Rita Isabel Lechuga1,2, Ana Cristina Castro3,4. 1. 1 Milken Institute School of Public Health, George Washington University, Washington DC 20052, USA. 2. 2 National Autonomous University of Mexico, Westhill Institute, Mexico City, Mexico. 3. 3 Department of Health Sciences, University of York, Heslington, York YO10 5DD, UK. 4. 4 Escuela de Kinesiologia, Clinica Alemana Universidad del Desarrollo, Santiago 7550000, Chile.