Since my first ISPGR World Conference in Fort Lauderdale in 2017, I have seen many studies on functional near-infrared spectroscopy (fNIRS). Whilst its use is still controversial, research has demonstrated that fNIRS assessments are feasible, and their results not only reinforce previous theories related to motor control but also bring new hypotheses regarding the involvement of cortical areas in balance and gait tasks, shedding light on a better understanding of fall risk. It was a great pleasure to have received the ISPGR Emerging Scientist Award 2023 because of my work in this emerging scientific field. Below, I summarise my research findings using fNIRS to examine complex balance and gait.

In a series of studies, I examined older adults at low and high fall risk and people with Parkinson’s disease (PD). These participants performed a range of stepping tests (simple choice stepping reaction time test (CSRT), CSRT with inhibitory response (iCSRT) and a Stroop version of CSRT (SST)), along with an adaptive walking test. The cortical areas examined were the prefrontal cortex (PFC), supplementary motor area (SMA) and premotor cortex (PMC). Older adults at high fall risk exhibited increased PFC activity and stepping response variability when completing the SST test compared to older adults at low fall risk and compared to the CSRT test [1]. In PD, the pattern of cortical activity differed. Whilst older adults increased their cortical activity (PFC, SMA and PMC) to handle more complex stepping tests (iCSRT and SST), people with PD exhibited a “slowdown” phenomenon, demonstrating reduced cortical activity in the same areas [2]. Finally, during adaptive gait, people with PD had little or no additional PFC, SMA, and PMC capacity beyond what they needed for simple walking and, therefore, presented with a more conservative gait pattern than their healthy peers [3].

Altogether, these results elucidate that older adults may not cope with task demands, relying heavily on their cortical resources, which reflects their increased risk of falling. Moreover, this increased cortical activity seems to reflect a compensatory process for deficits in postural control or a degree of neural inefficiency in those at high fall risk. In PD, the reduced cortical activity during complex stepping tests might reflect multiple pathways and/or subcortical damage, resulting in deficient use of cognitive and motor resources and poor overall motor behavior.  Finally, the cortical activity and behavior exhibited by people with PD during adaptive gait appear consistent with concepts of compensatory over-activation and capacity limitation.

Publications

[1]  Paulo H S Pelicioni, Stephen R Lord, Daina L Sturnieks, Bethany Halmy, Jasmine C Menant. Cognitive and Motor Cortical Activity During Cognitively Demanding Stepping Tasks in Older People at Low and High Risk of Falling. Front Med (Lausanne). 2021; 8: 554231. doi: 10.3389/fmed.2021.554231

[2]  Paulo H S Pelicioni, Stephen R Lord, Yoshiro Okubo, Daina L Sturnieks, Jasmine C Menant. People With Parkinson’s Disease Exhibit Reduced Cognitive and Motor Cortical Activity When Undertaking Complex Stepping Tasks Requiring Inhibitory Control. Neurorehabil Neural Repair. 2020 Dec;34(12):1088-1098. doi: 10.1177/1545968320969943.

[3]  Paulo H S Pelicioni, Stephen R Lord, Yoshiro Okubo, Jasmine C Menant. Cortical activation during gait adaptability in people with Parkinson’s disease. Gait Posture. 2022 Jan:91:247-253. doi: 10.1016/j.gaitpost.2021.10.038.

About the Author

By Dr Erika Pliner

Ladder use is a hazardous activity and the leading cause of fatal falls from a height. Older adults are at highest risk of experiencing a ladder fall during household activities, such as clearing a roof gutter. Climbing (foot and body position, handhold force) and environmental (climb direction, ladder angle) factors are known to affect ladder fall risk, but little is known about individual characteristics that may predispose someone to a ladder fall. Therefore, we conducted a study to determine individual factors that contribute to effective ladder use.

We recruited 100 older adults and asked them to clear a gutter using a straight ladder in the laboratory (Figure 1). The gutter was 2.1 m above the ground, 5.8 m in length, and filled with tennis balls. The straight ladder was partially fixed to the experimental setup that supported the gutter, simulating a straight ladder leaning against a wall. The ladder was easily moved laterally along the wall to the desired location. To completely clear the length of the gutter, participants had to move and climb the ladder multiple times. We recorded time to complete this task as the outcome measure.

