Associations of Computed Tomography-Based Trunk Muscle Size and Density With Balance and Falls in Older Adults.
Deficits in balance and muscle function are important risk factors for falls in older adults. Aging is associated with significant declines in muscle size and density, but associations of trunk muscle size and density with balance and falls in older adults have not been previously examined.



Trunk muscle size (cross-sectional area) and attenuation (a measure of tissue density) were measured in computed tomography scans (at the L2 lumbar level) in a cohort of older adults (mean ± SD age of 81.9±6.4) residing in independent living communities. Outcome measures were postural sway measured during quiet standing and Short Physical Performance Battery (SPPB) at baseline, and falls reported by participants for up to 3 years after baseline measurements.



Higher muscle density was associated with reduced postural sway, particularly sway velocities, in both men and women, and better Short Physical Performance Battery score in women, but was not associated with falls. Larger muscle size was associated with increased postural sway in men and women and with increased likelihood of falling in men.



The results suggest that balance depends more on muscle quality than on the size of the muscle. The unexpected finding that larger muscle size was associated with increased postural sway and increased fall risk requires further investigation, but highlights the importance of factors besides muscle size in muscle function in older adults.
Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Boston, Massachusetts. Department of Orthopedic Surgery, Harvard Medical School, Boston, Massachusetts. danders7@bidmc.harvard.edu.
Dennis E
DE
Anderson
Data Coordinating Center, Boston University School of Public Health, Massachusetts.
Emily
E
Quinn
Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
Emily
E
Parker
Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
Brett T
BT
Allaire
Department of Biomedical Engineering, Stony Brook University, New York.
Jesse W
JW
Muir
Department of Biomedical Engineering, Stony Brook University, New York.
Clinton T
CT
Rubin
Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore.
Jay
J
Magaziner
Institute for Aging Research, Hebrew SeniorLife, Boston, Massachusetts. Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
Marian T
MT
Hannan
Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Boston, Massachusetts. Department of Orthopedic Surgery, Harvard Medical School, Boston, Massachusetts.
Mary L
ML
Bouxsein
Institute for Aging Research, Hebrew SeniorLife, Boston, Massachusetts. Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
Douglas P
DP
Kiel
D000058:Accidental Falls; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D057187:Independent Living; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D060726:Torso / Q000000981:diagnostic imaging* / Q000502:physiology*
Balance-biomechanics; Incident falls; Muscle composition; Postural sway; Sarcopenia