Walk into any gym, and you’ll undoubtedly see two types of training being performed isotonic exercises and isometric exercises. Isotonic training include classic lifts that are more commonly performed, with a concentric or “lifting” phase, and an eccentric or “lowering” phase to every rep. For simplicity’s sake, think of a standard biceps curl.
There’s nothing wrong with isotonic training, and it’s been tried, tested and true for facilitating gains in size and strength. But adding another type of exercise to the mix, can be a missing link to unlocking more gains and busting through plateaus you may have encountered in your quests for both insane strength or added size. That type of exercise is isometric exercises.
What Are Isometric Exercises?
Simply put, whereas isotonics training involve a shortening and lengthening of a muscle to create repetitions, isometric exercises involve no change in length of the muscle while applying forces against a resistance. For that to be made possible, it would mean the resistance would be too heavy to have the muscle tissue length change—in other words, immovable. A simple example of an isometric contraction would be trying to push against a concrete wall with the intent of moving it (knowing, of course, it won’t budge).
Admittedly, at this time 10 years ago, I was not on board with the idea that isometrics could have any reliable impact on either goal. It took reviewing plenty of credible research and investing in coaching myself with a muscle activation techniques specialist using strictly isometrics as the training method to realize its benefits firsthand. And benefits are plenty.
Isometrics Improve Mobility
This sounds counterintuitive but it’s important to realize what mobility actually is. It’s strength!
What makes mobility different than flexibility is the fact that a flexible person can display lengthened muscle tissue by way of stretching – and this is usually isolated to one or maybe two muscle groups at a time and relying on an anchor of some sort to move passively around (think about standing tall, putting a foot up on a bench with a straight knee and leaning forward over that foot for a hamstring stretch. That’s a display of your hamstrings’ flexibility). Mobility relies on the contractile strength of a group of muscles to affect the range of motion at a joint. It’s based on actively pulling a joint through that range, rather than passively pushing it into that range (so again, think about that hamstring stretch above, but this time imagine the bench was removed from under the foot. To keep the same joint angles, it would mean the hips and quads on the front of the thigh now have to contract to hold the leg up there at the same level). In everyday life, having good mobility by far outweighs having good flexibility in its importance. And once again, having access to strength through a range of motion will make mobility better.
Isometric training can help with this tenfold by simply challenging end ranges of lifters’ mobility. Here’s an example. If a lifter has poor shoulder mobility both in extension and/or flexion, it is fairly simple to set something immovable up at the limits of the lifter’s ability and apply isometric force into that object. Over time, once it becomes easy to reach that point and apply full force for a set amount of time, the object can be moved further away from the lifter to create a new challenge to what’s now a new end range of motion. In the case of shoulder extension (see video below), this would simply mean raising the bar a couple of inches higher.
How Does Isometric Exercises To Improve Strength
Being isometric, as we discussed, muscles don’t change in length, and in an ideal world, the skeleton doesn’t change or shift in position when performing the exercise in question. That’s invaluable to a lifter who’s looking to avoid injury, since 99% of injuries happen when the body changes position under load.
This also allows you to do something conventional isotonic training can’t provide: Strengthen your max effort at every single phase and joint angle of a movement’s force curve.
The Isometric Deadlift
As you can see in this deadlifting example, I’ve blocked the bar at the bottom position of my deadlift to work on giving it everything I’ve got there. Next, I could just as easily set up the pins to block me at just below knee level—a place where the moving bar would typically only PASS THROUGH using isotonic training—even if it’s a one rep max effort. The presence of kinetic energy/force at play means I’d never really be able to establish a true maximum force production through those ranges.
This is humbling work, and won’t take many more than 6 sets of 15 second holds to really drain your CNS.
Isometric Bench Press
You can replicate the same idea with bench presses and military presses, or even squats.
Isometrics Can Trigger Size Gains
Using this training method tactically can go a long way for someone who wants to increase muscle mass. Think about it this way: Building muscle is going to be a product of recruiting high threshold motor units, exhausting fast twitch fibers through heavy efforts (or going to similar exhaustion through lighter efforts), and of course, supplementing it all with a goal-based diet.
Using an isometric exercise to amp up the CNS and recruit plenty of said high threshold units for a given movement can make moving on to the isotonic version of that movement even more effective in a) creating time under tension, and b) encouraging muscles to “overfire” due to the fact that they were just “tricked” by working against something immovable. A good example of this would be performing the isometric deadlift seen above, and immediately following it up with an 8RM deadlift.
Suffice to say, the possibilities for isometrics are endless. Incorporating them into your program is a surefire way to see gains while placing your body at no additional risk to work hard. It’s also important to remember that no matter your skill level or athleticism, we’re working with energy systems. As long as the implement matches your strength, you’re likely to feel the same sensations and die out after the same period of time whether you’re a beginner or a pro bodybuilder. That’s the beauty of it.
As a general guide, start with 15-20 second isometrics for any of the above movements, aiming for max effort. After 4 weeks, go up to 20-30 second isometrics.