Papers by Noah Rosenblatt
that an increase in the "good variance" component of the joint configuration variance may be an e... more that an increase in the "good variance" component of the joint configuration variance may be an effective method of ensuring high stability of gait patterns during conditions requiring increased control of foot placement, particularly if a postural threat is present. Ultimately, designing interventions that encourage a larger amount of "good variance" may be a promising method of improving stability of gait patterns in populations such as older adults and neurological patients.
The risk of falling reportedly increases almost 2.5-times in those with lower extremity osteoarth... more The risk of falling reportedly increases almost 2.5-times in those with lower extremity osteoarthritis (OA LE ) compared with age-matched controls. However, the mechanisms underlying the increased risk are not clear. The risk factors for falls in people with OA LE found in the literature are mostly the same as the risk factors for people without OA LE . It is hypothesized that risk factors for falls are exacerbated by OA LE , such that these individuals are more likely to become dynamically unstable and, once this has occurred, are less able to perform an appropriate compensatory stepping response compared with people without OA LE . To the extent that this is true, task-specific training targeting the compensatory step, which decreases falls in middle-aged and older women, should be effective for people with OA LE . The purpose of the present review is to provide the rationale for the above hypothesis. Furthermore, the present authors present evidence that the fall risk of people with OA LE could be efficiently and effectively reduced using task-specific training previously shown to reduce falls in middle aged and older women.
Recent experimental findings support theoretical predictions that across walking conditions the m... more Recent experimental findings support theoretical predictions that across walking conditions the motor system chooses foot placement to achieve a constant minimum "margin of stability" (MOS min )-distance between the extrapolated center of mass and base of support. For example, while step width varies, similar average MOS min exists between overground and treadmill walking and between overground and compliant/irregular surface walking. However, predictions regarding the invariance of MOS min to step-by-step changes in foot placement cannot be verified by average values. The purpose of this study was to determine average changes in, and the sensitivity of MOS min to varying step widths during two walking tasks. Eight young subjects walked on a dual-belt treadmill before and after receiving information that stepping on the physical gap between the belts causes no adverse effects. Information decreased step width by 17% (p = .01), whereas MOS min was unaffected (p = .12). Regardless of information, subject-specific regressions between step-by-step values of step width and MOS min explained, on average, only 5% of the shared variance (β = 0.11 ± 0.05). Thus, MOS min appears to be insensitive to changing step width. Accordingly, during treadmill walking, step width is chosen to maintain MOS min . If MOS min remains insensitive to step width across other dynamic tasks, then assessing an individual's stability while performing theses tasks could help describe the health of the motor system.
Marone JR, Rosenblatt NJ, Troy KL, Grabiner MD. Fear of falling does not alter the kinematics of ... more Marone JR, Rosenblatt NJ, Troy KL, Grabiner MD. Fear of falling does not alter the kinematics of recovery from an induced trip: a preliminary study. Arch Phys Med Rehabil 2011;92:2093-5.
Rosenblatt NJ, Grabiner MD. Relationship between obesity and falls by middle-aged and older women... more Rosenblatt NJ, Grabiner MD. Relationship between obesity and falls by middle-aged and older women. Arch Phys Med Rehabil 2012;93:718-22.
This study evaluated the discriminant capability of stability measures, trunk kinematics, and ste... more This study evaluated the discriminant capability of stability measures, trunk kinematics, and step kinematics to classify successful and failed compensatory stepping responses. In addition, the shared variance between stability measures, step kinematics, and trunk kinematics is reported. The stability measures included the anteroposterior distance (d) between the body center of mass and the stepping limb toe, the margin of stability (MOS), as well as time-to-boundary considering velocity (TTB v ), velocity and acceleration (TTB a ), and MOS (TTB MOS ). Kinematic measures included trunk flexion angle and angular velocity, step length, and the time after disturbance onset of recovery step completion. Fourteen young adults stood on a treadmill that delivered surface accelerations necessitating multiple forward compensatory steps. Thirteen subjects fell from an initial disturbance, but recovered from a second, identical disturbance. Trunk flexion velocity at completion of the first recovery step and trunk flexion angle at completion of the second step had the greatest overall classification of all measures (92.3%). TTB v and TTB a at completion of both steps had the greatest classification accuracy of all stability measures (80.8%). The length of the first recovery step (r r0.70) and trunk flexion angle at completion of the second recovery step (r r À 0.54) had the largest correlations with stability measures. Although TTB v and TTB a demonstrated somewhat smaller discriminant capabilities than trunk kinematics, the small correlations between these stability measures and trunk kinematics (9r9r 0.52) suggest that they reflect two important, yet different, aspects of a compensatory stepping response.
A compensatory stepping response (CSR) is a common strategy to restore dynamic stability in respo... more A compensatory stepping response (CSR) is a common strategy to restore dynamic stability in response to a postural disturbance. Currently, few studies have investigated the CSR to laterally directed disturbances delivered to subjects during quiet standing. The purpose of this study was to characterize the CSR of younger adults following exposure to a series of similar laterally directed disturbances for which no instructions were given with regard to the recovery response. We hypothesized that in the absence of externally applied constraints to the recovery response, subjects would be equally as likely to perform a crossover step as a sidestep sequence (SSS). We further hypothesized that there would be an asymmetry in arm abduction that would be dependent on the disturbance direction. Finally, we were interested in characterizing the effect of practice on the CSR to repeated disturbances. Ten younger adults were exposed to thirty laterally directed platform disturbances that forced a stepping response. Subjects responded by primarily utilizing a SSS that differs from previously reported results. Further, five of the ten subjects utilized a different recovery response that was dependent on the direction of the disturbance (i.e., left or right). Greater arm abduction was characterized for the arm in the direction of the external disturbance in comparison with the contralateral arm. Lastly, subjects modified their recovery response to this task within 12 disturbances. Taken together, these results suggest that recovery responses to laterally directed disturbances can be quickly modified but can be quite variable between and within subjects.
Gait & posture, Jan 1, 2010
Biophysical Journal, Jan 1, 2007
… and biophysical research …, Jan 1, 2004
Physical review letters, Jan 1, 2006
Physical Review E, Jan 1, 2008
Journal of …, Jan 1, 2007
Annals of biomedical …, Jan 1, 2007
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Papers by Noah Rosenblatt