Internal consistencies of the delayed trunk muscle reaction times following a treadmill-induced slip perturbation while holding and not holding a tray

A study on the effects of visual condition on postural stability in adults with and without chronic low back pain

This study was conducted to compare postural stability during repeated unilateral standing tasks between adults with and without chronic low back pain (LBP) while considering visual input. The study involved 26 participants with LBP and 39 control participants. Each participant performed three trials of standing tasks on the dominant limb using a stable platform. The Falls Efficacy Scale was utilized to assess fall-related self-efficacy and fear of falling due to potential physical frailty. The center of pressure (COP) sway excursion was analyzed at 10 mm and 20 mm thresholds for the time-in-boundary (TIB). The results indicated a significant fear of falling difference in the LBP group compared to the control group (t = 3.27, p = 0.001). The LBP group demonstrated a significant interaction between visual condition and TIB (F = 8.45, p = 0.01), particularly in the LBP group, which demonstrated a notable decrease in TIB at 10 mm (54.02 % compared to the control group's 70.40 %) and 20 mm (70.93 % compared to the control group's 85.92 %) thresholds during the second trial and at 10 mm (59.73 % compared to the control group's 73.84 %) during the third trial in the eyes open condition. Overall, visual condition demonstrated significant interactions on thresholds (F = 15.80, p = 0.001, η2p = 0.21) as well as trials  ×  thresholds (F = 4.21, p = 0.04, η2p = 0.07). These findings indicate a potential adaptation in postural control among the LBP group with visual feedback. Further research is warranted to explore group differences when considering visual conditions and sway excursion thresholds.

Normalized stability time analysis within the boundaries between adults with and without fear of falling

BACKGROUND

The unilateral stance test, measured by the center of pressure (COP), has been widely used to identify balance deficits. However, there is a critical gap in understanding the specific COP thresholds on postural stability in adults with a fear of falling (FOF).

AIMS

To investigate the normalized stability time, which was defined as the ratio of time spent within stability boundaries to the total test duration, under different visual conditions and specific thresholds between adults with and without FOF.

METHODS

Twenty-one older adults with FOF and 22 control subjects completed the unilateral limb standing test in eyes-open and eyes-closed conditions. Normalized stability times were computed based on five pre-determined COP sway range thresholds: 10 mm, 15 mm, 20 mm, 25 mm, and 30 mm.

RESULTS

Receiver operating characteristic analysis determined the diagnostic accuracy of FOF. There were significant differences in the effects of both visual conditions (F = 46.88, p = 0.001) and threshold settings (F = 119.38, p = 0.001) on stability time between groups. The FOF group significantly reduced normalized stability time at the 10 mm COP threshold under eyes-closed conditions (t = - 1.95, p = 0.03).

DISCUSSION

The findings highlight the heightened sensitivity of the 10 mm COP threshold in identifying group variances in postural stability when eyes are closed. Moreover, the FOF group displayed a marked reduction in stability duration based on visual scenarios and normalized thresholds.

CONCLUSION

The study highlights the need to account for both COP boundaries and visual conditions in adults with FOF. When assessing postural control during unilateral stances, clinicians must also give attention to non-visual cues.

Effectiveness of virtual reality-based balance and gait in older adults with fear of movement: A systematic review and meta-analysis

OBJECTIVE

To summarize the current evidence from randomized controlled trials (RCTs) regarding the effectiveness of Virtual Reality (VR) training and functional mobility in older adults with fear of movement. TYPE: Systematic review and meta-analysis of randomized clinical trials.

METHODOLOGY

An electronic search was performed using PubMed, Embase, Medline, SPORTDiscus, Scopus, and CINAHL. A data search from January 2015 to December 2022 and a manual electronic literature search were conducted to identify published RCTs. The effectiveness of VR-based balance training for balance and gait was evaluated in older adults with a fear of movement, which was measured by the Timed Up and Go (TUG) test and the Falls Efficacy Scale (FES). Three reviewers independently performed the study selection, and the quality assessment of the included studies was performed using the Physiotherapy Evidence Database (PEDro) scale. The reporting was based on the new Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Guidelines.

