Resistance-induced contraction (RC) is a term and concept that may be even less familiar than dynamic contraction (DC); which is the term and concept that I explained in the precursor article to this one, Exercise Intensity: the #1 Key to Building Muscle, Part III; the Role of Dynamic Contraction. So this series of articles on exercise intensity is probably your very first introduction to the term.
In fact, other than Maximum Intensity Training (MIT) and Maximum Intensity Strength Training (MIST), I’m not aware of any workout plans that even use the term resistance-induced contraction (RC).
Nonetheless, resistance-induced contraction (DC), specifically maximum resistance-induced contraction “per unit of time”, is essential to triggering the anabolic process that can lead to maximum muscle growth. And that’s because as I explained in the first article of this series, Exercise Intensity: the #1 Key to Building Muscle, Part I; Exercise Intensity Defined, exercise intensity is “the amount of contraction generated in the working muscle, per unit of time“.
And as I stated in the second article of this series,
Exercise Intensity: the #1 Key to Building Muscle, Part II; Muscular Contraction Defined,
there are two types of contraction that you need to maximize, in order to achieve maximum intensity; and thus maximum muscle growth. And resistance-induced contraction (RC) is one of them.
What Exactly is Resistance-Induced Contraction?
As I stated in Part II of this series on exercise intensity, resistance is the “net external force” that your muscle is working against, when you’re strength-training or weight-training. And as the muscle works against that force, resistance–induced contraction (RC) is generated in the muscle.
And the greater the resistance is, the more resistance-induced contraction is generated in the working muscle. And for any amount of dynamic contraction that you generate in a muscle, the more resistance-induced contraction that you generate in the muscle, the higher the level of intensity; and thus, the greater the muscle growth is likely to be.
The Rule of Progressive Resistance
I introduced and explained the Rule of Progressive Intensity in Part I of this series of articles on exercise intensity. And now we have another rule that you need to follow; if you want to achieve maximum intensity, and thus build maximum muscle in minimum time. And that’s the Rule of Progressive Resistance.
The Rule of Progressive Resistance simply states that you need to continually subject your muscles to “progressively higher amounts of resistance“, in order to generate “progressively higher” amounts of resistance-induced contraction in the muscle, per unit of time. And doing so enables you to generate “progressively higher” levels of intensity, that are needed to trigger the process that leads to prolonged, sustained, continual muscle growth.
So your ultimate goal when working out to build muscle is to apply the Rule of Progressive Intensity. And in order to apply that rule, you also need to apply the Rule of Progressive Resistance.
How to Generate Maximum Resistance-Induced Contraction (RC) in a Muscle: It’s Not All About the Amount of Weight!
Explaining how to generate maximum dynamic contraction (DC), as I did in Part III of this series of articles, is relatively easy. Explaining how to generate maximum resistance-induced contraction (RC) is more complicated.
And that’s because when you’re weight-training, resistance can be determined by 3 different variables. So any one of those variables can also determine the amount of “resistance-induced contraction” generated in the muscle; and thus the level of intensity that you generate in the muscle. Which then determines how much muscle you build; or whether you build any muscle at all!
Many people erroneously believe that resistance is the “amount of weight” that the muscle has to work against, when you’re performing a weight-training exercise. And I could have used the term “weight-induced contraction”, instead of the term “resistance-induced contraction”, to refer to this type of muscular contraction. Certainly “weight-induced contraction” is easier to say, and it’s an easier concept to grasp, than is “resistance-induced contraction”.
But the term “weight-induced contraction” is misleading. And that’s because there’s a lot more to resistance than just the “amount of weight” that the muscle has to work against, as I explain in the following section. In fact, “resistance” and “weight” are not the same at all; although the terms are often used synonymously.
