What happens to the effort required by arm muscles as the frontal surface area of the hand against water increases?

When the frontal surface area of the hand increases while moving through water, the resistance encountered by the arm muscles also increases. This resistance is due to the properties of fluid dynamics, particularly drag, which forces players to exert more effort to overcome the increased surface area of the hand pushing against the water.

As the hand’s surface area expands, it displaces a greater volume of water, resulting in a higher drag force that the arm muscles need to overcome to maintain movement. For example, if a person were to use a larger paddle or their hand splayed wide, they would feel more resistance compared to a smaller or more streamlined movement. Thus, as hand surface area against the water increases, the effort required from the arm muscles correspondingly increases to propel through the water effectively.