(This article is edited from Pete Sisco's AMAZING bodybuilding e-Book, TRAIN SMART!)
I have counseled the practice of going to failure as a means to ensure muscle growth stimulation. (Failure refers to performing a set until the point of being unable to complete one more rep, despite all effort you "fail" to complete the last rep.) But over the years much confusion has developed regarding the use of this principle. Having a clear understanding of the failure principle will save you wasted effort and prevent you from accepting what has become dogma as scientific fact.
Over the last thirty years a great deal has been written about going to failure during weightlifting exercises. Like nearly every other aspect of bodybuilding, the concept of failure is one that has fallen victim to misapplication, misunderstanding and improper logic. Used properly, failure can serve as a useful tool in guiding progress. However, there is no valid reason for its near mythic importance to some bodybuilders who believe that progress cannot be made without employing this principle. In point of fact, exercising to momentary muscular failure is not, and never has been, a requirement of stimulating muscle growth.
The fact is, outside of a gym, there is virtually no human activity that involves going to failure. For example, a person who makes his living by digging with a shovel would never dig to the point where he could not lift one more shovel of dirt. He would never swing a pick ax until he could no longer lift it to complete one more "repetition". And yet, people who perform such manual labor can develop tremendous muscularity. How is it that they can develop above average muscularity without ever, in their entire life, going to failure? Similarly, sprinters are distinguished by tremendous hamstring and quadriceps muscles compared to the nominal muscularity of a distance runner. This is because sprinting requires a great amount of muscular work in a unit of time. But who sprints to failure? Who crosses the finish line and cannot take one more step? Indeed, you might even find a weight lifter in your own gym who made great progress in his size and strength gains without ever exercising on a program that prescribed sets to failure. All of these people have the ability to stimulate new muscle growth without every going to "failure". So how can anyone characterize failure as an indispensable requirement of stimulating muscle growth? All the evidence - not just some evidence - but all evidence goes against that assertion.
The human body operates by complex mechanisms that are always taking averages into account. In a normal day your body is adjusted to accept "x" amount of sunshine, "y" amount of temperature variation, "z" amount of humidity, etc. for hundreds of different environmental and biological variables. For every variable the body makes complex calculations and adjustment to characteristics like our blood viscosity, hormone levels, degree of skin tanning and muscle growth. If, on average, you are exposed to the same amount of sunlight every day of the year, your skin will darken to the point where it has sufficient protection from that average level of sunlight, but no more. Similarly, if you lift weights on a regular basis with the same amount of intensity every workout your muscles will develop to a point where they can comfortably handle the intensity of lifting that they are, on average, subjected to, without unduly depleting its recovery resources.
In order to increase the thickness or viscosity of your blood it is not necessary to subject your body to the absolute coldest temperature that it can withstand before losing consciousness. Nor, if you want to increase the darkness of your tan, is it necessary to subject your skin to the most intense sunlight it can withstand up to the moment before blistering. Muscle growth stimulation operates on the same principle. Consequently it is not necessary to operate a muscle to its absolute limit of muscular failure in order to stimulate new muscle growth.
You may have seen a new product on the market that utilizes a wristwatch style device to use while sun bathing. It is designed to monitor and measure the intensity of sunlight that your skin is subjected to and compare that intensity to user-provided information like color of skin and the SPF of the sunscreen being used. The device calculates the safe interval of sun intensity and rings an alarm when limits have been reached. Bodybuilders would greatly benefit from the same style of device if it could be adapted to measure the intensity of muscular output. Leaving aside the technicalities of measuring the intensity of muscle groups, imagine if you could wear a wristwatch style device that monitored and measured your average muscular intensity throughout the day.
Suppose at the end of the day the device indicated your average muscular output was one hundred pounds per minute. Let's call that your baseline muscular intensity. If every day for the next six months you engaged in an amount of muscular activity that caused the device to register a one hundred pounds per minute average, you would not increase in your muscle mass because there would be no reason (no requirement) for your body to grow new muscle.
Now suppose that each day you engaged in an amount of muscular activity that caused the average intensity to rise by 5%. (i.e. 100, 105, 110, 116, 122, etc.) At the end of thirty days, if you were able to sustain such a steady increase, your wrist monitor would indicate 412 pounds per minute of average muscular intensity. You can see that in order to safely cope with 412 pounds per minute of muscular output your body would have to make itself substantially more muscular that it has to be to cope with one hundred pounds per minute of muscular output.
