When people think about strength training, they typically imagine large compound movements through extensive ranges of motion i.e., back squat, deadlifts, bench press, etc. Contrarily, what they typically don’t think of are isometric exercises, which I cannot fault them for. At the surface level, there doesn’t appear to be much to them, making them an underwhelming afterthought in the resistance training realm. The benefits, however, of isometric training are not only abundant but also unique. Isometric training is an excellent complement to nearly any training program and can be implemented with ease. Understanding the benefits and equipping yourself with isometric strength training knowledge is essential in fine-tuning your strength training arsenal.
What is Isometric Training?
When considering resistance training, two primary actions occur, concentric and eccentric. Concentric actions occur when our muscle(s) contract and shorten to change a joint angle. The easiest example to consider is a bicep curl, where we actively bring our closed fist towards the same side shoulder to shorten the bicep. Contrarily, eccentric actions occur when our muscle lengthens, the inverse action of what I previously described where instead of bringing the weight up, we lower it back down.
Between these two movements, we have isometric muscle contractions, where there is no change in muscle length at all. The interesting part is that isometric contractions can occur at nearly any range of motion (more on this in a bit) and they offer a unique twist to most conventional exercises. Everybody does some variation of isometric muscle contractions in their daily lives whether know it or not. When you are standing completely still you are technically performing an isometric contraction to support your body weight, although it might not feel like much. Isometric contractions vary tremendously in terms of their difficulty and benefits depending on how they are manipulated as well as what their cofactors are. Asking you to go from standing on both legs to only standing on one is a simple example of this. Both require isometric contractions to occur, however, the input of only having one leg to stand on changes the dynamic dramatically.
Benefits and Placement of Isometric Training
As previously mentioned, the benefits of isometric exercise are abundant. One of the greatest offerings is the ease with which you can work on maximum voluntary contractions (MVC). MVC is essentially our body’s ability to recruit as many motor units as possible to perform a given task, i.e., how hard can we push/pull something or how much force we can generate. This may not sound like a groundbreaking principle, but consider that rarely, if ever do we test our MVC. To reach peak MVC in the gym via movements involving changes in muscle length (concentric and eccentric) like the back squat for example, we would need to be at or near failure on said movement. This is daunting and quite frankly a bit unsafe for most people for obvious reasons. Conversely, when we train MVC through isometric exercise we are improving our capacity to generate force which then carries over into our ability to apply force at all ranges.
Another added benefit of isometric training is its utility in rehabilitation programs for injured athletes. If for example, an athlete has suffered a knee injury that limits their ability to move through a full range of motion, then most movements are off the table. In this instance, isometric exercises can serve to train strength in some capacity without risking injury or further damage. This could be done with something as simple as an isometric leg extension where the athlete extends their leg (depending on their injury) and contracts for a set period (i.e., 30 seconds). In a scenario where severely limited or restricted altogether, this can be a saving grace and something an athlete latches onto until they can begin adding further variety back in.
One of the most unique aspects isometric training offers is its potential for “highly specific” positional training. Take for example an alpine ski racer, an athlete with whom I have a lot of experience working. We can put them in a low crouched position like their stance while gliding on the racecourse and have them actively resist against a load whether it be on their back, pulling from one side, or pushing from another side. This provides a stimulus unlike anything else they would be able to perform in a conventional movement and may aid them in training more specifically. I won’t tout it as a magic bullet by any means, but it is certainly a unique offering that gives isometric training a leg up in “specificity”.
Last but most certainly not least, isometric movements can be an excellent addition to a warmup or “activation” portion of a training session. I commonly incorporate isometric split squat holds on days when I will be doing heavy lower body work to get my body ready for what’s to come. By doing an isometric movement before anything dynamic, you’re allowing your body and more specifically your nervous system the chance to “turn on” a bit before you add further load. For those who are slightly more injury-prone or like to take their warm-up a bit more seriously, this is a phenomenal addition and can be placed in nearly any training program with ease.
There isn’t necessarily one protocol to definitively train isometric movements, as it will greatly depend on an individual’s situation, goals, training history, the movement they are performing, etc. There are some solid general guidelines, however. According to the International Journal of Sports Medicine, the following guidelines can help you find the right protocol for your situation:
– 70-75% of your MVC (about 7.5 out of 10 maximum effort) for exercises intended to increase hypertrophy. This should be sustained for 3-30 seconds per repetition with a total contraction time duration of 80-150 seconds per session.
– 80-100% of your MVC (8-10 out of 10 maximum effort) for exercise intended to increase maximum strength. This should be sustained for 1-5 seconds per repetition with a total contraction time of 30-90 seconds per session.
Isometric training methods can be an excellent addition to most programs, and they offer a unique approach to achieving many different goals. They are often overlooked because they are often misunderstood or thought to be ineffective however that is far from the truth. Nearly everyone who performs some form of resistance training can and should incorporate some type of isometric training into their program regularly to yield maximum results. Give them a try sometime and consider incorporating them in one or more of the several ways discussed previously in this article.