Purpose The multidimensional role of hamstring muscle group strength in athletic performance
and injury prevention is well documented, and nordic hamstring exercise (NHE) is a
popular method for the development of hamstring strength. Our aim was to examine the
EMG characteristics of the eccentric NHE as well as the effects of long-term eccentric
NHE training on muscle strength and vertical jump performance in 10- to 11-year-old
female handball players. Methods Players from the same handball team were randomly
assigned to an eccentric NHE training (13 players) or a control group (10 players).
Both groups continued their regular handball training routine, but the NHE group performed
additional eccentric NHE exercises once or twice a week, with progressively increasing
volume, over 20 weeks. To test training effects, countermovement jump (CMJ) height,
eccentric hamstring impulse, peak torque, and angle of peak torque were evaluated
before, during and after the training period. In the pre-exercise test, EMG activity
of the medial and lateral hamstring muscle was also assessed during NHE. Results Hamstring
activities ranged between 98 and 129%. Lateral hamstring activity was greater than
medial only in the right leg during NHE. Eccentric hamstring impulse improved in both
legs at 10 weeks in both groups. Then, at 20 weeks, it remained unchanged in the NHE
but decreased in controls. A similar adaptation was seen in eccentric hamstring torque,
without change in the optimum knee angle. CMJ height improved only in the NHE. Conclusion
It is concluded that NHE activates the hamstring musculature effectively, and a favourable
mechanical adaptation to long-term NHE exercise in girls can be triggered as early
as 11 years of age.
