T Nation

Power Factor


I cannot beleive the amount of people knocking power factor training. This is best thing ever to happen for natural bodybuilders. It needs to be approached with an open mind. Just because everyone has been taught non scientific programs that do not work for natural trainers - we need to shatter this full rep training style myth. Of course their is a science to bodybuilding, just as their is to human physiology. Wake up people, do not listen to steroid training styles that are not scientific, and only enable you to use them if you are on the juice.


Most people knocking it have tried it. It an old program after all, been around a long time.


It's even older than you think! Power factor is nothing but a revamp of the functional isometric course by Bob Hoffman. This course was based on the training of olympic lifter Bill Marsh. At the time Marsh did record some amazing gains in his lifting by performing functional isometrics (partial reps with very heavy weights) twice a week and the competition lifts once a week.

Because of Marsh' success Bob Hoffman started to sell isometric racks and wrote the article "The most important article I've ever written" touting the merits of isometrics and functional isometrics.

Now, lifters started to use the method and few got results... one thing that we only found out later on, is that Bill Marsh was among Dr. John Ziegler's first guinea pig for dianabol use!

Power factor training is nothing but a rehash of this protocol, to which they added a little scientific cloud to make it sound novel and miraculous.

Their whole premise is based on the formula for power P = Mass x Distance/time. They argue that since partials use a lot more weight and that the reps last a lot less time, the power output is greater.

Well this is based on bad science. Power is the rate of performing work. However it's easy to artificially increase the rate of work by using short reps. However the fact remains that the total amount of work performed is very low. Power factor training goes against what is currently known on the process of muscular hypertrophy. Their problem lies in the fact that they tried to use mechanics to prove a biological process. I am myself a M.Sc. student in biomechanics, the formulas we use are used to quantify certain movements, not to explain what happens inside the body. Trying to explain the hypertrophy stimulation process with mechanical formulas is live trying to explain digestion with mathematical algorythms!


And with Christian's statement,there is simply nothing left to say. Well put. All intellegent trainers know, you must vary your training. It's just like the HIT mindset. If it (Power factor,or (s)HIT) was sooo great,EVERYONE would be using it,all the time. Wake up!


One more thing ...

Power factor training is justified by wrong assumptions.

Pete Sisco (originater of the Power Factor System) go on to say in his articles that training intensity is one of the most important factor in stimulating hypertrophy and strength gains. I agree. However he uses this fact to prove his point by inventing his own definition of intensity! Sisco state that intensity is " the amount of weight lifted per unit of time" and then goes on to say that the resulting intensity is called the "Power Factor". Well the problem is that his definition is NOT intensity. It's density! Intensity refers to the load used compared to your maximum capacity (e.g. if you can bench press 300lbs, 200lbs is an intensity level of 67%).

Now, I'm not saying that density is not important. However the problem is that Sisco uses the accepted scientific fact that intensity level is one of the key to stimulating hypertrophy and strength to validate his claims. The problem is that "his" intensity is not really intensity!

Density plays a role in stimulating hypertrophy, mostly because it influences hormonal responses to training. However it's not a capital factor. The most important factors being the tension present in the muscle and the duration for which the tension is present in the muscle (sometimes called TUT). The main stimulus for hypertrophy is muscular protein degradation. When muscle protein is degraded during training it's an alarm signal that starts the adaptation and adaptive reconstruction (sometimes called surcompensation) process. The amount of protein degraded is influence by the rate of degradation and the duration of degradation.

The first factor (the importance of the tension present in the muscle) is the principal responsible factor for the quality of the gains stimulated, the higher the intramuscular tension, the more functional the stimulated hypertrophy will be. The intramuscular tension refers to the effort of the muscle necessary to produce a certain force output. Since F = MA, tension can be increased by adding load or acceleration. The tension present in the muscle will affect the "rate of protein degradation"

The second factor (TUT) is the principal responsible factor for the quantity of stimulated hypertrophy. A greater volume of work will stimulate more hypertrophy (as long as the stimulation doesn?t exceed the capacity to recover). Now, to get a high TUT, you do not need to do sets of a lot of reps. It is the total time under tension (TTUT) for an exercise that's important, not the TUT for a set! In other words if you do 5 sets of 5 reps with a 201 tempo, your TTUT is 75 seconds. Considering the TTUT instead of TUT enable us to see that lifting heavy weight for less reps can be effective to gain size if we increase the number of sets slightly. TTUT influences the "duration of degradation".

Anyway, back to Power Factor Training! As I said their view uses a simplistic concept for muscle hypertrophy and misuse several mechanical concepts to justify their methodology. Sadly, individuals with little physiological and biomechanical knowledge can easily be fooled by their smoke screen.


