The Role of Core Strengthening for Chronic Low Back Pain

Strength and Power-Related Measures in Assessing Core Muscle Performance in Sport and Rehabilitation

While force-velocity-power characteristics of resistance exercises, such as bench presses and squats, have been well documented, little attention has been paid to load, force, and power-velocity relationships in exercises engaging core muscles. Given that power produced during lifting tasks or trunk rotations plays an important role in most sport-specific and daily life activities, its measurement should represent an important part of the test battery in both athletes and the general population. The aim of this scoping review was 1) to map the literature related to testing methods assessing core muscle strength and stability in sport and rehabilitation, chiefly studies with particular focus on force-velocity-power characteristics of exercises involving the use of core muscles, 2) and to identify gaps in existing studies and suggest further research in this field. The literature search was conducted on Cochrane Library databases, Scopus, Web of Science, PubMed and MEDLINE, which was completed by SpringerLink, Google Scholar and Elsevier. The inclusion criteria were met in 37 articles. Results revealed that among a variety of studies investigating the core stability and core strength in sport and rehabilitation, only few of them analyzed force-velocity-power characteristics of exercises involving the use of core muscles. Most of them evaluated maximal isometric strength of the core and its endurance. However, there are some studies that assessed muscle power during lifting tasks at different loads performed either with free weights or using the Smith machine. Similarly, power and velocity were assessed during trunk rotations performed with different weights when standing or sitting. Nevertheless, there is still scant research investigating the power-velocity and force-velocity relationship during exercises engaging core muscles in able-bodied and para athletes with different demands on stability and strength of the core. Therefore, more research is needed to address this gap in the literature and aim research at assessing strength and power-related measures within cross-sectional and intervention studies. A better understanding of the power-force-velocity profiles during exercises with high demands on the core musculature has implications for designing sport training and rehabilitation programs for enhancement of athletes' performance and/or decrease their risk of back pain.

Asymmetric atrophy of the multifidus in persons with hemiplegic presentation post-stroke

Objective: To identify the asymmetry of fatty infiltration and cross-sectional areas (CSAs) of individual paravertebral muscles in persons with hemiplegic presentation post-stroke.Methods: We retrospectively reviewed 26 patients with unilateral hemiplegia who underwent lumbar magnetic resonance imaging post-stroke. CSAs and functional CSAs (FCSAs) of individual paraspinal muscles (multifidus, erector spinae, quadratus lumborum, and psoas major) at the mid-disc level were bilaterally measured from L1-L2 to L5-S1 on T2-weighted lumbar axial images. The FCSA-to-total CSA ratio of each paraspinal muscle was also calculated. These parameters were compared between the more-affected and less-affected sides, and between the less chronic and chronic phases.Results: FCSA (p = .049) and FCSA-to-total CSA ratio (p = .044) were significantly smaller at the L5-S1 multifidus on the more-affected side than on the less-affected side in the chronic phase. Other muscles showed no meaningful changes. The erector spinae on the more-affected side and the multifidus on the less-affected side significantly increased in size in the chronic phase compared with the less chronic phase.Conclusions: Persons with hemiplegic presentation may have unilateral atrophy and fatty infiltration of the multifidus on the more-affected side during the chronic phase. The comparison between the less chronic and chronic phases suggested that the recovery pattern of the trunk muscles could differ between sides in unilateral hemiplegia: increased size of the multifidus, a tonic stabilizer, on the less-affected side and of the erector spinae, a phasic muscle, on the more-affected side. This finding could be applied to trunk rehabilitation strategies for persons post-stroke.

Pelvic floor muscle function and urinary incontinence in the female athlete

Urinary incontinence, defined as involuntary leakage of urine, is often considered a disorder of post-partum and post-menopausal women. However, this disorder is not exclusive to older women, as recent research has demonstrated a high prevalence of urinary incontinence among young, nulliparous female athletes. In fact, females participating in repetitive, high-impact sports are at the highest risk for urinary incontinence. In these athletes, the absence of sufficient pelvic floor strength and coordination to withstand sport related increases in intra-abdominal pressure results in physical activity related urinary incontinence, and may be a predictor of urinary incontinence in later adulthood. Pelvic floor dysfunction and urinary incontinence in this population is under-reported and consequently under-diagnosed and under-treated. Therefore, the prevalence is higher than one might expect, and the effects can include decreased performance, change in sport and avoidance of physical activity all together. This manuscript highlights the prevalence of pelvic floor dysfunction and outlines its pathophysiology, diagnosis, treatment, and rehabilitation. We discuss how greater recognition of this disorder by health care providers and routinely querying active females is a critical step in addressing this issue. Identification, education and appropriate rehabilitation can positively affect outcomes in regards to urinary incontinence symptoms and maintain physical activity participation in these athletes.

