If you are more of the adventurous type then check some of these activities out.
A waterfall of emotions.
Centro Rafting le Marmore is a sports facility that offers: Rafting, Hydrospeed, River Walking, Soft Rafting, Tubing, Kayak and Canyoning.
Read about Marmore waterfalls here.
The company Rafting Umbria offers a range of activities: Mountain biking, Paragliding, Speleology, Hiking with Donkey, Archery, Adventure trail and Water Rafting.
A multi-event outdoors center.
The Pangea outdoor center offers a lot of different activities. Check out their web site and contact them to see if they can accommodate english speaking guests.