This article is from the Aerobics Fitness FAQ, by firstname.lastname@example.org (Robles) with numerous contributions by others.
The two major certifying bodies in the US for Aerobics Instructors
and Personal Trainers are the American Council on Exercise (ACE) and
the Aerobics and Fitness Association of America (AFAA). Many other
organizations provide certifications as well, including the National
Strength and Conditioning Association (NSCA), the American College of
Sports Medicine (ACSM), and a number of regional organizations.
(from Larry DeLuca <email@example.com>)