Biomechanical analysis of failed sit-to-stand

Riley, Patrick O.; Krebs, David E.; Popat, Rita A.

doi:10.1109/86.650289

Cited by 123 publications

(97 citation statements)

References 13 publications

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“…The preponderance of research into human angular momentum behaviors has focused not on walking but on other movement tasks such as sit-to-stand maneuvers (Riley et al, 1997), running (Hinrichs et al, 1983;Hinrichs, 1982;Hinrichs, 1987;Hinrichs, 1992) and various sporting activities (Frohlich, 1979;Dapena and McDonald, 1989;Dapena, 1978;Dapena, 1993;LeBlanc and Dapena, 1996;King 1999). Specific to walking maneuvers, Elftman (Elftman, 1939) calculated the angular momenta of all body segments across one walking step, from heel strike to toe-off.…”

Section: Introductionmentioning

confidence: 99%

Angular momentum in human walking

Herr

Popović

2008

Journal of Experimental Biology

415

361

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SUMMARYAngular momentum is a conserved physical quantity for isolated systems where no external moments act about a bodyʼs center of mass (CM). However, in the case of legged locomotion, where the body interacts with the environment (ground reaction forces), there is no a priori reason for this relationship to hold. A key hypothesis in this paper is that angular momentum is highly regulated throughout the walking cycle about all three spatial directions [͉L(t)͉≈0], and therefore horizontal ground reaction forces and the center of pressure trajectory can be explained predominantly through an analysis that assumes zero net moment about the bodyʼs CM. Using a 16-segment human model and gait data for 10 study participants, we found that calculated zero-moment forces closely match experimental values (R 2 x =0.91; R 2 y =0.90). Additionally, the centroidal moment pivot (point where a line parallel to the ground reaction force, passing through the CM, intersects the ground) never leaves the ground support base, highlighting how closely the body regulates angular momentum. Principal component analysis was used to examine segmental contributions to whole-body angular momentum. We found that whole-body angular momentum is small, despite substantial segmental momenta, indicating large segment-to-segment cancellations (~95% medio-lateral, ~70% anterior-posterior and ~80% vertical). Specifically, we show that adjacent leg-segment momenta are balanced in the medio-lateral direction (left foot momentum cancels right foot momentum, etc.). Further, pelvis and abdomen momenta are balanced by leg, chest and head momenta in the anterior-posterior direction, and leg momentum is balanced by upper-body momentum in the vertical direction. Finally, we discuss the determinants of gait in the context of these segment-to-segment cancellations of angular momentum.

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Section: Introductionmentioning

confidence: 99%

Angular momentum in human walking

Herr

Popović

2008

Journal of Experimental Biology

415

361

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“…Thus, the waist-and seat-assist modes were found to be the most dynamically stable modes of assisted STS, indicating that subjects were less likely to have a "step" or "sit back" failure [27] when using these assistance modes than with the other assistance modes. Figure 4 shows the trajectory of the horizontal projection of the CoP for a representative subject.…”

Section: Dynamic Stabilitymentioning

confidence: 97%

Comparison of seat, waist, and arm sit-to-stand assistance modalities in elderly population

2013

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Abstract-The ability to perform a sit-to-stand (STS) motion is important for ambulatory adults to function independently and maintain daily activities. Roughly 6% of community-dwelling older adults experience significant difficulties with STS, a major risk factor for institutionalization. While mechanical STS assistance can help address this problem, full dependence on STS assistance provided by devices such as lift chairs can lead to atrophy of the leg muscles. We investigated the mechanics of assisted STS motion in order to better understand how loadsharing STS mechanisms may facilitate STS motions while still requiring activation of the leg muscles. Experiments were conducted with 17 nondisabled older adults performing unassisted and assisted STS rises with grab bar, arm, seat, and waist assistance. Each mode of rise was evaluated based on a subject questionnaire and key biomechanical metrics relating to stability, knee effort reduction, and rise trajectory. Results show that the seat-and waist-assist modes provide statistically significant improvements in stability metrics and reductions in required knee torques over unassisted rises and bar assistance. The assists most preferred by the subjects were the seat and bar assists. Overall, our results favor a seat-assisted STS modality for nonclinical applications and indicate further testing of this modality with a clinical population.

