One soccer player said she was coerced into a sexual relationship with her coach, and later collapsed during a game because of a panic attack. Another said her coach pressured her into kissing a teammate for his enjoyment. A third recently left her team altogether, she said, after being bullied and belittled so much that she lost her love for the game.

All three women played for teams in the National Women’s Soccer League, the top professional league in the United States, or its predecessors. Their stories and accusations — recounted in a series of recently published reports — are a seismic shock to a nine-year-old league still struggling to find its footing, and a troubling reminder of the dynamics that can put women in vulnerable positions even as their power and prominence grow in professional sports.

In a blistering statement Thursday, the players’ union for the National Women’s Soccer League demanded immediate action from the league after a series of accusations that coaches, owners and team executives had abused or preyed on athletes in recent years, and that the league had no effective system in place to investigate or stop misbehavior.

“The N.W.S.L. has failed us,” the union said, announcing that it was making counseling available to any player seeking help and setting up a pathway for N.W.S.L. players to report abuse.

The players’ union also called for an immediate investigation into accusations against one of the league’s most high-profile coaches; suspensions for any employees accused of violating the league’s anti-harassment policy or not reporting such abuse; and explanations for how some previous accusations were handled.

The N.W.S.L., which has collective bargaining sessions scheduled with the players’ union this week, did not respond to requests for comment on Thursday.

The call came in the wake of multiple published reports that coaches in the league had abused their players verbally and sexually — sometimes for years, and even after players had reported the abuse to team and league officials.

This season alone, a prominent team executive and a top coach working for different teams were fired after league investigations into their workplace conduct. And several prominent N.W.S.L. players have gone public with their complaints, and their anger, about league anti-harassment policies that they say do nothing to protect athletes.

The biggest revelation came Thursday morning, when The Athletic published an article that included allegations that Paul Riley, who is one of the most prominent women’s soccer coaches in the country and is in charge of the North Carolina Courage, coerced a player into having sex with him; forced two players to kiss and then sent them unsolicited sexual pictures; and yelled at and belittled players.

The Athletic also reported that Riley was let go from his head coaching job with the Portland Thorns in 2015 in part because of violations of team policy. Riley denied most of the allegations to The Athletic, and did not respond to a request for comment from The New York Times.

In its statement on Thursday, the N.W.S.L. players’ union also demanded to know how Riley was twice hired by N.W.S.L. teams — the Courage and the Western New York Flash — even after one of his previous employers, the Thorns, had been made aware of accusations against him.

Earlier this week, the N.W.S.L. concluded an investigation into another one of its teams, the Washington Spirit. The league did not share findings from the investigation, but announced that the Spirit’s coach, Richie Burke, had been fired for cause and would no longer be allowed to work in the N.W.S.L., and that the Spirit’s owners would be barred from participating in leaguewide governance matters. “The N.W.S.L.’s board of governors has determined that the Spirit and its ownership have failed to act in the best interests of the league,” the N.W.S.L. said in the statement.

The investigation was prompted by reporting in The Washington Post that Burke would regularly “unleash a torrent of threats, criticism and personal insults” on his players. One player, Kaiya McCullough, said she had left the team over the abuse she said she endured.

The accusations had precedent: Two years ago, youth players accused Burke of using abusive language in a previous job. The Spirit stood behind him at the time.

Across many of the stories of abuse from women’s players, a few consistent themes emerged. One was the players’ feelings of powerlessness, or of a responsibility to accept inappropriate behavior rather than report it for fear of causing public problems for nascent pro leagues that often exist on precarious financial foundations. While many members of the World Cup champion United States women’s national team are household names and earn hundreds of thousands of dollars annually, about three-quarters of the players in the N.W.S.L. earn $31,000 or less each season, according to its players’ union.

“This isn’t just something that has happened at one club,” Meghan Klingenberg, a longtime member of the Thorns and a World Cup winner, wrote on Twitter last month after earlier reports of a coach who had been accused of abusing his players verbally and emotionally. “This is systemic and we need accountability.”

On Friday morning, Nadia Nadim, an Afghan-Danish striker who plays for Racing Louisville, wrote that she had not been harassed, but that the league had done nothing “when a certain club forged my signature to fake an extended option, to gain benefits from a trade.” She added: “N.W.S.L. is such a joke.”

While issues of abuse and corporate governance in women’s soccer have intensified in recent months, they fit a longstanding pattern. The predecessor league to the N.W.S.L., Women’s Professional Soccer, folded in 2012 in part because of legal fight between the league and the owner of the magicJack team, Dan Borislow, after players accused Borislow of bullying and threatening players.

Last year, Major League Soccer forced Dell Loy Hansen, who owns Real Salt Lake and who also owned the Utah Royals in N.W.S.L., to sell his teams after former players and employees detailed his history of racist and sexist comments. And earlier this season, the N.W.S.L.’s New York-area club, Gotham F.C., fired its general manager, Alyssa LaHue, for what it said were unspecified violations of league policy.