Low-Frequency Oscillations and Force Control Capabilities as a Function of Force Level in Older Women

Nyeonju Kang

doi:10.3390/app12041812

Abstract

Force variability is potentially related to altered low-frequency oscillations in motor outputs. This study examines the contributions of low-frequency oscillations in force to altered force control performances from lower to higher targeted force levels in older women. Fourteen older women executed unilateral hand-grip force control tasks at 10% and 40% of maximum voluntary contraction (MVC). Force control performances were estimated by calculating force accuracy (root-mean-square-error), force variability (standard deviation), and force regularity (approximate entropy). We additionally quantified low-frequency oscillations in force using absolute powers across four different frequency bands: (a) 0–0.5 Hz, (b) 0.5–1.0 Hz, (c) 1.0–1.5 Hz, and (d) 1.5–2.0 Hz. The findings reveal that from lower to higher targeted force level older women show greater force error, force variability, and force regularity with increased values of absolute power in force across the four frequency bands. The multiple regression models identified a significant relationship between greater force frequency power below 0.5 Hz and more impairments in force control performances. These findings suggest that force frequency oscillation below 0.5 Hz is a key predictor indicating altered stability of task performances across different targeted force levels in older women.

Highlights

Force control capabilities are essential for successfully conducting various activities of daily living [1,2]
Post hoc analyses showed that the absolute power for four frequency bands significantly increased from 10% to 40% of maximum voluntary contraction (MVC)
In summary: the current study identifies that increased force frequency oscillations below 0.5 Hz in older women are significantly associated with more impairments in force control performances from lower to higher targeted force levels

Summary

Introduction

Force control capabilities are essential for successfully conducting various activities of daily living [1,2]. A recent literature review raised the possibility that force variability properties in the motor system may be associated with changes in the low-frequency oscillations of motor outputs [8]. For healthy young adults, when the concurrent visual information was removed, force oscillations below 0.5 Hz increased with greater force variability during the index finger’s abduction force control tasks [9]. Older adults and patients with stroke revealed more low force oscillations with higher motor variability than those in the control groups [9,10]. While processing a greater amount of visual information (i.e., higher visual gain conditions), elderly people especially elevated force frequency properties below

Objectives

Methods

Results

Discussion

Conclusion