Age-related differences in the timing aspect of lumbopelvic rhythm during trunk motion in the sagittal plane

Spinal loads during dynamic full flexion and return to standing posture in different age and sex groups: A musculoskeletal model study

During forward flexion, spine motion varies due to age and sex differences. Previous studies showed that lumbar/pelvis range of flexion (RoF) and lumbo-pelvic ratio (L/P) are age/sex dependent. How variation of these parameters affects lumbar loading in a normal population requires further assessment. We aimed to estimate lumbar loads during dynamic flexion-return cycle and the differences in peak loads (compression) and corresponding trunk inclinations due to variation in lumbar/pelvis RoF and L/P. Based on in vivo L/P (0.11-3.44), temporal phases of flexion (early, middle, and later), the lumbar (45-55°) and hip (60-79°) RoF; full flexion-return cycles of six seconds were reconstructed for three age groups (20-35, 36-50 and 50+ yrs.) in both sexes. Six inverse dynamic analyses were performed with a 50th percentile model, and differences in peak loads and corresponding trunk inclinations were calculated. Peak loads at L4-L5 were 179 N higher in younger males versus females, but 228 N and 210 N lower in middle-aged and older males, respectively, compared to females. Females exhibited higher trunk inclinations (6°-20°) than males across all age groups. Age related differences in L4-L5 peak loads and corresponding trunk inclinations were found up to 415 N and 19° in males and 152 N and 13° in females. With aging, peak loads were reduced in males but were found non-monotonic in females, whereas trunk inclinations at peak loads were reduced in both sexes from young to middle/old age groups. In conclusion, lumbar loading and corresponding trunk inclinations varied notably due to age/sex differences. Such data may help distinguishing normal or pathological condition of the lumbar spine.

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.

Sample Entropy as a Tool to Assess Lumbo-Pelvic Movements in a Clinical Test for Low-Back-Pain Patients

Low back pain (LBP) obviously reduces the quality of life but is also the world’s leading cause of years lived with disability. Alterations in motor response and changes in movement patterns are expected in LBP patients when compared to healthy people. Such changes in dynamics may be assessed by the nonlinear analysis of kinematical time series recorded from one patient’s motion. Since sample entropy (SampEn) has emerged as a relevant index measuring the complexity of a given time series, we propose the development of a clinical test based on SampEn of a time series recorded by a wearable inertial measurement unit for repeated bending and returns (b and r) of the trunk. Twenty-three healthy participants were asked to perform, in random order, 50 repetitions of this movement by touching a stool and another 50 repetitions by touching a box on the floor. The angular amplitude of the b and r movement and the sample entropy of the three components of the angular velocity and acceleration were computed. We showed that the repetitive b and r “touch the stool” test could indeed be the basis of a clinical test for the evaluation of low-back-pain patients, with an optimal duration of 70 s, acceptable in daily clinical practice.

Effect of Age on Thoracic, Lumbar, and Pelvis Coordination During Trunk Flexion and Extension

The purpose of this study was to investigate normative and age-related differences in trunk and pelvis kinematics and intersegmental coordination during sagittal plane flexion–extension. Trunk and pelvis kinematics were recorded while 76 participants performed a maximal range of motion task in the sagittal plane. Cross-correlation was calculated to determine the phase lag between adjacent segment motion, and coupling angles were calculated using vector coding and classified into one of 4 coordination patterns: in-phase, antiphase, superior, and inferior phase. A 2-way mixed-model multivariate analysis of variance was used to compare lumbar spine and pelvis angular kinematics, phase lags, and cross-correlation coefficients between groups. Young participants exhibited greater trunk range of motion compared with middle-aged participants. The lumbar spine and pelvis were predominantly rotating with minimum phase lag during flexion and extension movement for both age groups, and differences in coordination between the groups were seen during hyperextension and return to upright position. In conclusion, middle-aged adults displayed lower range of motion but maintained similar movement patterns to young adults, which could be attributed to protective mechanisms. Healthy lumbar and pelvis movement patterns are important to understand and need to be quantified as a baseline, which can be used to develop rehabilitation protocols for individuals with spinal ailments.

