Of the nearly 1,700 Adidas employees at the Portland campus, fewer than 4.5 percent identify as black, according to internal employment figures from last summer that were shared with The New York Times.

Adidas employees who spoke to The Times said that in the company cafeteria, black employees often sit together. Some said they had been told that this made some of their white colleagues nervous and could hurt their chances of getting promotions or being put on important marketing campaigns if it appeared that they were not trying to fit the Adidas mold.

Several current and former Adidas employees said they were frequently the only black person in meetings and often felt their input was not valued when decisions were being made. And an overall lack of racial diversity, they said, meant it was not uncommon for negative stereotypes to creep into work discussions or marketing pitches involving black athletes, sometimes creating backlash outside the company. Even when such ideas were scuttled before becoming part of official advertising campaigns, black employees said, the conversations left them feeling uncomfortable.

For many, the internal tensions at Adidas reflect a larger issue facing the American sports apparel industry, which has a combined annual revenue of more than $20 billion on shoe sales alone. Companies like Adidas, Nike and Under Armour have work forces that are primarily white, but their most influential customers — those who make their products desirable to others — often are not.

At Adidas, the issues involving race are not limited to business, black employees said.

Two black employees said they had been referred to with a common racist slur by white co-workers, one verbally and one in a text message seen by The Times. In both instances, the people believed the slur was intended as a joke, which they felt only highlighted the company’s skewed perspective on race.