Longitudinal study of risk factors for decreased cross-sectional area of psoas major and paraspinal muscle in 1849 individuals

Prevalence of Osteoporosis and Sarcopenia in Middle-Aged Subjects with Low Back Pain

Objective  The genesis of both osteoporosis and sarcopenia is multifactorial, complicated, and interrelated. The present study has been undertaken to analyze the prevalence of low bone mineral density (BMD) and the pattern of imaging markers of sarcopenia (paraspinal skeletal muscle area [SMA] and skeletal muscle index [SMI] with respect to clinicodemographic profile in middle-aged patients (30-45 years) undergoing evaluation for low back pain (LBP). Materials and Methods  Magnetic resonance imaging (MRI) of the lumbosacral spine and/or sacroiliac joints was done on 3T MRI. BMD of the lumbar spine (L1 to L4) was assessed using a dual-energy X-ray absorptiometry scan. SMA was calculated by measuring the cross-sectional area of paraspinal muscles (bilateral psoas, erector spinae, and multifidus), and SMI was calculated by dividing SMA by height 2 . Results  The prevalence of osteoporosis was 12.1% in patients of age 30 to 45 years presenting with LBP. Both osteoporosis and paraspinal muscle mass were statistically associated with the duration of symptoms ( p -value <0.05). No statistically significant difference was observed in different MRI findings, that is, normal, inflammatory, infective, and degenerative etiology. Conclusion  Low BMD and loss of muscle mass in cases with LBP are more related to duration of disease rather than etiology or gender in middle-aged subjects. Early intervention to manage LBP may prevent progression to osteoporosis and sarcopenia in young adults.

Association between modifiable and nonmodifiable risk factors with paralumbar muscle health in patients with lower back pain

Background

Prior studies have linked sarcopenia and fat infiltration in paraspinal muscles with lumbar pain, spinal pathology, and adverse postoperative outcomes in lumbar spine surgery. A recent magnetic resonance imaging (MRI)-based method for assessing muscle health, incorporating parameters such as Goutallier Classification (GC) and the Paralumbar Muscle Cross-Sectional Area to Body Mass Index ratio (PL-CSA/BMI), has shown that higher muscle grades correlate with significant improvements in patient-reported outcomes. Despite these advancements, there is limited research on the associations between paralumbar muscle health and factors such as age, BMI, walking tolerability, and spondylolisthesis. Our study aimed to evaluate such associations.

Methods

This Institutional Review Board-approved retrospective cohort study included patients aged 18 or older presenting with back pain symptoms who underwent lumbar spine MRI within 12 months of presentation to a single orthopedic surgeon. Patients with incomplete imaging, cancer pathology, or trauma-induced injuries were excluded. MRI-based measurements of Lumbar Indentation Value (LIV), Goutallier Classification (GC), and PL-CSA/BMI were used as outcome measures. Paralumbar muscles on axial T2-weighted lumbar MRIs were outlined using ImageJ to determine the PL-CS and LIV through the L1-L5 disc spaces, with GC classified by the primary author. Quantile regression analysis was used for continuous variables, and negative binomial regression with an estimated ancillary parameter was applied for ordinal variables, with statistical significance set at p<.05.

Results

Our analysis found that increasing age was associated with increased GC, decreased PL-CSA, and CSA/BMI at all lumbar levels. Age was associated with increased LIV at L1/L2. We found that increasing BMI was associated with increased LIV and PL-CSA and decreased CSA/BMI at all lumbar levels while it was only associated with increased GC at L1/L2, L2/L3 and L3/L4. Higher grade spondylolisthesis was associated with worse GC at all lumbar spinal levels except L3/L4 and with decreased LIV at L1/L2. An inability to walk > 1 block predicted LIV and GC at L2/L3 while predicting CSA/BMI at L4/L5. Increasing age was associated with decreased CSA at L1/L2, L2/L3 and L4/L5 while it was associated with decreased CSA/BMI and increased GC at all lumbar levels. Age was only associated with decreased LIV at L1/L2, L2/L3. Lastly, increasing BMI was associated with increased CSA, LIV, and decreased CSA/BMI at all lumbar levels and associated with increased GC at all lumbar levels except L4/L5. All statistically significant associations had p-values<.05.

