Final answer:
The statement that isokinetic exercises involve muscle contraction or tension against resistance is true. These exercises include concentric and eccentric contractions, where muscles either shorten or lengthen under load.
Step-by-step explanation:
Isokinetic exercises are indeed involving muscle contraction or tension against resistance, which makes the statement A. True.
In such exercises, the muscle change their length while lifting a load, and this can be either shortening during the concentric contractions or lengthening in eccentric contractions.
An example of a concentric contraction would be the biceps brachii muscle shortening when lifting a weight, which decreases the angle at the elbow joint as the forearm moves toward the body.
Conversely, an eccentric contraction would involve the slow lowering of a weight, extending the angle at the elbow as the muscle lengthens.