Electromyographic and Kinematic Analysis of Trunk and Limb Muscles During a Holding Task in Individuals With Chronic Low Back Pain and Healthy Controls

The Role of Back Muscle Dysfunctions in Chronic Low Back Pain: State-of-the-Art and Clinical Implications

Changes in back muscle function and structure are highly prevalent in patients with chronic low back pain (CLBP). Since large heterogeneity in clinical presentation and back muscle dysfunctions exists within this population, the potential role of back muscle dysfunctions in the persistence of low back pain differs between individuals. Consequently, interventions should be tailored to the individual patient and be based on a thorough clinical examination taking into account the multidimensional nature of CLBP. Considering the complexity of this process, we will provide a state-of-the-art update on back muscle dysfunctions in patients with CLBP and their implications for treatment. To this end, we will first give an overview of (1) dysfunctions in back muscle structure and function, (2) the potential of exercise therapy to address these dysfunctions, and (3) the relationship between changes in back muscle dysfunctions and clinical parameters. In a second part, we will describe a framework for an individualised approach for back muscle training in patients with CLBP.

Delayed response in rectus abdominis muscle following a step perturbation in subjects with and without recurrent low back pain

BACKGROUND

Delayed trunk and lower limb muscle activation is associated with balance loss and fall injuries in subjects with recurrent low back pain (LBP).

PURPOSE

This study was conducted to compare differences in the onset of muscle contractions of the trunk and lower limb muscles following a treadmill-induced step perturbation between subjects with and without LBP.

METHODS

Eighty-three right limb dominant individuals (43 subjects with LBP and 40 control subjects) were exposed to the perturbation (0.31 m/s velocity for 0.2 m). The electromyography (EMG) reaction times were analyzed during the first step following the perturbation. The EMG electrodes were placed on both sides of the trunk and lower limbs, including the rectus abdominis (RA), erector spinae (ES), tibialis anterior (TA), and gastrocnemius (GA) muscles.

RESULTS

The group x muscle interaction was statistically significant (F = 9.44, p = 0.003). The TA muscle activation was significantly delayed compared to the RA, ES, and GA. There was a significant interaction on side x muscle (F = 4.14, p = 0.04). The RA muscles were significantly delayed on the non-dominant (t = - 3.35, p = 0.001) and dominant (t = - 2.53, p = 0.01) sides in the LBP group.

CONCLUSION

The LBP group demonstrated a delayed reaction time on the RA muscles, which indicated poor trunk control relative to the lower limbs. The delayed bilateral RA muscle might indicate possible coordination problems relative to the ES and lower limb muscles, which may lead to potential fall hazards.

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.

Effects of Custom-made Insoles on Plantar Biomechanics and Upper Extremity Muscle Performance

OBJECTIVE

To investigate the effectiveness of molding custom-made insoles for female patients with foot pain.

METHODS

The study included 20 patients whose insoles were prescribed according to biomechanical evaluations and molded by repositioning the subtalar joint in its neutral position using a simple set of tools. Plantar biomechanics were measured under the following conditions: static stand, walking at self-comfortable walking speed (CWS) barefoot, walking in patient owned running shoes, and walking in running shoes plus insoles. Each patient's upper arm isometric muscle strength and subjective feelings before and after the insole intervention were assessed.

RESULTS

The molded insoles increased plantar contact area both during static standing and walking at CWS compared to the barefoot condition. The insoles also had more evenly distributed plantar contact area and loading rate, with the changes in the medial arch area being most significant. Moreover, the custom-made insole intervention immediately increased maximum resistance and duration of bilateral upper arms, as well as improved foot comfort, especially at the medial arch area during single leg squat tests.

CONCLUSION

Molding custom-made insoles by repositioning the subtalar joint in its neutral position can be accomplished with a simple set of tools, making this method highly applicable for a majority of less developed regions. Insoles molded using this method are effective in immediately improving plantar biomechanics disorders and enhancing isometric upper muscle performance in female patients with foot pain.

The influence of Kinesio Taping on muscle fatigue in individuals with low back pain: A randomised controlled trial

OBJECTIVE

To evaluate the effect of different taping techniques on back muscle fatigue in people with low back pain.

METHODS

Sixty women with chronic non-specific low back pain were randomly assigned to four groups of 15 participants each: control (CG), Kinesio Taping (KT) with tension (KTT), KT no tension (KTNT) and Micropore® (MP), which were applied over the erector spinae muscles. The median frequency (MF) fatigue slopes of the longissimus muscle and sustained contraction time during a trunk fatigue test (Ito test), and pain using the numerical pain rating scale (NPRS) were collected at three time points: pre-treatment, three and ten days after intervention at a university laboratory.

