Relationship between postural stability and fall risk in elderly people with lumbar spondylosis during local vibratory stimulation for proprioception: a retrospective study

Does proprioceptive reweighting contribute to reactive balance strategies during slip-like perturbations? a proof-of-concept in healthy adults

Falls commonly occur during walking, particularly when struggling to respond to unexpected perturbations. Proprioception plays a significant role in detecting body destabilization even before reactions to perturbations are required. This study investigates the contribution of proprioceptive reweighting strategies to reactive balance during walking. This cross-sectional, proof-of-concept study included fifteen healthy adults (18-40 years). Ankle and back muscle vibrators disrupted proprioceptive input in stance, allowing calculation of the proprioceptive reweighting index. Walk-slip perturbations were then administered on an ActiveStep treadmill. A linear regression model assessed the significance of proprioceptive reweighting in predicting post-slip stability (margin of stability). Participants shifted from an ankle-steered to a central-steered proprioceptive strategy on a foam surface with closed eyes (Difference = 15.70 % (SD=37.87), 95 %CI [0.41, 30.99], p = 0.045). The regression model explained 22.7 % of the variance in pre-touchdown margin of stability, with proprioceptive reweighting on foam significantly contributing to post-perturbation postural control (p < 0.001). Proprioceptive reweighting provides a moderate explanation for the mechanisms of reactive balance, highlighting that the key to effective balance recovery strategies may lie in the person's ability to both detect and respond to imbalances. Further research should explore if these proprioceptive strategies are a matter of directional control and if responses differ in older adults.

What are the temporal and physical characteristics of locally applied vibration that modulate balance in older adults? - A systematic review of the literature

BACKGROUND

Compromised balance is known to contribute to falls, which are associated with increased morbidity and mortality for older adults. Evidence suggests that the application of local vibration to the lower limbs of older adults has the potential to modulate balance.

RESEARCH QUESTION

To identify the temporal and mechanical parameters of vibration applied locally to the lower limbs of older adults that modulate measures of balance, and to define the short- and long-term effects of vibration on balance in this population.

METHODS

The PRISMA 2020 guidelines were used to conduct a systematic search including the PUBMED, EMBASE, and Scopus databases to identify peer-reviewed literature where vibration was applied to the lower limbs of older adults to modulate balance. Data was extracted using a study-specific data extraction form and risk of bias assessed. Where possible, effect sizes were calculated.

RESULTS

Of 7777 records screened, ten randomised controlled trials and 43 prospective laboratory-based studies met the inclusion criteria. Vibration frequencies ranged from 1 to 272 Hz, most studies (n=41) used ≤100 Hz. Amplitude ranged from 0.2 to 3.0 mm, most studies (n=28) used ≤1 mm. Effects of short-term vibration (applied for seconds to hours) were measured during and/or immediately after application. Short-term suprathreshold perceived muscle/tendon vibration had a 'large' destabilising effect size on balance in healthy older adults, but little or no effect on older fallers. Short-term subthreshold vibration to the soles of the feet had a 'small' stabilising effect size. Suprathreshold muscle, tendon or sole vibration applied for 10-30 min over days to weeks improved balance measures, but most (8 of 10) had increased risk of bias.

SIGNIFICANCE

The heterogeneity of methodology, populations, and vibration and balance parameters precluded conclusions about the relative effects of lower limb vibration in older adults. However, these results suggest that the application of local vibration to the lower limbs of older adults can modulate balance in the short- and long-term.

Vibration-induced postural reactions: a scoping review on parameters and populations studied

Objective

Mechanical vibration is an effective way for externally activating Ia primary endings of the muscle spindles and skin mechanoreceptors. Despite its popularity in proprioception and postural control studies, there is still no review covering the wide variety of vibration parameters or locations used in studies. The main purpose of this scoping review was thus to give an overview of general vibration parameters and to identify, if available, the rationale for justifying methodological choices concerning vibration parameters.

Methods

Three databases (Pubmed, CINHAL, and SPORTDiscus) were searched from inception to July 2022. Included articles were to focus on the study of muscle spindles and skin mechanoreceptors vibration in humans and assess postural control. Following inclusion, data regarding demographic information, populations, vibration parameters and rationale were extracted and summarized.

Results

One hundred forty-seven articles were included, mostly targeting lower extremities (n = 137) and adults (n = 126). The parameters used varied widely but were most often around 80 Hz, at an amplitude of 1 mm for 10-20 s. Regarding rationales, nearly 50% of the studies did not include any, whereas those including one mainly cited the same two studies, without elaborating specifically on the parameter's choice.

Conclusion

This scoping review provided a comprehensive description of the population recruited and parameters used for vibration protocols in current studies with humans. Despite many studies, there remain important gaps of knowledge that needs to be filled, especially for vibration amplitude and duration parameters in various populations.