PORTRAIT AND HILBERT TRANSFORM METHODS FOR EVALUATING CONTINUOUS RELATIVE PHASE BETWEEN LOWER-LIMB JOINTS IN THE ELDERLY DURING WALKING

In order to calculate the continuous relative phase (CRP) between joints, the portrait method based on the joint angle and angular velocity and the Hilbert transform method based on the analytical signal have been widely used. However, there are few comparisons of these methods. Therefore, the aim of this study is to quantitatively compare these methods by calculating the CRP in the lower-limb joints of the elderly during level free walking. Eighteen elderly female adults ([Formula: see text] year-old, [Formula: see text][Formula: see text]cm, [Formula: see text][Formula: see text]kg) wearing a Helen Hayes full-body marker set walked 10[Formula: see text]m on level ground at a self-selected velocity. The angles of the hip, knee, and ankle were measured. To calculate the CRP using the portrait method, the angular velocities were measured. Then, the phases between the angle and the angular velocity were calculated. To calculate the CRP using the Hilbert transform method, analytical signals were acquired. Then, the phases between the real and imaginary parts were calculated. A CRP was calculated as the difference between the phase in the proximal joint and the phase in the distal joint. To evaluate the similarity in the shape between the portrait and Hilbert transform methods, the cross-correlation was calculated. Bland–Altman plot analyses were performed to assess the agreement between these methods. For the root mean squares (RMSs) and standard deviations (SDs), a paired [Formula: see text]-test and the Pearson correlation between methods were evaluated. There were similarities in the in-phase or out-of-phase features and in the RMS and SD between the methods. Additionally, a higher cross-correlation and agreement between them were found. These results indicated the similarity between the portrait and Hilbert transform methods for the calculation of the CRP. Therefore, either method can be used to evaluate joint coordination.

Changes in Lumbo-Pelvic Coordination of Individuals With and Without Low Back Pain When Wearing a Hip Orthosis

Individuals with low back pain demonstrate an abnormal lumbo-pelvic coordination compared to back-healthy individuals. This abnormal coordination presents itself as a reduction in lumbar contributions and an increase in pelvic rotations during a trunk forward bending and backward return task. This study investigated the ability of a hip orthosis in correcting such an abnormal lumbo-pelvic coordination by restricting pelvic rotation and, hence increasing lumbar contributions. The effects of the hip orthosis on the lumbo-pelvic coordination were investigated in 20 low back pain patients and 20 asymptomatic controls. The orthosis reduced pelvic rotation by 12.7° and increased lumbar contributions by 11%. Contrary to our expectation, orthosis-induced changes in lumbo-pelvic coordination were smaller in patients; most likely because our relatively young patient group had smaller unrestricted pelvic rotations compared to asymptomatic individuals. Considering the observed capability of a hip orthosis in causing the expected changes in lumbo-pelvic coordination when there is a relatively large pelvic contribution to trunk motion, application of a hip orthosis may provide a promising method of correcting abnormal lumbo-pelvic coordination, particularly among patients who demonstrate larger pelvic rotation, that warrants further investigation.

The immediate and prolonged effects of military body armor on the relative timing of thorax and pelvis rotations during toe-touch and two-legged squat tasks

Although military body armor is an effective life saver, it considerably loads more weight on the warfighters, increasing the risk of musculoskeletal injury. This study investigated the immediate and prolonged effects of wearing body armor on timing aspect of lumbo-pelvic coordination during the toe-touch (TT) and two-legged-squat (TLS) tests. A cross-over study design was used wherein twelve asymptomatic and gender-balanced individuals completed two experimental sessions with and without body armor. A session included two similar sets of tests, before and after exposure to a treadmill walk, containing a TT and a TLS test with ten cycles of fast bending and return. Reflective markers were attached on the participants to capture the kinematics of body segments in conjunction with a motion capture system. The mean absolute relative phase (MARP) and deviation phase (DP) between the thorax and pelvis were calculated for each test. The pre-walk MARP in the return was significantly larger with versus without body armor (p = 0.022), while there were no significant effects of body armor on the other outcome measures. In addition, the pre-walk MARP and DP in the bending and return, as well as the walk-induced changes in the MARP in the bending phase were significantly larger in TLS versus TT (p < 0.026). Therefore, using a body armor immediately made the lumbo-pelvic coordination less in-phase during return, but no prolonged effects were found. Further investigation is necessary to specify chances wearing a body armor increases the risk of musculoskeletal injuries in the lower back and lower extremities joints.

A prospective study of lumbo-pelvic coordination in patients with non-chronic low back pain

