Abstract
Muscle coordination in human movement has been assessed through muscle synergy analysis. In sports science, this procedure has been mainly applied to the comparison between highly trained and unexperienced participants. However, the lack of knowledge regarding strength training exercises led us to study the differences in neural strategies to perform the power clean between weightlifters and untrained individuals. Synergies were extracted from electromyograms of 16 muscles of ten unexperienced participants and seven weightlifters. To evaluate differences, we determined the pairwise correlations for the synergy components and electromyographic profiles. While the shape of activation patterns presented strong correlations across participants of each group, the weightings of each muscle were more variable. The three extracted synergies were shifted in time with the unexperienced group anticipating synergy #1 (−2.46 ± 18.7%; p < 0.001) and #2 (−4.60 ± 5.71%; p < 0.001) and delaying synergy #3 (1.86 ± 17.39%; p = 0.01). Moreover, muscle vectors presented more inter-group variability, changing the composition of synergy #1 and #3. These results may indicate an adaptation in intermuscular coordination with training, and athletes in an initial phase of training should attempt to delay the hip extension (synergy #1), as well as the upper-limb flexion (synergy #2).
Highlights
Regular practice of strength training is associated to increases in maximal strength, changes in neuromuscular function, and in muscle morphology
Considering that Kristiansen and colleagues [26] provided the only study associating the extraction of muscle synergies and the neural strategies developed in a strength training process, we aimed to study a task with more degrees of freedom regarding strength training: the power clean exercise
No differences were shown between groups for age (p = 0.173) nor height (p = 0.120), while significant differences were found for body mass (p = 0.001; 68.6 ± 6.3 and 85.9 ± 9.0 kg for UNE and experienced weightlifters (EXP), respectively) and 5 RM load (p < 0.001; 53.3 ± 9.8 kg and 102.1 ± 9.6 kg for UNE and EXP, respectively)
Summary
Regular practice of strength training is associated to increases in maximal strength, changes in neuromuscular function, and in muscle morphology. Neural adaptations to strength training occur earlier than muscle adaptations and the initial gains in strength are not accompanied by an increase in muscle size [1,2,3]. Changes in the neural drive have been inferred from surface electromyography (EMG) studies that show increases in EMG activity of the agonist muscle during first weeks of training [1,2,3,4,5]. This increase in EMG reflects increases in fiber recruitment or firing frequency [1,4]. The coordination of all muscles would allow to produce the required joint moments in the intended direction to perform specific movements [1,4,6,7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