For each participant, we assessed individual metrics of strength, upper limb control, balance, cognition, and propensity for risk-taking. To determine which individual factors are related to effective ladder use, we performed regression analysis with the individual metrics on task completion time. Our results showed that the time taken to clear the gutter was predicted by multiple individual factors. Specifically, participants with greater quadriceps strength, better upper limb coordination, more controlled leaning balance, and a greater propensity for taking risks completed the gutter clearing task faster, suggesting these participants to be more effective ladder users.

Knowledge of individual factors that are associated with effective ladder use can be used to direct ladder fall interventions. Ladder users who take longer to complete ladder tasks (increasing their ladder use exposure and fall risk) may be identified and warned of their fall risk through screening tools and targeted for strength and balance training interventions to reduce their fall risk. Further, this knowledge can guide ladder design and safety instruction. Specifically, ladders could be designed to reduce the need for superior balance control and quadriceps strength with a greater base-of-support at lower rungs commonly used for working heights. Safety instructions may be updated to inform users to utilize additional tools to avoid strenuous postures that require greater upper limb coordination. Future work is needed to assess the trade-off between efficient ladder use (faster task completion times) and risky ladder use (completing the task near or outside stability limits).

Figure 1. Experimental set-up

Pliner, E.M., Sturnieks, D.L., Lord, S.R. (2020). Individual factors that influence task performance on a straight ladder in older people. Experimental Gerontology, 142: 111127. https://doi.org/10.1016/j.exger.2020.111127

About the Author

By Dr Tarun Arora, Dr Alison Oates and Dr Kristin Musselman

After someone has injured their spinal cord, the communication between their brain and body is disrupted, which can make movement challenging. In more than half of spinal cord injuries (SCI), the spinal cord is not completely damaged (i.e., an “incomplete” injury ). The majority of individuals with an incomplete SCI (iSCI) are able to walk. Unfortunately, about three-quarters of people with an iSCI report at least one fall per year. This risk of falling is similar or even higher than other populations who are prone to falls such as older adults (33%) or those living with stroke (73%) and Parkinson’s disease (68%). Research shows that individuals with iSCI walk slower, take shorter steps, and spend more time in double support which improves their mechanical stability. Thus, they are less likely to lose their balance during walking, but can they recover once their balance is perturbed? Our research studied reactive responses to an unexpected slip perturbation in people with an iSCI.

We brought 20 individuals with iSCI and 15 age-and-sex matched individuals without SCI (niSCI) to the Biomechanics of Balance and Movement Lab at the University of Saskatchewan. A slip device embedded into the floor becomes highly slippery (comparable to that of clean ice at 0 deg. celsius!) when unlocked (Figure 1). Without knowing when the slip device will be unlocked, participants walked for several “normal walking” trials. Then we unlocked the slip device for an “unexpected slip”without telling them  (click here for videos). The velocity of the slipping heel was used to categorize the severity of the slip as hazardous (>1m/s) or non-hazardous. Using 3-D motion capture, we measured stability at the first compensatory step after the slip. We also measured when and how much the muscles in the leg activated in reaction to slip.

Both groups had similar proportions of hazardous and non-hazardous slips suggesting a comparable slip severity. The iSCI group could not regain as much stability as the niSCI group using a compensatory step. Also, the iSCI group demonstrated lower calf muscle activation compared to the niSCI group.

Using the unexpected slip paradigm, we demonstrated some important limitations in the reactive balance of individuals with iSCI. This research highlights the importance of evaluating reactive balance during clinical balance evaluations in individuals with iSCI. Clinicians should consider evaluating reactive balance evaluation (e.g., mini-BESTest) in their practice.

Figure 1. Slip device and schematic lab setup for data collection (modified from Arora T et al., PM&R 2019)

Note: this study was a part of a larger research project that was funded by the Saskatchewan Health Research Foundation (awarded to AO and KEM).

