Have you ever tried to push or pull something really heavy and found your muscles getting really tired without anything actually moving? Have you wondered why?
There is a simple scientific reason for this which I’d like to explain in this blog.
This type of movement is called an isometric contraction, which basically means that you were contracting/shortening/working the muscle but without any movement or change to the joint (where the two or more bones meet ie. elbow joint).
Naturally, we do this every day but can range from light to heavy objects or from a short to a long period of time. For example, using the same joint mentioned earlier, we could use the examples of brushing your teeth (light object short amount of time) to carrying a heavy bag/shopping in your hand and bending the arm at a right angle. What you find with the latter is that your bicep muscle will start to expand and possibly burn (lactic acid).
This can be related to so many other day to day actions, but this type of muscle contraction doesn’t just happen in everyday life but is also used very extensively in the fitness industry for its body improving benefits, but let’s look at its origination.
The History of Isometric Exercise
Isometric is actually two separate words combined, with ‘iso’ meaning ‘same’ and metric meaning ‘length’.
It goes as far back as 3000 BC, as yoga dates back to then, based on stone carvings of some of the first yoga poses found in the Indus Valley.
With yoga dating back far, there is much belief amongst many martial art historians that many of the martial arts we see today have some sort of link back to yoga.
Martial arts then carried forward the usage of isometric training to develop strength, power, speed, flexibility, dexterity, and muscle mass, primarily using just one’s bodyweight to achieve this.
With martial artists developing such athletic physiques and strength, the fitness industry soon caught on to this and started to bring this into training programmes and classes, as people could develop these aspects with minimal equipment and little stress on joints.
Although not essential, some knowledge of anatomy and physiology would definitely help us understand what’s happening during the 3 types of muscle contraction. These are:
Concentric and eccentric muscle contractions come under the ‘isotonic’ as they involve actively moving or taking the joint through its full range, whereas an isometric contraction involves no movement at the joint whatsoever.
To contract a muscle isometrically or isotonically the brain must tell the muscles to contract via the central nervous system.
Below is a few more in-depth and visual explanation of how that occurs:
I generally like to think of it as a WiFi router connecting to a device in the house like a computer or mobile phone.
With understanding how the brain gets muscles to move and contract, the next point to note is that we have different muscle fibre types.
There are 3 muscle types in the body and which fall under two brackets, these are fast twitch and slow-twitch muscle fibres. Different activities predominantly activate certain muscle fibre types.
The 3 types are type 1 (slow-twitch), type 2A (fast twitch oxidative glycolytic), type 2B (fast-twitch glycolytic).
When breaking these muscle fibre types down, you will see that they have different force, resistance, endurance, and energy requirements:
With knowing this information, we can generally bracket ourselves into what form of exercise suits us best due to what forms of activity we fatigue less at:
With all this info on muscle fibre types we can see that isometric training works both slow and fast-twitch muscles fibres, but this is down to the amount of force production needed plus the duration the fibres need to work for ie a maximum isometric contraction for a short period of time would predominantly use more type 2b fibres, a moderately maximal isometric contraction for a moderate amount of time ie greater than 10 seconds would use more type 2a fibres as you feel more lactic acid production, and a low amount of force production for a long period of time ie greater than 3 minutes, would be more type 1 fibres used predominantly.
Strength and Hypertrophy
Understanding the amount of force and time worked allowed some well-established strongmen to use this in different ways over the decades.
Max Sick, born in 1882, created a form of isometrics called ‘static tension isometrics,’ where you would contract/squeeze the muscle as hard as you could for a period of time without moving the joint. This allowed Max to develop his strength and muscle mass, even though he was very sick from a young age, had severe lung problems, dropsy, and rickets. Max could lift a man forty pounds heavier than him above his head sixteen times.
Charles Atlas is probably one of the most well-known strongmen from decades ago and he invented the ‘yielding isometrics’ or ‘dynamic tension’ method. This is when you put a muscle against a muscle and use the force that your own muscles generate to create fatigue, an example would be pushing both of your own hands against each other. Some of Charles Atlas’ feats of strength were:
- Tearing a Thick Telephone Book & Deck of Cards in Half.
- Bending a 6 Inch Spike Double.
- Smashing a 3 1/2 Inch Nail Through 2 Inches of Sturdy Pine Planks.
- Bending a Steel Bar 6 Feet Long and 1/2 Inch Thick.
- Pulling an Automobile with His Neck.
- Lifting One End of a Car Clear Off the Ground.
- Lifting a Pony into the air
Alexander Zass developed a different but similar type of isometrics, which allowed him to build extreme strength and quality muscle while in prison. He developed a method called ‘overcoming isometrics’ in which the person exerts maximal pressing/pulling force against an immovable object. Some of Alexander’s feats of strength were:
- Breaking shackles and bending iron bars (which is how he escaped from prison).
- Carrying a full piano on his back with people on top.
- Snapping smaller sized trees in half.
These three strongmen have allowed us to evolve isometric training over the years by using not just our body weight (planks, wall-sit) but also dumbells (standing dumbell curl+hold) barbells (squeezing at the bottom of a barbell bench press) or bands (holding the top horizontal position of a lateral raise) to give us so many different ways and tools to challenge and overload any exercise you want.
As you can see from different equipment used, isometrics can be used on their own for a specific exercise ie wall-sit or added into an exercise to increase the strength/force depending on a certain muscle group or movement, ie holding/squeezing at bottom of a barbell back squat for a few seconds before coming back up.
T-nation owner Christian Thibaudeau put together a very good bodyweight workout using isometrics over the COVID-19 pandemic for people training at home.
Flexibility And Mobility
Isometric training not only has its benefits to develop strength and muscle mass, but as previously stated, martial artists would use this to develop flexibility in the muscle and mobility in the joints.
A well-known method in the fitness industry for developing flexibility is a method called PNF stretching (proprioceptive neuromuscular facilitation) in which isometric contractions are used to help you increase your flexibility on a certain muscle or group of muscles.
There are 3 types of PNF stretching:
- Hold-relax with agonist contraction
These are advanced techniques and I find are somewhat better to visually show than to describe. The videos below will do this:
Hold-relax with agonist contraction
As you can see, these are quite detailed and require partner assistance or an external resistance, but can provide great benefits in regards to flexibility.
There is another method/system that is quite new in the fitness industry from a brand called FRC (functional range conditioning), which was developed by Dr Andreo Spina. It uses every part of the body to increase/improve mobility and overall joint health. In this system they use their own principles called PAILS (progressive angular isometric contractions) and RAILS (regressive angular isometric contractions) which basically allows us to build strength and tissue adaptations in both a fully shortened (close) and lengthened (far away) range of movement at a joint. Below is an example of how PAILS and RAILS are done:
These are very intense on the body and should be done with the correct coaching and guidance so that the correct parts of the joint (shortened or lengthened) ranges are improved.
As you can see, isometric training is constantly evolving, even though it has been about for thousands of years. Top coaches and doctors are looking to improve and make this method of training even more efficient and effective. The main point to take from it is that anyone can benefit from isometric training, whether that be to increase strength or flexibility, you just need a goal and a baseline to start from.
If you have any questions or comments, please leave below.
“If it doesn’t challenge you, it won’t change you”,