Drag in a fitness context refers to:

In a fitness context, drag refers to the resistance encountered by an object moving through a medium, such as water or air. This resistance can significantly affect performance and efficiency while engaging in activities such as swimming or running.

When an object, such as a swimmer, moves through water, drag acts against their motion, requiring greater effort to maintain speed. The amount of drag is influenced by various factors including the object's shape, surface area, and the speed at which it moves through the medium. Understanding drag is crucial for athletes seeking to improve their performance, as they can implement techniques to minimize it, such as refining their technique or adjusting their body position to decrease resistance.

The other choices might relate to concepts of buoyancy, weight, or speed, but they do not capture the essence of drag in the context of resistance, making the chosen answer the most accurate in describing this important physical principle in fitness and exercise settings.