Dumpers Part IV, Segment E

18 comments written by Joshua Trentine

Part IV
Segment E

Ken Hutchins, Josh Trentine, Gus Diamantopoulos,
Drew Baye & Al Coleman


On January 11, 2012, the team traveled to Evansville, Indiana to experience the Exerbotics.

Despite our biased expectations of what these devices would provide, we did hold some glimmer of hope that they could provide a similar feel to what one might experience with a set of properly applied manual resistance exercise. Manually resisted exercise is the most efficient approach to exercise with regard to muscular loading, however it is fraught with danger and inconvenience. We stand ready to abort our present products in favor of a tool that can supply this efficiency of loading if devoid of the adverse issues. Our hopes for Exerbotics were dashed.

For starters, the Exerbotics technology operates on the faulty premise that each individual has specific and personal strength curves for each exercise. The machine provides no predetermined curve. The subject is, therefore, tested for the purpose of determining his strength curve for both the positive and then the negative phase. The administered test is a “dynamic maximal force production.” This dangerous, inaccurate, and unnecessary test is made yet more dangerous by requiring this of a fresh musculature.

By the way, researchers commonly report that, as part of their methods, resistance selection for a strength-training exercise is determined as a percentage of a one-repetition maximum performance. This must never be done! This must be outlawed for everyone—including researchers!

A provided monitor displayed the subject’s force output as a graph for both the positive and the negative excursion. We were repeatedly told that a negative curve should be “different than the positive because the musculature is much stronger during the negative.” This statement is a non sequitor. These two concepts are not to be connected by the word, “because.” The first phrase is not dependent upon the second.

In addition, the magnitude of force potential of the negative is greater than the positive, but this will provide similar force profiles, not different.

Their statement provides the most profound example of this misconception that we’ve encountered to date. How might a muscle possess a different strength profile (shape of its curve) just because it is now un-contracting instead of contracting? There is nothing physiological or physical to explain this. The displayed test curves did display a difference between the positive and negative excursions, but the shape of their profiles—these were also different—was not because the targeted musculature was stronger while lengthening.

By the way, only the MedX testing equipment is capable of rendering accurate strength testing. To do this, it must be a static test and performed on equipment with rigid immobilization and stabilization. Dynamic testing—as is performed in the Exerbotics—is dangerous, inaccurate and useless. And although we deplore the MedX testing for general application, it remains the only way to obtain accurate strength measurement.

Instead, we experienced a motor that ramped up after the upper turnaround to force values based on the manufacture’s ideas of what should be happening. The test curve changed, because the increased resistance provided by the motor necessitated that the body brace and recruit outside help to handle the increased load—thus skewing the resulting curve. Once again, our best imagery regarding the experience on this equipment was that of being inside a trash compactor. Along this line, Ken Hutchins remembers an old episode of Superman where the man of steel rescues Jimmy Olson and Lois Lane from a room designed to slowly shrink and crush them.

Their “idealized” graph is depicted in this link:


The chest press is quite a bizarre experience and seems to be the best example of the potential danger of these devices. Once the motor is set to its predetermined speed it begins to rev and the subject is expected to somehow gradually apply force as this is happening. This is nearly impossible. The graduation of force is abrupt and disrupting.

During the positive, the subject is instructed to “keep the line of force above the one presented on the screen.” With the arms just shy of lockout the subject sustains force as the motor redirects and increases its output in preparation for the negative excursion.

Once again, this is abrupt and promotes body bracing to absorb what is being placed against the subject.

We consider ourselves to be on the higher end of the motor control continuum and found it absolutely impossible not to have our shoulder girdle driven upwards towards our ears. Our shoulders felt as though they were going to dislocate. We fear this experience for a subject with a lower skill set and/or with debilities.

The later half of the negative felt like a load respite, and there was essentially no lower turnaround as we had to statically apply effort while waiting for the motor to change again. Hence, the principle of a meaningful and continuous load is violated on this equipment.

The set of muscles that were responsible for the positive were not the same that were involved during the negative. Each rep essentially involved two different exercises. We believe that, even though these devices do provide deep levels of inroading, they do so in an inefficient manner, and do not provide direct inroading. The inroading was global as though wrestling a bear.