SYNTHESIS

The search product produced 345 results, from which 23 full text articles were studied. Seven RCTs of good methodological quality, including 265 participants, were included in the review. Overall, the studies reported that VR had a significant improvement on the TUG (Cohen's d = -0.91 [-1.38; -0.44], p = 0.001), while the FES was not significantly different (Cohen's d = -0.54 [-1.80; 0.71] p = 0.40). The average for PEDro scores (6.14) was good, and the risk of bias revealed that more than one-third of the studies correctly described the random sequence generation and allocation concealment procedures.

CONCLUSION

VR-based training is effective on balance or gait training based on the TUG; however, there were mixed results to improve FES scores following VR intervention. These inconsistent results might be limited due to variations in the studies, including heterogeneous training paradigms, sensitive outcome measures, small sample sizes, and short intervention durations, which limit the validity of our findings. Future investigations should compare different VR protocols to help establish better guidelines for clinicians.

Ankle reaction times with tray usage following a slip perturbation between subjects with and without chronic low back pain

BACKGROUND

Abnormal stepping strategies have been associated with handheld tasks in subjects with chronic low back pain (LBP). However, the dominant ankle reactions of subjects with LBP remain unclear following a perturbation during handheld tasks.

RESEARCH QUESTION

Are there differences in the reaction times of the ankle muscles during handheld tasks between subjects with and without LBP following a treadmill-induced slip perturbation?

METHODS

Thirty-seven right limb dominant subjects with LBP and 37 subjects without LBP participated in the study. Each subject was introduced to a slip perturbation (1.37 m/sec velocity for 8.22 cm) with and without a handheld tray in random order. Subjects were allowed to recover by stepping forward for a 0.12 s duration while bilateral tibialis anterior (TA) and gastrocnemius (GA) muscle reaction times were measured by electromyography (EMG).

RESULTS

The EMG results indicated that the groups demonstrated significant interactions on the limb sides and muscles (F = 4.86, p = 0.03). The dominant TA reaction time was significantly faster in the LBP group (t = 2.14, p = 0.03) while holding a tray.

SIGNIFICANCE

The LBP group demonstrated faster reaction times on the dominant TA muscles during perturbations. Clinicians need to consider dominance-dependent compensatory ankle dorsiflexion strategies in LBP patients to help enhance dynamic balance and control.

The reaction times and symmetry indices in the bilateral trunk and limb muscles in control subjects and subjects with low back pain that persisted two months or longer

PURPOSE

This study was conducted to investigate the reaction times and symmetry index (SI) of the bilateral trunk and limb muscles between control subjects and subjects with low back pain (LBP) that persisted for two months or longer.

METHODS

Fifty-seven right limb dominant subjects (31 healthy control subjects and 26 subjects with LBP) participated in this study. The subjects were exposed to a slip perturbation (0.24 m/sec velocity for 1.20 cm), which caused them to move forward for 0.10 s in standing while holding a tray. The electromyography (EMG) electrodes were placed on the bilateral erector spinae (ES), rectus abdominis (RA), rectus femoris, hamstring, tibialis anterior, gastrocnemius, biceps brachii (BB), and triceps brachii muscles. The reaction times were analyzed, and the SI was used to compare the bilateral trunk and limb muscles for the degree of asymmetry between groups.

RESULTS

The ES reaction time was significantly delayed in the control group (0.33 ± 0.22 vs. 0.22 ± 0.17; t = 2.25, p = 0.03). The SI of reaction times was significantly different on the RA (t = -2.28, p = 0.03), ES (t = -2.36, p = 0.04), and BB (t = -2.15, p = 0.04) muscles between groups.

CONCLUSION

The delayed non-dominant ES reaction time might indicate a freedom of pain recurrence in the control group. Although the asymmetry increased on the RA and BB muscles in the LBP group, it decreased on the ES muscle. The asymmetries on the trunk and BB muscles were evident in the LBP group. The asymmetrical reactions in the arm-trunk muscles need to be considered for rehabilitation strategies.