Watching musical theatre can elicit a cardiovascular response equivalent to a half-hour workout, according to a new study.

Researchers measured the heart rates of 12 seated volunteers at a production of “Dreamgirls” in London. They spent an average of 28 minutes with a heart rate between 50 and 70 percent of its maximum—an optimal range for stimulating cardio fitness and stamina, according to the researchers.

"This demonstration paints quite a clear picture that attending a live performance has an impact on cardiovascular activity,” Joseph Devlin, lead researcher and head of experimental psychology at University College London, said in a press release. UCL and ticket provider Encore Tickets carried out the research.

“By the end of the first act, heart rates nearly doubled from their resting state at the beginning, while in the second act, it tripled. You see comparable changes in heart rate in professional tennis players during bursts of highly intense exertion such as long and fast rallies.”

The study noted the heart rate increases occurred during scenes with intense drama and songs, with peaks occurring before the intermission and finale.