The Skatelog thread on the DA45s that the Invaders use mentioned manueverability as a major part of the reason they helped with foot, ankle, leg and back pain -- loosening trucks may have a similar effect!

Although I've found that with my Vixens there was a trade-off where looser trucks made me do more compensating and just moved the pain to different places, but I think that's more to do with bad boot fit to begin with. Slidey feet make it harder to control where your wheels are pointing...