Journal of Aging Research And Healthcare

Journal of Aging Research And Healthcare

Current Issue Volume No: 3 Issue No: 1

Research-article Article Open Access
  • Available online freely Peer Reviewed

  • Reactive Stepping Responses Mediated By Predictable Manual Waist-Pull Perturbations Are Associated With Fall History In Older Adults

    1 Department of Physical Therapy, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL 60612 

    2 Department of Physical Therapy, College of Pharmacy and Health Professions, Campbell University, Buies Creek, NC 

    3 Riverspring Home Health Care, New York, NY 

    Abstract

    Background and Purpose

    The ability to respond effectively to perturbations is a key element of reactive postural control and is a crucial mediator of falls. Several studies exist in the literature that determine older adults responses to perturbations, however those studies typically involve procedures that lack objectivity or applicability outside a laboratory. A study involving waist-pull perturbations with a spring-scale (SS) is an exception. In that study, fall history was most accurately differentiated by a reactive stepping response to a perturbing force of 10% total body weight. Using data from that study, we retrospectively examined the association between fall history and the number of steps accompanying a SS perturbing force of 10% total body weight in older adults. For perspective, the association of fall history with Timed-Up-and-Go (TUG) and single limb stance (SLS) times was also determined.

    Methods

    Fifty-eight healthy older adults (mean age = 80.7 years) participated in the study. Their 2-year fall history (yes, no) was recorded. All participants underwent SS testing with one-pound incremental, horizontal sagittal plane manual waist-pull perturbations. The number of steps in response to perturbation with 10% total body weight was recorded; TUG and SLS tests were performed. Associations between variables were examined using Spearman (rank-biserial) correlations.

    Results

    The median number of steps for fallers was 5 in both anterior and posterior directions. For non-fallers, the median number of steps was 1 and 2 in the anterior and posterior directions, respectively. The significant correlations between fall status and number of steps were 0.772 and 0.813 for the anterior and posterior directions, respectively. Similarly, the significant correlations between fall status and balance tests were 0.722 and -0.456 for the TUG and the SLS, respectively.

    Conclusions

    The number of steps accompanying waist-pull perturbations with forces of 10% of body weight were highly explanatory of experiencing a fall during the preceding 2 years.
    Author Contributions
    Received Jun 25, 2020     Accepted Jul 18, 2020     Published Aug 01, 2020

    Copyright© 2020 Gangwani Rachana, et al.
    License
    Creative Commons License   This work is licensed under a Creative Commons Attribution 4.0 International License. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

    Competing interests

    The authors have declared that no competing interests exist.

    Funding Interests:

    Citation:

    Gangwani Rachana, Bhatt Tanvi, Bohannon Richard, DePasquale Louis et al. (2020) Reactive Stepping Responses Mediated By Predictable Manual Waist-Pull Perturbations Are Associated With Fall History In Older Adults Journal of Aging Research And Healthcare. - 3(1):39-47
    DOI 10.14302/issn.2474-7785.jarh-20-3461

    Introduction

    Introduction

    Falls are a common occurrence among older adults that can result in injury, hospitalization, decreased mobility, fear of another fall, decreased quality of life, and even death. 12345 Considering the higher fall incidence in older adults and its consequences, it is crucial to study factors that predispose older adults to falls and determine measures that can best identify those at fall-risk. Limited balance is one of the chief risk factors for falls. 678 Horak et al have proposed that 6 systems underlie balance, with “postural responses” to perturbations being one among them. 9 They incorporated postural reactions to perturbations in their Balance Evaluation Systems Test (BESTest)9 as did Rose et al in their Fullerton Advanced Balance (FAB) scale. 10 In both test batteries, the tester observes the tested individual’s response to the release of a push force. The postural responses are graded ordinally and take compensatory stepping into account.

    Considering the subjective nature of grading postural responses, procedures for obtaining more objective measures of postural responses to perturbations have been described. 11121314 However, they have involved the use of motorized treadmills or waist pulls and are not easily adopted for use outside a laboratory setting. An exception is the Repeated Incremental Predictable Perturbations Reactive Stepping (RIPPS) test which incorporates a portable spring scale (SS) tethered to the waist. 15 The test was described by DePasquale and Toscano over 10 years ago. They reported the maximum perturbation force (as a percentage of body weight) associated with an effective protective stepping response (limit 3 steps) had high test-retest reliability and was an excellent explanator of fall history. They found a force cut point of 10% of the total body weight as the most sensitive and specific explanator. They also found that the 10% total body weight criterion to be superior to Timed-Up-and-Go (TUG) and single limb stance (SLS) times as an explanator of fall history.

    The purpose of the present study was to expand on the findings of the DePasquale and Toscano study. Specifically, we sought to determine the association between a history of falls and the number of steps accompanying a SS perturbing force of 10% total body weight in a sample of older adults. We hypothesized that the number of steps in response to 10% total body weight waist-pull unloading force would be associated with fall history. This hypothesis was based on evidence from the previous literature which indicated that individuals who resort to multiple stepping responses are at a higher risk of falls compared to those who take fewer or a single compensatory step to recover from a perturbation. 51112 However, most of these studies resorted to perturbations induced via motorized treadmills and lean-release systems and indicated the need for specific tests that target the capacity to perform reactive stepping to identify those at risk of falls. 11121416 Thus, if the hypothesis is proven, it will provide an opportunity to healthcare professionals to assess reactive stepping responses and differentiate fallers from non-fallers in clinical settings. For perspective, the association of fall history with TUG and SLS times was also determined. The present study is based on the secondary analysis of the data collected for the publication of the first study by DePasquale and Tascano in 2009. 15 As the previous study only assessed the reliability and validity of the SST and determined that 10% TBW measure can discriminate fallers from non-fallers and with a growing interest in the field of reactive balance assessment and the lack of simple, portable, feasible and objective tools for reactive balance assessment in clinical settings, we went back to the data collected from the SST to determine whether the reactive stepping response measures derived from the SST can correlate with fall history in older adults and thereby bridge the gap in the literature and provide healthcare professionals with a tool that assesses reactive stepping responses and identify those at risk of falls in clinical settings.

