Final answer:
Eccentric contractions in Yolanda's workout are demonstrated by the controlled lengthening of her muscles, like when she slowly lowers a hand weight after a bicep curl. This type of muscle action helps with decelerating movements.
Step-by-step explanation:
Yolanda is focusing on eccentric contractions during her workout. This is most likely demonstrated when her muscles increase in length while still maintaining tension. A typical example of an eccentric contraction is lowering a hand weight slowly after performing a bicep curl. During this action, her biceps brachii muscle would be actively controlling the descent of the weight by lengthening, which helps to decelerate the forearm movement as the angle of her elbow joint increases.
Eccentric contractions play a crucial role in muscle function, as they not only involve lengthening of the muscle but also contribute to muscle strength and control. Yolanda's deliberate descent of the hand weight showcases the biceps brachii actively resisting gravity, emphasizing the significance of eccentric contractions in promoting muscle stability and overall fitness gains.