Normally our underwear is just the piece of fabric between us and our pants. It doesn't need to do much else except be there. When you start high-stepping, climbing, or walking double-digit miles for a few days on end, you start to realize that your regular y-fronts just aren't up to the job. You actually need your underwear to do a little more than just hang around. The reality is that ordinary underwear won't give you the support, comfort, and moisture control that you need when putting in the miles.