Acute effects of Nordic hamstring exercise and Romanian deadlift on hamstring shear modulus and flexibilityKalc, Klemen (Avtor) Jelen, Amadej (Avtor) Nakamura, Masatoshi (Avtor) Warneke, Konstantin (Avtor) Jovanović, Živa (Avtor) Budja, Leja (Avtor) Kozinc, Žiga (Avtor) hamstring musclesstiffnessultrasoundThe aim of this study was to investigate the acute effects of Romanian deadlift (RDL) and Nordic hamstring exercise (NHE) on the stiffness and flexibility of hamstring muscles. We hypothesized that a) the RDL would have a greater acute effect on increasing the flexibility, b) the NHE would have a greater acute effect on the increase in stiffness of the biceps femoris (BF) and semitendinosus (ST) in comparison to the semimembranosus (SM), and c) RDL would have a greater acute effect on the increase in stiffness of the SM in comparison to the ST. Twelve young, healthy participants (6 females; 22.8±3.0 years) performed RDL, and 12 participants (8 females; 22.8±3.1 years) performed NHE, with both interventions comprising 5 sets of 10 repetitions. Baseline and post-intervention stiffness was measured using shear– wave elastography, and flexibility using the passive straight leg raise test. There were no significant main effects of time (p=0.744), group (p=0.202), nor the interaction between time and group (p=0.131) for shear modulus. Similarly, no significant main effects of time (p=0.717) and group (p=0.856), nor an interaction between time and group (p=0.444), were observed for flexibility. These findings suggest that neither RDL nor NHE induce immediate measurable changes in hamstring muscle stiffness or flexibility. However, given the small group-specific sample size, the absence of significant effects should be interpreted cautiously and cannot be generalized beyond young, healthy recreationally active individuals.20262026-06-01 00:13:17Članek v reviji23076sl