Recent experimental findings support theoretical predictions that across walking conditions the motor system chooses foot placement to achieve a constant minimum “margin of stability” (MOSmin)—distance between the extrapolated center of mass and base of support. For example, while step width varies, similar average MOSmin exists between overground and treadmill walking and between overground and compliant/irregular surface walking. However, predictions regarding the invariance of MOSmin 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 MOSmin 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 MOSmin was unaffected (p = .12). Regardless of information, subject-specific regressions between step-by-step values of step width and MOSmin explained, on average, only 5% of the shared variance (β = 0.11 ± 0.05). Thus, MOSmin appears to be insensitive to changing step width. Accordingly, during treadmill walking, step width is chosen to maintain MOSmin. If MOSmin 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.
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Sensitivity of Dynamic Stability to Changes in Step Width During Treadmill Walking by Young Adults
Noah J. Rosenblatt, Christopher P. Hurt, and Mark D. Grabiner
Clinicians’ Attitudes, Perspectives, and Clinical Practices on Gait Retraining After Anterior Cruciate Ligament Reconstruction
Kyle Southall, Laura Vogtle, Harshvardhan Singh, Matthew P. Ithurburn, C. Scott Bickel, and Christopher P. Hurt
Introduction: It has been shown that 45%–85% of patients with anterior cruciate ligament reconstruction (ACLR) will have early-onset arthritis within 10–12 years following surgery. Over the past two decades, the amount of literature regarding ACLR, gait maladaptations after ACLR and their potential link to early-onset arthritis, and rehabilitation techniques has grown exponentially; however, long-term patient outcomes remain modest. Methods: To evaluate current clinicians’ attitudes, perspectives, and clinical practice approach for rehabilitation of patients following ACLR, a survey questionnaire was designed using the Delphi technique. Results: Of the 263 respondents, 84.4% (n = 226) reported that they believed gait training to be “Very” or “Extremely Important.” However, only 35.7% (n = 94) reported objectively measuring gait during ACLR rehabilitation. Of the total respondents, only 6.8% (n = 18) assessed gait during rehabilitation using two-dimensional or three-dimensional motion capture technologies. Discussion: Our results suggest that while gait evaluation was perceived as important, most respondents did not objectively measure gait metrics as a clinical outcome during ACLR rehabilitation. These findings provide a prospective rehabilitation target to potentially mitigate a known risk factor of early-onset arthritis (gait maladaptations) in individuals following ACLR.
Development of Dynamic Measures to Assess Balance Confidence and State Anxiety While Walking at Increasing Speeds in Young and Older Adults
Jutaluk Kongsuk, Suzanne E. Perumean-Chaney, David C. Knight, Cynthia J. Brown, Amy W. Amara, and Christopher P. Hurt
The purpose of this study was to determine the test–retest reliability and construct validity of tools to assess how balance confidence (BC) and state anxiety (SA) change with progressively increasing walking speeds. Sixteen young adults and 15 older adults attended two sessions. Individuals began walking on a treadmill at 0.4 m/s Participants chose to continue increasing the treadmill speed (up to 2.0 m/s) or to discontinue the protocol while rating their BC and SA after completing each speed. BC at participants’ fastest speed attempted demonstrated high and moderate test–retest reliability among young (intraclass correlation coefficient [ICC] = .908) and older adults (ICC = .704). SA for young adults and older adults was good (ICC = .833) and fair (ICC = .490), respectively. Our measures also correlated with measures of dynamic stability while walking for young (r = −.67, p = .008) and older adults (r = .54, p = .046). Our dynamic measures of BC and SA are valid and reliable in young and older adults.
