Hamstring strain injuries are a major problem in modern sports. Their incidence and frequency of recurrence are among the highest in sports such as football, athletics, rugby, American and Australian football. One of the most effective preventive measures is eccentric strengthening, which includes the Nordic hamstring exercise (NHE), which has many positive and some negative characteristics. The two potential disadvantages are the universal difficulty of the exercise and the load in (too) short lengths of the hamstring muscle-tendon complex. The purpose of this master's thesis was to present adjustments of the NHE, which would allow for individualisation and loading of the hamstring at longer lengths. The main objective was to verify the characteristics of the variations of the NHE, obtained by altering the slope of the lower leg support and by maintaining a different hip flexion positions while performing the exercise, on a sample of 18 subjects. Electromyographic and kinematic measurements were performed during exercises and the data were statistically tested with the analysis of the variance for repeated measurements and the paired 2-tailed post-hoc t-test. Changing the slope of the lower leg support (0°, 20°, 40°) of the NHE enabled the subjects to perform in larger or even total amplitudes in controlled manner at the same maximum knee torque as for standard NHE. Increasing in hip flexion (0°, 25°, 50°, 75°) enabled the subjects to achieve greater maximum knee torque, which was achieved at longer lengths of the hamstring. The results show that it is reasonable to use the presented adjustments of the NHE in the context of optimising individual fitted training programs for general physical preparation, injury rehabilitation and prevention.
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