GLENDALE, Ariz. -- The idea sounded good, if not great.

Arizona Cardinals coach Bruce Arians has said since March that he wants running back David Johnson to average 30 touches per game this season. This feat has been accomplished once in NFL history, when former Tampa Bay running back James Wilder averaged 30.8 touches in 1984. And since Johnson led the NFL in total touches (373) and ranked third in per-game average (23.3) last season, the idea didn't seem far-fetched.

But the reality of Johnson touching the ball that many times each game could lead to a decline in the near future.

Since Wilder in 1984, seven players -- all running backs -- have averaged at least 28 touches per game, led by Ricky Williams' 29.2 in 2000 over the course of 10 games with the New Orleans Saints. Former Kansas City Chiefs running back Larry Johnson averaged 28.6 touches per game in 2006, which is the most since Wilder during a full 16-game season, according ESPN Stats & Information.

Pittsburgh's Le'Veon Bell was the most recent back to average 28 touches per game -- in 2016 when he played in 12 games.

However, with the exception of Bell, the running backs who averaged more than 28 touches per game generally saw a decline in their production the following season, though most experienced a slight rebound in the year after that. The reasons varied. Some, like Larry Johnson in 2007 or DeMarco Murray in 2015, sustained injuries. Others, like Eddie George in 2001, just didn't have their number called as often.

Nobody, with the exception of Edgerrin James in 2001, increased their per-game average in the season immediately following their historic workload. James went from 28.1 touches per game in 2000 to 29.2 in 2001, when he played in just six games. Four running backs managed to rebound from those down seasons, posting higher averages two years after averaging 28 touches per game.

Though it's possible for Johnson to increase his average from 23.3 to 30, it could come at a price.

Three running backs who averaged more than 28 touches per game were injured the following season. Four were injured in the year after that -- including Larry Johnson and James.

Cardinals quarterback Carson Palmer believes in trying to get Johnson 30 touches a game, but he's also a realist.

"I think getting him 30 touches is the plan until he's sore or he loses a little bit of flexibility or whatever it may be as things pop up during the season," Palmer said. "Ideally that's great. I think that's the plan. If something changes, like it can in this game, and you have a hamstring or shoulder or the thing that comes up, the plan changes, but it's a great plan to start with."

And it could lead to the best offensive season in NFL history.

If Johnson's 2016 numbers -- 373 touches for 2,118 scrimmage yards, an average of 5.68 yards per touch -- were prorated to reflect 30 touches per game, the running back would have averaged 170.4 yards per game and totaled 2,726 scrimmage yards for the season. That would eclipse the current single-season mark of 2,509 scrimmage yards, which teammate Chris Johnson set with the Tennessee Titans in 2009.

Since 2001, just one player has led the league in touches in back-to-back seasons: LaDainian Tomlinson. As Johnson revealed to ESPN, he talked to Tomlinson about sustaining that kind of workload over the 2001 and 2002 seasons. What Johnson learned from Tomlinson could be the key to leading the league in touches again in 2017.

Neither Johnson nor Arians are concerned about the long-term effects of averaging 30 carries per game.

"No, not at all," Johnson said. "I’m focused on right now, getting better, helping out the team. If that comes with having 25, 30 carries, then so be it."

Arians said there's a significant difference between Johnson averaging 30 touches in 2017 and Wilder doing it 33 years ago. Wilder saw his production drop in the two seasons following his record-setting pace in 1984. He averaged 26.1 touches in 1985 and 19.4 in 1986, while playing in just 12 games because of a chest injury.

"James Wilder ran the ball 30 times," Arians said. "(There's) a big difference in catching 10 passes than running the ball 30 times. If you're going to run the ball 30 times, you're not going to last long in this league. We all know that. But 20 runs, and not all up-the-middle type things, just getting his hands on the ball where he can create in space, those tackles, they don't take much out of you."

Johnson tweaked his offseason workouts in order to prepare his body for a heavier workload, thanks in part to his conversation with Tomlinson.

Tomlinson, who led the NFL in touches in 2001, 2002 and 2007, told Johnson that the key to his longevity and durability was stretching. Johnson responded by losing a few pounds and picking up yoga this offseason.

Johnson noticed late last season that his body wasn't responding as well as it had earlier in the season. His legs felt heavier, like they were dragging, causing him to lose speed.

He can already feel the difference this season.

"I feel like my body won't fatigue so fast toward the end (of the season)," Johnson said. "I feel like my muscle will be able to last a little longer where I'm able to feel more energized, feel more flexibility to do stuff."

But what about the future beyond the 2017 season? What kind of toll can 30 touches a game -- if he gets there -- take on Johnson, regardless of how well he's conditioned?

Even if Johnson doesn't average 30 touches a game but leads the NFL in touches, his body will still take a beating every week.

A year after Adrian Peterson led the NFL in touches in 2015, averaging 22.3 per game, he suffered a lateral meniscus injury and went on IR. After Arian Foster led the NFL in touches in 2012, he had back surgery and was placed on IR. Maurice Jones-Drew suffered a left foot injury in 2012, the year after he led the NFL in touches. And Larry Johnson had a foot injury in 2007, the season after he averaged 28.5 touches per game.

Were their injuries related to their previous season's workload? It's tough to tell. But there's a difference between these backs and Johnson, who will be used largely as a receiver. Touches through the air should limit the number of between-the-tackle hits he receives.

Of the four running backs who played in all 16 games the season after they led the league in touches -- LeSean McCoy in 2014, Chris Johnson in 2010, Peterson in 2009 and Tomlinson in 2008 -- none topped their totals from their league-leading year.

But they all came close, which could be the path Johnson takes in 2018.

McCoy had 340 touches in 2014, just 26 fewer than the season before. Johnson led the NFL with 408 touches in 2009 and had 360 in 2010. Peterson dropped from 384 in 2008 to 357 in 2009. Tomlinson finished 2008 with 344, 31 fewer than the previous season.

Johnson has proven he can produce when the ball is in his hands. Reaching Arians' goal of 30 touches per game -- or simply leading the NFL in touches -- will depend on his ability to stay healthy.

"That's going to be a lot of offense," Arians said. "When he has his hand on the ball, either as a wide receiver, coming out of the backfield, in the slot and running, that's a lot of potential offense for us."