The word „isotonic“ means equal tension or weight. In this contraction, the tension developed is constant as the length of the muscle changes. It involves muscle shortening and active contraction and relaxation of the muscles and occurs during movements such as walking, running, jumping, etc. Dynamic strength is the force that is shown, or the force that is generated when the length of a muscle changes as the muscle contracts. Dynamic contractions can be concentric or eccentric. Concentric contractions shorten muscle contractions, while eccentric contractions prolong muscle contractions. Eccentric contractions can generate more tension per contractile unit at a lower metabolic cost than concentric contractions.166 167 Indeed, eccentric contractions more effectively use elastic elements in muscle and metabolic processes and require fewer motor units to produce the same force as in a concentric contraction. Therefore, eccentric contractions can be used early in the rehabilitation process, even if a patient cannot contract concentrically in the entire available AROM. In these situations, eccentric contractions can be introduced to allow some form of amplification in this ROM.

An example is the use of eccentric right leg lifts (LRT) in a knee rehabilitation program. Immediately after surgery, the first exercise would be sets of quadriceps (an isometric contraction of the quadriceps against gravity), followed by eccentric SLRs. This exercise can be performed by the rehabilitation specialist by passively lifting the leg and then directing the eccentric contraction, while the patient lowers the leg to the starting position. In this situation, the quadriceps performs an isometric contraction and the iliopsoas an eccentric contraction. The advantages and disadvantages of isotonic strengthening exercises are listed in Table 5-4. An example of this related to a bench press would be that an isometric of performance would keep the rod in a certain place, although it could be pushed higher, and an overtaking would be to push the rod into the safety devices of a squatting cage that prevent the bar from being pushed higher. This can happen unintentionally (when you try to move a weight that is too heavy for the muscle to lift) or voluntarily (when the muscle „smoothes“ a movement). In the short term, strength training, which involves both eccentric and concentric contractions, seems to increase muscle strength more than training with concentric contractions alone. The term „isotonic contraction“ is directly defined as „equal tension“, while the word „isotonic“ is derived from two Greek words: „iso“ means „equal“ and „tonikos“ means „tension“ in relation to the muscles [1]. As the name suggests, an isotonic contraction is a contraction in which the muscles maintain the same tension as they contract or shorten.

During isotonic contractions, a tension or force develops to a certain level. After this level, the tension remains constant, while the length of the muscle changes thereafter. These motor units within the skeletal muscles are effectively activated, allowing the necessary tension to develop in the muscle [4]. Isotonic contractions are often used when the limbs move. Common examples of such activities include walking, running, or even lifting objects. Unlike isotonic contractions, isometric contractions generate force without changing the length of the muscle. This is typical of the muscles found in the hands and forearm: the muscles do not change the length, and the joints are not moved, so the strength for grip is sufficient. An example is when the muscles of the hand and forearm grasp an object; The joints of the hand do not move, but the muscles generate enough force to prevent the object from falling. Isometric is directly defined as „same length“, where „iso“ means the same and „metric“ means „length“ when it comes to muscles [5]. During isometric contractions, the length of the muscle itself does not change, while the tension never exceeds the load that must be carried.

This means that even if the muscle itself does not shorten, the tension never exceeds the counterforce. Isometric contractions, small isotonic contractions in the middle range, vibrations, rhythmic stabilization or agonist/antagonist inversions are appropriate methods to improve muscle support in the middle range (see Table 6.3). Closed-chain positions provide joint pressure forces that lead to sensory feedback, which in turn helps activate and support the postural muscles (videos 2.24, 6.16, and 6.18).63 Coordinated muscle activation around the joint creates a central axis of movement and increases the stability of the lever system. Closed chain exercises involve movement across multiple joints, and movement over proximal or distal joints can be used to distribute forces. When movement is distributed to the surrounding joints, the forces are reduced to the injured or hypermobile area and there is less chance of reaching the extreme areas where the tissues are most sensitive to combinations of stress and tension. Training in the mid-range and avoidance of the end area reduces the shear forces and excessive movements made possible by flaccid structures or the lack of support of inert structures. Therefore, it is important to include area-specific goals to improve muscle activation, endurance, and strength. Balance activities trigger vestibular and ocular reflexes that automatically stimulate balance and balance responses that involve postural muscle activity to bring the body back to a middle position (videos 6.21 and 6.26).

Therefore, the use of balance reactions is one of the fastest and most automatic methods to promote the stability of the postural muscles. Vibrations or disturbances challenge the alternating muscles and also produce the same effect (videos 6.21 and 6.25).64,65 A comparison of the types of training and parameters used for hypomobility and hypermobility disorders is shown in Figure 6.5 and can be found in Table 6.4. Depending on the amount of force acting against an individual`s body, one of two types of isotonic contractions takes place. These are concentric contractions and eccentric contractions.[5] Concentric contractions occur when muscles shorten when their tension is greater than the force between them.[2] Eccentric contractions, on the other hand, occur when the muscles stretch in length. The strength in eccentric contractions is usually greater than the muscle tension that causes stretching. Lengthening the muscles during eccentric contractions puts a lot of pressure on the working muscles and therefore the possibility of muscle injury is much higher compared to concentric contractions [3]. • The liberating heat of the isometric contraction is lower and therefore the isometric contraction is more energy efficient, while that of the isotonic contraction is more and therefore less energy efficient. When a person holds his length against his body. Until this person encounters no resistance, he will not have a change in the length of his body. .