The value of isometrics

Isometric movements make up one out of thee possible muscle actions. With the other two being concentric and eccentric motions. But why or when would you want to include isometric exercises into a training regime and which benefits can you expect? That and more will be discussed below.

In general, isometrics are the simples form of a muscle contraction, as per definition they activate a given muscle without moving the joint. Therefore the activated muscle will not induce any motion. An example would be to lift a weight with your hands by flexing your elbow (biceps curl) but then resting the weight at a 90 degree angle of elbow flexion. Holding the weight firmly in that position for a certain amount of time would be called an isometric contraction. Whereas lifting the weight up fully would be called a concentric motion and then lowering it down would make an eccentric movement.

Isometric training can generally be put into two different categories. For one "holding isometrics" where the muscle actively tries to resist an external force and for the other "pushing isometrics" where you actively push against an immovable object. These two differ in their training adaptation, as pushing implies active force production and muscle activation in a specific direction and holding emphasizes muscle endurance and stabilization (Oranchuk et al., 2019).

Interestingly though, it might seem that training with isometrics will not give you transferable results in other joint angles, but it does. As the concept of "angle specific strength" describes, training a muscle in a given joint angle will make you stronger especially in that angle but it will also lead to slight increases in strength some degrees above and below the training angle (Khouw & Herbert, 1998).

Isometric exercises are very commonly used by physio therapists and other medical trainers as they can lead to different muscular adaptations. One such adaptation would be an increase is muscular stiffness. A big promotor of isometric training would be the renowned back specialist Stuart McGill, as big "Big 3" for the lower back are all exercises that are performed isometrically to increase core stiffness (Lee & McGill, 2015).

Another health benefit that intelligent isometric training can give you concerns blood pressure. This might be something you don't expect isometric training to assist you in, but a recent meta-analysis from 2023 showed isometric exercising to bring the best benefits, outdoing even endurance training (Edwards et al., 2023).

Intent:

A great way to get the most out of isometric training for athletes is to perform them with a "ballistic intent", which increases neuromuscular activation (Oranchuk et al., 2019). This means that while performing isometrics you are trying to activate your muscles fully as if you were trying to exert maximal force. For example if you are performing the wall sit, try activating the musculature to such a degree as if you were trying to jump upwards as high as possible.

Muscle length:

Another thing to increase the efficiency of isometric training, especially for hypertrophy, is to perform the exercises at longer muscle lengths, as this has been shown to put the muscle under greater stretch and as this position consumes more oxygen it increases metabolism and therefore leads to greater muscle growth (Oranchuk et al., 2019). Still, don't worry too much about getting the perfect angle and instead stick to one that is comfortable for you.

Programming:

Performing an isometrics only training regime could surely reveal itself as a fun alternative to some people but probably not for most of us. Therefore including one or two exercises into a traditional program will usually be enough, depending on your goals. For overall health including one exercise per session which is held for longer durations and lower intensity (f.ex. 4 x 2 min wall sit, for the blood pressure benefits) and another core exercise that is held less time but for with higher intensity to increase muscular stiffness (for back health and endurance) could be an option. But feel free to play around on this approach. In general though, if you chose to include isometrics, then performing them for multiple sets (3-5) with a 45-seconds hold seems to elicit the best benefits. Then switch it up by altering contraction intensity and duration as well as changing joint angles.

Weak link training:

If you are struggling at a particular range of motion when performing a certain movement or lift, then you can get into that position and hold the position that seems to impair you for a longer period of time to get stronger in it. This is one of the few aspects where isometrics can be included to increase dynamic sports performance.

Rehabilitation:

When it comes to medical training and rehabilitation, then isometric exercise precedes all other motions. Especially when putting a muscle or joint under load is painful for the patient, isometric training is a great way to get a patients strength back without activating his symptoms. These isometric exercises can then over time be increased via volume (more sets or holding duration), intensity (switching from two legs to just one) or switching to longer muscle lengths when rebuilding strength and size are the main goal. Isometrics have also been shown to reduce pain, which makes them a great option to include at the beginning of a workout (Rio et al., 2017). Meaning you can precede a dynamic movement that usually is quite painful with a few sets of isometrics to increase your blood flow and pain tolerance and regain the ability to train pain free (or at least with less pain). This is crucial information especially for athletes, as for them training of any kind is important when injured. Or imagine a person having pain at 40 degrees of shoulder abduction. Then usually people would either train the abduction in the lower 30 degrees or not train that movement at all. But you could utilize isometrics, especially as it doesn't take as big of a toll on shoulder stability (which can often be the cause of pain) and perform isometrics below and above the painful area to maximize training adaptations while injured.