Despite the current knowledge about abnormalities in the lumbo-pelvic coordination of patients with non-specific low back pain (LBP), it is unclear how such abnormalities change with time. Timing and magnitude aspects of lumbo-pelvic coordination during a trunk forward bending and backward return task along with subjective measures of pain and disability were collected at three-time points over a six-month period from 29 patients who had non-chronic LBP at the time of enrollment in the study. To enable investigation of abnormalities in lumbo-pelvic coordination of patients, we also included lumbo-pelvic coordination data of age and gender-matched back healthy individuals from an earlier study of our group. Finally, differences in lumbo-pelvic coordination between patients with moderate-severe LBP (i.e., those whose level of pain was ≥ 4 (out of 10) at all three data collection sessions; n = 8) and patients with low-moderate LBP (n = 21) were investigated. There were clear distinctions in measures of lumbo-pelvic coordination between patients with low-moderate and moderate-severe LBP. Contrary to our expectation, however, the abnormalities in magnitude aspects of lumbo-pelvic coordination were larger (F > 4.84, P < 0.012) in patients with low-moderate LBP. These abnormalities in patients with low-moderate LBP, compared to controls, included larger (>12°) pelvic and thoracic rotations as well as smaller (>10°) lumbar flexion. The abnormal lumbo-pelvic coordination of patients with non-specific LBP, observed at baseline, persisted (F < 1.96, P > 0.156) or worsen (F > 3.48, P < 0.04) over the course of study period despite significant improvement in their pain (18% decrease; F = 12.10, P < 0.001) and disability (10% decrease; F = 4.39, P = 0.017). Distinct but lingering abnormalities in lumbo-pelvic coordination, observed in patients with low-moderate and moderate-severe LBP, might have a role in persistence and/or relapse of symptoms in patients with non-specific LBP. Such inferences, however, should further be studied in future via investigation of the relationship between abnormalities in lumbo-pelvic coordination and clinical presentation of LBP.

Discriminating spatiotemporal movement strategies during spine flexion-extension in healthy individuals

BACKGROUND CONTEXT

The spine is an anatomically complex system with numerous degrees of freedom. Due to this anatomical complexity, it is likely that multiple motor control options exist to complete a given task.

PURPOSE

To identify if distinct spine spatiotemporal movement strategies are utilized in a homogenous sample of young healthy participants.

STUDY DESIGN

Kinematic data were captured from a single cohort of male participants (N=51) during a simple, self-controlled spine flexion-extension task.

METHODS

Thoracic and lumbar flexion-extension data were analyzed to extract the continuous relative phase between each spine subsection. Continuous relative phase data were evaluated using a principal component analysis to identify major sources of variation in spine movement coordination. Unsupervised machine learning (k-means clustering) was used to identify distinct clusters present within the healthy participants sampled. Once distinguished, intersegmental spine kinematics were compared amongst clusters.

RESULTS

The findings of the current work suggest that there are distinct timing strategies that are utilized, within the participants sampled, to control spine flexion-extension movement. These strategies differentiate the sequencing of intersegmental movement and are not discriminable on the basis of simple participant demographic characteristics (ie, age, height, and body mass index), total movement time or range of motion.

CONCLUSIONS

Spatiotemporal spine flexion-extension patterns are not uniform across a population of young healthy individuals.

CLINICAL SIGNIFICANCE

Future work needs to identify whether the motor patterns characterized with this work are driven by distinct neuromuscular activation patterns, and if each given pattern has a varied risk for low back injury.

The effects of backpack type on lumbo-pelvic coordination during trunk bending and return tasks

Backpacks with ergonomic features are recommended to mitigate the risk of developing low back pain due to carrying a heavy school backpack. A repeated measure study was conducted on 40 college-age students to investigate the immediate changes in magnitude and timing aspects of lumbo-pelvic coordination when carrying an ergonomically modified vs. a normal backpack relative to no backpack condition during trunk forward bending and backward return tasks. We found a smaller reduction in the thoracic range of rotation, an increase vs. a decrease in pelvic range of rotation and a larger reduction in lumbar flexion for a modified vs. a normal backpack. Furthermore, during the forward bending, a less in-phase motion for the modified backpack was observed. Our results suggest that participants have likely experienced larger spinal loads with the modified backpack; a conclusion that should be investigated in future to determine whether ergonomic backpacks can reduce the risk of low back pain in children. Practitioner summary: Research participants performed trunk bending and return closer to their habitual way under modified versus normal school backpack. From an equilibrium point of view, therefore, individuals are likely experiencing larger spinal loads during activities of daily living with a modified backpack. However, such a conclusion may change when considering stability requirements.

Gender difference of shoulder-pelvic kinematic integration for trunk rotation directions in healthy older adults

BACKGROUND

The trunk coordination pattern has been extensively studied, and there is a higher pain prevalence and asymmetry in female older adults. However, there is a lack of investigation of different directions of trunk rotation and asymmetrical compensatory strategies of motor control between genders. The purpose of this study was to investigate shoulder and pelvic ranges of motion (ROM) as well as relative phases (RP) for the different directions of trunk rotation between genders in healthy older adults.

METHODS

There were 62 right hand dominant older adults in this study (31 female subjects (68.4 [5.62]years) and 31 male subjects (68.7 [5.68]years)). The participants performed trunk axial rotation from the left to the right direction (RP1) and then returned to the left side (RP2), three times repeatedly in standing. The measurements included shoulder and pelvic ROM, RP1, and RP2. The RP was defined as the average absolute relative phase, which was the difference between the phase angle of the shoulder and the phase angle of the pelvis during trunk rotation.

