Final answer:
The buoyant force acting on an athlete or object is equal to the weight of the fluid displaced. This force is determined by Archimedes' principle.
Step-by-step explanation:
The buoyant force acting on an athlete or an object is equal to the weight of the fluid that the athlete or object displaces when immersed in the fluid. This force is determined by Archimedes' principle, which states that the buoyant force on an object equals the weight of the fluid it displaces. For example, if an object displaces 1 liter of water, it experiences a buoyant force equal to the weight of 1 liter of water.