Amelia, Syeni Ratna, et al. “Effectiveness of Exercise Program on Abdominal Muscular Endurance and 20 Meters Running Speed During Covid-19 Pandemic”. Gladi : Jurnal Ilmu Keolahragaan, vol. 13, no. 04, Dec. 2022, pp. 435-41, doi:10.21009/GJIK.134.08.