Muscle Activation Profile While Walking with Perturbations

Uri Rosenblum, Itshak Melzer, Gabi Zeilig, Meir Plotnik

Research output: Contribution to journalArticlepeer-review


To avoid falling consequential to unexpected balance loss i.e., perturbation, requires people to readjust their footing rapidly and effectively (i.e., recovery stepping response). We aimed to investigate lower limb muscle activation and differences between ankle and knee muscle recruitment due to unexpected support-surface perturbations during walking. This was measured by frequency content changes of surface electromyography (sEMG). Twenty adults (27.00textpm2.79 years, 10 females) were exposed to perturbations while walking on a treadmill in virtual reality environment. Perturbations were applied randomly in different phases of gait in 4 directions (i.e., anterior/posterior/right/left). sEMG signals from the tibialis anterior (TA) and vastus lateralis (VL) muscles were studied. sEMG total spectral power for all signal frequencies and for specific bands (40-150 Hz, 150-250 Hz, 250-400 Hz) were compared 4 seconds before perturbation (i.e., baseline) versus four seconds after perturbations. We found that compared to baseline there was a significant increase in the total spectral power of lower-extremity muscles at the first 3 seconds after perturbation, for all frequencies. TA had a significant differential change in frequency bands: 150-250Hzgt;40-150Hz, while VL demonstrated a different differential response in frequency bands 40-150Hz amp; 150-250Hzgt;250-400Hz. Both muscles showed an increase in total spectral power for the first second after perturbation followed by gradual decrease to baseline total spectral power subsiding after 3 seconds. Our findings suggest that muscle operating frequency is modulated in real time to fit functional goal requirements such as a rapid change of footing in response to unexpected loss of balance.New amp; Noteworthy To study muscle spectral profiles in response to loss of balance, we investigated the dynamics of muscle spectral power changes, across different frequency bands after unannounced physical perturbations during walking. Our analysis showed increased activation of high-frequency motor units of the lower-limb muscles, subsiding 3 seconds after perturbation. Differential power increase of specific frequency bands suggests that muscle activation is modulated in real time to fit functional goal requirements.Competing Interest StatementThe authors have declared no competing interest.
Original languageEnglish
StatePublished - 2021


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