Excerpted from The Ultimate Isometrics Manual by Paul Wade
An exercise (or training program, or methodology) can be both effective
and inefficient. In reality, this is the case with most modern training methods. They get the job done, but with a huge amount of waste.
In contrast to most in-gym methods, correct
IsoMax isometric training is the most efficient form of resistance training possible. Understanding why this is, we simply have to clearly understand the concept of
efficiency.
Efficiency in training is essentially the ratio of effective training (amount of training effect) to resources used.
So, what comprises "effective" training? A common way to judge the efficacy of a training method is to look at fiber recruitment. When you want to increase strength or size, your goal should be to recruit as many muscle fibers as possible.
This is due to a phenomenon in neurology known as
Henneman’s size principle, which states that the largest muscle fibers—Type II fibers, those with the greatest capacity to respond with strength or size increases—are always the last fibers in line to be recruited.
As a result—whether strength or size is your goal—you need to recruit the maximum number of muscle fibers you can during your training, in order to reach those large fibers.
Henneman’s size principle also states that the only way to recruit more fibers is through higher intensity contractions. Lower intensity contractions—light activities, like jogging or walking—only recruit the smaller fibers, the Type I which are useless for size and strength; they adapt to stress by improving their oxidative metabolism—by gaining stamina (which is why champion marathon runners are never big and strong).
Type II fibers, on the other hand, respond to stress by hypertrophy—these are the fibers you want to recruit if you’re interested in getting bigger and stronger.
So maximal fiber recruitment is a good way of judging the efficacy of a resistance training program.
Intensity of contraction and fiber recruitment
So—just how intensely do your muscles need to contract to maximize fiber recruitment?
The answer is:
it depends on which muscles you’re training. Different muscles possess different ratios of small-to-large fibers.
The forearms and muscles of the ankle, for example, have evolved for endurance, thus have more small fibers; as a result, they reach maximal recruitment at lower levels of contraction (because there are fewer large fibers to recruit with bigger contractions).
The big workhorse muscles so loved by strength athletes and bodybuilders—the thighs, chest, back and upper arms—have higher ratios of large fibers, and so require higher levels of contraction before maximal recruitment is obtained.
To give an example, a study published in the journal
Brain Research demonstrated that maximal fiber recruitment of the biceps only occurred at 88% of maximal contraction. So, using the biceps as an example, our goal in resistance training is at least 88% of maximal contraction to be optimally effective.
Anything under 88% and biceps training will not be as effective as it could be. It will still be effective to some degree, it’s just that—because energy is being wasted on lower intensity contractions—it is a less efficient way to train.
Working at intensities which don’t recruit the maximum amount of fibers is analogous to driving a vehicle to a destination in the wrong gear. You’ll still get there, but you could’ve got there faster and with less waste.
Contraction-Intensity graphs and training efficacy
Now we have a concept of what comprises effective training—
working at levels of contraction which generate maximal fiber recruitment. How do different methods of training match up to this ideal?
First, let’s look at an example of isometric biceps training. Let’s say an athlete pushes upwards against the
IsoMax bar and holds it steady in the curl position. He pushes as hard as he possibly can against the bar, for ten seconds.