The Cubs had planned as early as spring training to find rest opportunities for relief pitchers as the summer wound toward August.

The thinking even then was that the young arms in the remade bullpen would get a lot of use, especially with the expected repeat scenario of veteran starters getting traded for prospects.

The Cubs’ relievers have been workhorses, and their collective 3.73 ERA and 3182/3 innings bear out what the team anticipated.

Sending one of the most efficient relief arms to Class AAA Iowa on Saturday was all about that rest plan for rookie right-hander Neil Ramirez, and it figures to be a pattern in the coming weeks for others.

‘‘We’re just going to give [Ramirez] a blow,’’ manager Rick Renteria said. ‘‘That’s all it is. We’ve used him extensively.’’

Ramirez has struck out 36 in 28 innings, has a 1-1 record, 0.96 ERA, three saves and 10 holds.

Brian Schlitter and Justin Grimm, each with team-high 47 appearances, also figure to be part of that minor-league shuttle-rest system. So will Blake Parker, who was recalled for Ramirez as the bullpen’s ‘‘fresh arm.’’

It won’t be the case for left-hander James Russell, 28, who has made 42 appearances and is still a possible trade candidate in the next five days.

Russell pitched in the seventh and gave up four runs in taking the 6-3 loss against the St. Louis Cardinals, who snapped a four-game losing streak. It was an uncharacteristic outing for Russell (0-2), who had allowed only nine earned runs in 301/3 innings.

‘‘We had a play at home [go against the Cubs when Jon Jay scored], then I made a 3-2 pitch [to Matt Holliday] I thought was there, and it would have been a different story,’’ Russell said. ‘‘But it’s part of the game. You have to be able to grin and bear it.’’

Holliday walked, and Matt Adams tripled home two more runs to end Russell’s atypical outing.

‘‘Every now and then, you have a hiccup,’’ Renteria said. ‘‘You still trust him. He knows how to grind out [against] a batter, whether it’s a lefty or a righty.’’

Russell was one of three relievers who came in after Jake Arrieta weathered a long first inning. Arrieta gave up two runs in the first before settling down to pitch five scoreless innings.

But the bullpen workload has been telling in the last four games. The relief corps has given up 11 earned runs in 14 innings (7.07 ERA).

‘‘We’ve had conversations within the organization since the beginning of spring training about a lot of our arms and how we’ve used them a lot, and we want to have the ability to give them a break through the course of the season,’’ Renteria said.

‘‘We’re [nearing] August, and we’re at a point where we’ve ridden these guys quite a bit, so now might be the appropriate time to do this. We want to be proactive in limiting them and guarding them a little bit.

‘‘We started with Neil. I’m sure he won’t be the last. This is a very short ‘catch your breath,’ and then he’ll come back with us [he is eligible to return in 10 days].’’

Renteria acknowledged that it’s easier to avoid over-using a pitcher if he just isn’t around.

‘‘In general, we’ve used our bullpen a lot, even when we’ve had [starters Jeff Samardzija and Jason Hammel]. Situations also dictate if I have to make a move. It’s tough to be in the big leagues and have some high-leverage situations and not use them. We take that element out of it.’’