Conclusions

Our analysis determined that increasing age, increased BMI, spondylolisthesis, and walking intolerability are significantly associated with poor paralumbar muscle health. Alongside these findings we discovered that increased age, BMI, spondylolisthesis and walking intolerability were significantly associated with varying degrees of increased Goutallier classification and LIV. Future research is required to determine whether there can be individual alterations in paralumbar muscle health following changes in modifiable risk factors. Additionally future efforts should focus on elucidating the impact of the underlying mechanism behind certain nonmodifiable risk factors such as age on Goutallier classification and poorer paralumbar muscle health.

Sarcopenia Predicts the Development of Early Adjacent Segment Disease After Transforaminal Lumbar Interbody Fusion

BACKGROUND AND OBJECTIVES

Predicting the development of adjacent segment disease (ASD) after lumbar spine fusion would help guide preoperative and postoperative therapies to prevent reoperation. We sought to evaluate whether sarcopenia predicts the development of early ASD after transforaminal lumbar interbody fusion (TLIF).

METHODS

Retrospective data were collected from 109 patients who underwent TLIF from 2013 to 2023. Patients older than 18 years who underwent elective posterior midline approach TLIF were included. Patients with prior lumbar instrumented fusions, cases of trauma, central nervous system infection, cancer, or long-construct thoracolumbar deformity corrections and those who lacked sufficient follow-up were excluded. The primary outcome was radiographic ASD development within 3 years of surgery. Psoas volumetric measurements were recorded from the most recent preoperative MRI. Odds ratios were calculated with logistic regression analyses.

RESULTS

In 109 patients undergoing elective TLIF, 22 (20.2%) developed ASD within 3 years. Gender, body mass index, and extent of surgery were not associated with ASD development. Multivariate analysis showed left/right psoas cross-sectional area, and psoas:vertebral body ratio (P:VBR) predicted early ASD (P < .0001). Sarcopenia was further categorized as having bilateral P:VBR ≥1 SD below gender mean (T-score -1). Of 18 sarcopenic patients, 15 developed early ASD (83.33%) vs 7 of 91 nonsarcopenic patients (7.69%; P < .0001). Postoperative mismatch between pelvic incidence and lumbar lordosis was predictive of ASD on univariate (P = .0480) but not multivariate analysis. Pelvic tilt and lumbar lordosis postoperatively were not associated with early ASD.

CONCLUSION

Sarcopenia, measured by decreased psoas area and P:VBR, predicts ASD formation within 3 years of surgery. Morphometric analysis of psoas size is a simple tool to identify patients at risk of developing ASD. This information can potentially guide preoperative and postoperative therapies, affect surgical decision making, and effectively counsel patients on risks of reoperation.

Vertebral bone quality score was associated with paraspinal muscles fat infiltration, but not modic classification in patients with chronic low back pain: a prospective cross-sectional study

BACKGROUND

The lumbar vertebra and paraspinal muscles play an important role in maintaining the stability of the lumbar spine. Therefore, the aim of this study was to investigate the relationship between paraspinal muscles fat infiltration and vertebral body related changes [vertebral bone quality (VBQ) score and Modic changes (MCs)] in patients with chronic low back pain (CLBP).

METHODS

Patients with CLBP were prospectively collected in four hospitals and all patients underwent 3.0T magnetic resonance scanning. Basic clinical information was collected, including age, sex, course of disease (COD), and body mass index (BMI). MCs were divided into 3 types based on their signal intensity on T1 and T2-weighted imaging. VBQ was obtained by midsagittal T1-weighted imaging (T1WI) and calculated using the formula: SIL1-4/SICSF. The Proton density fat fraction (PDFF) values and cross-sectional area (CSA) of paraspinal muscles were measured on the fat fraction map from the iterative decomposition of water and fat with the echo asymmetry and least-squares estimation quantitation (IDEAL-IQ) sequences and in/out phase images at the central level of the L4/5 and L5/S1 discs.

