Putri, L.S., Anjasmara, B. and Widanti, H.N. 2023. Differences in Nordic Hamstring Exercise and Contract Relax Stretching on Increasing Flexibility in Students with Hamstring Tightness at Muhammadiyah University of Sidoarjo: Perbedaan Nordic Hamstring Exercise dan Contract Relax Stretching Terhadap Peningkatan Fleksibilitas pada Mahasiswa dengan Hamstring Tightness di Universitas Muhammadiyah Sidoarjo. Journal of Islamic and Muhammadiyah Studies. 5, (Aug. 2023), 10.21070/jims.v5i0.1571. DOI:https://doi.org/10.21070/jims.v5i0.1571.