17th Annual ECSS-Congress, Bruges 2012

Abstract details

Abstract-ID: 708
Session: [OP-BN10] Muscle function
Lecture room: L4 & L5
Date & time: 08.07.2016 / -
Title of the paper: Regional activity of the biceps femoris and semitendinosus muscles in Nordic hamstring exercise and stiff-leg deadlift
Authors: Hegyi, A., Finni, T., Péter, A., Cronin, N.J.
Institution: University of Jyväskylä
Department: Department of Biology of Physical Activity
Country: Finland
Abstract text Introduction Sprinting-type hamstring strain injuries mainly occur in the biceps femoris (Malliaropoulos et al., 2010), with the highest incidence in the proximal region (Silder et al., 2008). It has been shown previously that during the hip-dominant stiff-leg deadlift exercise, biceps femoris is preferentially activated compared to other hamstring muscles (Ono et al., 2011), while in the knee-dominant Nordic hamstring exercise, the semitendinosus is primarily involved (Bourne et al., 2015), implying task-specific relative involvement of hamstring muscles. In this study, we examined whether proximal, middle and distal regions of the biceps femoris and semitendinosus are activated heterogeneously during these exercises. Methods To date, 10 male subjects without previous hamstring injury have participated in this study, which is ongoing. 16-channel array electrodes were attached over the biceps femoris and semitendinosus muscles to record electromyographic activity from different muscle regions during the Nordic hamstring and stiff-leg deadlift exercises. Root-mean-square activities for the distal, middle and proximal regions of the muscles were calculated in the lengthening phase of the tasks and normalized to the activity in maximal voluntary isometric contraction. Regional differences were analyzed using one-way repeated-measures ANOVA. Significance level was set at P<0.05. Results During Nordic hamstring exercise, biceps femoris muscle activity was 22% lower in the proximal region compared to the distal region on average (p<0.001), while semitendinosus muscle did not show regional differences in muscle activity. However, in stiff-leg deadlift, no differences were observed between regions in either of the muscles. Discussion Our results imply that recruitment of biceps femoris muscle regions is heterogeneous and task-specific. Lower activity in the proximal region may be a contributing factor to region-specific muscle strain injuries. Future studies should determine whether these findings can be replicated in real-life movements associated with hamstring strains; and how lower contribution of the proximal region can be modified by training. References Bourne et al. (2015) Scand J Med Sci Sports, doi: 10.1111/sms.12494. Malliaropoulos et al. (2010) Am J Sports Med 38: 1813-1819. Ono et al. (2011) Res Sports Med 19(1):42-52. Silder et al. (2008) Skelet Radiol 37(12): 1101-1109. Contact andras.a.hegyi@jyu.fi
Topic: Biomechanics
Keyword I: hamstrings
Keyword II: Nordic hamstring exercise
Keyword III: muscle activity