Nugraha, Afif Dwi, Yudanto Yudanto, and Samsul Bahri. “The Impact of Using Surgical Masks and Non-Masks When Exercising on Heart Rate, Calories and VO2max During the Covid-19 Pandemic”. Jurnal SPORTIF : Jurnal Penelitian Pembelajaran 7, no. 1 (April 17, 2021): 84-92. Accessed May 22, 2022. https://ojs.unpkediri.ac.id/index.php/pjk/article/view/15698.