Two-and-a-half-year-old Maryn Cox woke up at 3:30 a.m., and her parents couldn’t get her to go back to sleep. The next morning, her parents sent her over to her grandparents with a note.
Walking into any legitimate CrossFit Box, you’ll see gymnastic rings dangling from the ceiling or pull-up rigs. They’re the go-to apparatus for performing the iconic muscle-up, which turns up in over ...