Decrease in force control among older adults under unpredictable conditions

Shunsuke Ebisu; Satoshi Kasahara; Hiroshi Saito; Tomoya Ishida

doi:10.1016/j.exger.2021.111649

Decrease in force control among older adults under unpredictable conditions

Exp Gerontol. 2022 Feb:158:111649. doi: 10.1016/j.exger.2021.111649. Epub 2021 Dec 5.

Authors

Shunsuke Ebisu¹, Satoshi Kasahara², Hiroshi Saito³, Tomoya Ishida⁴

Affiliations

¹ Department of Physical Therapy, Rehabilitation part, Hokuto Social Medical Corporation Tokachi Rehabilitation Center, Japan.
² Department of Rehabilitation Sciences, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan. Electronic address: kasahara@hs.hokudai.ac.jp.
³ Department of Physical Therapy, School of Rehabilitation, Tokyo Kasei University, Sayama, Japan.
⁴ Department of Rehabilitation Sciences, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan.

PMID: 34875350
DOI: 10.1016/j.exger.2021.111649

Abstract

Objectives: Falls in older adults generally occur during unpredictable situations. Controlling posture through fine-tuned muscle force before and after falls is necessary to avoid serious injuries. However, details regarding force control among older adults during unpredictable situations are unclear. This study determined the features of force control in a random force-tracking task among older adults.

Methods: Ten healthy older adults (67-76 years) and eight healthy young adults (20-23 years) participated in three force-tracking tasks with ankle plantar flexion: low-range (LR), high-range (HR), and pseudo-random (PR) force tasks. Force control ability was assessed using the root mean square error (RMSE) between the target and muscle forces produced by the participants. Muscle activities from the lateral head of the gastrocnemius and the tibialis anterior during each task were measured using surface electromyography to calculate the co-contraction index (CCI).

Results: In all tasks, older adults (RMSEs: 1.09-3.70, CCIs: 29.4-56.4) had a significantly greater RMSEs and CCIs than young adults (RMSEs: 0.49-1.83, CCIs: 11.7-20.6; all, p < 0.05). The RMSEs during force generation were significantly greater than those during force release (LR: p < 0.01, HR: p < 0.05), except for the random force-tracking task in older adults. CCIs during the force release phase in both groups (older adults: 27.8-56.4, young adults: 15.0-20.6) were consistently greater than those during force generation (older adults: 24.5-50.4, young adults: 11.7-17.2). CCIs in force-tracing tasks differed in older adults, whereas those in the random force-tracing task increased. RMSEs and CCIs in the random and LR force-tracing tasks were significantly negatively correlated with the functional reach test (all: r > 0.5, p < 0.05).

Conclusion: Force control in older adults declines in low-band and random muscle force output. Moreover, increased CCIs in older adults are particularly pronounced during unpredictable situations.

Keywords: Aging; Ankle muscles; Electromyography; Motor control; Muscle strength.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aged
Aging* / physiology
Ankle Joint
Electromyography
Humans
Muscle Contraction / physiology
Muscle, Skeletal / physiology
Postural Balance* / physiology