In addition to the chest press, we performed the pulldown, the leg press, and the compound row. The experience on these exercises mirrored that of the chest press. One of our staff, Al Coleman, injured his neck during the pulldown. This injury was debilitating for about a month and remains at least a faint presence with some meaningful resistance to cervical rotation today—five months later.

The poor bio-mechanical design of the exercises adds another level of complexity and danger to these devices. They are devoid of proper tracking of the muscle and joint functions. Apparently the human body is to adapt to the designs rather than the other way round.

We were fatigued after the session but without the usual oxygen debt that goes on with our regular training sessions.

We experienced little to no direct muscular fatigue or soreness in the days following, but the insertion points of all the secondary muscles did ache quite a bit for days. The effect was extreme joint stiffness.

Following are more video links, each immediately followed by our annotated criticism:

This video shows different subjects performing squat in an exhibit hall. In addition to seeing some of the operation of the Exerbotics equipment, witnessed is common and accepted but inappropriate yelling at subjects, group insults to the subject, irrational mind psyching lingo, long sustained yells and screams by the subjects, etc. There were no attempts to quell or educate the subjects or the bystanders against this defocusing and counterproductive nonsense. Also shown is the incorrectly assisted lifting of one subject from the floor: pulling him up by one of his arms from a somewhat oblique direction of pull.

Progress in exercise equipment design and its proper application is extremely unlikely when the designers and promoters of said equipment do not understand the required environment to engender focus and sobriety.

This video shows a man performing leg press in an exhibit hall. In addition to seeing some of the operation of the Exerbotics equipment, witnessed is common and accepted but inappropriate hamming for the camera, cute talk and laughing without education to quietly focus. Several obvious discrepancies: feet too high, feet too wide, seat back too upright, hands in hip angle, head turning out of neutral position.

This concludes our opinions regarding Exerbotics.

{ 18 comments… read them below or add one }

avatar marklloyd June 28, 2012 at 1:40 pm

It appears that many of the leg press problems could be fixed in a minute with proper instruction, but the colorful off-center monitor -encourages- subjects to twist the neck while the lower body’s exhibiting great tension. We already know not to into a mirror while exercising; certainly putting, (high-tech), “mirrors” off to the side is even worse. If the monitor is only for the instructor, it should be designed to turn completely away from the subject.


avatar Donnie Hunt June 28, 2012 at 9:31 pm

Something that I have been thinking about for awhile is the potential damage that may or not happen to my joints from exercise. Someone made the comment that even when done at it’s safest, strength training puts stress on the joints. Yes I am aware that there is potential danger the moment I walk out the door in the morning. Possibly getting into a car wreck, getting injured playing sports, and what not. After reading some of the details Ken posted here about dips and some recent writings elsewhere, just really puts the whole lifting safely thing into perspective. Yes I know there are those who like to lift explosively and love squatting and deadlifts. My views of exercise compared to what I use to do in my garage at age 15 at quite different from the way I see things now. Not really sure where I’m going with all this. I guess I just don’t want to do something with the purpose of making me stronger and end up with joint problems or what not down the road. The whole idea of slow controlled movements and static contractions with managable loads definately make more sense to me safety wise than the other stuff.


avatar SimonR June 28, 2012 at 9:35 pm

Could you expand on this comment, please?

“… By the way, researchers commonly report that, as part of their methods, resistance selection for a strength-training exercise is determined as a percentage of a one-repetition maximum performance. This must never be done! This must be outlawed for everyone—including researchers!…”


avatar Joshua Trentine June 30, 2012 at 12:17 am


We are working on an article in specific response to your question. Please stay tuned. This is going to take some work.



avatar Mark July 1, 2012 at 2:23 pm

Perhaps the wording was misleading: -Any- resistance selected is -some- percentage of whatever one’s one-rep max -would- test to be. What’s being referred to is to not actually -test- a subject’s one-rep max. / (Using the old “how do you lift a car” analogy, it seems to me that with perfect RenEx Technique, a one-rep max test -would- be safe, (though still never necessary). No?)


avatar Gus Diamantopoulos July 4, 2012 at 9:08 am


A quick answer is that intensity of effort is a subjective term.

