Seats in U.S. theaters have gotten bigger during the last century to accommodate the expanding size of the members of the audience.
A new report by Theatre Projects Consultants, a company that helps to design theaters, showed that from 1900 to 1990, the width of seats increased from 19 to 21 inches (48 to 53 centimeters).
In the last 20 years seat size has expanded an inch. Leg room has increased and space between rows has also grown.
"People have certainly gotten taller and wider over the years so many people find they are just not comfortable in the seats that would have worked 30 or more years ago," said John Coyne, an author of the report and a U.S. director of the company.
Bigger seats have meant higher costs for theaters and their patrons because modern auditoriums can hold only half the number of people as a similar size auditorium built in early 1900, according to the report.
Since 1990, the size and cost of auditoriums have grown almost 30 percent.
Mostly a U.S.-only trendTheatre Projects Consultants, which has helped design more than 1,200 theaters in 70 countries, used data from the company's U.S. clients for the report and looked at both new facilities and renovations.
Between 1960 and 2000 the average weight of an adult American has increased more than 24 pounds, or 15 percent, according to the Centers for Disease Control and Prevention.
For audience comfort and to keep pace with cinemas and sports stadiums which offer other amenities as well as wide seats, theaters have had to adapt.
But Coyne said a balance is needed to provide comfort for audiences and to keep them engaged in the productions they are viewing.
"Theater is about communication between the performer and the audience," said Coyne, adding that it is important for actors to the close to the audience.
But Broadway theaters in New York seem to be an exception, he added, because people will sacrifice some comfort for a hot ticket.
Although larger seats are mainly a U.S. trend, Coyne said the company is seeing similar issues in theaters and auditoriums overseas.
"We think it is less about accommodating larger sizes and expectations but rather following trends in the U.S.," he explained.