RESULTS

This study included 476 patients with CLBP, including 189 males and 287 females. 69% had no Modic changes and 31% had Modic changes. There was no difference in CSA and PDFF for multifidus(MF) and erector spinae (ES) at both levels between Modic type I and type II, all P values>0.05. Spearman correlation analysis showed that VBQ was weakly negatively correlated with paraspinal muscles CSA (all r values < 0.3 and all p values < 0.05), moderately positive correlation with PDFF of MF at L4/5 level (r values = 0.304, p values<0.001) and weakly positively correlated with PDFF of other muscles (all r values<0.3 and all p values<0.001). Multivariate linear regression analysis showed that age (β = 0.141, p < 0.001), gender (β = 4.285, p < 0.001) and VBQ (β = 1.310, p = 0.001) were related to the total PDFF of muscles. For MCs, binary logistic regression showed that the odds ratio values of age, BMI and COD were 1.092, 1.082 and 1.004, respectively (all p values ＜  0.05).

CONCLUSIONS

PDFF of paraspinal muscles was not associated with Modic classification. In addition to age and gender, PDFF of paraspinal muscles is also affected by VBQ. Age and BMI are considered risk factors for the MCs in CLBP patients.

Low Daily Step Count Associated with Small Erector Spinae Muscle Area and Sarcopenia in Idiopathic Pulmonary Fibrosis

Objective The daily step count is associated with mortality in idiopathic pulmonary fibrosis (IPF). However, the factors associated with this phenomenon are not yet fully understood. We therefore clarified its association with clinical parameters. Methods Fifty-nine patients with IPF with available data for daily step counts; 6-minute walk distance (6MWD); chest, abdominal, and pelvic computed tomography (CT); pulmonary function; psychological evaluations; and sarcopenia assessments were prospectively enrolled. The daily step count was measured continuously for seven consecutive days. The cross-sectional areas of the erector spinae muscles at the level of the 12th vertebra (ESMCSA) and psoas major muscle volume (PMV) obtained by CT were assessed. Results The average age of the patients was 73.3±8.1 years old, and the percent predicted forced vital capacity was 81.6%±15.8%. The median daily step count was 4,258 (2,155-6,991) steps. The average 6MWD, ESMCSA, and PMV were 413±97 m, 25.5±6.7 cm2, and 270±75.6 cm3, respectively. A linear regression analysis for daily step count showed that the ESMCSA and 6MWD were independent factors for the daily step count, whereas the PMV and skeletal muscle index were not. The daily step count, ESMCSA, and 6MWD were lower in patients with sarcopenia than in those without sarcopenia. Conclusion A lower daily step count was associated with a smaller erector spinae muscle area and sarcopenia in patients with IPF. Further studies are warranted to confirm the importance of physical therapy for muscle strengthening in patients with IPF.

Evaluation of the association between osteoporotic vertebral compression fractures and psoas major/paraspinal muscle mass and ADC measured on MRI

OBJECTIVE

Evaluate magnetic resonance imaging factors associated with osteoporotic vertebral compression fractures.

MATERIALS AND METHODS

We retrospectively reviewed 457 patients' records. Age, sex, and body mass index were recorded. Two blinded readers measured psoas major and paraspinal muscle areas at the L3 vertebral body level on transverse T2-weighted magnetic resonance images and the mean apparent diffusion coefficient values of the non-fractured vertebrae from Th12 to L5. Inter-reader reliability for continuous variables was assessed by intraclass correlation coefficients.

