Originally Posted by vomitron

The real reason why people (or swimmers, anyway) shave is because is produces a greater adrenaline response.

When you shave, you leave exposed, sensitive skin. When this skin comes in contact with water, or air, it produces a measurable increase in adrenaline, which means greater performance.

In the water, hair causes very significant hydrodynamic drag, but in the open air, it's next to nothing. The real "performance" difference comes from the adrenal response.