Wainwright tossed the equivalent of two innings in the bullpen.
"This was my third throwing session off the mound [to a crouched catcher]," he said. "The first two times we did one set of 30. This one we're kind of progressing, now we're doing two sets of 20. So the up-down, but you're also adding some throws in there."
It is certainly another positive step forward for Wainwright, who turned 30 on Aug. 31.
"Every time I get used to doing something, we increase the volume or we start doing something new," he said. "So it adds that shock to your body. So I got really used to throwing at 150 feet, really comfortable with that, and then got on the mound and I threw and I was a little bit sore. The next time I threw, I was starting to feel pretty good and it was easy, so now we increased the volume. So I'll probably be a little bit sore tomorrow. Then I'll get used to that and we'll change it up again."
Wainwright said he only threw fastballs on Thursday, but one of the next steps in his rehabilitation process will be to throw changeups.
"My understanding is in a couple weeks, we'll start throwing some changeups," he said. "Unless we start carrying this thing deep into October, I think we're going to hold off on the breaking balls until January. I'm going to try to talk them into a few before we leave, but it's really my job to follow what they tell me to do. If they see my arm is able to make some steps, progressions, then that's what we'll do."
Wainwright said he will take off November and December, as he would in a normal offseason, and then resume his throwing program in January.
For now, the righty, who won 39 games over the past two seasons, has to sit back and watch his teammates and the rest of the starting rotation fight it out with the Braves down the final stretch of the National League Wild Card race.
"I came in yesterday and I looked at Carp, [and yelled], 'And I can't even throw a pitch!' But it's been fun to watch," Wainwright said.