A TV show called “Steve Austin’s Broken Skull Challenge” could seem daunting to some people. But Jodi Theriault, a Portland mother of three who has been a competitive body builder and has continued to run marathons and urban obstacle courses since being hit by a car in 2014, had a “blast” while filming an episode of the competition series last summer. Her idea of fun times included running an obstacle course with a 45-pound log on her back in 100-plus-degree heat, climbing 12-foot walls, and wrestling with other well-conditioned athletes.