Longman Dictionary of Contemporary English
Wiktionary
n. a form of aerobics involving repeated stepping up onto, and down from a block or platform
Wikipedia
Step aerobics is a form of aerobic exercise using of an elevated platform (the step). The height can be tailored to individual needs by inserting risers under the step. Step aerobics classes are offered at many gyms and fitness centers which have a group exercise program.
Step aerobics was developed by Gin Miller around 1989. After a knee injury, Gin consulted with an orthopedic doctor, who recommended she strengthen the muscles supporting the knee by stepping up and down on a milk crate and from this she developed the step regimen.
Step aerobics can also be involved in dancing games, such as Dance Dance Revolution or In the Groove.
Usage examples of "step aerobics".
She had the ankles of Angela the check-out girl, the legs of the woman who taught step aerobics at the sports centre, the torso of the barmaid at The Bear Flag, the facial bone structure of Sue the solicitor's secretary.
Since leaving work I have nearly slipped a disc, wheezing through a step aerobics class, scratched my naked body for seven minutes with a stiff brush.