We're sorry, but online registration is not allowed for this activity. Group Exercise classes, Yoga & Pilates and personal training are available for full members of the facility. Please contact us during regular business hours for registration information. Fierce improves overall health using interval training, functional resistance and core exercises. Designed for all fitness levels. This is a prerecorded class taught by a YMCA instructor that plays on-site at the branch. Category Exercise, Health and Wellness Location Aerobics Studio at West Chester Branch Instructor Leslie Seifert