“The Relationship Between Interval Training Frequency and Aerobic Endurance Level Among Futsal Extracurricular Students at SMPN 3 Ungaran”. COMPETITOR: Jurnal Pendidikan Kepelatihan Olahraga 17, no. 2 (June 30, 2025): 1909–1916. Accessed August 24, 2025. https://competitor.idjournal.eu/index.php/competitor/article/view/97.