Major League Soccer announced on Monday that it will be among several U.S. leagues that will take part in a pilot program to implement concussion substitutions, starting with the 2021 regular season.

The protocols involved in the program have been approved by FIFA and the International Football Association Board (IFAB), which oversees possible changes to the Laws of the Game. The IFAB has set an initial 20-month trial period to test the concussion substitutes initiative in competitions around the world through Aug. 31, 2022.

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In terms of which leagues in the U.S. that will take part, a concussion task force comprised of sporting and medical leaders from MLS, NWSL, U.S. Soccer, the USL, and NISA, have worked over the last several months to implement the initiative, and have been approved by the IFAB and FIFA to participate in the trial.

"The single most important priority for us in this initiative is to make sure players have a safer environment to play in," said Jeff Agoos, MLS Senior Vice President, Competition, Medical Administration. "Our club medical staffs, our technical staffs are aligned in the process, and, we think that this is a really important step for this trial to continue. We really look forward to seeing how this rolls out through the course of the year, and we believe that it'll be a real benefit for our players."

The NWSL, which begins its season on April 9, also released a statement in support of the pilot programme.

"The new concussion protocol is another steppingstone in our continued efforts to create robust player safety guidelines for all teams and athletes," NWSL Director of Sports Medicine Hughie O'Malley said. "The welfare of our players is a priority at the NWSL, and we're pleased to collaborate with the other professional leagues and U.S. Soccer on this pilot program to continue protecting our athletes."

ESPN television analyst Taylor Twellman saw his soccer career ended at the age of 30 by a series of concussions, and he has since pushed for more concussion awareness through his advocacy organization ThinkTaylor.org. He lauded the step taken by the IFAB, FIFA and the various stakeholders in the U.S.

"My natural reaction is, it's about time," he said. "But I'm also not going to sit here and not be thankful that we're actually here having this conversation."

The treatment of concussions, especially on the field, has long been an area of concern in the sport. At the professional level, teams had been limited to three substitutions, a number that had been increased to five due to the COVID-19 pandemic. Throughout the game's history, a substituted player wasn't allowed to re-enter a match.

Under the rules spelled out by FIFA and the IFAB, teams will be allowed to make up to two substitutions per match to replace players suffering from a concussion or suspected concussion, regardless of how many substitutions a team has already used. The idea is to use such substitutions in the interest of player health and safety.

Once the protocol is implemented, games will see up to three types of substitutions. Each team will have at its disposal five so-called normal substitutes per match, which can be made over three separate opportunities. Any substitutions made during half-time, or between regulation and extra time, or between the two halves of extra time in the postseason will not count as one of the three opportunities.

A concussion substitution can be made immediately after a concussion occurs or is suspected after an on-field assessment, and/or off-field assessment, or at any other time when a concussion occurs or is suspected. This includes when a player has previously been assessed and has returned to the field of play.

If a team uses a concussion substitution, the opposing team will then receive an additional substitution beyond the five normal substitutions. The hope is that these rules will take at least some of the conflict out of the decision by allowing for a substitution to take place without negatively impacting the number of subs a team has.

Each club's technical staff will be responsible for designating the substitution type by providing the fourth official with the appropriate color substitution card: white for a normal substitution, pink for a concussion substitute, and blue for an additional substitute.

While referees may stop play due to a suspected head injury, the match officials will not be a part of the decision-making process to determine whether a player should or should not be replaced, nor will they determine if a normal substitute or a concussion substitute should be used.

Medical professionals in the facility, including team athletic trainers, team doctors and the Venue Medical Director, will continue to follow policies and protocols established by the MLS Concussion Committee for on-field and off-field assessment and management.

MLS will also continue to make use of a "medical spotter" in which trained professionals monitor the match broadcast to identify potential head injuries and possible concussions. Those medical spotters are able to quickly provide video to the Venue Medical Director at the fourth officials table to assist in assessing head injuries and possible concussions.

"Using medical communications now on the bench is a huge step for medical professionals to get more information, [and help] the spotter to be able to get information to see when that injury occurs," said Dr. George Chiampas, who in addition to being the Chief Medical Officer of the U.S. Soccer Federation, is an emergency and sports medicine physician, as well as an assistant professor of emergency medicine and orthopedic surgery at Northwestern University.

While the rule is a clear step forward, there are still concerns that the pilot program doesn't go far enough. It is estimated that it takes between seven to 10 minutes to adequately assess whether a player has sustained a concussion, and a preliminary rule change that was submitted to the IFAB by the USL back in 2019 requested that the concussion substitute could be temporary, with the injured player allowed to return once she or he was properly assessed.

"The challenge that everybody would use is that the medical professional is concerned to pull someone because they only have three subs, but that's not the case," Chiampas said. "That whole challenge or hurdle is removed. And if a physician or the athletic trainer deem a player to have a head injury, and they even suspect it - that's what we have to remind ourselves, if they even suspect it - you have a huge amount of backing and support."

The coming years should reveal any weak spots in the rule, and Twellman is of the belief that pilot program isn't the last word on concussion substitutions.

"I think this is going to evolve," he said. "I look at the mechanism and the structure of what it is now. Do I think it's gonna be the same way three years from now, five years from now? No. I think FIFA, for whatever reason, will say they need more data. I'm okay with them saying that to see how it works."

Chiampas added, "I think we're going to learn and that's what I think a pilot is. How can we learn from this? If it doesn't meet what the players need, and if there's ways that we can improve, you better believe that we're going to make sure we speak up."