The Mediation Effect of Pain on the Relationship between Kinesiophobia and Lumbar Joint Position Sense in Chronic Low Back Pain Individuals: A Cross-Sectional Study

(1) Background: Fear of movement (kinesiophobia) and impaired lumbar joint position sense (LJPS) play a vital role in developing and maintaining non-specific chronic low back pain (CLBP). However, how kinesiophobia impacts LJPS is still being determined. The aims of this study are to (1) assess the correlation between kinesiophobia and LJPS in individuals with chronic low back pain; (2) compare LJPS between individuals with CLBP and those who are asymptomatic; and (3) evaluate if pain can mediate the relationship between kinesiophobia and LJPS in CLBP individuals. (2) Methods: Eighty-three individuals (mean age = 48.9 ± 7.5 years) with a diagnosis of CLBP and 95 asymptomatic individuals (mean age = 49.4 ± 7.0 years) were recruited into this cross-sectional study. Fear of movement in CLBP individuals was assessed using the Tampa Scale for Kinesiophobia (TSK). LJPS was determined using the active target repositioning technique using a dual-digital inclinometer. LJPS was evaluated in lumbar flexion, extension, and side-bending left and right directions, and the repositioning accuracy was determined in degrees using a dual digital inclinometer. (3) Results: Kinesiophobia showed a significant (p < 0.001) moderate positive correlation with LJPS (flexion: r = 0.51, extension: r = 0.41, side-bending left: r = 0.37 and side-bending right: r = 0.34). LJPS errors were larger in CLBP individuals compared to asymptomatic individuals (p < 0.05). Mediation analyses showed that pain significantly mediated the relationship between kinesiophobia and LJPS (p < 0.05) in CLBP individuals. (4) Conclusions: Kinesiophobia and LJPS were positively associated. LJPS is impaired in CLBP individuals compared to asymptomatic individuals. Pain may mediate adverse effects on LJPS. These factors must be taken into account when assessing and developing treatment plans for those with CLBP.

Effects of a Modified Tap Dance Program on Ankle Function and Postural Control in Older Adults: A Randomized Controlled Trial

Older adults are at a high risk of falling due to age-related degradations in physical fitness. This study aimed to examine the effects of a modified tap dance program (MTD) on ankle function and postural control in older adults. Forty-four healthy older adults (mean age = 64.1 years, with 9 men) were recruited from local communities and were randomly divided into the MTD group and the control (CON) group. The MTD group received 12 weeks of MTD training 3 times per week for 30 min per session. Outcomes were measured using the five times sit-to-stand test (FTSST) for ankle strength, the universal goniometer for ankle range of motion, and the Footscan^® to trace the center of pressure. Results revealed significant improvements in FTSST in the MTD group (mean difference = 1.01), plantar flexion (left = 9.10, right = 10.0). In addition, the MTD group displayed significantly more improvements at midtest than the CON group in FTSST (mean difference = 1.51) and plantar flexion (mean difference: left = 6.10; right = 4.5). Therefore, the MTD can be an effective exercise program for ankle function improvement, but it has limited effects on improving postural control among healthy older adults.

Association between Trunk Muscle Strength and Fall Risk in Older Men and Women with Lumbar Spondylosis

Various factors significantly affect the risk of falls among older adults with lumbar spondylosis. However, the relationship between falls and trunk muscle strength in older men is poorly explored. Thus, we aimed to investigate the relationship between back muscle strength and fall risk in older men and women with lumbar spondylosis. Based on self-reported fall scores, 39 outpatients were classified into two groups. Back and abdominal muscle strength, among other data, were compared between the two groups. Spearman's rank correlation analysis was used to assess the relationship between fall scores and selected variables. Back (r = -0.491, p = 0.002) and abdominal muscle strength (r = -0.415, p = 0.009) were related to the fall score. Furthermore, back and abdominal muscle strength were related to the fall score in women with a high risk of falls, whereas back muscle strength, erector spinae, and lumbar multifidus cross-sectional areas, and visual analog scale were related to the fall score in men with a high risk of falling. Back muscle strength and fall scores may be useful to assess the risk of falls in older patients with lumbar spondylosis. However, evaluating this relationship may require separate sex-specific analyses.

Postural Sway in Older Patients with Sagittal Imbalance and Young Adults during Local Vibratory Proprioceptive Stimulation

This study aimed to assess differences in somatosensory control strategies between older patients with sagittal imbalance and young adults during postural tasks. The center of pressure displacement in 27 older patients with sagittal imbalance and 27 young adults was determined upon standing blindfolded on a balance board. Vibratory stimulation at 56 to 100 Hz was applied bilaterally to the gastrocnemius and soleus muscles (GS) and lumbar multifidus to evaluate the contributions of proprioceptive signals to postural control. Data of older patients and young adults were compared using the Mann–Whitney U-test or independent sample t-tests. Compared with the young adults, the older patients were significantly more reliant on the GS (p < 0.005) for their postural control and showed a higher relative proprioceptive weighting ratio (RPW) (p = 0.038). The postural strategy adopted by the older patients depended on the level of proprioceptive stimulation applied to the GS, and the postural control strategy of the ankle correlated with RPW. Overall, this study identifies RPW as a novel measure of postural strategy in older patients with sagittal imbalance and provides an understanding of strategies used to maintain balance, which may assist in developing preventative measures to reduce the risk of falls.