Correlation between architectural variables and torque in the erector spinae muscle during maximal isometric contraction

Relationship between paraspinal muscle morphology and function in different directions in a healthy Chinese population at different ages: a cross-sectional study

BACKGROUND

Paraspinal muscle degeneration occurs with age; however, it is unknown whether strength and endurance change with muscle cross-sectional area (CSA) and fatty infiltration (FI) parameters in Chinese healthy individuals.

METHODS

A total of 94 asymptomatic Chinese volunteers were enrolled in this study. The participants were divided into three groups: young (20-39 years old, n = 27), middle-aged (40-59 years old, n = 49), and elderly (≥ 60 years old, n = 18). CSA and FI of the psoas (PS), quadratus lumborum (QL), multifidus (MF), and erector spinae (ES) were measured using magnetic resonance imaging. The Bionix Sim3 Pro was used to evaluate the maximum isometric torque and the Ito test to evaluate endurance.

RESULTS

The CSA of the PS and ES in the elderly group was smaller than those in the other groups, while the CSA of QL in the young group was larger than that in the other groups. There were differences in the MF and ES FI among the three groups. The maximum isometric torque and endurance test time decreased with increasing age; however, these differences were not statistically significant. Maximum isometric torque positively correlated with the average paraspinal muscle CSA and negatively correlated with the torque and FI of the MF and ES muscles. The endurance test was found to be positively correlated with the FCSA of the MF and to be negatively correlated with the FI of the MF and ES. PS and QL can predict the maximum isometric torque, and MF and PS can predict the endurance time.

CONCLUSION

MF and ES showed earlier degeneration than PS and QL. MF is the first paraspinal muscle to undergo functional area atrophy, and it plays an important role in the endurance test. The maximum moment of equal length in all directions of the lumbar spine is not completely symmetrical, but it is correlated with the imaging parameters of the paraspinal muscles. QL and PS were more activated in the lumbar activity.

TRIAL REGISTRATION

The study was registered in Chinese Clinical Trial Registry and the registration number is ChiCTR2000039073 on 15/10/2020 ( https://www.chictr.org.cn/showproj.html?proj=62785 ). Ethical Approval was obtained from the Peking University Third Hospital Medical Science Research Ethics Committee (IRB00006761-M2020305).

Quantifying thoracolumbar fascia deformation to discriminate acute low back pain patients and healthy individuals using ultrasound

Reduced shear strain and deformability of the thoracolumbar fascia has been linked to low back pain. A number of ultrasound examination methods have been developed for laboratory rather than clinical practice. The aim of this study was to examine the reliability and discriminative validity (patients vs. healthy individuals) of an ultrasound (US) measurement method for the quantification of thoracolumbar fascia deformation (TLFD). A cross-sectional study with US assessment and rater blinding was conducted in a manual therapy clinic and a university laboratory. 16 acute low back pain (aLBP) patients and 15 healthy individuals performed a standardized trunk extension task. US measurements of TLFD were carried out independently by two raters by imaging the TLF in the starting and ending positions of the movement. Intra-rater and inter-rater reliability were calculated using intraclass correlation coefficients (ICCs) and minimal detectable changes (MDC) were calculated. Receiver operating characteristic (ROC) curve analysis was used to determine the cut-off for TLFD to discriminate the study groups. Kappa statistics were performed to assess rater agreement in discrimination. Intra-rater reliability was excellent (ICC: .92, MDC: 5.54 mm, p < .001) and inter-rater reliability was good (ICC: .78, MDC: 8.70 mm, p < .001). The cut-off for TLFD was 6 mm with a sensitivity of 100% and a specificity of 93.75% and the raters agreed moderately (κ = 0.74, p < .001) when distinguishing patients and controls. The reliability of the US method for assessing TLFD is moderate to excellent, and the ability to discriminate aLBP patients from healthy individuals is moderate. The method could be used to capture an additional parameter in morphological aLBP screenings.

Thoracolumbar fascia deformation during deadlifting and trunk extension in individuals with and without back pain

Background

Alterations in posture, lumbopelvic kinematics, and movement patterns are commonly seen in patients with low back pain. Therefore, strengthening the posterior muscle chain has been shown to result in significant improvement in pain and disability status. Recent studies suggest that thoracolumbar fascia (TLF) has a major impact on the maintenance of spinal stability and paraspinal muscle activity, and thus is likely to have an equal impact on deadlift performance.

Objective

Aim of the study was to evaluate the role of thoracolumbar fascia deformation (TFLD) during spinal movement in track and field athletes (TF) as well as individuals with and without acute low back pain (aLBP).

