Age related changes of the motor excitabilities and central and peripheral muscle strength

Yu-Fen Chuang; Chih-Chung Chen; Miao-Ju Hsu; Nan-Jing Huang; Ying-Zu Huang; Hsiao-Lung Chan; Ya-Ju Chang

doi:10.1016/j.jelekin.2018.12.007

Age related changes of the motor excitabilities and central and peripheral muscle strength

J Electromyogr Kinesiol. 2019 Feb:44:132-138. doi: 10.1016/j.jelekin.2018.12.007. Epub 2018 Dec 24.

Authors

Yu-Fen Chuang¹, Chih-Chung Chen¹, Miao-Ju Hsu², Nan-Jing Huang³, Ying-Zu Huang⁴, Hsiao-Lung Chan⁵, Ya-Ju Chang⁶

Affiliations

¹ School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, and Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan; Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan.
² Department of Physical Therapy, College of Health Science, Kaohsiung Medical University; Department of Physical Medicine and Rehabilitation, and Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
³ School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, and Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan.
⁴ Department of Neurology, Chang Gung Memorial Hospital, Linkou, and School of Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan.
⁵ Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan; Department of Electrical Engineering, College of Engineering, Chang Gung University, Taoyuan, Taiwan. Electronic address: chanhl@mail.cgu.edu.tw.
⁶ School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, and Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan; Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan. Electronic address: yjchang@mail.cgu.edu.tw.

PMID: 30640164
DOI: 10.1016/j.jelekin.2018.12.007

Abstract

Introduction: The purpose was to investigate the age effects on central versus peripheral sources of strength, fatigue, and central neural excitabilities.

Methods: 42 healthy subjects were recruited as young group (23.73 ± 2.15 years; n = 26) and middle-aged group (57.25 ± 4.57 years; n = 16). Maximum voluntary contraction force (MVC), voluntary activation level (VA), and twitch force of quadriceps were evaluated to represent general, central, and peripheral strengths. Central and peripheral fatigue indexes were evaluated using femoral nerve electrical stimulation. Cortical excitabilities were evaluated using transcranial magnetic stimulation (TMS).

Results: The middle-aged group had lower MVC and twitch force of quadriceps, but not VA, than young group. No between group differences were found in fatigue indexes. The cortical excitability in middle-aged group was different from young group in paired TMS with inter-stimulus interval of 7 ms.

Conclusion: The age-related strength loss at early stage was primarily caused by peripheral muscular strength. The deviation of central neural excitability can be detected but the activation level was not impaired in middle-age adults.

Keywords: Central fatigue; Motor evoked potential (MEP); Peripheral fatigue; Transcranial magnetic stimulation (TMS); Twitch force; Voluntary activation level.

MeSH terms

Adult
Aging / physiology*
Evoked Potentials, Motor*
Female
Humans
Male
Middle Aged
Muscle Fatigue
Muscle Strength*
Muscle, Skeletal / growth & development
Muscle, Skeletal / physiology*
Transcranial Magnetic Stimulation