Final answer:
An isotonic contraction refers to the muscle shortening at a constant speed over the full range of motion. There are two types of isotonic contractions: concentric contraction and eccentric contraction. In concentric contraction, the muscle shortens to move a load, while in eccentric contraction, the muscle lengthens while maintaining tension.
Step-by-step explanation:
An isotonic contraction refers to the muscle shortening at a constant speed over the full ROM (range of motion). It involves the muscle changing length while maintaining constant tension. There are two types of isotonic contractions: concentric contraction and eccentric contraction.
In concentric contraction, the muscle shortens to move a load. For example, when the biceps brachii muscle contracts to bring a hand weight upward, the muscle tension increases as the muscle shortens. This is often seen when lifting weights.
In contrast, in eccentric contraction, the muscle lengthens while maintaining tension. This occurs when a load is lowered in a slow and controlled manner. For instance, when the biceps brachii muscle gradually lengthens as a hand weight is lowered, the muscle tension decreases but the muscle is still engaged. Eccentric contractions are important for movement control and balance.