The 3 Variables That Determine Resistance
It’s very important to remember that when you’re weight-training, resistance is actually determined by these 3 different variables:
1) the amount of weight that the muscle is working against
2) the amount of leverage that the muscle is working against; if any
3) the speed at which the reps (repetitions) are executed (often called the rep cadence); if reps are done, as opposed to static holds
And since each of those variables can play a significant role in determining the amount of resistance that the muscle has to work against, and thus the amount of resistance-induced contraction (RC) generated in the muscle, and thus the level of intensity generated in the muscle, they need to be addressed individually.
The Role of Weight in Determining Resistance
It’s pretty obvious that the “amount of weight” that the muscle has to work against determines the amount of resistance that the muscle has to work against.
Imagine holding a 30 lb. dumbbell in your hand, palm facing up, forearm extended in front of you and parallel to the ground. Holding the weight in place creates resistance for the biceps to work against, which generates resistance-induced contraction (RC) in the muscle, thereby generating intensity in the muscle. And you would have to generate enough “muscular contraction per second” (i.e. intensity) in the biceps, in order to hold the forearm and the weight in place.
Now imagine holding a 50 lb. dumbbell in the exact same position. That would obviously create a greater resistance than the 30 lb. dumbbell would, thereby generating even more resistance-induced contraction (RC) in the biceps. And thus, the intensity would be even higher than with the 30 lb. weight.
In the above example, increasing the amount of weight does increase the amount of resistance, and thus the amount of “muscular contraction generated per unit of time” (i.e. the intensity). And that’s because the other variables that determine the resistance (i.e. “leverage” and “speed of execution of the reps”), and thus the intensity, were not changed at all.
Just remember, however, that increasing the amount of weight for any particular type of motion or exercise doesn’t always increase the resistance, or the intensity of the exercise. In fact, it’s actually possible to generate a lower amount of resistance, and thus a lower level of intensity, by using a heavier weight; depending upon what happens with the other variables that determine the resistance (i.e. “leverage” and “speed of execution of the reps”).
And this explains why lifting heavier weights doesn’t always lead to higher levels of intensity or more muscle growth, than lifting lighter weights would. The bench press is a perfect example of this fact. And I explain that further in the next section.
Also, it’s important to remember that whenever you do reps of any kind, the “amount of weight” that you use to perform an exercise is not always the same as the “amount of weight” that the muscle is actually working against. In fact, whenever you do reps, it sometimes happens that your muscles aren’t working against any of the weight being used at all; depending upon where you are in your range of motion.
The “amount of weight” that you use to perform an exercise always stays the same, of course. But whenever you do reps, the “amount of weight” that the muscle actually has to work against often fluctuates; sometimes dropping down to zero. And that causes a fluctuation in the amount of resistance, and the amount of resistance-induced contraction (RC) generated in the muscle. Which causes a fluctuation in the amount of intensity generated in the muscle.
So that adds another variable, that makes determining the exact amount of resistance, and thus the amount of resistance-induced contraction generated, even more complicated and harder to track.
The Role of Leverage in Determining Resistance
Have you ever wondered why the bench press enables you to lift more weight than does any other chest exercise? Well, this might be a blow to the ego, but it has nothing to do with the strength of your pectoral muscles. You’ve got the same pectoral muscles, regardless of what chest exercise you do; whether it’s the dumbbell fly, the double-cable crossover, the pec dec, or the bench press.
The reason is leverage. The bench press enables you to lift more weight, simply because when you do the bench press, your pectoral muscles have “less leverage” to work against, than when you do other chest exercises. And that’s because when you do the bench press, the “line of force” of the weight is closer to your shoulder joint, than it is for other chest exercises; like the dumbbell fly, for example.
So whenever you’re weight-training by doing rotary-type motions (such as those used for the bench press, the squat, the triceps kickback, the lat pull-down, the lateral raise, the biceps curl, etc.), it’s very important to remember this fact:
The “amount of leverage” that the muscle has to work against is just as important as the “amount of weight” that the muscle has to work against, in determining the “amount of resistance” the muscle has to work against.