FINDINGS

The female group demonstrated significantly greater pelvic rotation compared to the male group (98.64 [24.67] vs. 86.96 [18.97]; t=2.09, p=0.04) during trunk rotation. The pelvic ROM demonstrated a significant positive correlation with shoulder ROM in both genders; however, the RP was negatively correlated with the pelvis. For pelvic rotation, the male group demonstrated a negative correlation with RP1 (r=-0.68, p<0.01) and RP2 (r=-0.60, p<0.01) while the female group demonstrated a negative correlation with RP2 (r=-0.53, p<0.01). The ageing factor demonstrated negative correlations with ROM for the shoulder and pelvis in both genders.

INTERPRETATION

Although no gender difference was indicated on the direction of RP, the pelvic ROM was significantly lesser in the male group. The male group demonstrated lesser pelvic rotation in both directions of rotation; however, the female group showed lesser pelvic rotation in RP2. The male group demonstrated stiffened pelvic rotation and greater shoulder rotation in both directions while the female group demonstrated pelvic stiffness only in the direction from right to left rotation. Clinicians need to consider this directional asymmetry of trunk rotation to enhance integrated shoulder-pelvic coordination in female older adults.

MINI ABSTRACT

A coordinative pattern of different directions of trunk rotation was investigated in healthy older adults. The pelvic range of motion was lesser in the male group compared with the female group. The female group demonstrated pelvic stiffness only in the direction from right to left rotation, while the male group demonstrated pelvic stiffness in both directions. Clinicians need to understand the gender difference of directional coordination as integrated coordination in female older adults.

Activity of Erector Spinae During Trunk Forward Bending and Backward Return: The Effects of Age

Electromyography (EMG)-based measures of the trunk muscles behavior have been used for objective assessment of biomechanical impairments in patients with low back pain (LBP); yet the literature on normal age-related differences in such measures is scant. A cross-sectional study was designed to assess age-related differences in activity of trunk extensors during forward bending and backward return. Sixty asymptomatic individuals were recruited to form five gender-balanced age groups between 20 and 70 years old. Participants completed two sets of trunk forward bending and backward return task using self-selected and fast motion paces. For bending and return phases of each task, the normalized lumbar flexion angles corresponding to different event times of erector spinae activity along with the peak normalized and non-normalized EMG activities of erector spinae were calculated. The mean normalized and non-normalized EMG activities of erector spinae during the entire task also were calculated. There was no age-related difference in normalized lumbar flexion angles corresponding to different event times of erector spinae activity. However, the peak normalized EMG activity during forward bending and backward return as well as the mean normalized EMG activity during the entire task were found to be larger in older vs. younger individuals. Given the suggested unreliability of normalized EMG in elders and considering that we did not find any age-related differences in non-normalized EMG activity of erector spinae, our results do not strongly support the existence of normal age-related differences in EMG profile of erector spinae during forward bending and backward return. Therefore, when interpreting EMG-based measures of trunk muscles behavior for identification of biomechanical impairment in patients with LBP, potential abnormalities in EMG activity of trunk muscles may not be attributed to patient's age.

Timing and magnitude of lumbar spine contribution to trunk forward bending and backward return in patients with acute low back pain

Alterations in the lumbo-pelvic coordination denote changes in neuromuscular control of trunk motion as well as load sharing between passive and active tissues in the lower back. Differences in timing and magnitude aspects of lumbo-pelvic coordination between patients with chronic low back pain (LBP) and asymptomatic individuals have been reported; yet, the literature on lumbo-pelvic coordination in patients with acute LBP is scant. A case-control study was conducted to explore the differences in timing and magnitude aspects of lumbo-pelvic coordination between females with (n=19) and without (n=19) acute LBP. Participants in each group completed one experimental session wherein they performed trunk forward bending and backward return at preferred and fast paces. The amount of lumbar contribution to trunk motion (as the magnitude aspect) as well as the mean absolute relative phase (MARP) and deviation phase (DP) between thoracic and pelvic rotations (as the timing aspect) of lumbo-pelvic coordination were calculated. The lumbar contribution to trunk motion in the 2nd and the 3rd quarters of both forward bending and backward return phases was significantly smaller in the patient than the control group. The MARP and the DP were smaller in the patient vs. the control group during entire motion. The reduced lumbar contribution to trunk motion as well as the more in-phase and less variable lumbo-pelvic coordination in patients with acute LBP compared to the asymptomatic controls is likely the result of a neuromuscular adaptation to reduce painful deformation and to protect injured lower back tissues.