Anti-phase action between the angular accelerations of trunk and leg is reduced in the elderly.
Quiet standing posture in humans has often been modeled as a single inverted pendulum pivoting around the ankle joint. However, recent studies have suggested that anti-phase action between leg and trunk segments plays a significant role in stabilizing posture by reducing the acceleration of the center of mass (COM) of the body. The aim of this study is to test the hypothesis that anti-phase action is attenuated in the elderly compared to the young. The anterior-posterior movements of leg and trunk segments were measured using 4 laser displacement sensors from 22 healthy young subjects (age range, 20-35 years) and 38 healthy elderly subjects (age range, 57-80 years) standing quietly for 30s twice. To focus on the segmental action between trunk and legs, we applied constraints (i.e., wooden splints) on each segment. We found that the velocity and acceleration of the COM (standard deviation of the time series was evaluated) were significantly higher for the elderly subjects than for young subjects. The increase in the acceleration of the COM resulted not only from an increase in the angular acceleration of the segments but also from the reduction of their anti-phase relationship, as demonstrated by an index that quantifies the degree of cancelation between both segments. We conclude that the degree of anti-phase action between trunk and leg segments during quiet standing is smaller for elderly subjects than for young subjects, and that this change of the anti-phase action due to aging resulted in increased COM acceleration in the elderly subjects.
Faculty of Systems Engineering, Shibaura Institute of Technology, Saitama, Japan.
Tomohisa
T
Kato
Departiment of Bio-Science and Engineering, College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama, Japan.
Shin-ichiro
S
Yamamoto
Faculty of Systems Engineering, Shibaura Institute of Technology, Saitama, Japan; Graduate School of Engineering, Iwate University, Iwate, Japan.
Tasuku
T
Miyoshi
Graduate School of Arts and Sciences, The University of Tokyo, Japan.
Kimitaka
K
Nakazawa
Rehabilitation Engineering Laboratory, Toronto Rehabilitation Institute - University Health Network, Toronto, Ontario, Canada M4G 3V9; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada M5S 3G9. Electronic address: k.masani@utoronto.ca.
Kei
K
Masani
Graduate School of Education, The University of Tokyo, Tokyo, Japan. Electronic address: nozaki@p.u-tokyo.ac.jp.
Daichi
D
Nozaki
D000054:Acceleration; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena; D005260:Female; D006615:Hip / Q000502:physiology; D006801:Humans; D007866:Leg; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009068:Movement / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D012016:Reference Values; D015203:Reproducibility of Results; D060726:Torso / Q000502:physiology*; D055815:Young Adult
Aging; Hip strategy; Intersegmental coordination; Posturography; Quiet standing