Differences in the elastic modulus of the lumbar muscles between female athletes with and without low back pain

Evaluation of Rectus Abdominis Muscle Using High-Frequency Ultrasound and Shear Wave Elastography to Construct a Risk Prediction Model for Postpartum Low Back Pain

RATIONALE AND OBJECTIVES

This study aimed to develop a risk prediction model for low back pain (LBP) using high-frequency ultrasound to measure rectus abdominis muscle activity in postpartum women.

MATERIALS AND METHODS

This study included 197 pregnant women who delivered at our hospital and underwent routine postpartum follow-up. High-frequency ultrasound was used to assess the inter-rectus distance, thickness, and elasticity of the rectus abdominis muscle. Follow-up data were collected until six months after delivery, including information on LBP and exercise. Statistical analysis was performed to identify independent risk factors for postpartum LBP and build a risk prediction model.

RESULTS

Univariate and multivariate logistic regression analyses revealed that rectus abdominis thickness and exercise were significant independent factors associated with postpartum LBP. There was no significant correlation between rectus abdominis diastasis, body mass index (BMI), or LBP. The risk prediction model corresponding to the minimum AIC value (205.19) was Y= 8.16-1.13 ×thickness of the rectus abdominis-3.09 ×exercise. The ROC curve indicated that the optimal diagnostic cut-off value of the prediction model was 0.314, with an area under the curve (AUC) of 0.813. The sensitivity, specificity, positive and negative predictive values, and accuracy were 62.0%, 78.0%, 65.3%, 75.4%, and 71.6%, respectively.

CONCLUSION

A risk prediction model for postpartum LBP built using high-frequency ultrasound measurements of the rectus abdominis muscle may accurately predict postpartum LBP during the early postpartum period.

Effects of high-frequency hyperthermia on the elastic modulus of the lumbar muscle in female athletes with low back pain: A randomized crossover trial

OBJECTIVE

To investigate the effects of capacitive and resistive monopolar radiofrequency (CRMF) on the shear elastic modulus of the multifidus and erector spinae muscles in female athletes with low back pain (LBP) and a history of LBP.

DESIGN

Randomized crossover trial.

SETTING

Academic institution.

PARTICIPANTS

Twenty female university athletes with LBP or a history of LBP were included.

INTERVENTIONS

All participants received CRMF, hotpack, and sham (CRMF without power) in a random order on the right side of the lumbar region. More than 2 days were allocated between the experiments to eliminate any residual effects.

MAIN OUTCOME MEASURES

The shear elastic moduli of the right multifidus and erector spinae were evaluated in the prone (rest) position while sitting with 35° trunk flexion (stretched) using shear wave ultrasound imaging equipment. The moduli were measured before, immediately after, and 30 minutes after the intervention.

RESULTS

Repeated-measures 2-way analysis of variance and post hoc analysis showed that the moduli of the CRMF group were significantly lower than those of the sham group in the stretched position immediately after intervention (P = .045). This difference diminished 30 minutes after the intervention (P = .920).

CONCLUSIONS

CRMF can be used to reduce the shear elastic modulus of the multifidus muscle in the short term. Further studies are warranted to determine how to provide longer effects.

TRIAL REGISTRATION

None.

Changes of trunk muscle stiffness in individuals with low back pain: a systematic review with meta-analysis

BACKGROUND

Low back pain (LBP) is one of the most common musculoskeletal conditions. People with LBP often display changes of neuromuscular control and trunk mechanical properties, including trunk stiffness. Although a few individual studies have examined back muscle stiffness in individuals with LBP, a synthesis of the evidence appears to be lacking. Therefore, the aim of this systematic review with meta-analysis was to synthesize and evaluate the available literature investigating back muscle stiffness in association with LBP.

METHODS

We conducted a systematic review of the literature according to the PRISMA guidelines. We searched Pubmed, Scopus, Web of Science and ScienceDirect for studies, that compared back muscle stiffness, measured either by ultrasound-based elastography or myotonometry, between individuals with and without LBP. Pooled data of the included studies were presented descriptively. Additionally, we performed two meta-analyses to calculate the standardized mean difference between the two groups for resting stiffness of the multifidus and erector spinae muscle. For both meta-analyses, the random effect model was used and the weight of individual studies was calculated using the inverse-variance method. The quality of the included studies was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Analytical Cross-Sectional studies. Furthermore, the certainty of evidence was evaluated using the GRADE approach.

RESULTS

Nine studies were included in our systematic review. Our results suggest that individuals with LBP have higher stiffness of the multifidus (SMD = 0.48, 95% CI: 0.15 - 0.81, p < 0.01; I2 = 48 %, p = 0.11) and erector spinae at rest (SMD = 0.37, 95% CI: 0.11 - 0.62, p < 0.01; I2 = 39 %, p = 0.14) compared to asymptomatic controls. On the other hand, the evidence regarding muscle stiffness during submaximal contractions is somewhat contradictory.

CONCLUSIONS

Based on the findings of this systematic review we conclude that people with LBP may have higher back muscle stiffness compared to asymptomatic controls. Addressing muscle stiffness might represent an important goal of LBP treatment. Nevertheless, our findings should be interpreted with extreme caution due to a limited quality of evidence, small number of included studies and differences in measurement methodology.