Modulation of force below 1 Hz: age-associated differences and the effect of magnified visual feedback. Academic Article uri icon


  • Oscillations in force output change in specific frequency bins and have important implications for understanding aging and pathological motor control. Although previous studies have demonstrated that oscillations from 0-1 Hz can be influenced by aging and visuomotor processing, these studies have averaged power within this bandwidth and not examined power in specific frequencies below 1 Hz. The purpose was to determine whether a differential modulation of force below 1 Hz contributes to changes in force control related to manipulation of visual feedback and aging. Ten young adults (254 yrs, 5 men) and ten older adults (715 yrs, 4 men) were instructed to accurately match a target force at 2% of their maximal isometric force for 35 s with abduction of the index finger. Visual feedback was manipulated by changing the visual angle (0.05, 0.5, 1.5) or removing it after 15 s. Modulation of force below 1 Hz was quantified by examining the absolute and normalized power in seven frequency bins. Removal of visual feedback increased normalized power from 0-0.33 Hz and decreased normalized power from 0.66-1.0 Hz. In contrast, magnification of visual feedback (visual angles of 0.5 and 1.5) decreased normalized power from 0-0.16 Hz and increased normalized power from 0.66-1.0 Hz. Older adults demonstrated a greater increase in the variability of force with magnification of visual feedback compared with young adults (P=0.05). Furthermore, older adults exhibited differential force modulation of frequencies below 1 Hz compared with young adults (P<0.05). Specifically, older adults exhibited greater normalized power from 0-0.16 Hz and lesser normalized power from 0.66-0.83 Hz. The changes in force modulation predicted the changes in the variability of force with magnification of visual feedback (R(2)=0.80). Our findings indicate that force oscillations below 1 Hz are associated with force control and are modified by aging and visual feedback.

published proceedings

  • PLoS One

author list (cited authors)

  • Fox, E. J., Baweja, H. S., Kim, C., Kennedy, D. M., Vaillancourt, D. E., & Christou, E. A.

citation count

  • 35

complete list of authors

  • Fox, Emily J||Baweja, Harsimran S||Kim, Changki||Kennedy, Deanna M||Vaillancourt, David E||Christou, Evangelos A

editor list (cited editors)

  • Jones, K. E.

publication date

  • February 2013