Many members of the "War Horse" cast have Facebook pages, but only a few of them have their own websites. In that group count Horse swing Isaac Woofter. If you log on to isaacwoofter.biz, you will learn that both his mother and his first language are Japanese; that he grew up in northern California and has an MFA in acting from Columbia; that he currently plays on a coed soccer team made up primarily of poets and is the straight captain on a gay soccer team; and that he loves sour gummy candies, whiffle ball, the Yankees, and passionate people who can laugh at themselves. 

What you will not learn is how hard he works as a Horse swing - roughly, the guy who takes over other roles among the show's three-person Horse teams as needed. As he explained his job the other day backstage before showtime, I gained newfound respect for what these cast members experience every night. 

"Members of the Horse teams," Woofter said, "do aspects of either Joey or Topthorn: head, heart, and hind." In addition to these physically taxing roles, Horse-team members also do things like puppeteering a crow or holding a pole. 

Woofter's experience with the production was a little different from most of the other Horse-team members, who have been with the show since the beginning of rehearsals last January. After Woofter joined "War Horse" around four months ago, he had to get up to speed quickly. "I started out by trying to learn one track" - actorspeak for a specific assignment - "a day, and then, more reasonably, one track every two days." 

Three steps were involved. "In the first," Woofter said, "I would go over the blocking of the track with stage management. In the second, I would watch the track from the audience. And, in the third, I would follow around the actor doing that particular track backstage. I would be just offstage, for example, if he had a costume change, so I could see exactly what went on." 

How did Woofter feel each time he went on in a new track? "I was a little amazed at how nervous I could get before doing something that seems like such a simple track." Frequently, his adrenalin flowed fast before he went onstage. "I always got through it," he said, "but it was quite an experience some nights." 

As one the cast's utility players, Woofter's experience has growing value for others. (I choose the athletic designation deliberately: many members of the Stable, as the Horses dressing room is called, are involved in fantasy-sports teams of one kind or another.) His knowledge is systematized: he keeps lots of notes on each role. "Stage management has a computer-accessible guide to each track," he said. "With what I've learned, I am sometimes able to help out by filling out or even correcting the guide." 

Woofter will be an especially vital resource when some cast members leave in early January. "When that changeover happens," the actor said, "I'll be moving to a regular role in a three-person team. But there will be some new Horse people coming in, and I'll be able to show them the ropes." 

Brendan Lemon is the American theater critic for the Financial Times and the editor of lemonwade.com.