Difference Between Isometric and Isotonic Contractions (With Table)

In our body, muscles help in the movement of our body and protect and act as a shield for our bones and various organs present. To perform various activities in day-to-day life for a human, his muscles need to perform these actions.

There exist contractions between the muscles for letting us perform our activities and their smooth functioning. Isotonic and isometric are two types of contractions available in the muscles.

Isometric Contractions vs Isotonic Contractions

The difference between isometric contractions and isotonic contractions is that when an isometric contraction takes place in a human body for performing various activities, there is no change in the length of a muscle, and, on the other hand, when an isotonic contraction takes place in the human body, there is a change in the length of the muscles.

Isometric contractions are contractions that are said to be of the same length waves. In this word, iso means some, and metric means length. The tension in a muscle increase exceeds the load that is initially carried on without having any change in the length of muscles. This, in shorts, means there will not take place any chance of exceeding the opposite force.

Isotonic contractions are contractions that occur with some tensions. The word isotonic is framed from a Greek word named is, which means some and toniko, which means tensions. In isotonic contractions of muscles, there is a change in lengths of muscles, but the tensions are the same or contracted. There is a certain amount of tension or contractions that are exerted in an isotonic contraction.

Comparison Table Between Isometric and Isotonic Contractions

Parameters of ComparisonIsometric ContractionsIsotonic Contractions
LengthThere is no change in length.There does occur some changes in length.
TensionsThere are some changes that occur in tension.There is no change in tensions; that is, they are always constant.
Period changesThe latent period and relaxation period is inversely proportional to the contraction period.The latent period and contraction period inversely proportional to the relaxation period.
External workThere is a non-occurrence of external work.There is occurrence of external work.
EnergyHigh efficiency of energy is required.Low efficiency of energy is required.

What are Isometric Contractions?

Isometric contractions are contractions that are said to be of the same length waves. In this word, iso means some, and metric means length. The tension in a muscle increase exceeds the load that is initially carried on without having any change in the length of muscles. This, in short, means there will not take place any excess for the opposite force.

When a person holds his or her or her length against his or her or her body. Till this person faces no resistance, he or she will have no change in his or her body length. This is exactly how an isometric contraction takes place inside the muscles. During an isotonic contact, the muscles remain their normal length. This means that the amount of force produced is directly proportional to the amount of increase in the length of the muscle pull.

Pushing an object in a stationary position, a person holding a weight in a special place are two examples where an isometric contraction takes place in a muscle. Although there is no change in the length of muscles, there does occur a change in the muscle fibres to shorten, which helps to increase the strength of muscles.

What are Isotonic Contractions?

Isotonic contractions are contractions that occur with some tensions. The word isotonic is framed from a Greek word named is, which means some and toniko, which means tensions. In isotonic contractions of muscles, there is a change in lengths of muscles, but the tensions are the same or contracted. There is a certain amount of tension or contractions that are exerted in an isotonic contraction.

At this time, there is a specific amount of change in the muscles without any kind of change in tensions. This helps to activate the skeletal muscles in our body. When it comes to moving limbs in mammals, that is when an isotonic contraction takes place. When a person runs, walks, exercises, or even sits, this is when an isotonic contraction takes place.

Depending on the force to be applied for a person’s activity related to his or her body, the isotonic contraction is divided into some contractions. They are the concentric concentrations that happen when the muscles require more force to shorten the muscle fibres and the eccentric contractions, which cause a muscle to elongate by giving more force.

Main Differences Between Isometric and Isotonic Contractions

  1. There are a lot of changes in the length of muscles in an isometric contraction, and, on the other hand, there does not occur any kind of change in the length of a muscle in an isotonic contraction.
  2. In an isometric contraction, when there is a long latent period, there are shorter contraction periods with longer relaxation periods, and, on the other hand, in an isotonic contraction, when there is a shorter latent period, there occur shorter contraction periods with a longer relaxation period.
  3. The isometric contraction requires high efficiency of energy to be produced, and on the other hand, an isotonic contraction requires less efficiency of energy to be produced.
  4. There is non-happening of external work in an isometric contraction due to less amount of heat released, and, on the other hand, there is happening of external work in an isotonic contraction due to its high amount of heat emitted.
  5. The tension in an isometric contraction is always constant, and on the other hand, the tension is an isotonic contraction that keeps changing.

Conclusion

For performing activities for humans in day-to-day life, both isotonic contractions and isometric contractions must be taken place. An individual should acknowledge the difference between an isotonic and an isometric contraction to help in knowing how a muscle works for performing actions in our life.

This also helps in defining the workout routine of how one should perform for an individual. A person under a medical working place or a fitness trainer should know the basic differences between them. An isotonic contraction and Isometric contraction both have their differences in how they are performed based on what context they take place in.

References

  1. https://rupress.org/jgp/article/56/6/732/13113
  2. https://journals.physiology.org/doi/abs/10.1152/jappl.1999.87.5.1758
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