise done this way and study it.

Let’s consider the prone leg curl (any conventional brand, including Nautilus.)

Select a load normally used for 10 conventional repetitions, enter the machine, lay prone, hook the legs, and apply force suddenly.

Assuming the selected weight is reasonable, on the first rep the pads will come all the way to the buttocks, the hamstrings experience an intense full range contraction, almost as if they are going to cramp, “ouch”!

On the next rep a similar experience, perhaps a few degrees less range of motion.

By the third or fourth rep the movement arm is nowhere near the buttocks, of course you continue on… you haven’t “failed”, have you?

In order to continue the set you will find that with each and every subsequent rep you will lose some range on the contracted end and as you continue also on the stretched (extended) end, but you continue… haven’t “failed” yet, have you?

This is high intensity training, therefore you continue along with these “reps” (partials) and you will find that as you continue to lose range of motion on the ends, movement in the middle of the range is still possible, but some more of it disintegrates as you plug away, you haven’t “failed” yet, have you?

Movement is still possible, small pulses somewhere around halfway between the knee being straight and it being bent to 90 degrees.

No matter how many times you replicate this set, at these speeds, the set will terminate the SAME way.  Reps may vary, but you will lose range on the ends until you can no longer budge the movement arm anymore.

Wait a minute…did you ever fail?

NO you didn’t!

You just congested the muscle beyond the point of function, gummed it up, pumped it, in the process eliminated the ability to recruit maximum musculature and eliminated any extended occlusion required to achieve a superior, long lasting and predictable pump.

And is it possible that the muscle always runs out of steam in the same part of the same set every time?


You ran into two problems; one is mechanical, which we will save for another article, the other metabolic.


So what happened?

In the article Negative Thoughts the author wrote; “It isn’t friction gentlemen, but whatever the hell it is; it affects us less by using slower protocols. Comparing when you get stuck going fast versus going slow screams that you don’t understand the salient factors involved.  Most guys who try and compare protocols don’t understand that reaching failure and inroading deeply are not the same.”

The muscle becomes so congested, so quickly, because of the aggressive action on the initiation of positive which contributes to the momentum, which contributes to momentarily decline in tension, which is followed by a poorly loaded negative. Very high efforts followed by moments of lower tension and respite, perhaps even moments below 60% MVC. The situation only worsens when you watch the more advanced subjects train.

“Their ability to contract and un-contract is extraordinary.  Intensity=inroad? – No way.  What you think you’re experiencing and what the muscles are truly experiencing may be very different.” – Negative Thoughts

The more advanced the subject, the more muscle and the better he can contract and uncontract- the more blood, oxygen and nutrition his muscles will require.

The method that he employs will ultimately determine if and when the pump arrives and if the pump helps or hinders his efforts, his intent.

Let me know your thoughts by posting them in the comments section below.

And if you liked this article, show your love by hitting the LIKE button as well!

{ 23 comments… read them below or add one }

avatar Scott Springston March 14, 2011 at 12:55 pm

Sorry but I don’t see a “like” button or I would have clicked it. Good article! I guess I must really be doing something wrong in my pathetic attempts at REN-EX reps. I find I get more pump from regular faster reps but I guess that’s because I really don’t know what I’m doing and I don’t have the proper equipment? Very frustrating.I know that getting a good pump may only be an indicator of a good set and only a by product of a set where you may or may not have deeply inroaded a muscle but other than that pump feeling it’s really hard to tell if I’ve pushed a set hard enough to make my body overcompensate and get stronger? I’m beginning to see that a muscle can fail for other reasons than one might suspect, like to much congestion vrs inroad but danged if it isn’t hard to figure out which it is? Keep talking, maybe it will eventually sink in on how to figure it out?? It seems there is no easy way to tell you have failed because your muscle got to congested or you inroaded the muscle more??


avatar Joshua Trentine March 15, 2011 at 10:33 pm

Poor strength curves and friction based respites will compromise the effect.


