Age-related differences in muscle synergy organization during step ascent at different heights and directions

Remco J. Baggen, Jaap H.van Dieën, Evelien Van Roie, Sabine M. Verschueren, Georgios Giarmatzis, Christophe Delecluse, Nadia Dominici*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


The aim of this study was to explore the underlying age-related differences in dynamic motor control during different step ascent conditions using muscle synergy analysis. Eleven older women (67.0 y ± 2.5) and ten young women (22.5 y ± 1.6) performed stepping in forward and lateral directions at step heights of 10, 20 and 30 cm. Surface electromyography was obtained from 10 lower limb and torso muscles. Non-negative matrix factorization was used to identify sets of (n) synergies across age groups and stepping conditions. In addition, variance accounted for (VAF) by the detected number of synergies was compared to assess complexity of motor control. Finally, correlation coefficients of muscle weightings and between-subject variability of the temporal activation patterns were calculated and compared between age groups and stepping conditions. Four synergies accounted for >85% VAF across age groups and stepping conditions. Age and step height showed a significant negative correlation with VAF during forward stepping but not lateral stepping, with lower VAF indicating higher synergy complexity. Muscle weightings showed higher similarity across step heights in older compared to young women. Neuromuscular control of young and community-dwelling older women could not be differentiated based on the number of synergies extracted. Additional analyses of synergy structure and complexity revealed subtle age-and step-height-related differences, indicating that older women rely on more complex neuromuscular control strategies.

Original languageEnglish
Article number1987
Pages (from-to)1-15
Number of pages15
JournalApplied Sciences (Switzerland)
Issue number6
Publication statusPublished - 14 Mar 2020


This study was funded by the European Commission through MOVE-AGE, an Erasmus Mundus Joint Doctorate programme (#2014-0691) fellowship awarded to R.J.B., the Fund for Scientific Research Flanders (FWO-Vlaanderen, #G0521-05) awarded to S.M.V., and the ERC-Starting Grant "Learn2Walk" (#715945) and the NWO VIDI-Grant "FirSTeps" (#016.156.346) both awarded to N.D. The authors would like to thank Tine De Reys for her assistance with data collection and processing and Hans Essers for his advice on the cluster analyses.

FundersFunder number
Fund for Scientific Research Flanders
Horizon 2020 Framework Programme715945
European Commission2014-0691
Nederlandse Organisatie voor Wetenschappelijk Onderzoek016.156.346


    • Aging
    • EMG
    • Forward stepping
    • Lateral stepping
    • Muscle synergies
    • Neural control


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