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The three faces of resistance

PETE GLADDEN
Pete’s World

Published: September 23, 2019

Back in a Feb. 4 column, Eccentric Muscle Contractions, I talked about one particular type of resistance training, isotonic, and one particular type of muscular contraction, eccentric. Well, in today’s column I’d like to add a couple of the lesser known types of resistance training to the group, isometric and isokinetic, and the various muscular contractions involved in each.

But first lets go back and review just what isotonic resistance training is. As defined by the National Strength And Conditioning Association, “In an isotonic contraction, tension remains unchanged and the muscle's length changes.”

Okay, so isotonic resistance training along with the concentric and eccentric muscular contractions represent the kind of weight lifting that most all of us are familiar with. Think of the simple biceps dumbbell curl, where you lower the weight down eccentrically and the biceps muscle lengthens, then you curl the dumbbell upwards concentrically and the biceps muscle shortens. Tension (the weight of the dumbbell) remains the same while the velocity will vary slightly because the speed of lowering and lifting won’t be precisely consistent.

We not only utilize this kind of resistance training with the biceps muscles, we utilize it with darned near every major muscle group of the body. The thing to remember about isotonic resistance training is that the weight remains unchanged but the speed of the eccentric and concentric muscle contractions - the speed of the lengthening and shortening - varies.

Now let’s move to isokinetic resistance training. On the one hand just as in isotonic resistance training, isokinetic training can involve both eccentric and concentric muscle contractions. The real difference between the two is that the velocity (speed) in isokinetic training remains absolutely constant, at a predetermined speed.

Now this kind of muscular action rarely occurs in sports. It’s typically utilized in performance labs and in rehab clinics. A specialized exercise machine, the dynamometer, is needed, and it’s able to control the velocity of exercise by fluctuating resistance throughout one’s range of motion. As such, speed remains consistent despite the force exerted.

Because isokinetic actions are so seldom produced in sporting situations, this kind of training is rarely utilized in the gym and fitness club environment. What’s more, the extent to which these kinds of muscular contractions transfer to sport movements is still a highly debatable topic.

The upside of using isokinetic resistance for sports testing and rehab tutoring is that the dynamometer can objectively measure the torque output of muscles, and that output is converted into foot-pound measurements. From a rehab standpoint this is great for PT’s because exercises can be monitored at an extremely precise level.

From a sports programming standpoint this is great because the strength ratios between muscle groups can be tested and assessed. This is critical when evaluating the under/over dominance of a particular muscle group. And such testing results enable strength coaches to prescribe exercises that will assist in the enhancement of an athlete’s performance and the prevention of injuries.

Let’s complete this triumvirate with isometric resistance training. The Merriam-Webster dictionary defines the word isometric as “of, relating to, or characterized by equality of measure.” Thus, isometric training, commonly called isometrics, is a type of resistance training in which the joint angles and muscle lengths do not change during the muscular contraction.

In layman’s terms we’re talking about static strength training––static contractions––and a few of the exercises that fall into this type of training include the wall sit, static slide lunge, iso hang, incline pushup hold, single-leg stand, wall supported hand stand, and the plank.

Isometric exercises are most often used in rehab situations because they strengthen muscles without stressing joints, very important for individuals who are trying to rebuild strength as they’re returning from an injury.

But isometrics are also great for strength training in general. We’re talking about intense efforts that contribute to burning fat and building strength. For example, in power lifting, olympic lifting, and bodybuilding most all of the lifts entail a sticking point––a point in the lift where the muscles are usually the weakest. Isometrically training the muscles at these precise sticking points can eventually strengthen the overall lift.

And the great thing about isometrics is that you can perform them daily, whenever your schedule allows. They also require minimal time - most general exercises take a minute or less to perform.

So check out these three faces of resistance. They just might change how you approach your resistance workouts. They sure did with me.


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