If his workout stories are true, and I have always doubted them ever since he was in college (some of his football peers have joked that the 1000's of pushups/situps are just for publicity), he must have the top 1% of 1% genetics, as that is a terrible workout for sports. There isn't one professional trainer (I'm talking about the people who train professional athletes not the "trainer" at your local gym) who would recommend doing situps or any exercise with that many reps.
Plus, the article states he only eats bread, vegetables, and doesn't care about protein...that is just BS for a professional athlete.
High reps do not build size. If they did the Tour de France would look like body builders from the waist down, and they are the exact opposite. Either Walker is a genetic freak or he lies about his workout and eating habits.
Also, machines are about the worst way to exercise.