As far as I can understand, the nasal decongestant phenylephrine, when placed inside the nose through spray or drops, causes blood vessels to relax and release the pressure. This same principle might be applied to the rest of the (external) body, but might be done using a different chemical.

A different decongestant-type chemical might be needed because the nose has a different type of skin inside, and the regular skin on a person's body might not be able to absorb the chemical. However, if this type of chemical existed, I propose that it be impregnated into a special brand of soap.

Pros:

It would improve circulation, making blood flow easier, removing lactic acid from the muscles, and thus stop aching.

It would relieve pressure in the body by making pooled blood go away.

It would make the skin feel "looser".

Cons:

The chemical might not exist.

The relaxing of blood vessels might not be a good thing for all extremities (I'm expecting a lot of comments about erectile function with this one).

Looser blood vessels might make it harder on the heart or lungs.

I'm no biological chemist, so the first person that brings up a problem for this idea can be assured that it will be swiftly put out of its misery.