Detection of balance in the elderly under the influence of stress (DEPIE): A cross-sectional study protocol - Bernardo Alarcos; Belén Díaz-Pulido; Olalla Fernández; Sara Fernández-Guinea; Antonio García Herraiz; María del Mar Lendínez-Chica; Javier Martínez Muela; Susana Nunez-Nagy; Yolanda Pérez-Martín; Isabel Rodríguez-Costa; Gloria M. Rubio González; Sara Trapero-Asenjo; et al. (PLoS ONE, 2026)