In late May, weeks after Nina Silitch finished her last race of the season, loads of her ski-mountaineering equipment still occupied more than half the space in her bedroom. Her husband, Michael, couldn’t understand why, after six months on the World Cup and international circuit, she wasn’t ready put it away. At 39, Silitch was coming off a career-best season in most respects – she became the first American to earn World Cup gold in...