Isometrics. What actually is an isometric? Is it an exercise? Is it a movement style? An isometric is defined as a contraction type of a particular muscle or group of muscles in which they don't noticeably change length and the related joint doesn't move. This means that we can perform an isometric contraction type in nearly any position someone has in the ability get to. With this in mind, isos can be further distilled down into two main categories; yielding & overcoming isometrics. Isos also have numerous benefits spanning from performance applications to rehabilitation uses and everything in between.
Yielding Isometrics (YI)
A yielding isometric encompasses setting yourself in a position and resisting deformation forces to continue holding said position. These deformation forces could be anything from weighted loads, band resistance to just gravity itself. Good examples of a YI are holding a weighted back squat, getting to the bottom of a push up and hovering off the ground without touching it or holding a static unweighted lunge without gravity pulling you out of position. The amount of possible YI's are nearly endless and only limited by your creativity. This would be the isometric type i would generally encourage most individuals to include in their programs as they're well suited for almost everyone.
Within the YI category, there is another style of iso that is reffered to as an extreme isometric. Like all YI's, an extreme iso has someone set themself in a position and resisting forces that want to move them out of this position but the deferentiation comes by way of continuing the attempt to hold this position past the point of starting to deform. This quasi isometric-eccentric contraction brings with it a higher level of intensity than most traditional YI's and is much more taxing but also comes with the ability to tap into higher thresholds of the benefits associate with isometrics.
Overcoming Isometrics (OI)
An Overcoming isometric is a movement type in which you set yourself in a position that allows you to try and move an immoveable object. The intensity of these can be scaled super easily by the individual performing them as all it takes to raise the level of the stimulus is push/pull/lift with more force (provided the immovable object has enough mass to resist the applied force or is truly immovable). OI are generally more of a performance orientated isometric as they have a higher risk than YI's but also have added benefits that YI's don't. Maximal muscle activation, huge neural output and the ability to practice positional stability without compensation under practically the highest intensity you can withstand are unique benefits.
Isometric Benefits
As they can be performed basically anywhere, with minimal equipment and modified to differing intensites, isos deserve a place in everyone's training programs. Now i'll touch on 5 benefits of isos and how they can benefit you, no matter what your training goals may be.
1) Improve connective tissue health
With all the attention your muscles get, tendons and ligaments will benefit from focused training too. Unlike your muscles which love traditional eccentric and concentric movements, your connective tissue benefits and adapts to much, much slower loading. This is due to the physiological processes of tendon creep and stress relaxation. Tendon creep takes place when a relatively constant, unchanging load is applied and has the tendon subtlely stretch out or 'creep' over time. This in combination with stress relaxtion in which the tendon relaxes due to the constant and unchanging load causes the collagen fibres that make up the tendon to tear apart. Just like with our muscles, our body repairs these fibres to be stronger and more resilient than last time to avoid tearing again, provided the tendon is relatively healthy and the intensity of the iso and creep are dosed properly.
2) Improve joint co-contraction efficiency
By practicing to stay in positions and resist deformation, we're essentially training our muscles and nervous system to work in synergy to find the most optimal and efficient position avaible. This can happen via exposing compensation patterns one may have and self correcting them or by way of pushing the intensity of the hold. Generally the deeper ingrained a compensation pattern is, the higher you'll have to push the threshold of isometric intensity to have it truly exposed and force the body to find another avenue in which to optimise the movement position. The training of your muscles to work in coordinated harmony and communicate well between one another to provide a joint with efficient stabilisation is often very underutilised.
3 & 4) Rehabilitation + Low Impact
Tying two points together here as they share a very similar vein of benefits. The usage of isometrics for rehabilitation can be applied after anything from a sprained joint/muscle to major surgeries. The reason an isometric can be a smarter alternative in a post surgery situation is that you're sending neural input, upregulating a muscle's activation and getting it firing... all keys in preventing post surgery atrophy. From a sprain + strain viewpoint, being able to specifically target positions/ranges of motion that your body is still comfortable in, allow you to reap the same benefits as above, without further aggrivating the already affected soft tissue.
Following any lower body surgery, sprain or strain, you may have a limb somewhat imobilised due to the need to protect incision sites or not weight bare on the limb. Isos can be an affective way to still give your muscles, ligaments and tendons some loading in which no impact load needs to be placed through the body.
5) Mental conditioning
Whilst all the other benefits i've listed here come under the physical, this one is a mental one. The mental battle that takes place while fighting a load to keep locked in and stable in a position when every muscle being used is screaming at you to sit your ass down can be as grueling as anything in the weightroom. Don't let anyone else tell you otherwise. Being able to push past your percived (and often self imposed) limits and continue going when you don't think you can is character building and raises the intensity threshold you know you can withstand. If you want to see what you're made of, get into an athletic lunge position and see how long you can hold it for. 5-7 minutes and you're doing very well, above 7 minutes and you're a savage.
As with anything in life, training styles fall in and out of favour like a pendulum swinging. Isometrics are very 'in' and all the rage at the moment. I strongly believe they have a place in everyone's training programs, albeit not comprising the majority of their training though. Balanced and adequately programmed dosage of isos is the key to utilising them for the best possible results.