avatar JOHN O'ROURKE March 14, 2011 at 1:26 pm

Hi Josh.
A very thought provoking article, thanks for taking the time to share it with us. I gather that you consider occlusion to be an important factor in growth stimulus. Lot’s to ponder, thank you.


avatar Joshua Trentine March 15, 2011 at 10:31 pm


It seems to be and it’s just another upside of this method.


avatar Scott Springston March 14, 2011 at 1:38 pm

Oh I forgot, nice pictures Joshua!! Please post more!!


avatar Joshua Trentine March 15, 2011 at 10:29 pm


Thank you, i will post more, i have many pictures. My goal is to exceed the condition i achieved in 2005-2007 and take new pictures in 2012.


avatar Andrew Shortt March 16, 2011 at 9:30 am

I had the exact issue with my hams in the prone leg curl. It wasn’t until I spent time learning to follow through to the top in the MedX version that I achieved some symmetry in my legs. I was so weak part way up that even with the reasonable fall off in the MedX it took a lot of will to keep it going. Over time I started to fail randomly and my biceps femoris started to come up.


avatar Joshua Trentine March 16, 2011 at 12:43 pm

It gets A LOT better on the MedX compared to most manufacturers, but I still think thier curve, on that machine, leaves much to be desired in the contracted position. None the less a example of what can be accomplished when we marry equipment and protocol; random failure points, deeper inroad, more complete development.


avatar Andrew Shortt March 21, 2011 at 3:29 pm

Yes I attempt your type of protocol on the leg curl, ext, chest press, pulldown, row etc – they pale in comparison to Ken’s leg press. The row is not bad though at least for me and fellows my dimensions. Need the chest press and standard leg press set a certain way to make it work reasonably well.


avatar Joshua Trentine March 21, 2011 at 3:57 pm


i try to explain this to people who use MedX, there is no way to know exactly what i mean until using Ken’s machines.

the subject experience is way different, not to mention the weight stack issues with MedX.


avatar Jonas Olofsson March 16, 2011 at 4:31 pm

Intresting! Still, my experience is that I never really got anything from the pump and often have problem achiving it. I have traditionally been
a “move the weight” guy instead of a “empty the tank” guy which is so very spot on. The RenEx experience have so far tought me a lot. Still curios what more to learn.



avatar Joshua Trentine March 16, 2011 at 4:48 pm


I am unaware what role muscular “pumping” plays in either stimulation or ultimate growth.

Although I will say that the ‘move the weight’ mentaliy does effect these circumstances.

thanks for taking the time to comment I hope we can provide that learning material.



avatar Donnie Hunt March 17, 2011 at 11:36 pm

Very thought provoking article as usual. The equipment I have access to is very simple, very conventional. Your talk about leg curls definately hits home. Seated leg curls seems to “feel” much better than prone for me personally. I’m a big proponent of both compound and so called isolation exercises. Your comments about “flying under the radar” made me think. Some of your recent comments on Dr. Darden’s site about using too much weight have made me think a lot also. It’s funny with some of the equipment I use is just very simple but seems to really match my strength curve.


avatar Joshua Trentine March 18, 2011 at 1:02 am


Thank you, i appreciate you taking the time to stop by. i would like to hear more about your equipment, in some cases simpler is better, I’m always curious to hear what is ‘working’.

Your sense of feel on the Seated Leg Curl is consistent with the biomechanics, most times in a Prone Leg Curl we have to over come passive insufficiency of the Rectus Femoris, which is a two joint muscle that crosses the knee and the hip, it is a knee extensor and a hip flexor, it can passively restrict your ability to flex your knee in the prone position. In the seated position the Rectus Femoris is on a slack and your knee flexors will not have to overcome it. Another “tip” on this exercise is to make sure you dorsiflex your ankle on the positive excursion, this will create sufficiency for the Gastrocnemius(the gastroc crosses the ankle&knee therefore it can function to assist in knee flexion) to assist the Hamstrings to flex the knee.



avatar Donnie Hunt March 21, 2011 at 12:55 pm

Thank you very much for the leg curl information, Joshua.

