1. Division of Biokinesiology and Physical Therapy, University of Southern California (USC), 1540 E. Alcazar Street, Los Angeles, CA 90033, USA
2. Department of Preventive Medicine, Keck School of Medicine, University of Southern California, USA
3. Division of Geriatrics, Geffen School of Medicine at the University of California, Los Angeles (UCLA), 924 Westwood Boulevard, Suite 200, Los Angeles, CA 90024, USA