Publication

Arora T, Musselman KE, Lanovaz JL, Linassi G, Arnold C, Milosavljevic S, Oates A. (2020) Reactive balance responses to an unexpected slip perturbation in individuals with incomplete spinal cord injury. Clin Biomech (Bristol, Avon), 78:105099. https//doi.org/10.1016/j.clinbiomech.2020.105099

About the Author

By Mr Peter Hong, Ms Helen Chong, Dr Vicki Komisar and Dr Steve Robinovitch

The COVID-19 pandemic has created challenges to the ISPGR research community, especially in the collection of new data with human participants. The pandemic has also highlighted the value of shared databases for reuse by other research groups. The Technology for Injury Prevention in Seniors (TIPS) team at Simon Fraser University hopes to foster innovation in the prevention of falls and fall-related injuries in older adults, by sharing a dataset of video footage of real-life falls experienced by older people.

Falls are the number one cause of injuries, and a major barrier to mobility for older people, especially in long-term care. Many ISPGR members pursue research on the cause and prevention of falls in older adults. Yet rarely are we able to draw on objective evidence on how falls occur. Video footage of falls in older adults provides a wealth of information on the circumstances of falls to drive innovation (Robinovitch et al, Lancet, 2013).

The TIPS program at Simon Fraser University (SFU), in partnership with the Fraser Health Authority and two long-term care homes in the Greater Vancouver Area, has recently posted to the Databrary Network an expanded dataset of videos of 239 real-life falls experienced by older adults in long-term care homes. The videos can be accessed at: https://nyu.databrary.org/volume/739.

Databrary is an online data repository, hosted by New York University, that allows for sharing of video data for reuse in research and teaching by investigators associated with an institution having an Institutional Review Board (IRB) for human participant research. To date, Databrary has users from 616 institutions in over 25 countries, and TIPS’s falls videos collection is currently being used by researchers in Canada, Europe and the US. Visit the Databrary website ( https://nyu.databrary.org/user/register?page=create) for extensive instructions on gaining access.

The 239 falls posted to Databrary were selected from a larger pool to represent the range of falls we have observed in long-term care, with respect to: fall direction, activity at time of falling, biomechanical cause of the fall, sex of the individual falling, height of the fall, use of mobility aids, frequency of head impact, and frequency of pelvis impact. The 239 falls were experienced by 100 individuals of mean age 83.3 years (SD = 7.4), all of whom were residents of the two long-term care homes. 52 women accounted for 152 falls, and 48 men accounted for 87 falls. All falls occurred in common areas (hallways, dining rooms, lounges). For 111 of the 239 falls, at least two camera views captured the fall, which could allow for subsequent 3D kinematic analyses.

In addition to the video footage, the Databrary dataset includes Excel spreadsheets that allow you to search the dataset based on: the number of camera views, the frame rate and resolution of the video, characteristics of the resident falling (age, sex, height, weight), injuries associated with the fall, use of  mobility aids, biomechanical cause of the fall, and the activity at the time of the fall. For those residents who provided consent, we include data on medications and disease diagnoses.

TIPS hopes to foster innovation in geriatric falls research and education by sharing the falls video database with researchers, healthcare professionals, and educators. The dataset may be particularly relevant for researchers pursuing sensor-based fall detection, and the design of exoskeletons, assistive devices, environmental modifications, and wearable protective gear. The dataset should also help to inform more externally valid approaches to assess postural stability and risk for falls in older adults.

Figure 1. Example of fall sequence captured by video footage in a long-term care home.

References and example publications related to the real-life falls database:

Komisar, V, Shishov, N, Yang, Y, Robinovitch, SN. (2020) Effect of Holding Objects on the Occurrence of Head Impact in Falls by Older Adults: Evidence From Real-Life Falls in Long-Term Care, The Journals of Gerontology: Series A, glaa168, https://doi.org/10.1093/gerona/glaa168

van Schooten KS, Yang Y, Robinovitch SN (2018). The association between fall frequency, injury risk and characteristics of falls in older residents of long-term care: do recurrent fallers fall more safely? The Journals of Gerontology: Series A, Volume 73, Issue 6, June 2018, Pages 786–791, https://doi.org/10.1093/gerona/glx196

Robinovitch SN, Feldman F, Yang Y, Schonnop R, Leung PM, Sarraf T, Sims-Gould J, and Loughin M. (2013) Video capture of the circumstances of falls in elderly people residing in long-term care: an observational study. The Lancet. 381(9873): 47-54. https://doi.org/10.1016/S0140-6736(12)61263-X

