Many people, when they start lifting weights, believe that training to failure on every set of every exercise is the key to growth. This is one of the biggest weightlifting myths, and one that is nearly impossible to squash unless you educate yourself on exercise physiology.
What Exactly is Failure?
Failure is weightlifting is defined as the inability to generate the force required to complete the full range of motion for a single repetition. Many people, experts and trainees, fall on both sides of this debate. Some coaches insist on leaving a couple reps in the bag, stopping well short of failure to avoid stressing the central nervous system (CNS), while others recommend taking each set to that last rep. In order to get to the bottom of it, we really have to examine the science behind the theory.
One fact that we have to accept, is that training to failure on a consistent basis will overload the CNS enough that it will be impossible to continue to train with high frequency. You will begin to notice that every other weightlifting session turns out to be a “bad day”. In fact, the CNS takes more than triple the recovery time that the muscles do. Chronically overloading the CNS will, in effect cause your muscles to detrain while your body fully recovers; you will end up with a series of “bad days”.
On the other hand, you’ve got many performance coaches who promote training to failure often in order to tear up and fatigue muscle fibers as much as possible. The penultimate theorists for this type of training are those that follow High Intensity Training (HIT) (not to be confused with High Intensity Interval Training [HIIT], which is an excellent form of training for superior conditioning). The idea behind HIT is to train once a week or so, but to cause as much damage as possible during that session.
In any case, as the theory goes, taking each muscle to the point of failure ensures that it has been sufficiently fatigued, and therefore the set was as productive as possible (short of forced negatives). As a fact, this has some merit, since it is not enough to simply recruit a given motor unit, but by virtue of adaptation any motor unit must be sufficiently fatigued in order to demonstrate growth. After all, you wouldn’t bench 100 lbs x 5 reps each and every week and hope for growth. Well, maybe you would but then you’d be a total tool.
Another important point we have to remember is that the CNS is a major factor in muscle performance. The CNS definitely has the overall say in performance. Your muscles could be as fresh as a spring flower, but if the CNS is still fatigued from a previous workout then you haven’t much hope of optimal performance. Due to a depletion of the neurotransmitters dopamine and acetylcholine, motor units won’t fire properly and coordination will be thrown completely off, thereby all but ensuring a “bad day” at the gym.
So then question then becomes:
In order progress as much as possible, should I train to muscular failure and invite CNS failure, or should I stop short of muscular failure thus guaranteeing proper CNS recovery?
And the Answer Is…
Depending upon the intensity of the exercise, you can do both. Simply stated, compound and explosive exercises require maximal recruitment of the CNS and therefore you should not train to failure with these types of movements. On the other hand, isolation exercises rely more on the health of the individual muscles, and therefore can be taken to failure. Sounds simple? It is!
Training with Absolute CNS Requirements
These types of exercise include Olympic lifting, dynamic effort lifting, and plyometrics. This type of exercise is CNS intensive, and you should stop your set when the speed of movement decreases, which is actually well short of failure. Training to failure with this type of exercise can really prove to be damaging, because when you begin to lose timing and coordination you are actually training CNS to perform the exercise with improper form. Not good.
Training with High CNS Requirements
These types of exercise include pressing with free weights (benching and overhead), squats, deadlifts, and any other exercise where a heavy free weight is on your back such as good mornings and barbell lunges. This type of exercise requires a high level of CNS recruitment, and you should stop your set when you perceive yourself to have 1-2 reps left in the tank OR if you feel that you are starting to lose your form. It is OK if you start to slow down as long as it is still pretty easy for you to maintain good form.
Training with Low CNS Requirements
These types of exercise include pulling and pressing on machines and isolation exercises for large muscle groups like hamstrings, quadriceps, chest, back, lower back, and abs. This type of exercise requires a moderate to low level of CNS recruitment. You should take at least one set to failure; and it is acceptable to take all sets to failure although I personally would only take the last two sets to failure.
Training with Minimal CNS Requirements
These types of exercise include small muscle isolation work such as traps, calves, bis and forearms, and tris. You should go to failure on all sets, and it is acceptable to take the last 1-2 sets past the point of failure by including drop sets, forced negatives, assisted negatives, half reps, etc… I typically would only take the last set past failure.
Is It Necessary to Perform Exercises with Minimal CNS Requirements
This depends on your goals. For sport specific athletic performance, you might do some isolation work on those muscles specific to your sport. For example traps in football, shoulders (rotators) in baseball, calves in basketball. For powerlifters, I see very little need to train with isolation exercises on a regular basis. For bodybuilders, you won’t be able to achieve that complete package without regular isolation training. For Olympic athletes, I would say isolation exercises are a definite no-no.
Choose your goals and select your exercises accordingly, but always remember to train smart rather than train hard.