It's something building after prolonged/multiple times. And runners are often not outside nearly as long as XC skiers. My runs are seldom much longer than an ho

It's something building after prolonged/multiple times. And runners are often not outside nearly as long as XC skiers. My runs are seldom much longer than an hour, and they start outside my door. XC sessions in the weekend are 30+ KMs and for me also includes long times outside getting to the tracks. Edit: also humidity probably plays a big role.