S. Douglas Pugh’s research while affiliated with University of North Carolina at Charlotte and other places

... ~ 392 ~ These centers provide a sense of ease, allowing women to exercise without the uneasiness or embarrassment they might feel when performing cardio exercises in the presence of the opposite sex. Women often fear being judged or mocked for their bodies in unisex settings, but in the presence of other women, they feel more at ease and supported., [57] and Dietz, Pugh, and Wiley (2004) [119] highlighted that in settings with high levels of customer interaction, the service climate plays a significant role in shaping customer experiences. Whether it is a unisex fitness center or a women-only facility, women consistently demand a comfortable service climate. ...

Reference:

Conceptualizing service quality and satisfaction in fitness services from women's perspective: Evidence from literature and qualitative interviews