We categorically deny the notion that intensity is represented by anyone’s one rep max. We abhor the concept of a one rep max. It is sophomoric, inaccurate, an invitation to injury. Most of all, it blatantly violates the real objective of exercise.

Aside from our mathematical expression of intensity as a measure of inroad over time, we declare that intensity must be defined as the proportion of possible momentary muscular effort exerted.

Realizing that only the extremes of the effort continuum can truly be known, this definition is still the only one that supports the real objective and the Definition of exercise.



avatar Joshua Trentine June 29, 2012 at 11:49 am

(Reposting on the current thread, I wanted everyone to see this)-Joshua-

Gus Diamantopoulos

Submitted on 2012/06/28 at 10:59 pm

Mike Mentzer was a close personal friend of mine as well as one of my first mentors in strength training.

One of our very first conversations centred around dips. He immediately presented his notion that dips are potentially one of the best exercises for working the upper body. But he also admitted very quickly that most people will face numerous dangers performing them and that some people should never perform them.

His plea to me was that I first try and find a machine for dips that might allow me to delimit range of motion at the stretch- this was by far his preference. He insisted that I actually shop around at health clubs to find a dip machine and then be certain to perform the exercise with a conservative range of motion. If I absolutely couldn’t find such a machine, I was to perform dips with a stepping stool that would allow me to delimit my range in the stretched position and never ever go below the “arms parallel to ground” level. Mike repeated his instruction to me several times and also warned that I must be vigilant in protecting my shoulders and cease the exercise at the first sign of any trouble.

Some months later he told me that the secrets to his upper body development was little more than the proportions of his upper extremities relative to his shoulder width which provided him with uncanny lever advantages in upper body exercises, particularly bodyweight movements. He was simply blessed with arms and shoulders that could dip with ease as well as a work ethic that’s almost as rare. Mike was able to dip with more weight for many reps than some bodybuilders could squat. And he told me of at least one story of a man who tried to copy his weighted dip set only to collapse to the floor in agony with what was very well likely a life-changing shoulder injury.

This is the problem: Mike represented a genetic anomaly of enormous proportions, muscularly speaking: A 5’7″ tall man with uniformly extra long muscle bellies and short tendons that are, quite honestly, non-existent in the general population.

Take a look at the picture of Mike at around 15 years of age in John Little’s book High Intensity Training the Mike Mentzer way and tell me how many 15 year olds look like that…

The truth is that for 99% of people, dips are not “exercise”, they are orthopaedic vandalism.



avatar Bradley June 29, 2012 at 12:49 pm

Very interesting to read about the dips being only suitable for a rare few, it is almost as if thier body are designed for acrobatic/gymnastic movements!


avatar Bradley June 29, 2012 at 12:58 pm

I am also curious about Arthur Jones comments on positive and negative strength (as mentioned in ‘My first half century’) he said something on the lines that friction in the muscle is the reason we have a stronger negative strength than we do positive? Probably that the friction built up in the muscle when it contracts gives it greater contractile force on the negative movement which allows you to make an almost 100% inroading into the muscle being worked. I was wondering if anyone else has read this and could elaborate on the topic for me please?


avatar Donnie Hunt June 29, 2012 at 4:24 pm

I really appreciate you guys taking the time to post all the recommendations regarding dips. Lots to think about here. I’m very interested in any information/recommendations like this. Does Ken go into alot of this in his book?


avatar Joshua Trentine June 30, 2012 at 12:11 am

You are welcome Donnie, it is what we do.

I don’t think there is much discussion on this in The RoE.


avatar Dennis Rogers June 30, 2012 at 7:55 am

Yes great posts concerning dips very helpful


avatar Steven Turner July 2, 2012 at 4:02 am

Hi Joshua,

The exerbotics looks like tremendous amounts compression/stress on the lower back and other major joints. I agree with Ken’s superman description of the crusher.

A question on osteoarthritis in particular the “knee” a segment on TV show last night looked at the huge increase in knee replacements for osteoarthritic knees. It reminded me of Arthur Jones statement Kenneth Cooper won’t be remembered for saving Americas hearts he will be remembered for wrecking Americas knees – he should have also included Australia’s knees in that statement.

