Alyssa Hawley likes trudging up hills carrying 50-pound buckets of gravel, or with heavy sandbags slung across her shoulders. She’s less fond of an obstacle known as the Twister – a pole with monkey-bar grips protruding from it in a spiral pattern, which spins each time an athlete shifts weight from one hand to another. Those are just a few of the challenges Hawley will face this weekend during her second appearance in the Reebok Spartan Race World Championship in Lake Tahoe, California.