About the Author

By Dr Thijs Ackermans

Stair negotiation is one of the most hazardous daily tasks for older adults, often resulting in falls. Indeed, falls on stairs have been identified as the leading cause of accidental death and place a substantial financial burden on the National Health Service in the UK. Identifying the individuals at risk for a fall is necessary to deliver effective fall prevention interventions. However, presently there are no specific screening tools for stair fall prediction. It is questionable whether generic fall screening methods can identify older people at risk for falls on stairs, especially as stair negotiation is a complex and specific skill. In this study, we aimed to investigate whether stair fallers could be differentiated from non-stair-fallers by biomechanical risk factors or physical and psychological parameters included in existing fall screening methods. In addition, we aimed to identify the individuals with the highest stair fall risk using a novel multivariate stepping profiling method.

Eighty-seven older adults negotiated an instrumented seven-step staircase (Figure) and performed assessments of physical and psychological function. We monitored falls and events of balance perturbation (combined as “hazardous events”) in daily life during a 12-month follow-up. We found that the physical and psychological parameters did not predict hazardous events on stairs. We further found that the Fall Risk Assessment Tool (FRAT), which is commonly used in the UK, classified only 1 out of the 17 stair fallers identified during the follow-up as being at risk for a fall. We found that single biomechanical risk factors could not predict hazardous events on stairs either. We then used K-means clustering to profile the overall stair negotiation behaviour of the older adults using biomechanical parameters indicative of fall risk as input (such as, foot clearance and the required coefficient of friction). This stepping profiling method identified that were linked with hazardous for stair ascent.

Our findings highlight the potential of our stepping profiling method to predict stair fall risk in older adults against the limited predictability of the FRAT and single parameter approaches currently used as screening tools. Future research should this novel method in larger populations in real life stair negotiation conditions to improve the predictive power and validate the stepping profiling method. This could eventually result in the development of targeted interventions for improving stair safety in older individuals.

Figure. Custom-built instrumented seven-step staircase used in the present study.

Publication

Ackermans, T., Francksen, N., Lees, C., Papatzika, F., Arampatzis, A., Baltzopoulos, V., Lisboa, P., Hollands M., O’Brien T., Maganaris, C. (2020). Prediction of balance perturbations and falls on stairs in older people using a biomechanical profiling approach: A 12-month longitudinal study. The Journals of Gerontology: Series A. https://doi.org/10.1093/gerona/glaa130

About the Author

By Andreas Skiadopoulos

Recent investigations have demonstrated that step width variability increases with age, which could be a signal of developing deterioration in gait stability. In the literature, step width variability has been extensively examined in an attempt to find which exercise-based interventions improve gait stability in older adults. However, it is not known when step width variability values in older adults should be considered as excessive. This is an issue of great importance as this information could be used to enroll participants who have the potential to benefit most from an intervention, tailor the intervention dose to match participant’s level of walking stability, and monitor or evaluate intervention effects. Thus, the main purpose of this systematic review and meta-analysis was to compare the amount of step width variability (expressed as the standard deviation of step width) between young and older adults and to identify the boundaries of optimal reference range of step width variability.

After screening 1408 studies from 11 databases we found 10 studies that met our criteria. We conducted a meta-analysis to compare the step width variability between older and younger adults (304 older adults and 219 younger adults). Additionally, a two-decision method was used on the meta-analytic data to identify optimal thresholds of step width variability to discriminate age-related gait changes. The results showed that older adults have greater step width variability than young adults (Figure). Step width variability values in older adults above the upper threshold value of 2.50 cm were considered excessive, while step width variability values below the lower threshold value of 1.97 cm were considered within the optimal reference range. For our purposes, the step width variability values in healthy young adults set the optimal reference range.

Based on our systematic review and meta-analysis, older adults with excessive step width variability form a plausible target population for effective exercises in preventing falls and lowering fall risk. Moreover, optimal thresholds levels of step width variability could potentially impact rehabilitation technology design for devices targeting lateral instability during walking.

Figure. Forest plot of standardized mean difference (SMD) and 95% confidence intervals (CI) for the step width variability between older and younger adults.