And as anyone with a basic, rudimentary knowledge of physics can tell you, this phenomenon is easily demonstrated by the following equation:
LOAD x LEVER = TORQUE
So if we apply that equation to weight-training, the “load” is supplied by the “amount of weight” that the muscle has to work against. The “lever” is the distance from the “working joint” to the “line of force” of the weight. And the “torque” is supplied by the “amount of resistance” that the muscle has to work against.
Then putting different numbers into that equation, we get the following:
3000 lbs. x 3 inches = 9000 inch-lbs. of torque
300 lbs. x 30 inches = 9000 inch-lbs. of torque
So as you can see, lifting 3000 lbs. with a 3 inch lever requires the same muscular force (indicated by the torque) as lifting only 300 lbs. with a 30 inch lever!
This explains why it is possible to achieve a higher level of intensity and build more muscle, by lifting a light weight with a long lever, than you would do by lifting a heavy weight with a short lever. And the bench press is a perfect example of this fact.
So all that extra weight that the bench press allows you to lift may make you feel like superman, and it may be good for your ego. But it’s all just an illusion. Nobody has chest muscles that are that strong! Most of that extra weight is simply due to the shorter lever that’s used when doing the bench press. Plus, when doing the bench press, you’re using additional muscle groups (such as your triceps), to get the weight up.
In fact, you can prove the power of leverage for yourself: lie on your back, extend your arm out to the side, arm straight and parallel to the ground, with a dumbbell in the palm of your hand. Just as you would do at the start of the dumbbell fly. Hold the weight in that position, and use your opposite hand to feel the amount of contraction in your pectoral muscle.
Now, keep holding the same dumbbell, and allow the arm to bend into a right angle, with only the upper arm parallel to the ground. Just as would do at the start of the bench press. Hold the weight in that position, and feel your pectoral muscle again. Notice how much less contraction there is in the muscle.
What’s the difference between the above two examples, that accounts for such a significant change in the amount of resistance-induced contraction (and thus intensity) generated in the muscle? The “amount of weight” that the muscle is working against hasn’t changed. And there is no rep cadence, or “speed of execution of the reps”, because you’re just doing static holds.
The only thing that changes between the two is the “amount of leverage” that the muscle has to work against. In the first example, the lever is your entire arm. Whereas in the second example, the lever is just your upper arm.
And at the start of the bench press, the lever is simply the length of your upper arm. And that’s much shorter than the length of your entire arm, which is the lever used at the start of the dumbbell fly.
So although the bench press does allow you to lift more weight than do other chest exercises, it doesn’t necessarily allow your pectoral muscles to work against a “greater amount of resistance” than other chest exercises do.
And ultimately, it’s the “amount of resistance” that the muscle has to work against, that determines the amount of resistance–induced contraction that’s generated in the muscle. The amount of weight that you use is simply “a means” of generating the “greatest amount of resistance“, and thus the greatest amount of resistance-induced contraction possible. And as I explain in this section, it’s only one of 3 different variables that can determine the resistance that the muscle has to work against; and thus the intensity of the exercise.
It’s also important to know that whenever you do reps for rotary-type motions (such as the bench press), the “amount of leverage” that the muscle has to work against constantly fluctuates; sometimes dropping down to zero. This causes the resistance to fluctuate, sometimes dropping down to zero. And that causes the resistance-induced contraction (RC) to fluctuate, sometimes dropping down to zero. And that, in turn, causes the intensity to fluctuate, sometimes dropping down to zero.
And, of course, if you have zero intensity, you have zero muscle growth stimulation!
This fluctuation in resistance and intensity occurs only when you do reps, however. It doesn’t happen when you do “static holds”, where the leverage and the intensity remain stable, throughout the entire exercise.
The Role of Rep Cadence (Speed of Execution of the Reps) in Determining Resistance
One frequently overlooked fact in strength-training and weight-training is that the “speed of execution of the reps” (a.k.a. the rep cadence) can have a big effect on the “amount of resistance” that the muscle has to work against. And thus, the rep cadence can also have a big effect on the level of intensity generated in the working muscle.
