It's also not for the faint-of-heart: While instructors are supportive and try not to come across as drill sergeants, they are nonetheless pushing their clients.
"The very first night, I wanted to quit. It was very intense," said one member.
This is a co-ed gym, but more women have signed up so far in Naperville.
You can read the full story in the Daily Herald's edition from Sunday, August 4, 2013, or online at dailyherald.com.