Several studies have reported inhomogeneous muscle use within and among the four muscles of the hamstring complex during resistance exercises commonly employed in the prevention and rehabilitation of hamstring muscle strains in football players. The non-uniform change in muscle morphology and architecture after a training intervention has been attributed to the region-specific muscle activation assessed by the transverse relaxation time (T 2) of functional magnetic resonance images (fMRI) during the training session. This non-uniform muscle adaptation to resistance exercise is particular true for eccentric training. Studies have reported that changes in morphology (e.g., anatomical cross-sectional area, muscle thickness) and architecture (e.g., fascicle length, pennation angles) in response to resistance training occurs non-uniformly along the length of the muscle. Increasing the eccentric strength of the hamstring muscles has therefore been proposed as a method to prevent hamstring injuries. The occurrence of hamstring muscle strains in football is generally believed to be related with the presence of repetitive high force eccentric actions, such as the ones observed during high-speed running, where the lengthening demands placed on the muscle could exceed the mechanical limits of the tissue. Hamstring injuries in football most commonly involve the proximal muscle-tendon unit junction (MTJ) of the BFl, accounting for approximately 60–85% of all hamstrings injuries. The predominant hamstring injury mechanisms in football occur during high-speed running and/or acceleration efforts, or during movements with large joint excursions (i.e., stretching-type injury) such as high-kicking, split positions and glide tackling. Thus, adequate prevention and rehabilitation processes are of major importance in this cohort group. Hamstring muscle tears are the most common muscle injuries in male football players, and are associated with significant time loss and high financial costs for the player and clubs. This does not alter our adherence to PLOS ONE policies on sharing data and materials. The specific roles of these authors are articulated in the ‘author contributions’ section.Ĭompeting interests: GR was employed by a commercial company: FC Barcelona. The funder provided support in the form of salaries for authors LSA, RFG and PT, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The work is made available under the Creative Commons CC0 public domain dedication.ĭata Availability: All relevant data are within the paper and its Supporting Information files.įunding: This study was made possible by NPRP grant #NPRP 6-3 from the Qatar National Research Fund (a member of Qatar Foundation).
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This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. Received: JAccepted: AugPublished: September 1, 2016
PLoS ONE 11(9):Įditor: Alejandro Lucia, Universidad Europea de Madrid, SPAIN (2016) MRI-Based Regional Muscle Use during Hamstring Strengthening Exercises in Elite Soccer Players. The relevance of such MRI-based inter- and intra-muscle use in designing more effective resistance training for improving hamstring function and preventing hamstring injuries in elite soccer players should be explored with more mechanistic studies.Ĭitation: Mendez-Villanueva A, Suarez-Arrones L, Rodas G, Fernandez-Gonzalo R, Tesch P, Linnehan R, et al. T 2 values substantially increased after hip-extension conic-pulley only in proximal and middle regions of BFl (11±5–7±5%) and ST (7☓–12±4%).
T 2 values after the Russian belt deadlift substantially increased in all regions of the BFl (6±4–7±5%), ST (8☓–11☒%), SM (6±4–10±4%), and proximal and distal regions of BFs (6☖–8±5%). Nordic hamstring induced a substantial T 2 increase in all regions of the BFs (13☘–16±5%) and ST (15☗–17±5%). T 2 values increased substantially after flywheel leg-curl in all regions of the BFl (from 9☘ to 16☘%), BFs (41☖–71☑1%), and ST (60☑–69☗%). The transverse relaxation time (T 2) shift from pre- to post-MRI were calculated for the biceps femoris long (BFl) and short (BFs) heads, semitendinosus (ST) and semimembranosus (SM) muscles at proximal, middle and distal areas of the muscle length. Thirty-six players were randomized into four groups, each performing either Nordic hamstring, flywheel leg-curl, Russian belt or the hip-extension conic-pulley exercise. The present study examined site-specific hamstring muscles use with functional magnetic resonance imaging (MRI) in elite soccer players during strength training.
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