Methods

A case-control study was performed with n = 16 aLBP patients (cases) and two control groups: untrained healthy individuals (UH, n = 16) and TF (n = 16). Participants performed a trunk extension task (TET) and a deadlift, being assessed for erector spinae muscle thickness (EST) and TLFD using high-resolution ultrasound imaging. Mean deadlift velocity (VEL) and deviation of barbell path (DEV) were measured by means of a three-axis gyroscope. Group differences for TLFD during the TET were examined using ANOVA. Partial Spearman rank correlations were calculated between TLFD and VEL adjusting for baseline covariates, EST, and DEV. TLFD during deadlifting was compared between groups using ANCOVA adjusting for EST, DEV, and VEL.

Results

TLFD during the TET differed significantly between groups. TF had the largest TLFD (-37.6%), followed by UH (-26.4%), while aLBP patients had almost no TLFD (-2.7%). There was a strong negative correlation between TLFD and deadlift VEL in all groups (r = -0.65 to -0.89) which was highest for TF (r = -0.89). TLFD during deadlift, corrected for VEL, also differed significantly between groups. TF exhibited the smallest TLFD (-11.9%), followed by aLBP patients (-21.4%), and UH (-31.9%).

Conclusion

TFLD maybe a suitable parameter to distinguish LBP patients and healthy individuals during lifting tasks. The cause-effect triangle between spinal movement, TFLD and movement velocity needs to be further clarified.

Clinical trial registration

https://drks.de/register/de/trial/DRKS00027074/, German Clinical Trials Register DRKS00027074.

Factors of Muscle Quality and Determinants of Muscle Strength: A Systematic Literature Review

Muscle quality defined as the ratio of muscle strength to muscle mass disregards underlying factors which influence muscle strength. The aim of this review was to investigate the relationship of phase angle (PhA), echo intensity (EI), muscular adipose tissue (MAT), muscle fiber type, fascicle pennation angle (θf), fascicle length (lf), muscle oxidative capacity, insulin sensitivity (IS), neuromuscular activation, and motor unit to muscle strength. PubMed search was performed in 2021. The inclusion criteria were: (i) original research, (ii) human participants, (iii) adults (≥18 years). Exclusion criteria were: (i) no full-text, (ii) non-English or -German language, (iii) pathologies. Forty-one studies were identified. Nine studies found a weak−moderate negative (range r: [−0.26]−[−0.656], p < 0.05) correlation between muscle strength and EI. Four studies found a weak−moderate positive correlation (range r: 0.177−0.696, p < 0.05) between muscle strength and PhA. Two studies found a moderate-strong negative correlation (range r: [−0.446]−[−0.87], p < 0.05) between muscle strength and MAT. Two studies found a weak-strong positive correlation (range r: 0.28−0.907, p < 0.05) between θf and muscle strength. Muscle oxidative capacity was found to be a predictor of muscle strength. This review highlights that the current definition of muscle quality should be expanded upon as to encompass all possible factors of muscle quality.

Exposure to Sustained Flexion Impacts Lumbar Extensor Spinae Muscle Fiber Orientation

The lumbar extensor spinae (LES) has an oblique orientation with respect to the compressive axis of the lumbar spine, allowing it to counteract anterior shear forces. This mechanical advantage is lost as spine flexion angle increases. The LES orientation can also alter over time as obliquity decreases with age and is associated with decreased strength and low back pain. However, it is unknown if LES orientation is impacted by recent exposures causing adaptations over shorter timescales. Hence, the effects of a 10-minute sustained spine flexion exposure on LES orientation, thickness, and activity were investigated. Three different submaximally flexed spine postures were observed before and after the exposure. At baseline, orientation (P < .001) and thickness (P = .004) decreased with increasingly flexed postures. After the exposure, obliquity further decreased at low (pairwise comparison P < .001) and moderately (pairwise comparison P = .008) flexed postures. Low back creep occurred, but LES thickness did not change, indicating that decreases in orientation were not solely due to changes in muscle length at a given posture. Activation did not change to counteract decreases in obliquity. These changes encompass a reduced ability to offset anterior shear forces, thus increasing the potential risk of anterior shear-related injury or pain after low back creep-generating exposures.

Muscle activity and architecture as a predictor of hand-grip strength

BACKGROUND

Grip strength is a powerful predictor of disability as well as a good indicator of physical activity.

OBJECTIVES

This study aimed to relate ultrasound (US) and electromyography (EMG) simultaneously to maximum hand-grip strength during an isometric contraction.

APPROACH

This is a cross-sectional study. Data acquisition was done with a dynamometer, US and EMG. Outcome variables included maximum strength during the hand-grip gesture, maximum muscle activity and change in muscle thickness. A non-linear regression analysis was performed to analyse the relationship between all outcome variables.