Lumbar Muscle Cross-Sectional Areas Do Not Predict Clinical Outcomes in Adults With Spinal Stenosis: A Longitudinal Study

BACKGROUND

Minimal longitudinal data exist regarding the role of lumbar musculature in predicting back pain and function. In cross-sectional study designs, there is often atrophy of the segmental multifidus muscle in subjects with low back pain compared with matched controls. However, the cross-sectional design of these studies prevents drawing conclusions regarding whether lumbar muscle characteristics predict or modify future back pain or function.

OBJECTIVE

The primary objective of this study is to determine whether the cross-sectional area (CSA) of lumbar muscles predict functional status or back pain at 6- or 12-month follow-up in older adults with spinal degeneration. The secondary objective is to evaluate whether these muscle characteristics improve outcome prediction above and beyond the prognostic information conferred by demographic and psychosocial variables.

DESIGN

Secondary analysis of a randomized controlled trial.

PARTICIPANTS

A total of 209 adults aged 50 years and older with clinical and radiographic spinal stenosis from the Lumbar Epidural steroid injection for Spinal Stenosis (LESS) trial.

METHODS

Using baseline magnetic resonance images, we calculated CSAs of the lumbar multifidus, psoas, and quadratus lumborum muscles using a standardized protocol by manually tracing the borders of each of the muscles. The relationship between lumbar muscle CSAs and baseline measures was assessed with Pearson or Spearman correlation coefficients. The relationship between lumbar muscle characteristics and 6- and 12-month Roland Morris Disability Questionnaire (RDQ) and back pain Numeric Rating Scale (NRS) responses was further evaluated with multivariate linear regression. A hierarchical approach to the regression was performed: a basic model with factors of conceptual importance including age, gender, BMI, and baseline RDQ score formed the first step. The second and third steps evaluated whether psychosocial variables or muscle measures conferred additional prognostic information to the basic model.

MAIN OUTCOME MEASURES

Function as measured by the RDQ and back pain as measured by the NRS at 6- and 12-month follow-up.

RESULTS

Lumbar muscle CSA was not a significant predictor of 6- or 12-month RDQ or pain score in multivariate analyses.

CONCLUSIONS

Cross-sectional areas of lumbar muscles do not predict function or pain at medium- and long-term follow-up in adults with lumbar spinal stenosis.

LEVEL OF EVIDENCE

III.

The effect of lumbar support on the ultrasound measurements of trunk muscles: a single-blinded randomized controlled trial

OBJECTIVES

To evaluate the effect of lumbopelvic belts on the thickness of lateral abdominal muscles and the cross-sectional area (CSA) of lumbar multifidus (LM) muscles.

DESIGN

A single-blinded randomized controlled trial.

SETTING

An academic and tertiary care referral spine and sports medicine center.

PARTICIPANTS

Sixty healthy volunteers with no history of low back pain in the previous year.

METHODS

The subjects were allocated into belt and control groups. Lumbar belts were given to the subjects in the belt group, and they were asked to use the belts during the study period except during sleeping hours. The subjects were assessed at baseline and at 4 and 8 weeks.

MAIN OUTCOME MEASURES

The thickness of lateral abdominal muscles and the CSA of the LM muscles were measured by ultrasound with the patient in the hook-lying position on an examination table.

RESULTS

The thickness of lateral abdominal muscles and the CSA of LM muscles on both sides decreased significantly among healthy subjects in the belt group after 8 weeks.

CONCLUSION

The results of this study show that lumbopelvic belts might influence the ultrasonographic measurements of lateral abdominal and LM muscles and thereby spine stability.