Burn calories WITHOUT running! Try this Incline Butt Buster Cardio Routine - It's only 30 minutes!
Yoga breathing exercises can boost how much air can be drawn into the lungs. http://yogaforbeginners-andmore.blogspot.com/
It would be a great mod to have for XC. I was thinking more along the idea of "What to pack before a run" and list some items that students bring to their meets!