Publication

Skiadopoulos, A., Moore, E.E., Sayles, H.R., Schmid, K.K., Stergiou, N. Step width variability as a discriminator of age-related gait changes. J NeuroEngineering Rehabil 17, 41 (2020). https://doi.org/10.1186/s12984-020-00671-9

About the Author

By Cameron Hicks

As we age, pain can become an all too familiar problem. While musculoskeletal pain has been shown to increase the risk of having a fall, the evidence is less clear for knee pain specifically. Factors that may contribute to people with knee pain experiencing more falls include joint pathology such as osteoarthritis, pain affecting muscular control or cognitive functions, and short term responses to developing leg pain such as compensatory movements. We sought to investigate whether older adults with self-reported knee pain experienced more falls than those without knee pain and why this may be the case.

We tested 330 older adults aged 70 years and over on a range of physical, psychological and medical factors. Specifically, we assessed, standing balance, leg strength and mobility, depression and anxiety as well as number of medications. One hundred and eighteen (35.5%) participants were categorised as having knee pain. We found older people with knee pain had twice the risk of multiple falls compared to people without knee pain. To determine mediating factors, that is, reasons as to why those with pain fall more often than their painless peers, we identified variables that were associated with pain and falls. Our analyses showed that having a fear of falling explains about 15% of the reason as to why people with pain are more likely to fall. Quadriceps strength was the strongest physical mediator identified, contributing a further 10% to the association with multiple falls. When these mediators are combined, fear of falling, quadriceps strength and standing balance explained almost one-quarter of the relationship between experiencing knee pain and having a higher risk of multiple falls.

Given the large proportion of older people who report pain and the high cost of fall-related injuries, our findings regarding the underlying mechanisms as to how pain may lead to falls have significant public health implications. These mediating factors (fear of falling, leg muscle weakness and poor balance) are easily identified and can be readily treated. Pain can be mediated through appropriate medication prescription and exercise might be an effective way to prevent falls in this vulnerable group of older people. Exercise may be particularly beneficial as targeted exercise can alleviate pain, reduce body weight as well as improve muscle strength and balance – two mediators for the relationship between pain and falls identified in our analysis.

Figure. People in the knee pain group have twice the risk of multiple falls than people with no knee pain (RR=2.0, 95% confidence interval = 1.28 to 3.14). Fear of falling, quadriceps strength and standing balance reduce relative risk by 23% (from RR= 2.0 (univariate) to RR = 1.55).

Publication

Hicks C, Levinger P, Menant JC, Lord SR, Sachdev PS, Brodaty H, Sturnieks DL. Reduced strength, poor balance and concern about falls mediate the relationship between knee pain and fall risk in older people. BMC Geriatr. 2020 Mar 6;20(1):94. doi: 10.1186/s12877-020-1487-2.

About the Author

​By Matthias König

Daily-life locomotion constantly challenges us to respond to sudden disturbances and changing environments. To improve such ‘fall-resisting skills’ in older adults, previous studies applied repeated trips or slips in the laboratory and demonstrated remarkable training effects, which could be partially retained for well over 1 year. Tailored recommendations for these falls prevention interventions require knowledge on the dynamics of learning and forgetting in groups of different age or performance capacities. It is also important to establish whether these learning effects can transfer between different tasks, considering that real-life falls can result from a variety of postural threats. We examined adaptation of recovery from gait perturbation, its retention over time and generalizability beyond the trained task across the adult lifespan.

To achieve this, young, middle-aged and older adults experienced eight unexpected trip-perturbations (i.e. an ankle suddenly pulled by a break-and-release system) while treadmill walking. A single trip-perturbation was repeated after 14 weeks to examine the retention of training effects. Secondary, before and after treadmill walking, all participants were exposed to an untrained lean-and-release transfer task (Figure B). For both tasks we used the margin of stability to quantify stability of the body during the first step after perturbation. All age groups rapidly improved their reactive response to a similar extent when exposed to repeated trip-perturbations and showed retention of learning effects after 14 weeks without training. We did, however, find an age-related decrease in the ability to retain learning effects. Furthermore, despite such robust adaptations to the balance control system, improvements to the untrained transfer task were not superior to those of age-matched control groups who did not undergo the trip-perturbation training.

