Variability in spatio-temporal pattern of trapezius activity and coordination of hand-arm muscles during a sustained repetitive dynamic task
- 603 Downloads
The spatio-temporal distribution of muscle activity has been suggested to be a determinant of fatigue development. Pursuing this hypothesis, we investigated the pattern of muscular activity in the shoulder and arm during a repetitive dynamic task performed until participants’ rating of perceived exertion reached 8 on Borg’s CR-10 scale. We collected high-density surface electromyogram (HD-EMG) over the upper trapezius, as well as bipolar EMG from biceps brachii, triceps brachii, deltoideus anterior, serratus anterior, upper and lower trapezius from 21 healthy women. Root-mean-square (RMS) and mean power frequency (MNF) were calculated for all EMG signals. The barycenter of RMS values over the HD-EMG grid was also determined, as well as normalized mutual information (NMI) for each pair of muscles. Cycle-to-cycle variability of these metrics was also assessed. With time, EMG RMS increased for most of the muscles, and MNF decreased. Trapezius activity became higher on the lateral side than on the medial side of the HD-EMG grid and the barycenter moved in a lateral direction. NMI between muscle pairs increased with time while its variability decreased. The variability of the metrics during the initial 10 % of task performance was not associated with the time to task termination. Our results suggest that the considerable variability in force and posture contained in the dynamic task per se masks any possible effects of differences between subjects in initial motor variability on the rate of fatigue development.
KeywordsFatigue development High-density electromyogram Functional connectivity
The study was partly supported by grants from The Ministry of Culture Committee on Sports Research in Denmark, The Danish Rheumatism Association and the Swedish Research Council for Health, Working Life and Welfare (Forte Dnr 2011-0075).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no personal or financial relationship which may influence their work.
- Gonzalez RC, Woods RE, Eddins SL (2004) Digital image processing using MATLAB. Prentice Hall, Upper Saddle RiverGoogle Scholar
- Holm S (1979) A simple sequentially rejective multiple test procedure. Scand J Stat 6:65–70Google Scholar
- Kawczyński A, Samani A, Mroczek D, Chmura P, Błach W, Migasiewicz J, Klich S, Chmura J, Madeleine P (2015) Functional connectivity between core and shoulder muscles increases during isometric endurance contractions in judo competitors. Eur J Appl Physiol 115:1351–1358. doi: 10.1007/s00421-015-3114-z CrossRefPubMedGoogle Scholar
- Kleine BU, Schumann NP, Stegeman DF, Scholle HC (2000) Surface EMG mapping of the human trapezius muscle: the topography of monopolar and bipolar surface EMG amplitude and spectrum parameters at varied forces and in fatigue. Clin Neurophysiol 111:686–693. doi: 10.1016/s1388-2457(99)00306-5 CrossRefPubMedGoogle Scholar
- Madeleine P, Hansen EA, Samani A (2014) Linear and nonlinear analyses of multi-channel mechanomyographic recordings reveal heterogeneous activation of wrist extensors in presence of delayed onset muscle soreness. Med Eng Phys 36:1656–1664. doi: 10.1016/j.medengphy.2014.09.003 CrossRefPubMedGoogle Scholar
- Maynard H (1948) Method-time-measurement (MTM). McGraw-Hill, PensilvaniaGoogle Scholar
- Nordander C, Balogh I, Mathiassen SE, Ohlsson K, Unge J, Skerfving S, Hansson GÅ (2004) Precision of measurements of physical workload during standardised manual handling. Part I: surface electromyography of m. trapezius, m. infraspinatus and the forearm extensors. J Electromyogr Kinesiol 14:443–454. doi: 10.1016/j.jelekin.2003.12.003 CrossRefPubMedGoogle Scholar
- Srinivasan D, Mathiassen SE, Hallman DM, Samani A, Madeleine P, Lyskov E (2016) Effects of concurrent physical and cognitive demands on muscle activity and heart rate variability in a repetitive upper-extremity precision task. Eur J Appl Physiol 116:227–239. doi: 10.1007/s00421-015-3268-8 CrossRefPubMedGoogle Scholar