When he left the Royals' 6-1 victory over the Rangers after five innings on Sunday, he went to a practice field and did some more running.
"I ran a few sprints," he said. "I ran a lot in the game, too, but hey, you've got to keep your legs in shape."
Although Cain is generally expected to step into the Royals' center-field job this year, he's taking nothing for granted.
That's why he felt so good after going 2-for-2 in the win. He singled in his first at-bat and raced to a double in his next chance. When Alex Gordon dumped a single into left field, Cain judged it shrewdly and scored from second to launch a four-run inning.
"I've got to use my legs as much as possible," Cain said. "So I take advantage of any opportunity I can. If they give me a shot, I'm going to take advantage of it."
Cain also used his speed to his advantage in two intrasquad games last week, beating out an infield roller that sparked a big inning and making a spectacular catch.
"My legs are a big part of my game," Cain said. "So any chance I get to use 'em, I'm going to do it as much as possible. Sooner or later I'm going to try to get on base and start stealing a little bit. So we'll see what happens with that."
So far the presumed successor to the traded Melky Cabrera is making a good impression.
"I've got to keep going," he said. "It's the first game and it's a long spring."