Minnesota high school baseball seasons will start a week earlier beginning next year so pitchers can receive focused instruction and conditioning to prevent arm injuries.

Only throwing programs and conditioning are permitted — no batting practice or scrimmages — as the season extends to a 14th week, according to the bylaw change approved Monday by the Minnesota State High School League’s Representative Assembly at its meeting in Brooklyn Center.

The five-day conditioning period, while not mandatory for all schools, also allows teams to develop more pitchers. The league instituted pitch-count limits this spring, also in recognition of preventing arm overuse.

“We’re taking active measure to make sure we’re doing all we can to have healthy, safe athletes and that includes arm care and conditioning,” said Troy Urdahl, co-head baseball coach at St. Anthony Village and vice president of the league’s board of directors.

Nine of the 45 voting members of the group opposed the change. Before the vote, Wayzata activities director Jaime Sherwood said he would not support it because softball wasn’t included.

Dave Stead, league executive director, said there’s time to address Sherwood’s concerns about equal opportunity through Title IX.

“This doesn’t take effect until next spring so by that time, if softball wants to do the same thing, it’ll be done,” Stead said.

Other changes approved Monday that take effect Aug. 1:

• Wrestlers will have 16 team events and a 45-match season limit. The nine additional matches will enable wrestlers to compete in the growing number of individual tournaments and not have to forfeit team competition.

• High school athletes can try out or audition for college coaches at any point during the season and remain eligible.

• Boys’ and girls’ tennis teams can play a 17th match — one more than the maximum — to determine championships in conferences with two divisions.