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. In the event of inclement weather, this class will be moved indoors. Les Mills CORE is a 30-minute workout, designed to tone your body, improve your core strength and aid with injury prevention. Category Exercise, Health and Wellness Location Outdoor Group Exercise at West Chester Branch Instructor Claire Y.