Coaches

Understanding and Overcoming Resistance

9/18/2012

Resistance

Water resistance affects a swimmer in different ways. One way is through the impact of water with a swimmer and the subsequent flow of water around the body. This is called “form resistance.” Another way is through water turbulence and waves that are created by moving water. This is called “wave resistance”. A third way is through water sticking to a swimmer's suit or skin and creating “friction resistance”. These three resistance components all have a negative effect on swimming performance and should be reduced whenever possible.

  • Form resistance is the most significant type of resistance and a swimmer’s technique influences it tremendously. Form resistance is the resistance from the water that is dependent upon body position. The more horizontal the body position becomes in the water, the more form resistance decreases. Swimmers should try to stay up near the water surface (especially with the hips) during all strokes. A slanted body position will enlarge the frontal surface area in the vertical direction and increase the resistance. Extreme lateral swaying in the water is another example of increasing the resistance due to greater frontal surface area. Simply put, try to make swimmers look more like racing boats than barges. 
  • Wave resistance is caused by turbulence at the water surface created by the moving swimmer. Again, the canoe shape is critical so that water flows easily and smoothly around the shape. Resistance rebounds off the sides and bottom of a pool, which is why deeper pools are generally considered "faster" pools. What can the swimmer do about wave resistance? First, push off underwater, not on top. Research shows that a push-off that is .6 meters deep is 20% more efficient that a push-off that is .2 meters deep. Second, when swimming in the end lane in competition, stay away from the side walls. 
  • Friction resistance originates from the contact of the skin and hair with the water. Well fitting suits and swim caps are elementary ways to reduce friction resistance. Swimmers shave body hair before important meets to minimize the effects of friction resistance. Note that friction resistance is probably the least significant resistance a swimmer faces. When dealing with young swimmers there are philosophical questions involved in encouraging or discouraging shaving body hair and purchasing expensive racing suits. A coach should review his or her position on the use of these suits and on shaving because it will become an issue with parents at some point.

 

Decreasing Resistance

Streamlining and adjustments to body position and body balance are two ways to significantly reduce resistance. 

  • Streamlining. The first “stroke” that the coach should teach is underwater swimming with streamlining. The hydrodynamic principle of streamlining applies to all four strokes. The streamline position should be used during starts and turns when the body is completely submerged underwater. The head placement is most critical to minimizing the water resistance. The most streamlined position is with the ears just slightly above the arms and the arms squeezed as tightly as possible. Just the slight motion of lifting the head doubles the resistance from the water. Often the head will lift before breaking the water surface after starting or turning, even at the elite level. This doubling of the resistance can add up to precious tenths of seconds, especially during races of long duration. The resistance is not dramatically affected if the head is placed forward toward the chest. 
  • Body Position and Balance. The human body tends to float upright in the water. This position is created by a center of gravity located somewhere near the hips and the center of buoyancy located in the lungs. Thus, the upper body tries to lift and the lower body tends to sink. A swimmer must “balance” his or her upper and lower body in the water so that both are perfectly horizontal in the water – the optimal position for fast swimming. This can occur in several ways: 
    • Put the arms and hands above the head, out in front of the body in the water. This shifts weight forward and thus moves the center of gravity closer to the center of buoyancy. o “Lower the head” by placing the chin closer to the chest. Lowering the head helps raise the hips and legs by shifting the center of gravity forward, closer to the center of buoyancy. 
    • Push the “buoy” or lungs downward. This brings the center of gravity closer to the surface.

Decreasing resistance is a major key to improvement. If the swimmer does not decrease resistance, the natural tendency to get the body into position is to kick harder. Kicking hard is extremely important to fast swimming, but it should not be emphasized to compensate for poor body position. Decrease resistance and kick hard… don’t kick hard because of high resistance.


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