Contrasting Age Effects on Complexity of Tracking Force and Force Fluctuations During Monorhythmic Contraction
in Journal of Aging and Physical ActivityClick name to view affiliation
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This study contrasted the stochastic force component between young and older adults, who performed pursuit tracking/compensatory tracking by exerting in-phase/antiphase forces to match a sinusoidal target. Tracking force was decomposed into the force component containing the target frequency and the nontarget force fluctuations (stochastic component). Older adults with inferior task performance had higher complexity (entropy across time; p = .005) in total force. For older adults, task errors were negatively correlated with force fluctuation complexity (pursuit tracking: r = −.527 to −.551; compensatory tracking: r = −.626 to −.750). Notwithstanding an age-related increase in total force complexity (p = .004), older adults exhibited lower complexity of the stochastic force component than young adults did (low frequency: p = .017; high frequency: p = .035). Those older adults with a higher complexity of stochastic force had better task performance due to the underlying use of a richer gradation strategy to compensate for impaired oscillatory control.
Chen is with the Department of Physical Therapy, College of Medical Science and Technology, Chung Shan Medical University, Taichung City, Taiwan; and Physical Therapy Room, Chung Shan Medical University Hospital, Taichung City, Taiwan. I.-C. Lin and Hwang are with the Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan City, Taiwan. Y.T. Lin is with Physical Education Office, Asian University, Taichung City, Taiwan. W.-M. Huang is with the Department of Management Information System, National Chung Cheng University, Chiayi City, Taiwan. C.-C. Huang is with Medical Device Innovation Center, National Cheng Kung University, Tainan City, Taiwan. Hwang is also with the Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan City, Taiwan.
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