Weight and resistance during training have different impacts—both negative and positive—on swimming mechanics. It’s important to be able to differentiate between the helpful benefits of added resistance and the potential negative impact of additional weight. There seems to be confusion about this in the swimming world, or perhaps just a sloppiness in use of terminology. This post outlines the differences between weight and resistance and highlights how resistance can be an effective tool in increasing muscle strength, stroke power, and ultimately speed.

The issue of weight versus resistance comes up often when people first try to describe DragSox®. It’s human nature to compare the new and unknown with the known. In this case people compare swimming in shoes with swimming with DragSox. This analogy is misleading. Although both are worn on the feet, DragSox create drag and wet shoes create weight. DragSox maintain streamlined body position whereas wet shoes pull you down.

DragSox are a resistance training tool designed specifically to create drag in the water. DragSox don’t absorb water; they cause resistance by creating an area of lower pressure directly behind the swimmer’s feet. This area of lower pressure pulls swimmers backward. This pull backward slows swimmer’s forward motion without negatively affecting his streamlined body position. To overcome the extra resistance created by DragSox, the swimmer has to increase propulsive (horizontal) force and, as a result, gains swimming-specific strength.

Running shoes, on the other hand, were created for running on hard, dry surfaces. Shoes absorb water. In the pool, they get heavy and start pulling the swimmer’s legs down. This downward pull breaks the swimmer’s streamlined body position. To bring the legs back up, the swimmer has to increase force. This, however, is not propulsive force, but force that moves the swimmers legs up from a broken streamline position. As a result, a lot of energy is wasted on trying to simply keep the legs from sinking. The swimmer gets tired but no swimming-specific skill or strength is gained.

The purpose of resistance training is to increase stroking power.^[1] More power leads to faster speed. For resistance training to be effective, though, proper stroke mechanics must be maintained. The reason why DragSox have been so effective is because they create resistance; the swimmer maintains proper stroke mechanics while increasing stroking power. Wet running shoes add weight, on the other hand, which inhibits proper stroke mechanics and prevents the swimmer from gaining swimming-specific benefits.

Weight and resistance are two different effects and should not be used interchangeably. Weight pulls you down, resistance pulls you back. Shoes pull you down, forcing you to expend energy on staying horizontal. DragSox pull you back, increasing swimming-specific strength.