Final answer:
Isotonic contractions involve change in muscle length to move a load, with two types: concentric (shortening) and eccentric (lengthening). Isometric contractions involve increase in muscle tension without changing muscle length, useful for maintaining posture and joint stability. Both types contribute to a wide range of bodily movements.
Step-by-step explanation:
Comparison of Isotonic and Isometric Contractions
Isotonic contractions are types of muscle contractions where the muscle length changes as it moves a load. Interestingly, there are two subtypes of isotonic contractions: concentric and eccentric. A concentric contraction involves the muscle shortening, such as when lifting a weight towards your body, while an eccentric contraction involves the muscle lengthening, as when lowering the weight in a controlled way. Although muscle length changes, the muscle tension remains fairly constant during isotonic contractions.
On the other hand, isometric contractions occur without any change in muscle length. Here, sarcomeres within the muscle may shorten and generate increasing tension, but the external load is not moved because the tension does not surpass the load's resistance. These contractions are common when maintaining posture and stabilizing bones and joints.
In every action requiring muscular effort, a combination of isotonic and isometric contractions work together to produce a wide range of outcomes, contributing to our ability to move and balance efficiently.