Isometric Contraction Phase

The isometric contraction phase is one of the phases of the cardiac cycle that occurs during ventricular systole. In this phase, the heart contracts and the blood vessels fill with blood.

During the isometric contraction phase, the ventricles of the heart contract, while the volume of blood inside them remains unchanged. This occurs due to the fact that the ventricles contract isometrically, that is, without changing their volume. This way, the volume of blood in the ventricles remains constant, allowing the heart to pump blood efficiently throughout the body.

The isometric contraction phase begins when the ventricles begin to contract and ends when they reach their maximum contraction. During this period, the heart works at full capacity to provide sufficient blood to all organs and tissues of the body.

It is important to note that the isometric contraction phase is one of the most important phases of the cardiac cycle. It ensures the efficient functioning of the heart and allows it to pump a sufficient amount of blood throughout the body, which is a necessary condition for maintaining human health and vital functions.

It is important to remember that isometric strength is not some new, separate physical strength, but a combination of various other forces, such as muscle strength and tendon stretching. The basic understanding is that when muscles contract, they simultaneously contract their tendons. When the strength of one muscle doubles but the length of its tendon does not increase, it is called an isometric contraction. Isometric contractions are a very common form of muscle activity in everyday life and can be used to perform many tasks such as heavy lifting, weight bearing, or even just climbing stairs.

**Who needs knowledge of such strength indicators?**

1. Athletes 2. Physiotherapists 3. Fitness instructors 4. Sports experts 5. Researchers 6. Anyone involved in strength training 7. You and anyone considering purchasing a gym membership

**How ​​to calculate**

There is a formula for measuring isometric strength (muscle strength during contraction with zero displacement) that you can use to get started:

https://www.researchgate.net/publication/349753803_Estimate_of_MCC_in_Weightlifting_Based_on_an_In-Pull_Range_of_Motion_on_-Weightlifting This formula has sufficient accuracy to determine the general direction and then apply the results to all others

The isometric contraction phase is the third stage of skeletal muscle contraction. It occurs after a period of latency and a shortening phase. This phase lasts several seconds and is characterized by maximum muscle contraction.

The phase contracts under the influence of two mechanisms: muscle stretching - its mechanical effect. The second mechanism operating during this phase is the contraction of striated fibers at the origin of the muscle. Together with rapid stretching, these fibers result in short, strong muscle work. During the isometric phase, the muscle acts like a very rigid cable. In contrast to the bending strength exercises (which form the basis of the squat), the squat is all about the downward movement, not the sideways movement. Squats are needed to lift weights upward.

During the contraction phase, metabolic processes occur, including energy production and the need for respiration. This period can last from a few seconds to