RESULTS

Significant differences were seen in the MF slopes between groups (p= 0.01, η2= 0.20), with the KTT showing a mean difference (MD = 0.31, p= 0.04) and KTNT (MD = 0.28, p= 0.04) compared with CG. Significant reductions in NPRS were seen between time points (p< 0.001, η2= 0.28), with a reduction between pre and 3 days (MD = 1.87, p< 0.001), and pre and 10 days (MD = 1.38, p< 0.001), with KTT and KTNT both showing clinically important changes.

CONCLUSION

KT, with or without tension, has a tendency to reduce back muscle fatigue and reduce pain in individuals with chronic non-specific low back pain.

Influences of Kinesio Taping with Therapeutic Exercise in Patients with Low Back Pain

The aim of this study was to evaluate the effect of core stability exercise combined with Kinesio taping on pain, endurance, and balance in patients with lower back pain (LBP). 46 patients with LBP were recruited and randomly allocated into the core stability exercise with taping (CSET) group and the core stability exercise (CSE) group. All participants performed core stability exercises for 40 min/day, 5 times/week for 8 weeks, and additional Kinesio taping was applied to the lower backs in the CSET group. The primary outcome measure was the pain intensity using the visual analog scale, and secondary outcome measures were trunk endurance and balance using the Biering-Sorensen test and force plate, respectively. After the intervention, the CSET group showed significant improvements in pain and postural balance compared to the CSE group (p < 0.05). However, there was no significant difference in trunk endurance between two groups (p > 0.05). This study found that core stability exercise was effective in reducing pain and enhancing balance in patients with LBP, and demonstrated that the application of additional Kinesio taping further increased these effects. Therefore, we recommend that core exercise combined with Kinesio taping may be used to improve the pain and postural balance of patients with LBP in clinics.

Compensatory spinopelvic motions with and without a handheld task following a perturbation in standing between subjects with and without chronic low back pain

BACKGROUND

A handheld task-related compensation strategy could be used to avoid injuries in subjects with chronic low back pain (LBP). Those who suffer with LBP demonstrate reduced spinopelvic motion; however, there is a lack of understanding on dynamic mobility with a handheld task.

RESEARCH QUESTION

Are there differences in three-dimensional spinopelvic motions following a treadmill-induced perturbation in subjects with LBP while considering a handheld task?

METHODS

Twenty-five subjects (11 female and 14 male) with LBP and 38 control subjects (15 female and 23 male) participated in the study. Each group was introduced to walking perturbations (0.86 m/sec, velocity in 0.1 sec) with and without a handheld tray in a standing position. The induced trip allowed subjects to recover by walking forward for a 5 second duration while the spinopelvic angles were measured during the trip and the subsequent recovery period.

RESULTS

There was no significant group difference in the three-dimensional (3D) spinopelvic motions while holding or not holding a tray. However, the groups demonstrated a significant interaction on tray usage with 3D motions in the spinopelvic regions (F = 13.46, p = 0.001). The sagittal plane motion was significantly minimized with a handheld task for both the lumbar spine and pelvis in the LBP group.

SIGNIFICANCE

The LBP group demonstrated minimized lumbar and pelvic motions in the sagittal plane, which underpins their concern to reduce motion while holding a tray. The significant interaction between groups on tray usage for spinopelvic compensation represents a strategy for avoiding injuries. Further studies are required to determine strategies to enhance lumbopelvic integration with handheld tasks in individuals with LBP.

Variation in the spatial distribution of erector spinae activity during a lumbar endurance task in people with low back pain

This study aimed to investigate the spatial distribution and redistribution of lumbar erector spinae (ES) activity during a lumbar extension endurance task in pain-free participants and how this is modified in people with low back pain (LBP). High density surface electromyography (HDEMG) was recorded using 13 × 5 electrode grids placed over the lumbar ES in 13 LBP and 13 control participants while completing an Ito test to task failure. The root mean square of the HDEMG signals was computed, a topographical map of the EMG amplitude generated and the centre of the activity (centroid) determined throughout the task. The centroid of the EMG amplitude map was systematically more cranial (F = 6.09, P = 0.022) for the LBP participants compared with the control subjects. Regression analysis showed that the extent of redistribution of ES activity was associated with longer endurance. These results show that LBP participants utilised a different motor strategy to perform the endurance task, characterised by greater activation of more cranial regions of the ES and less redistribution of ES activity throughout the task. This study provides new insight into the functional activation of the lumbar ES and how it is modified when people have pain.