Our results demonstrate that the ability to adapt to repeated exposure to balance-challenging perturbations remains highly effective up to old age, but the ability to retain acquired skills appears to be diminished as age increases (Figure A). In addition, these learning effects from one type of perturbation training do not seem to necessarily transfer to a different perturbation task (Figure B). Hence, although single perturbation training sessions show large learning effects, more regular sessions may be needed for middle-aged and older adults to counteract the greater decay in training effects. It remains to be seen whether there are specific neuronal factors promoting or limiting adaptability (i.e. adaptation, retention and transfer) of the ageing balance control system.

Figure: Schematic illustration of the adaptability of the human balance control system to trip-perturbation training. While rapid learning to perturbation training may be preserved, the ability to retain acquired skills seems diminished with increasing age (A). We found no evidence for transfer of training effects to an untrained reactive balance task (B). Adapted from König et al. (2019). Copyright © 2019 the American Physiological Society. Used with permission.

Publication

König M, Epro G, Seeley J, Potthast W, Karamanidis K (2019). Retention and generalizability of balance recovery response adaptations from trip perturbations across the adult life span. Journal of Neurophysiology, 122(5):1884-93. https://doi.org/10.1152/jn.00380.2019

About the Author

By Dr Toby Ellmers.

During walking, we rely on visual information to identify tripping hazards and navigate safely through the environment. The way we shift our gaze and scan the environment (visual-search behaviour) is affected by ageing and fall-risk. For example, when navigating obstacles or stepping targets, older adults deemed to be at a high risk of falling will adopt less-variable patterns of visual-search behaviour. Specifically, they will visually prioritise the initial/immediately upcoming stepping target, at the expense of previewing future obstacles or targets. Such restricted visual-search behaviours are hypothesized to impair an individual’s ability to plan future stepping actions and are associated with both reduced stepping safety and increased fall-related anxiety. Researchers have thus proposed that heightened fall-related anxiety may underpin these maladaptive visual-search behaviours in high-risk older adults. We sought to test this hypothesis.

Forty-four older adults walked along a path and stepped into two stepping targets (with raised edges). All participants completed walks at ground level, while participants deemed to be at a low risk of falling (n=24) also completed walks under conditions designed to induce fall-related anxiety (walkway elevated 0.6m; ‘Threat’ condition). Outcome measures included both gaze behaviours and gait kinematics (e.g., stepping accuracy and stance times before target steps). During ground level trials, high-risk participants reported greater fall-related anxiety compared to low-risk participants. As predicted, high-risk participants also visually prioritized immediate walkway areas (1–2 steps ahead), doing so at the expense of previewing future stepping constraints (second stepping target). When controlling for age, cognitive and physical functioning, these ‘high-risk’ visual-search behaviours were significantly correlated with greater attention directed towards consciously controlling walking movements. When completing walks on the elevated walkway, low-risk participants reported increased fall-related anxiety and adopted visual-search behaviours identical to those observed in the high-risk participants at ground level. However, unlike their high-risk counterparts, the low-risk participants appeared capable of adapting their gait to compensate for this restricted visual previewing of the second stepping target. Specifically, the low-risk participants exhibited increased stance durations prior to stepping into the un-previewed second target, thereby acquiring the visual information required for safe negotiation. Consequently, while the restricted visual-search behaviours appeared to negatively affect high-risk participants’ stepping safety (with increased stepping errors observed for the second target in the high-risk group), no such decreases in safety were observed for low-risk participants.

These findings provide evidence of a link between fall-related anxiety and ‘high-risk’ visual-search behaviours. Further research is currently being undertaken to investigate why high-risk older adults, unlike their low-risk counterparts, failed to adapt their stepping behaviours to compensate for these restricted (anxiety-related) visual search behaviours, and thereby experienced reduced stepping safety as a result.

Figure. Comparisons of low- and high-risk participants at Ground, and low-risk participants at Ground and Threat, for duration of fixations (as a % of overall fixations) towards: (A) the immediate walkway and (B) the second target. **p < .01, ***p < .001, data shown as mean ± standard error of the mean. C: Schematic diagram of the walking task.

Publication

Ellmers, T. J., Cocks, A. J., & Young. W. R. (2019). Evidence of a link between fall-related anxiety and high-risk patterns of visual search in older adults during adaptive locomotion. The Journals of Gerontology: Series A, Biological and Medical Sciences. Advanced online publication. https://academic.oup.com/biomedgerontology/article/doi/10.1093/gerona/glz176/5541624/

About the Author