During Ironman Arizona I had this done.

Quick story: few weeks before the race I started having metatarsal pain in one foot. During the bike leg of Ironman, my foot starting hurting maybe 20 miles from the end. In transition, a lady comes up and asks me if anything hurts. I tell her about the foot, and she starts taping it w/Kinesio tape to support the metatarsals.

No foot pain the entire marathon run! However after the race it is pretty sore and I am going to the doc soon to get it looked at. But that stuff works!!