^^^ Yeah, alpinism is an endurance sport, for sure. Huge routes in Alaska had guys like Mark Twight and his ilk on the go for over 40 hours. That's a long time to be operating at a high physical and mental level. I did a climb that took us 30 hours, we left at midnight and got down at 6:00am the next day. I was completely fried, mentally and physically. The km walk to the parking lot is a foggy memory.