Final answer:
Muscles usually contract and shorten in a concentric contraction, but they can also lengthen during contraction, which is known as eccentric contraction, such as when lowering a hand weight.
Step-by-step explanation:
The question 'Muscle contractions cause muscles to get shorter, yet muscles can contract while getting longer. a True b False' addresses a key concept in the study of muscle physiology, specifically the types of muscle contractions. Indeed, muscles predominately contract by shortening, a process known as concentric contraction. However, muscles can also contract in a process called eccentric contraction where the muscle actually lengthens while it is still contracting.
An example of eccentric contraction is when you lower a hand weight slowly; the biceps muscle is contracting while it lengthens. This concept is vital for understanding how muscles work to control movement and maintain balance during physical activity.