You should check out the Ötzi-Alpin-Marathon which takes place only about 30km or so south of Prato Allo Stelvio in April. It's called a marathon because it covers a distance of 42.2km but it is actually a triathlon. First you mountain bike, then run and finally climb on touring skis. The respective distances are 24.2km biking with 1538m of climbing, 11.8km running with a vertical gain of 495m and finally 6.2km of ski touring with 1201m of vertical gain. The finish is on a glacier at 3200m.

http://www.naturns.it/...alpine-marathon.html