For example, imagine going though the eccentric phase of motion for the biceps curl, done unilaterally (only one arm at a time), using a 50 lb. dumbbell. The eccentric phase of motion is that part in your range of motion, where the muscle “elongates” and ” de-contracts dynamically“; as gravity pulls the weight towards the ground.
First, imagine letting the 50 lb. dumbbell “drop” through the eccentric phase of motion, entirely due to gravity. Obviously, there would be no resistance–induced contraction generated in the biceps, and thus no work for the biceps to do. And thus, there would be zero intensity.
Now remember: during the eccentric phase of motion, your muscle is not moving the weight at all. Gravity is always moving the weight during the eccentric phase of motion. During the eccentric phase, your muscle comes into play only to the extent that you “slow the weight down”, against the pull of gravity.
And the more you slow the weight down, the harder the muscle has to work, to resist the pull of gravity; and thus, the greater the resistance becomes. And the greater the resistance becomes, the more contraction (i.e. resistance-induced contraction) you generate in the muscle per unit of time. And thus, the higher the intensity becomes, at any given point in the eccentric phase of motion.
So now imagine using that same 50 lb. dumbbell to go through the eccentric phase of motion for the biceps curl “super-slowly”. That would be a lot more work for the biceps to do, than if you were to go through the eccentric phase quickly, with the same amount of weight. And that’s because the amount of resistance for the biceps to work against would be much higher. Which means that the amount of resistance-induced contraction (RC) generated “per unit time” would be much greater; resulting in a much higher level of intensity.
So what’s the primary difference between the above two examples, that accounts for the significant change in resistance, resistance-induced contraction (RC) and intensity? The only significant difference between the two is the rep cadence, or “speed of execution” of the reps. And that’s what accounts for all of those changes.
It’s also important to note that the rep cadence can fluctuate as you do reps. And if it does, that causes the amount of resistance to fluctuate. Which, in turn, causes the amount of resistance-induced contraction (RC)to fluctuate. And that, of course, causes the intensity to fluctuate.
That isn’t a problem when you perform “static holds’ however, since there is no rep cadence for those exercises.
It’s Not Only the Amount of Weight That Counts; Ultimately, It’s How You Use the Weight That Determines Intensity, and Muscle Growth!
Finally, what I’ve explained in the previous 3 sections brings out a very important, yet usually overlooked fact in strength-training, weight-training and bodybuilding:
It’s not only the amount of weight that you lift, or even just the amount of weight that the muscle “is actually working against”, that determines intensity and muscle growth. Ultimately, it’s “how you go about using” any given amount of amount of weight, that determines how much intensity you generate in the working muscle; and thus the amount of muscle that you’re likely to build.
So although you ideally want to use the heaviest weights you can, remember that a lighter weight used with a longer lever, a slower rep cadence (during the eccentric phase), or with a greater amount of dynamic contraction (DC) can actually generate greater intensity and build more muscle, than a heavier weight can; depending upon “how the weight is used“.
In Conclusion: Putting it All Together
So now that I’ve explained all 3 of the variables that determine resistance, the question is this: how do you generate maximum “resistance-induced contraction” (RC) in a muscle, so that you can generate maximum intensity, and thus achieve maximum muscle growth?
Simply stated, maximum resistance-induced contraction (RC) occurs when you combine those three variables in a way so as to generate the “highest level of resistance possible”; and that resistance is doing the exact opposite of what the working muscle is doing, at any point in time during the exercise.
Then when you combine maximum resistance-induced contraction (RC) with maximum dynamic contraction (DC) simultaneously, you get “maximum contraction per unit of time”. And that results in maximum intensity, which means that the muscle is working as hard as it possibly can. And that is the key to generating maximum muscle-growth stimulation, and building “maximum muscle in minimum time”.
Now, for a summary of all of the variables that determine exercise intensity, and for an analysis of some common, popular definitions for exercise intensity, read the next article in this series,
Comments? Questions” Care to agree or disagree? Feel free to do so!