Have you had any success with muscle-building and strength programs for ultra-marathoners and endurance athletes?

I am currently training an ultra-marathoner who runs more than 50k per week. Her main goal is to build strength and gain muscle definition. Nutrition plays a massive role, obviously, and I'm wondering if any of you have had success with this type of situation? Cutting back on the distance running is not an option. I'd love to hear your thoughts!