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“…However, as older adults require increasing levels of stability for the horizontal movement of COM after buttocks-off during STS, they may have decreased kinematic synergy for stabilization of the vertical movement of COM as a result. In fact, a failure to achieve STS might occur when the subject rises only slightly off the chair and then sits back down, due to either muscle weakness or balance control and coordination impairment 1) . In the present study, the older group comprised individuals with no impairment or disability who did not sit back down after attempting to rise.…”

Section: Discussionmentioning

confidence: 99%

“…It requires two tasks: transitioning the center of mass (COM) from a wide base of support (BOS) provided by the buttocks, thighs, and feet to a narrow BOS provided by the feet alone, and lifting the COM from the height of sitting to that of standing. STS also represents a motion for which the muscle strength of lower extremities is particularly important 1,2 ) . STS is associated with applied motions such as transfer and walking, and its acquisition is an essential factor to improve mobility capability.…”

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confidence: 99%

The coordination of joint movements during sit-to-stand motion in old adults: the uncontrolled manifold analysis

Anan

Hattori²,

Tanimoto

et al. 2017

Phys Ther Res

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ABSTRACT. Objective: Sit-to-stand motion (STS) is a dynamic motion utilized in fundamental activities of daily living and requires extensive joint movement in the lower extremities and the trunk and coordination of multiple body segments. The present study aimed to investigate whether aging affects the motor coordination of joint movements required to stabilize the horizontal and vertical movement of center of mass using the uncontrolled manifold (UCM) analysis. Method: We recruited 39 older adults with no musculoskeletal and/or neuromuscular conditions that affected STS, along with 21 healthy younger adults. All subjects performed five STS trials from a chair with the seat height adjusted to the length of their lower leg at a selfselected motion speed. Kinematic data were collected using a three-dimensional motion analysis system. We performed the UCM analysis to assess the effects of joint angle variance (elemental variable) to stabilize the horizontal and vertical movement of COM (performance variable) and calculated the joint angle variance that does not affect COM (VUCM), the variance that affects COM (VORT), and the synergy index (ΔV). Results: ΔV values in the horizontal direction were higher in the older adults than in the younger adults, but ΔV values in the vertical direction were lower in the older adults than in the younger adults. Conclusion: Older adults require increasing levels of stabilization of horizontal movement of COM after buttocks-off in the STS maneuver. As a result, variance in the joint angle of the lower extremities indicated no kinematic synergy for stabilizing the vertical movement of COM. Key words: Uncontrolled manifold analysis, Sit-to-stand, Aging (Phys Ther Res 20: 44-50, 2017)T he Sit-to-stand motion (STS) is a highly common motion that is performed as frequently as gait in daily life. It requires two tasks: transitioning the center of mass (COM) from a wide base of support (BOS) provided by the buttocks, thighs, and feet to a narrow BOS provided by the feet alone, and lifting the COM from the height of sitting to that of standing. STS also represents a motion for which the muscle strength of lower extremities is particularly important 1,2 ) . STS is associated with applied motions such as transfer and walking, and its acquisition is an essential factor to improve mobility capability. STS results from interactions characteristic of task-related, individual, and environmental constraints 3) . Alexander et al. 4) reported that aging affects STS acquisition, and that older adults with difficulty performing this maneuver require prolonged STS time. We reported that older subjects who experienced dif- The coordination of joint movements during STS motion 45 ficulty with this motion performed the STS using less energy and with more consideration for stability, relative to younger healthy subjects 5) . It is important to control the redundant degrees-offreedom (DOFs), which coordinate with each body segment to accomplish tasks. STS is a whole-body movement that requires simultaneous ...

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Biomechanical analysis of failed sit-to-stand

Cited by 123 publications

References 13 publications

Angular momentum in human walking

Angular momentum in human walking

Comparison of seat, waist, and arm sit-to-stand assistance modalities in elderly population

The coordination of joint movements during sit-to-stand motion in old adults: the uncontrolled manifold analysis

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