title: Gait Variability Related to Muscle Quality and Muscle Power Output in Frail Nonagenarian Older Adults.
abstract: BACKGROUND
  Frailty has become the center of attention of basic, clinical, and demographic research because of its incidence level and the gravity of adverse outcomes with age. Moreover, with advanced age, motor variability increases, particularly in gait. Muscle quality and muscle power seem to be closely associated with performance on functional tests in frail populations. Insight into the relationships among muscle power, muscle quality, and functional capacity could improve the quality of life in this population. In this study, the relationship between the quality of the muscle mass and muscle strength with gait performance in a frail population was examined.
  
  
  METHODS
  Twenty-two institutionalized frail elderly individuals (93.1 ± 3.6) participated in this study. Muscle quality was measured by segmenting areas of high- and low-density fibers as observed in computed tomography images. The assessed functional outcomes were leg strength and power, velocity of gait, and kinematic gait parameters obtained from a tri-axial inertial sensor.
  
  
  RESULTS
  Our results showed that a greater number of high-density fibers, specifically those of the quadriceps femoris muscle, were associated with better gait performance in terms of step time variability, regularity, and symmetry. Additionally, gait variability was associated with muscle power. In contrast, no significant relationship was observed between gait velocity and either muscle quality or muscle power.
  
  
  CONCLUSIONS
  Gait pattern disorders could be explained by a deterioration of the lower limb muscles. It is known that an impaired gait is an important predictor of falls in older populations; thus, the loss of muscle quality and power could underlie the impairments in motor control and balance that lead to falls and adverse outcomes.
authors.affiliation: Mathematics Department, Public University of Navarra, Navarra, Spain. Electronic address: jon.martinikorena@gmail.com.
authors.forename: Ion
authors.initials: I
authors.lastname: Martinikorena
authors.affiliation: Mathematics Department, Public University of Navarra, Navarra, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Martínez-Ramírez
authors.affiliation: Mathematics Department, Public University of Navarra, Navarra, Spain.
authors.forename: Marisol
authors.initials: M
authors.lastname: Gómez
authors.affiliation: Mathematics Department, Public University of Navarra, Navarra, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Lecumberri
authors.affiliation: Division of Geriatric Medicine, Complejo Hospitalario de Navarra, Pamplona, Spain.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Casas-Herrero
authors.affiliation: Exercise Research Laboratory, Physical Education School, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Eduardo L
authors.initials: EL
authors.lastname: Cadore
authors.affiliation: Mathematics Department, Public University of Navarra, Navarra, Spain.
authors.forename: Nora
authors.initials: N
authors.lastname: Millor
authors.affiliation: Department of Health Sciences, Public University of Navarra, Navarra, Spain.
authors.forename: Fabricio
authors.initials: F
authors.lastname: Zambom-Ferraresi
authors.affiliation: Radiology Department, Clínica San Miguel, Pamplona, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Idoate
authors.affiliation: Department of Health Sciences, Public University of Navarra, Navarra, Spain.
authors.forename: Mikel
authors.initials: M
authors.lastname: Izquierdo
mesh_terms: D000369:Aged, 80 and over; D005260:Female; D016330:Frail Elderly; D005684:Gait / Q000502:physiology*; D006707:Homes for the Aged; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed
keywords: Inertial sensors; frailty; gait variability; muscle power; muscle quality