Using Power Factor principles, if you were to construct a month worth of bench press exercise routines you could begin by establishing baseline Power Factor and Power Index numbers that represent a measurement of the muscular intensity that you are capable of generating in that exercise. You could then engineer a number of workouts to perform over the next month ensuring that each had intensity 5% higher than the last. That progressive increase in muscular intensity would be all that is required to ensure steady increases in muscularity. It would not be necessary to go to failure, it would not be "necessary" to perform one set only, two sets only, three sets only, eight reps per set, twelve reps per set or any of the other so-called "requirements" for growth. It would also not be necessary to perform four different exercises in addition to the bench press, it would not be necessary to "periodize" your workouts by including several workouts at twenty to thirty percent below your baseline intensity, it would not be necessary to stop all aerobic exercise for a month. It would not be necessary to work out three days per week. It would only be necessary to increase the intensity of that exercise on a workout to workout basis.
While failure is a crude gauge, it can be used as an effective tool in finding your baseline of intensity. For example, if you are performing three sets of fifteen reps with 200 pounds and during your first set you perform fifteen, your second set you perform fifteen but on your third set (to failure) you perform twenty six reps it is an indication that your first two sets were at sub maximal intensity and that you should be using a heavier weight or performing more reps. The limitation here should be obvious. How much lower was your intensity compared to what it could be? What are the units of measurement? How high is high? How low is low? When you use Power Factor and Power Index numbers in place of these vagaries your training is imbued with a precision behooving a proper science. Furthermore, if you are seriously overtrained you will reach failure at a point lower than the progressive intensity that you require in order to stimulate new muscle growth. For example, suppose that you started with a baseline intensity of one hundred pounds per minute and a few sessions later your intensity is 160 pounds per minute in the same exercise. At this point you become overtrained and next time in the gym you go to "failure" at 140 pounds per minute of muscular intensity. There is no possible way that can stimulate new muscle growth despite going to failure. Why? Because going to failure is not a requisite of muscle growth stimulation. Progressive intensity is!
To exaggerate the point, consider what your strength is when you are recovering from a serious bout of flu or perhaps a stay in the hospital. You can return to the gym and take every set to failure but the intensity will be so low that it cannot stimulate new muscle growth. That's the reason why some people can train to failure on every exercise for month after month and never show any sign of progress while they are convinced they are going all out and delivering 100% of momentary muscular effort. It's irrelevant, since what matters is a tangible progression of overload intensity. Since the Power Factor and Index measurements exist there is no excuse for a rational person not to employ these more precise measurements of muscular intensity into his or her workouts. No reason except blinkered dogmatism and a blind adherence to tradition and "the way its always been done".
Advocates of training to failure, particularly those who adhere to the Arthur Jones model of only one set to failure, believe that the last rep is the most productive rep of the set. As the rational goes, the first reps takes very little of your effort, the second, third and forth reps take corresponding more effort until you reach that last rep which requires all the effort you can muster and yet can not be completed. This most difficult rep is considered by some to be the most productive rep in the set as it is the one that triggers muscle growth stimulation. However, as we have already discussed, it is the progressive increase in intensity that triggers muscle growth and since that increase can be reached without ever going to failure, the last rep (as it's described as being impossible to complete) can be entirely unnecessary. For example, if the required increase in intensity would have been reached at the sixth rep of that set then the sixth rep is the one that triggers growth. The reps beyond the sixth were not even necessary to perform. If you have a baseline intensity of one hundred pounds per minute and you have set a goal intensity of 110 pounds per minute then the moment you reach 110 pounds per minute of intensity you can stop the exercise even if you've only completed five and a half reps. The number of reps is irrelevant, failure is irrelevant, it is the amount of intensity generated that is the only relevant factor.
And how does a scientific mind measure intensity? With a mathematical Power Factor and Power Index. How does the unscientific mind measure intensity? By feel, by perceived effort, by burn, by pump, by soreness, by failure, by rep count, by set count, by vague, non-specific, irrelevant intangibles that are not indispensable conditions of growth stimulation.
In science we measure the intensity of light, not by squint factor, or headache potential but by Lumens and Candle Power. We measure the intensity of sound not by ear pain or stomach vibration but by Decibels - precisely defined measurements that can be compared mathematically and used to discover other properties of the science. Anyone who claims there is a "science" of bodybuilding but rejects an objective measure of muscular intensity is a poseur and a dogmatist.