Aging and Time to Instability in Posture

Slobounov, Semyon; Moss, Sarah; Slobounova, Elena S.; Newell, Karl M.

doi:10.1093/gerona/53a.1.b71

Cited by 100 publications

(76 citation statements)

References 17 publications

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“…With increasing age, there is a decrease in sensory function (Wolfson et al, 1992;Era et al, 2006) and a decrease in muscle strength (Porter et al, 1995). Slobounov et al (1998) measured postural sway in older adults aged 67 to 92 years and found that postural sway, with eyes open and closed, increased with age, but was aŠected to a much greater extent when visual cues were removed. Hasan et al (1990) investigated changes in postural sway in women over the age of 65 during eyes open double stance, eyes open single stance, eyes closed double stance, and eyes closed single stance.…”

Section: Discussionmentioning

confidence: 99%

Effects of Body-weight Squat Training on Muscular Size, Strength and Balance Ability in Physically Frail Older Adults

Fujita

Takeshima

Kato

et al. 2016

Int. J. Sport Health Sci.

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The purpose of this study was to evaluate the eŠects of a 12-week group-based body-weight squat training program on muscle mass, muscle strength, and balance in physically frail community-dwelling older men and women. Fifteen older adults (mean age ＝78.7 yr) who needed assistance performing activities of daily living (ADL) according to long-term care insurance regulations in Japan participated in the study. Participants performed squat exercise in a groupsetting using body-weight as resistance while singing for one set consisting of 48 reps twice weekly for 12 weeks. Body mass, thigh girth, thigh muscle thickness assessed by B-mode ultrasound, knee extension torque (KET), static and dynamic balance (static (SB): sway velocity (SV) standing onˆrm or foam surfaces with eyes open or closed; dynamic (DB): limits of stability) were measured before and after the intervention. Following the intervention, participants signiˆcantly (P＜0.05) decreased body mass and increased KET relative to body mass. Although thigh girth did not change, thigh muscle thickness did increase. There were no appreciable changes in DB nor in SB, except SV standing on aˆrm surface with the eyes open improved. Group-based body-weight squat exercise in physically frail older adults improves muscle mass and strength but has little eŠect on balance parameters.

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Section: Discussionmentioning

confidence: 99%

Effects of Body-weight Squat Training on Muscular Size, Strength and Balance Ability in Physically Frail Older Adults

Fujita

Takeshima

Kato

et al. 2016

Int. J. Sport Health Sci.

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“…Slobounov et al [29] subsequently built on this theoretical and empirical background and investigated the VTC in standing-still posture as a function of cohort group (60-69, 70-79, 80-89, and 90-96 years of age). The functional stability boundary for each participant was initially determined through having the individuals lean as far outward as they could in all directions without falling.…”

Section: Aging and The Time To Instability In Postural Controlmentioning

confidence: 99%

Aging-related temporal constraints to stability and instability in postural control

Slobounov

Haibach

Newell

2006

Eur. Rev. Aging.Phys. Act.

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In this study, we review the evidence that older adults tend to have both a shorter time to lose stability in the maintenance of standing posture and the functionally related but inverse problem of needing more time to reacquire stability in transitioning to a postural state. These age-related time limitations to processes of stability are hypothesized to enhance the probability of falling with aging and the problems that can occur in the transition between activities, such as sitting to standing and standing to walking. The potential role of fitness and health variables in mediating the temporal constraints on the acquisition and loss of postural stability in aging is discussed.Keywords Aging . Posture . StabilityThe conduct of daily life involves the engagement in a variety of physical activities that have been historically categorized into subgroups, such as activities of daily living, work, sport, music, and play. These activities in all contexts are manifestations of the fundamental physical activities of posture, locomotion, and manipulation. Thus, even in a single day in the lifetime of an individual, that person switches from the execution of one action to another in a sequence and time course that is determined by many environmental and individual factors. This time course of the change in behavior over time implies that an individual in switching activities is also caught in the continually evolving dynamical spiral of moving from stability to instability to stability and so on. The temporal limitations in acquiring or moving away from stability in standing posture as a function of aging is the focus of this review.It is well established that aging tends to lead in most individuals to a number of limitations and problems in the conduct of perceptual motor skills. The information processing [1-4], neurophysiological [5,6] and fitness [7][8][9] perspectives to aging and physical activity have all revealed age-related trends including: poorer performance (no matter how it is measured), slowness of thought and action, and loss of fitness properties such as strength, flexibility, and endurance. The more recent emphasis on dynamical processes of aging through the metaphor of selforganization has opened up new approaches and findings to aging-related limitations in physical activity [10][11][12][13][14][15]. A particular thrust has been the investigation of age-related changes in the complexity of behavior through a consideration of the evolving dynamics of movement in action [12,16], with emphasis on the health outcomes of dynamical stability and instability. Glass and Mackey [10] have viewed some processes of aging and movement disorders as an example of a dynamical disease in which behavioral and physiological systems change as a consequence of aberrations in the temporal organization of the evolving dynamics.The role and consequences of dynamical stability and instability are magnified in whole body physical activities such as standing posture and locomotion because of the potential severe negati...

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“…TtC has been used to assess postural stability in quiet stance conditions involving relatively small CoM velocities and accelerations. Some calculate TtC as the distance to the base of support boundary divided by the velocity of the center of pressure (CoP) (Van Wegen et al 2002;Hertel et al 2006;Hertel and Olmsted-Kramer 2007) or CoM (Forth et al 2007), while others also include CoP acceleration (Slobounov et al 1997;Slobounov et al 1998;Patton et al 2000;Slobounov et al 2006;Haibach et al 2007). Comparison of these methods by Haddad et al (2006) suggested that the addition of acceleration information might better represent static postural control.…”

Section: Introductionmentioning

confidence: 99%

Predicting dynamic postural instability using center of mass time-to-contact information

Hasson

Emmerik

Caldwell

2008

Journal of Biomechanics

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Our purpose was to determine whether spatiotemporal measures of center of mass motion relative to the base of support boundary could predict stepping strategies after upper-body postural perturbations in humans. We expected that inclusion of center of mass acceleration in such time-tocontact (TtC) calculations would give better predictions and more advanced warning of perturbation severity. TtC measures were compared with traditional postural variables, which don't consider support boundaries, and with an inverted pendulum model of dynamic stability developed by Hof et al. (2005). A pendulum was used to deliver sequentially increasing perturbations to 10 young adults, who were strapped to a wooden backboard that constrained motion to sagittal plane rotation about the ankle joint. Subjects were instructed to resist the perturbations, stepping only if necessary to prevent a fall. Peak center of mass and center of pressure velocity and acceleration demonstrated linear increases with postural challenge. In contrast, boundary relevant minimum TtC values decreased nonlinearly with postural challenge, enabling prediction of stepping responses using quadratic equations. When TtC calculations incorporated center of mass acceleration, the quadratic fits were better and gave more accurate predictions of the TtC values that would trigger stepping responses. In addition, TtC minima occurred earlier with acceleration inclusion, giving more advanced warning of perturbation severity. Our results were in agreement with TtC predictions based on Hof's model, and suggest that TtC may function as a control parameter, influencing the postural control system's decision to transition from a stationary base of support to a stepping strategy.

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Aging and Time to Instability in Posture

Cited by 100 publications

References 17 publications

Effects of Body-weight Squat Training on Muscular Size, Strength and Balance Ability in Physically Frail Older Adults

Effects of Body-weight Squat Training on Muscular Size, Strength and Balance Ability in Physically Frail Older Adults

Aging-related temporal constraints to stability and instability in postural control

Predicting dynamic postural instability using center of mass time-to-contact information

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