Pain management:

There has been some compelling research showing that the analgesic effect of isometrics can reduce pain coming from tendinopathies (Rio et al., 2015). As with certain painful tendinopathies there comes a change in recrution patterns that is also one of the determining factors of chronic pain patients. Isometrics have been shown to reduce the pain, as well as cortical inhibition and thereby normalize the altered recrution pattern for about 45 minutes. Which makes it a perfect first exercise for people with tendinopathies at the beginning of their training routine.

Tendon training:

As isometrics, do have an analgesic effect in painful joints, the same is true for painful tendons. They can be used to slowly increase tendon stiffness. But in order for that to happen training intensity needs to be fairly high (>70% MVC). Thereby isometrics could reduce electromechanic delay and improve rapid force production. But start with an intensity that enables you do perform them pain free (if >70% flares up the painful area, start with 50% or less and work your way up).

Expectations / Limitations:

When looking at the training transfer of static isometric exercises to dynamic sport activities the results concerning performance will probably be low at best, therefore think of it more as a tool to change body structure. Since excessively compliant tendons are frequently encountered in individuals who are untrained or have suffered injuries, gradually ramping up the intensity during isometric contractions could serve as a prudent and effective approach to condition tendinous tissue for upcoming dynamic loading. Also, if the training of specific of weak links is an athletes goal or when an injury is present and a particular muscle group can not only be trained through a limited range of motion, then training the pain free ranges via isometrics is a great option. And people with low back pain might be wise to include some isometric core strengthening into their daily routine.

References:

Rio E, Kidgell D, Purdam C, et alIsometric exercise induces analgesia and reduces inhibition in patellar tendinopathyBritish Journal of Sports Medicine 2015;49:1277-1283.

Oranchuk DJ, Storey AG, Nelson AR, Cronin JB. Isometric training and long-term adaptations: Effects of muscle length, intensity, and intent: A systematic review. Scand J Med Sci Sports. 2019 Apr;29(4):484-503. doi: 10.1111/sms.13375. Epub 2019 Jan 13. PMID: 30580468.

Edwards JJ, Deenmamode AHP, Griffiths M, et alExercise training and resting blood pressure: a large-scale pairwise and network meta-analysis of randomised controlled trialsBritish Journal of Sports Medicine Published Online First: 25 July 2023. doi: 10.1136/bjsports-2022-106503

Lee, Benjamin C. Y.; McGill, Stuart M.. Effect of Long-term Isometric Training on Core/Torso Stiffness. Journal of Strength and Conditioning Research 29(6):p 1515-1526, June 2015. | DOI: 10.1519/JSC.0000000000000740

Jonathan P Folland, Kate Hawker, Ben Leach, Tom Little & David A Jones (2005) Strength training: Isometric training at a range of joint angles versus dynamic training, Journal of Sports Sciences, 23:8, 817-824, DOI: 10.1080/02640410400021783

Khouw, W., & Herbert, R. (1998). Optimisation of isometric strength training intensity. Australian Journal of Physiotherapy, 44(1), 43–46. https://doi.org/10.1016/S0004-9514(14)60364-0

Rio, E., van Ark, M., Docking, S., Moseley, G. L., Kidgell, D., Gaida, J. E., van den Akker-Scheek, I., Zwerver, J., & Cook, J. (2017). Isometric Contractions Are More Analgesic Than Isotonic Contractions for Patellar Tendon Pain: An In-Season Randomized Clinical Trial. Clinical Journal of Sport Medicine: Official Journal of the Canadian Academy of Sport Medicine, 27(3), 253–259. https://doi.org/10.1097/JSM.0000000000000364