The 6-foot-5, 260-pound Stevensville-Lakeshore second-year varsity player has been on the offensive line since the seventh grade.
"I think I've improved quite a lot this year," Hartline said. "I think I'm a little quicker this year. I'm definitely stronger from lifting during the winter and summer seasons."
As a lineman, Hartline has been paving the way for three-year starter Hunter Wright at quarterback, who threw for 1,400 yards last year and running back Micah Nelson, who rushed for 1,300 yards.
"As a tackle in our offense, you have to be able to pull well," Hartline said. "I think the offensive line has done a fair job as a whole this year. What's really hard is a lot of times we haven't been injury free. Other than the first week of football, I don't think we've had everyone there. People have had the flu or other nuisances they've had to go through. It's hard to get some continuity going when we're changing things all the time. We have a lot of talent."
Hartline will have familiar company when he leaves Lakeshore for Central Michigan. Linemate Adam Behnke, a guard, has also verbally committed to CMU.
"We're pretty close," Behnke said. "We've known each other pretty well for awhile. It's nice to know someone who will be coming with you."
Hartline decided to become a CMU Chippewa last spring. "I thought about it and did a little research on it. I had a chance to talk to some of the coaches and teachers," he said.
From an academic and football standpoint, Hartline saw Central as a perfect fit. While he's hoping to lead Stevensville-Lakeshore to title contention, Hartline also wants to get ready for the college level.
"I definitely want to work on my strength," he said. "Right now, I'm not as big as I'd like to be. I also want to work on my speed. In the winter, I'll work with the track coaches. But it will be important to improve my size and agility. A lot of hip flexibility is needed."
As Stevensville-Lakeshore heads into the final games of the regular season and prepares for action in the playoffs, Hartline is putting the college career on the backburner to try ending his prep career on a championship note.
"The best thing about being 6-1 is that we've yet to play our best game," Hartline said. "There are a lot of areas on offense and defense where we can use some work."