    Results

    Results

    Of the 58 participants, 19 were men and 39 were women. The mean (SD) and range of their ages were 80.7(7.2), 65-94 years, of their height were 165.3(10.2), 135.0-185.0 cm, and of their weight were 67.8(12.4), 46.7-90.2kg. Twenty-nine reported having fallen in the past 2 years. Table 1 summarizes explanatory variables relative to fall history.

    Summary of Explanatory Variables and Their Relationship with Fall History*
    Explanatory Variables Fallers(n=29) Non-fallers(n=29) Correlationᵻ  95% CI
    Anterior steps at 10% weight (n) 5 (1-5) 1 (0-5) 0.772 0.641 - 0.859
    Posterior steps at 10% weight (n) 5 (1-5) 2 (1-5) 0.813 0.703 - 0.886
    Timed Up & Go (s) 9.2 (1.3) 7.0 (1.0) 0.722 0.569 - 0.826
    Single limb stance time (s) 3.2 (3.3) 10.3 (9.6) -0.454 -0.637 - 0.221

    (Figure 2a and Figure 2b) indicate the number of anterior and posterior steps taken by fallers and non-fallers in response to unloading 10% total body weight waist-pull force. These data are further summarized in Table 1 as is participant performance on the TUG and SLS tests and the relationship between all explanators and fall history. All balance tests provided a significant (p<.001) explanation of fall history. The correlations of number of steps and TUG times with fall history (rs = 0.722 to 0.813) were all positive and were not significantly different in magnitude. Thus, indicating that participants who took more steps in response to the unloading 10% total body weight waist-pull perturbation force or required more time to complete the TUG were more likely to have fallen. The correlation between SLS times and fall history was negative- suggesting that participants who could not balance as long on one lower limb were more likely to fall. This correlation was also of significantly less magnitude and therefore a weaker explanator of fall status than the other balance variables.

    Bar graph illustrating number of anterior steps taken in response to a 10% perturbation force by individuals with a history of falls (no vs yes). Bar graph illustrating number of posterior steps taken in response to a 10% perturbation force by individuals with a history of falls (no vs yes).

    Discussion

    Discussion

    When perturbations of sufficient magnitude are encountered, appropriate postural responses are required if a fall is to be avoided. 9 Considerable research has focused on quantifying postural responses to motor (treadmill or waist-pull) generated perturbations. 11121314 While informative, the research does not translate well to clinical practice. An alternative, the RIPPS system, is portable and has already been shown in community settings to differentiate between older adults with and without a history of falling on the basis of their response to a perturbation force equal to 10% of total body weight. The purpose of this study was to further examine the ability of the RIPPS system to differentiate between individuals with and without a fall history, but on the basis of the number of steps they took in response to a constant perturbation force (10% total body weight) applied at the waist via a spring scale.

    The study clearly showed that the number of steps taken in response to unloading 10% perturbation force, whether anterior or posterior, was higher among fallers than non-fallers. Our study indicated that the median number of steps for fallers was 5 in both anterior and posterior directions whereas non-fallers almost always took 2 or fewer steps, a number which is also referred to by Rose et al in the scoring of reactive postural control. 10 Previous literature has also demonstrated that a multiple stepping response to perturbations is common in fallers. 1819 This might be due to several reasons such as age-related changes in older adults and the inability to accurately assess the perturbation parameters, resulting in an ineffective first compensatory step and thus having to resort to multiple stepping strategy to regain balance. 1620 Thus, our study results support the literature that the ability to take an efficient single step response might be associated with a lower fall-risk, 5 thereby suggesting that examining the stepping strategy could be an essential component of fall-risk assessment.

    The relationships between step number and fall history were strong and comparable to the relationship between TUG times and fall history. This is noteworthy as the TUG addresses different systems of balance, that is, anticipatory postural adjustments and stability in gait , 9 and is according to Lusardi et al, one of the most evidence-supported functional measures to determine individual risk of future falls. 21 The relationship between SLS, an example of an anticipatory postural adjustment, 9 and fall history was significant but only fair in magnitude.

    This study has several limitations. First, it focused on only one measurement from the RIPPS. This was deemed appropriate as it incorporated a 10% perturbation force already shown to be explanatory.15 Second, the study used fall history as an indicator of fall status. The ability to predict future falls is of greater importance. Finally, the analysis of the present study while appropriate, was different from that of the earlier study using RIPPS data.15 This difference, while driven by characteristics of the step data, limits between study comparisons.

    Conclusion

    Conclusion

    The number of steps taken in response to a 10% total body weight waist-pull perturbation is strongly related to fall history. However, future studies should validate and determine whether the step frequency at 10%TBW can predict real-life prospective falls, thereby further ensuring the use of SST in fall-risk assessment protocols.

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