A guide to different intensities of exercise, vaccination, and sports nutrition in the course of preparing elite athletes for the management of upper respiratory infections during the COVID-19 pandemic: a narrative review - Agha-Alinejad, H.; Ahmadi Hekmatikar, A. H.; Ruhee, R. T.; Shamsi, M. M.; Rahmati, M.; Khoramipour, K.; Suzuki, K. (International Journal of Environmental Research and Public Health, 2022)