You had me at, "Hello"


I don't have a big problem with Power Factor; I used it to gain a massive amount of strength when I was powerlifting. Just a couple of cautions though; I see guys in the gym doing partial reps all the time (in fact, I've been training at my current gym for a year and I think I'm the only guy there who does bicep curls properly!), but they never grow an ounce. Also, Ian King noted in one of his old heavy metal columns that the guys who invented Power Factor were famous for their extensive abuse of dianabol.


Well, Solster? Nothing to say?

I have to say that one of the great pleasures of the T-Mag is having the opportunity to watch someone get his ass handed to him in a debate. (Not that this really qualifies as a debate.) Despite all the BS routinely strewn about your average gym, one rarely has the chance to see someone just get shut down. But here, ahhhh, HERE! Happens all the time...

Nice one, Christian.


Debo, Ian is right (if you read my earliest post in this thread you'll get the whole story).

If you want the full story on dianabol use by the first "functional isometric guinea pigs" you can consult the excellent strength history book "Muscletown USA" by John D. Fair. It's a great reference that details the growth of the York barbell empire and US olympic lifting as well as the birth of powerlifting.

You can also find an online article on the subject of functional isometrics and steroids written by John D. Fair at the Amateur Athletic Foundation of Los Angeles web site. The url for the article is:

www.aafla.org/SportsLibrary/ JSH/JSH1993/JSH2001/ jsh2001b.pdf#xml=http:// www.aafla.org/ search/highlight. gtf?nth=0&handle=000002c3

Just cut and paste it in your browser


Cheers Christian, you sure know your stuff. I'll check out those links.


To Christian.
Thanks for your response.
Where do you get the information that for hypertrophy full range is better, from my readings a muscle is either contracted fully or not contracted at all. As to time under tension, Sisco does mention the two ways of increasing workload are to increase the ammount you work in a period of time and to increase the duration for which you are able to complete the work (power factor and power index). The main point of his book is to show a way of measuring progress by maths (progressive resistance) not hap hazaerd as with most trainers.
The issue about Dinabol is interesting, the training Sisco advocates insists on much longer rest time between workout than the regular workout time. The reason for the rest is for the system and muscle to recover and then grow, without this happening you are overtraining. I did not realise my post would create such controversy but at least it got a response.


Muscles do not "contract fully or not at all." That's muscle FIBERS! That's probably one of the most common misconceptions that people generally use to further their argument. If your brain tells a muscle fiber to fire, it will contract fully. The difference between lifting a 5 lb weight and a 100 lb weight is the number of muscle fibers activated. It's not that difficult a concept to understand.


DocT is right. The "all or none" principle for contraction holds true for motor units/muscle fibers, NOT a whole muscle. Think about it, if a muscle could only either contract fully or relax there would be no force gradation. E.g. if you can curl 65lbs with your right arm, you would also apply 65lbs of force when bringing a glass of water to your mouth! You would have ZERO fine motor control. Force gradation (the capacity to modulate and change force production as required) is a function of the nervous system. To do so it increases/decreases the number of motor units/muscle fibers that are contracting and it increases/decreases the frequency at which the fibers will contract. Full range movements require the implication of more motor units, a great contraction frequency and more motor unit coordination. Both facilitate muscle hypertrophy and motor learning. As far as Power Factor trying to quantify training with maths, as I said they are not even using the correct formulas and concepts. They are quantifying alright, but they are not quantifying the right thing!


Much of what Christian wrote is covered more extensively in Science and Practice of Strength Training by Vladimir Zatsiorsky; which also covers among other things the difference in force production betwheen land and water sports, the relation between force and velocity, speed strength, strength speed, etc.

If this is all entirely new, I would really recommend getting the book; even if you are only interested in bodybuilding, the chapter on injuries, particularly back would make useful reading.


I know about fibres contracting, also that full range requires motor skill, but would this not be offset by using much heavier weights for partial/static contraction that in many instances would require motor skill to balance the extreme weight. Thanks Roland I will track down this book. Christian about the maths - if you lift more weight per minute than before or are able to sustain a static contraction for longer, this would tend to show progress. I am not trying to be a smart ass but to find the most superior way of training. I do appreciate your answers.


Quit trying to be a bunch of smart asses! Solster is having a good discussion with some smart people and then you punks come on here writing posts that show what a bitch you are. Get a life. Way to be a gentleman Solster!!!!


Kyle, what exactly are you talking about? Everything I see posted above has to do with the topic at hand. Nobody's trying to be a "smart ass." You see, that's what happens around here. People actually present facts and differing viewpoints, and sometimes we agree to disagree. The only post I see so far that hasn't contributed to the original topic is yours (well, and this one too).