Challenging Horizontal Movement of the Body During Sit-to-Stand: Impact on Stability in the Young and Elderly

Abstract

There are 3 significant challenges to sit-to-stand: (a) bringing the center of mass forward, (b) vertically raising the center of mass from the sitting to standing position, and (c) transition from a relatively large and stable base of support in sitting to a considerably smaller base of support when standing. The authors explored the challenges to stability control following sit-to-stand when the requirement for horizontal movement of the center of mass was influenced by foot position and their potential effect on the preceding phases of sit-to-stand. Eleven healthy young and 11 healthy elderly individuals performed the sit-to-stand with their feet further away and closer to the chair. Kinetic and kinematic data were recorded. Regardless of foot position, challenges in stability were greater in elderly participants than young participants despite their similar movement time and shear forces. The greater instability in elderly participants, despite their comparable movement characteristics, emphasizes the importance of stability control following sit-to-stand performance. For both young and elderly participants, the sit-to-stand duration and the shear forces were greater in the far condition. However, foot position did not affect the stability measures (i.e., duration of the stabilization phase and the total center of pressure path during the 1st second of the stabilization phase).

Postural stability with exhaustive repetitive sit-to-stand exercise in young adults

“…An increase in COP excursions about the feet when rising from a chair would suggest a reduced ability to control whole body dynamics due to fatigue as greater deviations and variability of COP occurring between starting (seated) and ending (standing) body positions (Hernandez, Ashton-Miller, & Alexander, 2012;Sparto et al, 1997). Furthermore, when rising from a seated position, a COP position at mid-foot is considered to be the most stable position away from the extreme LOS in preparation for a rapid reduction in support surface once contact is lost with the seat (Akram & McIlroy, 2011;Mourey, Grishin, d'Athis, Pozzo, & Stapley, 2000;Shultz et al, 1992). This may suggest that a stabilization strategy to improve postural stability was adopted in preparation for seat-off and narrowed postural boundaries.…”

“…The ability to rise from a seated position is a basic, but challenging skill associated with numerous activities of daily living that requires the development of relatively high muscular efforts even in healthy young adults (Bieryla, Anderson, & Madigan, 2009;Hortobágyi, Mizelle, Beam, & DeVita, 2003), which may lead to substantial accumulation of fatigue with repetitive actions. Additionally, STS exercise is especially demanding in terms of its reliance on balance control capabilities in order to achieve an upright standing position as it requires the precise control of COM over a rapid reduction in support surface the moment contact is lost with the seat (Akram & McIlroy, 2011;Doorenbosch, Harlaar, Roenbroeck, & Lankhorts, 1994;Fugimoto & Chou, 2012;Shultz, Alexander, & Ashton-Miller, 1992). Therefore it is understandable why its capacity has been shown to be a predictor of disability in populations experiencing functional declines (Tiedemann et al, 2008).…”

The influence of upper limb immobilization on lower limb muscular activity during the sit-to-stand task

“…The EMG signal and Fx were digitally filtered using an IIR type filter, Low-pass 6 Hz, for the Fx [15,16] and a IIR type filter, Band-pass 20-500 Hz, for the EMG signal [17][18][19]. Finally, the EMG was transformed by the root mean square (RMS) calculation into 100 samples [20].…”

“…Phase 3 -extension and stabilization: It corresponds to a coordinated activation of the lower limb extensor muscles, allowing to reach a standing position. This phase began after phase 2 and ended with a fluctuation smoothing -the mean plus or minus two standard deviations within the baseline amplitude over a period greater than 50 ms [15].…”

Movement analysis of sit-to-stand – research informing clinical practice

“…(e.g., 43,45 ) Interaction from other determinants such as age, disability and motor strategy used for rising to stand likely have impacts on muscle activation patterns. Balance ability has been highlighted as a determinant of STS in the elderly 43,47 and in subjects with impairments, 46 but is probably of less importance in non-disabled young adults. Further, in the elderly, many interacting determinants, e.g., sensation and psychological status, are reported to influence STS performance.…”