Colts at Texans, 1 p.m. Sunday, CBS

INDIANAPOLIS – The tube is cylindrical and gigantic, with nobs and gauges and electrical cords and flashing lights. It’s the kind of thing you’ll find in a hospital. Or in Henry Anderson’s guest bedroom.

Anderson is a defensive tackle for the Indianapolis Colts, and for two weeks he has been dominant. He has been this way before, back in his rookie season in 2015, but then he got hurt. And then hurt again. But for two weeks he has been unstoppable, a serious and star performer lost in the sideshow that is the Colts’ unraveling season. He is playing better on Sunday, and I want to know why.

Tell me about Sunday, I’m asking Henry Anderson.

And so he tells me about Monday and Tuesday. He tells me about Wednesday and Thursday and Friday. He tells me about his guest bedroom, and the tube that is gigantic and cylindrical, and the girlfriend who encouraged him to buy it from Robert Mathis but now isn’t so sure. She’d like to see more of her boyfriend, but she can’t get him out of that damn tube.

“I think there are certain days she wishes I hadn’t got it,” Anderson says, but he’s smiling. He’s teasing.

“She wants me to show up with my body feeling as good as I can make it,” he says. And he’s smiling again. Because he hasn’t felt this good in five or six years.

* * *

Shotgun snap. Henry Anderson is lined up over center. Cincinnati Bengals quarterback Andy Dalton sees him there and claps his hands. It must sound to Anderson like a starter’s pistol, because he bolts from the blocks like a sprinter.

Before the play is over, Anderson will have gored two men and mauled a third. It is the kind of play they talk about when your team is good, or short of that when your team has found a way to win on this particular Sunday. Given that the Colts are not good and did not find a way to beat the Bengals — nobody is talking about it.

Let’s talk about it here.

Directly in front of Anderson is Bengals center Russell Bodine. He is 6-3, 308 pounds, and has started all 55 NFL games since leaving North Carolina. Anderson swipes at him with his left arm, a grizzly with somewhere to go, and Bodine is gone.

Now in front of Anderson is Bengals left guard T.J. Johnson. He is 6-4, 300 pounds. Normally a backup center, he is playing guard because of a teammate’s injury. Johnson has started seven NFL games after starting all 53 at South Carolina, where he was second-team All-SEC. Anderson swipes at him with his right arm, and T.J. Johnson disappears.

From high above the field, from the press box, it looks like Anderson has eaten Andy Dalton — because Dalton is gone, somewhere underneath or maybe inside the 6-6, 295-pound Colts defensive tackle.

A few days later, Anderson shrugs off the play. He notes that Johnson was a backup. He says there might have been a miscommunication by the Bengals offensive line. Besides, he’s been trying to tell me: What happens on Sunday isn’t the story.

The story is Monday and Tuesday, and Wednesday and Thursday and Friday.

* * *

Back in the day Henry Anderson ate what he wanted, and he wanted cheeseburgers. He didn’t want to stretch on his own, so he didn’t. He was young and unstoppable, nicknamed “The Freak” at his high school just north of the Atlanta airport, and he rolled through Stanford and into the third round of the 2015 NFL draft by doing it his way.

His way was working until the ninth game of his rookie season, when 300-pound Colts teammate Kendall Langford tripped over Denver Broncos center Max Garcia and landed on Anderson’s right knee. When Anderson rose to leave the field, he said, “It felt like the bottom of my leg was dangling from my knee.”

Anderson, a rookie revelation ranked by Pro Football Focus in 2015 as the second-best 3-4 lineman against the run, didn’t return until the third game of 2016. He wasn’t the same, and then he tweaked his other knee and missed three more games, and soon the 2016 season was finished. In 11 games Anderson had recorded 12 tackles. No sacks, no tackles for loss, no fumbles forced or recovered. He was just a guy, taking up space.

“An ‘F’,” he says, was the grade his 2016 season deserved.

But ageless Colts linebacker Robert Mathis retired and offered Anderson a deal on the hyperbaric chamber that had been in Mathis’ home. Anderson had used one before. He believes in the benefits of a tube that produces three times the normal atmospheric pressure and allows its user to breathe 100 percent pure oxygen, the oxygen entering the bloodstream at 10 times the normal rate and carrying the healing power of red blood cells. Mathis had been spending two hours a day in his hyperbaric chamber.

Now the chamber is in the second bedroom of Anderson’s two-bedroom townhouse. And he spends two hours a day in it. Plus he’s eating smarter, giving up ground beef and eating a rotation of salmon, chicken and turkey. He’s also stretching three times as often as he used to, doing it before practice with the team and then again after practice with the help of a strength coach. And then again at night, at home in his townhouse.

Add it up, and Anderson says he feels “better than I have probably since my early days of college.”

“I’m doing the little things that I can outside the facility to make me play my best on Sundays,” he says. “I thought this year I wanted to do everything I could. I wanted to leave no stone unturned. I know what I can do when I’m healthy, and the things that held me back the first couple years is injuries, and not feeling great when I’m out there on the field. This year I just wanted to make sure my body is 100 percent every time I go out there on Sunday.”

The numbers aren’t lying. After recording one sack in his first 26 career games — that one coming during his rookie season — Anderson has posted a sack in each of the last two games.

He is coming on strong now, playing the best of his career, better even than his rookie season. Against Jacksonville he had four tackles, the sack and a forced fumble that Colts safety Darius Butler recovered. Against Cincinnati he had a monstrous game, a J.J. Watt game, with seven tackles, including a sack and two other stops behind the line of scrimmage, and a blocked field goal.

“He’s a solid defensive end, but the more he plays inside, the ceiling gets much higher,” says longtime former NFL coach Rick Venturi, an analyst on WFNI-AM (1070). “Now that he’s healthy again, he’s showing the athleticism and length that he showed in college. He was an eight-sack-a-year guy (at Stanford), mostly inside. I don’t know if he can find that on Sundays, but with his toughness, he definitely can be a force.”

Now that he’s healthy again …

We see the results, and so does Anderson. It is why he leaves early most days for the Colts complex and comes home at 6 p.m., where a dinner of salmon or chicken is waiting but the hyperbaric chamber is calling. And Anderson answers the call. For two hours he will lie in that pressurized tube, breathing pure oxygen and letting the red blood cells do their work.

Find IndyStar columnist Gregg Doyel on Twitter: @GreggDoyelStar or at facebook.com/gregg.doyel.

More from Gregg Doyel

► Why everyone is winning the Pacers-Thunder trade

► Colts dig deep to lose to the Bengals

► Out of a coma, back on the field for this high school football player