Every time we move we are utilising muscular contractions to do so, taking a step forward can at different points involve two major types of contraction: Isotonic and Isometric.
Isotonic contractions are used for lifting and for most body movements. If you wanted to pick up a weight off the floor you would be using two types of Isotonic contraction, a concentric contraction (where your muscle shortens in length), and an eccentric contraction (where your muscle lengthens).
An Isometric contraction is different to Isotonic contractions as it does not involve the changing (either lengthening or shortening) of muscle length. An Isometric contraction would involve you holding your muscles still, an example of an isometric contraction would be holding a barbell out in front of you with both arms straight. The muscles would require energy to fight the pull of gravity and your shoulders, arms, and Trapezius muscles would immediately feel the strain.
A common form of isometric contraction would be the bodybuilder pose, if you’ve ever held one you’ll know that it can be a lot more tiring than you would have thought. The reason for this is that a prolonged isometric contraction can actually recruit more motor units (and therefore muscle fibres) than a regular isotonic contraction.
What are the Benefits of Isometric Exercises?
The main benefits to training isometrically are strength and hypertrophy gains, that come from the superior muscle damage that isometric training creates. Another benefit of isometric training – when used strategically, is the elimination of sticking points on certain lifts.
Let’s say that you are attempting your 1 rep max on the bench press, but once the bar has touched your chest and you’ve raised it an inch or two the bar stops moving and you require your spotter to help you move the weight. This is what’s known as a sticking point, and most people just assume it’s because the bar is too heavy.
Which is technically true, but you managed to lift it through every other part of the movement, there was just one point where you became ‘stuck’. So if you returned to that position (with a lighter weight on the bar) and held it as long as possible, your muscles would become stronger at that position. Therefore allowing you to lift the weight fully once you had adapted. This is the best use for isometric exercises, particularly when performed using perfect posture and technique.
The main downside to isometric training is CNS fatigue, or in other words: your central nervous system becomes overloaded by the intensity of this type of training and you find it difficult to recover. To avoid this, try to be sensible with the amount of isometric training you perform.
Limit it to a couple exercises within your session, and make sure that you rest the muscles the day afterwards. Doing so should allow for recovery and help you to avoid overtraining and fatigue.
Examples of Isometric Exercises
The most commonly used and known isometric exercise is the wall squat. This exercise is used in High School, and in outdoor bootcamps and circuit classes as a finisher leg exercise. To perform it you’ll need a wall. Lie with your upper back flush with the wall and lower yourself down into a squat position, with feet out in front of you and quads parallel. All you then have to do is hold that squat position for as long as possible.
Another example of an isometric exercise is the plank, or side plank. A great abdominal exercise that you can perform at the end of an ab workout. Place your forearms on a mat and your toes with your legs straight and a straight line from your shoulder down to your elbow (which should be in contact with the mat). Hold this position for as long as you can and ensure that your hips do not sag.
The final example of an isometric exercise is the barbell deadlift or rack pull. Load a barbell with a weight that is so heavy you cannot even move it off the floor/rack. Then set yourself up in the deadlift position and pull the bar, it is very important that you don’t let your technique fail you. Push your chest out and keep your shoulders back. Hold it for ten seconds and then relax. Repeat 3-4 times max.