The most common type of muscle contraction encountered with most exercises is meaning the contraction proceeds at a consistent muscle tension while the body part moves through its range of motion.

The most common type of muscle contraction encountered with most exercises is isotonic, meaning the contraction proceeds at a consistent muscle tension while the body part moves through its range of motion. This contraction results in the muscle shortening.
The muscle contracts and as a result it changes its length (it is shortened) and this causes movement of a body part.