Intra- and Intermuscular Coherence and Body Acceleration Control in Older Adults during Bipedal Stance.

Tadayoshi Minamisawa,Noboru Chiba,Eizaburo Suzuki

doi:10.3390/geriatrics6040114

Tadayoshi Minamisawa, Noboru Chiba + Show 1 more

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https://doi.org/10.3390/geriatrics6040114

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Abstract

Our aim was to clarify the effect of aging on the coherence of electromyograms of plantar flexor pairs during bipedal stance and to clarify the relationship between coherence and center-of-mass acceleration (COMacc). The subjects were 16 adults and 18 older adults. Intra- and intermuscular coherence and phase analyses were used to analyze the muscle pairs of bilateral and unilateral plantar flexor muscle groups. The relationship between coherence value and anterior–posterior COMacc of the plantar flexor muscle pairs was also examined to determine whether the connectivity of the lower limb muscle pairs is functionally important. The older adults showed higher coherence in the frequency range of 0–4 Hz for muscle pairs than the younger adults. In phase analysis, the older adults showed a phase difference between bilateral heteronymous muscle pairs in the frequency range of 0–6 Hz, which was one of the characteristics not seen in the younger adults. Correlation analysis showed that all the muscle pairs were moderately correlated with COMacc in the older adults. Not only does aging affects the organization of the bilateral and unilateral postural muscle activity of the plantar flexors during bipedal stance, but such organization may also be related to the increased COMacc characteristics of older adults.

Highlights

The problem of balance loss due to weak physical function is one of the main health problems faced by older adults
The center of pressure in the anterior–posterior direction (COPap) and the center of pressure in the medial–lateral direction (COPml) of Geriatrics 2021, 6, 114 each lower limb were calculated from the two force plates with the aim of clarifying the asymmetry of the kinematic characteristics of both lower limbs
Since frequencies below 10 Hz have been reported as one of the characteristic frequency bands of intermuscular coherence, we focused our analysis on this frequency band in this study

Summary

Introduction

The problem of balance loss due to weak physical function is one of the main health problems faced by older adults. It is interesting to see how this heteronymous pair of muscles relate to each other across the lower limbs, because differences in EMG responses (i.e., intermittent or sustained activity) have been observed between MG and SOL in functional tasks such as weight shifting and walking [9]. Co-contraction of co-activation muscles, and homonymous muscle pairs and heteronymous muscles across both lower limbs, may interfere with joint motion redundancy of the lower limbs in the standing posture, where joint motion freedom is high [10]. Whether these interlimb muscle networks are related in standing has not been systematically examined. The first purpose of this study was to investigate the age dependence of intermuscular coherence of both lower limbs in bipedal stance as a function of postural stability

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