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. Journal of Islamic and Muhammadiyah Studies. 5, (Aug. 2023), 10.21070/jims.v5i0.1571. DOI:https://doi.org/10.21070/jims.v5i0.1571.