MAIN RESULTS

A total of 38 subjects (18 men and 20 women) participated in the study. The mean results for hand-grip strength were 25.50 (SD 6.55) kg of maximum strength, a change in muscle thickness of 1.83 (SD 0.75) mm and an EMG activity of 499.29 (SD 224.20) µV. Hand-grip strength had a high correlation with muscle thickness (R ² = 0.61) and EMG activity (R ² = 0.95). The correlation between maximum muscle activity and change in muscle thickness was R ² = 0.83.

SIGNIFICANCE

The results of the present study demonstrate that this new method based on electromyographic activity and muscule architecture could be important in the development of the hand-grip test.

Foot Dorsiflexion Velocity and Torque Variance Explained through Architectural and Electromyography Variables Comparing Elders and Stroke Survivors

OBJECTIVES

The objectives of this study are to analyze the relationship between electromyographic variables, tibialis anterior (TA) architecture, and functional variables (torque and kinematic variables) during maximal isometric and isotonic foot dorsiflexion (FD), and to compare the described relationship between stroke survivors (SS) and healthy elders (HE).

METHODS

Twenty-eight participants (14 SS and 14 HE) over 65 years old performed 3 maximal isometric and isotonic FDs parameterized by ultrasound, electromyography (EMG), inertial sensor, and load cell. Common variables (TA) include muscle thickness, pennation angle, muscle activation, and EMG area under the curve. Specific variables include torque for isometric FD, and velocity and displacement for isotonic FD.

RESULTS

There are significant differences in all variables when comparing the 2 groups. Among these differences, all the outcome variables show higher values in the HE group than in the SS group. However, in the 2 dependent variables obtained during isometric FD (median and maximal torques), the independent variables can explain nearly 70% of the variability of the dependent variable, with values of 68.4%-71.9% for SS and 69.1%-70.2% for HE. Similar results were found during isotonic FD.

CONCLUSIONS

Even though the TA of the SS group is capable of generating less force (isometric FD) and is slower (isotonic FD) than that of the HE group, the contribution of the independent variables (muscle activation, pennation angle,and muscle thickness) can explain the same proportion of variability of the dependent variables.

Localized Electrical Impedance Myography of the Biceps Brachii Muscle during Different Levels of Isometric Contraction and Fatigue

This study assessed changes in electrical impedance myography (EIM) at different levels of isometric muscle contraction as well as during exhaustive exercise at 60% maximum voluntary contraction (MVC) until task failure. The EIM was performed on the biceps brachii muscle of 19 healthy subjects. The results showed that there was a significant difference between the muscle resistance (R) measured during the isometric contraction and when the muscle was completely relaxed. Post hoc analysis shows that the resistance increased at higher contractions (both 60% MVC and MVC), however, there were no significant changes in muscle reactance (X) during the isometric contractions. The resistance also changed during different stages of the fatigue task and there were significant decreases from the beginning of the contraction to task failure as well as between task failure and post fatigue rest. Although our results demonstrated an increase in resistance during isometric contraction, the changes were within 10% of the baseline value. These changes might be related to the modest alterations in muscle architecture during a contraction. The decrease in resistance seen with muscle fatigue may be explained by an accumulation of metabolites in the muscle tissue.

Tibialis anterior analysis from functional and architectural perspective during isometric foot dorsiflexion: a cross-sectional study of repeated measures

Background

The purpose of the present study is to establish the relationship and degree of contribution between torque and sonomiography variables (pennation angle – muscle thickness), and electromyography variables (EMG_{AreaUnderCurve} – EMG_MaximalPeak) of the tibialis anterior muscle during (TA) maximal and relative isometric foot dorsiflexion (IFD). Secondary aim: To determine the measurement’s reliability.

Methods

Cross-sectional study. 31 participants (15 men; 16 women) performed IFD at different intensities (100, 75, 50, and 25 %) of the maximal voluntary contraction (MVC) (three times for each intensity). Outcome variables: To determine the torque, pennation angle, muscle thickness, EMG_MaximalPeak, and EMG_{AreaUnderCurve}. Statistical analysis: In order to test the measurement’s reliability, Cronbach’s alpha and standard error of the measurement were determined. An inferential analysis was carried out using Pearson correlations(r). For each contraction intensity, a multiple regression analysis was performed, where the dependent variable was torque and the independent variables were EMG_{AreaUnderCurve}, EMG_MaximalPeak, muscle thickness and pennation angle.

Results

All outcome variables show excellent reliability. The highest correlation value was 0.955 (thickness 100 % – thickness 25 %). R² values ranged from 0.713 (100 % MVC) to 0.588 (25 % MVC).

Conclusion

The outcome variables demonstrated excellent reliability in terms of measuring IFD at different intensities. The correlations between all outcome variables were moderate-to-strong. TA functional and architectural variables have a significant impact on the torque variance during IFD at different intensities.