These exercises involve no muscle fiber lengthening or shortening. During these exercises, the length of the muscle is not changed, but the muscle is contracted in this way. Also, during the contraction, no joints will be moved. The brain spearheading is done by the effect of the central nervous system and this causes the contractions of the muscles. The muscles are then activated by the signal that the brain sends with the help of a nervous system to the motor neuron. Then they create tension by the myosin and actin, which are cross-bridged muscle fibers. When we say muscle contraction, we mean tension manufactured by the muscle fibers that are under the effect of motor neurons. There are four categories of muscle contractions and they are isokinetic, isometric, eccentric and isotonic. The focus of this article will be the isometric type of muscle contractions and first we will see what isometric contraction is. We have mentioned that during this contraction, a muscle stays in length without any lengthening or shortening of the muscle. This is a type of exercises during which there is a fixed length to the muscle's activity. Also, joints are not moved either, and if this is the case, there will still be firing of the muscle fibers. There is another name for these contractions and it is static contractions, which are totally depending on the length of the muscle contracted, since there is notmovement.
For example, there is no movement of the joint or muscles when we carry an object in front of us. We will try to push the weight up, while the weight will push downwards. During this activity, the arms have to remain in the same position, and during this, isometric contractions are conducted. Next example is griping a tennis racket. There is a lot of force used for gripping the racket, but there is no movement of the joint or muscles. Isometric contractions provide this force, which is influenced by the used muscles. Length of the muscle will determine the maximum isometric force.
These are basically straining exercises and they may prove useful in the gym. These exercises put on strain on the joint and they can be used for strengthening and rehabilitation. Static strength will be increased by doing isometric contraction exercises. Pushing or pulling heavy objects depends on this strength. Also, it is important to say that these exercises will not increase the muscular endurance. Doing these exercises is not advised for those with heart problems, because they cause less supply of the heart with blood, they raise the blood pressure, and stop the blood flow to the muscles.