The equipment that I have had access to recently is pretty basic. I have access to I believe an “Icarian” 45 degree leg press. I know what you mean by the congestion problems using this type of a leg press and the safety concerns. The chest press machine I have access to (i’m not sure of the maker) doesn’t quite “feel” right. The movement arm is fixed. The handles allow you to use a wider horizontal grip, or a closer neutral grip. I’ve found kinda angling my hands a bit on the neutral grip “feels” pretty good. For pulldowns I use a standard overhead pulley. I’ve experimented with various grips on these. The seated rowing machine is very basic. It also allows for a close neutral grip or wider horizontal grip. I usually use the neutral. This machine seems to “feel” right. The load feels heavy and seems to match my changes in strength closely throughout the movement. The row doesn’t use any kinda of variable resistance system. I don’t think the chest press does either.

I’ve pretty much chucked the squat or any movement that I have to worry about how i’m going to get the weight back down when I fail. Additionally after listening to what Bill DeSimone had to say about the architecture of the spine, the squat just doesn’t seem like a good idea to me.

I would say my current method of strength training are strongly influenced by you, Jones, McGuff, Little, Baye, Sisco, Darden, etc. There are definant differences in the protocols but also alot of common ground.


avatar Donnie Hunt March 21, 2011 at 12:59 pm

I need to put Hutchins in there as well.


avatar Joshua Trentine March 28, 2011 at 8:53 pm

i’m with you, in the year 2011 there are better ways to load the lower extremity than with a bar across you back


avatar Donnie Hunt March 18, 2011 at 12:58 am

A comment that Mike Mentzer made on an old interview continues to pop in my mind when I reading about strength training. He says something along the lines of, “On a much deeper, technical level, the science of bodybuilding revloves around muscular contraction”. This comment makes me think of something you said, Joshua. Something along the lines of, “Getting everything you can from, or focusing on every second of every rep when doing an exercise”.


avatar Wilson March 27, 2011 at 4:19 pm

Hi Joshua,
Great article but I did not quite understand it. Are you saying that a real pump set is when one goes slow and controlled on both the negative and the positive portion of a lift, contract during the whole positive and negative portion of a lift and at the end of a lift un-contract before contract again for a following rep and failed at an undetermined numbers of reps per set?
Let me know if I got the gist of it.

Thanks, Wilson.


avatar Joshua Trentine March 28, 2011 at 8:46 pm

we get a better pump, more sustained, more predictable and longer lasting from Renex.

what this ultimately means….i don’t know, but i don’t really see any point in “pumping” muscles with light weights and short ROM unless you are getting ready to step on stage at a bodybuilding contest.

and… certainly don’t want the “pump” to keep you from reaching the greatest level of stimulation from your exercise set, especially if you only train with one single set.

i’m not sure if i understand your un-contract question, but i do not recommend any respite…only continuous tension during the set. the pump will arise after the set once the respite occurs.


avatar Chad Mullens A.K.A. theTummy April 27, 2011 at 9:08 pm

I finally have gotten around to read some articles on this site. Very informative and explained in a way that makes me want to really s-l-o-w things down and focus on the stimulation – not the pounds and not the number of reps.

My real concern is if the Cybex equipment at my gym will be conducive to this type of protocol?
*now I really need to read your thread on Darden’s site.


avatar Joshua Trentine April 27, 2011 at 10:37 pm

welcome Chad,

i think you are getting our message; focus on the qualitative over the quantitative and internal cues over external cues.

by definition our protocol can only be done in an ideal environment, some will take this as a negative i just see it as an ideal.

I’d have to judge equipment on a case by case basis, some equipment can allow you to get closer to this ideal than others. I’ve used a few pieces of cybex that work fairly well.


avatar Bradley warlow February 14, 2013 at 3:13 pm

Could too much occlusion cause a rise in blood pressure? I have noticed a very uncomfortable feeling when using continuous tension; when approaching failure the congestion seems to build up towards the end and i get a senalsation which is disconcerting! Just wondering if anyone else has had this experience, i dont seem to noice it when i relax the muscles incrementally between each progressive contraction. i.e. Standard repetition speed.


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