The show went on about rehabilitation and what did the rehabilitation exercises consist of back to the same type of activities that caused the knee problems in the first place walking, jogging.

In my anatomy and physiology book a section on osteoarthritis (OA) it uses words, “wear and tear”, cumalitive effects of years of compression, uneven orientation of forces cause extensive microdamage, badly aligned or overworked joints are likely to develop OA. The preceeding sounds to me like going to a commercial fitness centre for improved and better health!


avatar Will July 3, 2012 at 9:03 am

I take it you mean to make the claim that running/walking are responsible for the rise in arthritis of the knee and, ultimately, an increase in knee replacement procedures? Doubtful. You fail to factor in the role of increasing obesity as well as medical/technical advances that make joint replacement a more ‘routine’ procedure. A fair implication to draw from your message is that we should avoid walking to cut down on the wear and tear on our joints. The best current knowledge on the subject would of course suggest otherwise – regular walking has tremendous health benefits; and, if the subject is not grossly obese, it poses, at most, minor structural risks.


avatar mark July 3, 2012 at 10:44 am

In the quest to safely inroad a meaningful % of strength from targeted muscles within 1-3 minutes, what exactly is the proposed advantage of any of the “dumpers”?


avatar Steven Turner July 4, 2012 at 7:54 pm

Hi Will,

To some extent I can speak from experience although it is observational and to some extent it is only my opinion. And as you have pointed out running and walking can be great activities. But I will factor in obesity for you.

I have noting against running or walking for many years I was an elite cross country runner and triathlete. I was also an elite member of the armed forces physical training intructors (PTI) branch. To be in the elite armed forces PTI branch you had to be the fittest, strongest, toughest in the armed forces, none of these people had obesity concerns.

Some thirty or forty years ago we were introduced to Ken Cooper “aerobics” craze. The aerobics boom of the 1970’s meant that people were heavily engaged in running, jumping, and other high impact activites placing large amounts of forces on the lower back, hips and knees – “all in the name of improving our hearts”. I would say that if you were there you would probably agree that these activities greatly contributed to “wear and tear” on the joints.

Some ten years ago I went to a armed forces reunion topics of conversation revolved around hips and knee replacments. Many of of my former colleagues now have trouble just walking on the flat, encountering a set of stairs that is a huge task to climb within itself. I would not consider any of these people to be obese.

Whilst walking is a great activity recently on a “reality” TV show the celebrity trainer had this large obese person walking and running on the beach within a week or two the obese person could not walk – his knee had blown up. If you go to most fitness centres as I often have to do the same “wear and tear”, high impact activities of the 1970′ is still occurring but under a different name “cardio” or “functional training”. But I suppose to some extent it easy to just to blame the obese.

My message is simple; strengthen your muscles in the most safest, efficent and effective means possible, reduce the external and internal forces to the lowest point possible, go out and enjoy your walks with family and friends, and if you wish you can run.

Will, in all sincerity when I see many of my former colleagues and see how incapacited many of them are and to know that a lot of the stupid things we did in 1970s, in the name of of improving our “hearts” it make me real angry. But as you alluded to it just my opinion.


avatar Joshua Trentine July 5, 2012 at 12:53 am

good post


avatar Patrick July 5, 2012 at 9:50 am

I did a three year stint in the Light Infantry and it was pure hell on the body. In garrison, physical training consisted of a ton of bodyweight exercises done in an explosive manner followed by three to five mile runs on mostly concrete, five days per week. Every Friday was a road march with a weighted forty five pound backpack plus weapons and often body armor. Distances were between ten miles up to 25. Ibuprofen was called “light fighter candy” because we were popping those orange pills like maniacs.

No doubt in my mind this was about the most unhealthy time in my life and I cannot imagine any Officer or NCO doing 20 years in certain fields not ending up like a broken down weightlifter or worse.

Yet every morning on the way to work I drive past a a so called bootcamp facility that people pay a trainer to put them thru the same type of physical training we did in the service. Madness.


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