RESULTS

We evaluated 210 patients (103 [49.0%] men). The osteoporotic vertebral compression fractures group was older and had lower BMI and smaller psoas major and paraspinal muscle areas than the group without vertebral compression fractures (p < 0.001). The mean apparent diffusion coefficient was weakly correlated with paraspinal muscle area in the osteoporotic vertebral compression fractures group. The intraclass correlation coefficient value was 0.83, and the intraclass correlation coefficients of the psoas major and paraspinal muscles were 0.94 and 0.97, respectively. Multivariate analysis revealed that decreased psoas major and paraspinal muscle areas and increased mean apparent diffusion coefficient values were significantly associated with the presence of osteoporotic vertebral compression fractures (all p < 0.05). Psoas major and paraspinal muscle areas showed relatively high predictive accuracy (57%, 61%).

CONCLUSION

Psoas major and paraspinal muscle areas at the L3 level and the mean apparent diffusion coefficient value of non-fractured vertebrae from the Th12 to L5 level were associated with osteoporotic vertebral compression fractures. This may contribute to detecting the potential risk of healthy individuals developing osteoporotic vertebral compression fractures.

Psoas muscle index and psoas muscle density are associated with functional status in patients with degenerative lumbar spinal stenosis

BACKGROUND

The factors affecting lumbar spinal function in patients with degenerative lumbar spinal stenosis (DLSS) are still unclear.

OBJECTIVE

This study explored psoas major muscle morphology in patients with DLSS and its association with their functional status.

METHODS

A retrospective study was conducted on 288 patients with DLSS and 260 control subjects. Psoas major muscle evaluation included three morphometric parameters at the L3/4 disc level: psoas major index (PMI), muscle attenuation, and psoas major morphological changes (MPM). The association between psoas major morphology and functional status was assessed using the Oswestry disability index (ODI).

RESULTS

Both female and male patients with DLSS had a higher PMI and lower muscle attenuation. PMI and muscle attenuation were inversely correlated with age in the DLSS group. After multivariable analyses, the PMI and psoas major muscle attenuation were positively correlated with patients' functional status.

CONCLUSION

The PMI and muscle attenuation were positively correlated with functional status in patients with DLSS. These findings have important implications for physiotherapy programs of postoperative rehabilitation and conservative management of DLSS.

Cumulative Experience of Neighborhood Walkability and Change in Weight and Waist Circumference in REGARDS

Neighborhood walkability-features of the built environment that promote pedestrian activity-has been associated with greater physical activity and lower body mass index (BMI; calculated as weight (kg)/height (m)2) among neighborhood residents. However, much of the literature has been cross-sectional and only a few cohort studies have assessed neighborhood features throughout follow-up. Using data from the Reasons for Geographic and Racial Differences in Stroke Study (2003-2016) and a neighborhood walkability index (NWI) measured annually during follow-up, we assessed whether the cumulative experience of neighborhood walkability (NWI-years) predicted BMI and waist circumference after approximately 10 years of follow-up, controlling for these anthropometric measures at enrollment. Analyses were adjusted for individual-level sociodemographic covariates and the cumulative experience of neighborhood poverty rate and neighborhood greenspace coverage. Almost a third (29%) of participants changed address at least once during follow-up. The first change of residence, on average, brought the participants to neighborhoods with higher home values and lower NWI scores than their originating neighborhoods. Compared with those having experienced the lowest quartile of cumulative NWI-years, those who experienced the highest quartile had 0.83 lower BMI (95% confidence interval, -1.5, -0.16) and 1.07-cm smaller waist circumference (95% confidence interval, -1.96, -0.19) at follow-up. These analyses provide additional longitudinal evidence that residential neighborhood features that support pedestrian activity are associated with lower adiposity.

Lumbar paraspinal muscle morphology is associated with spinal degeneration in patients with lumbar spinal stenosis

BACKGROUND CONTEXT

Lumbar spinal stenosis (LSS) has been reported to induce changes in paraspinal muscle morphology, but objective physical function and degenerative spine conditions are rarely assessed.

PURPOSE

To identify factors associated with paraspinal muscle morphology using objective physical and degenerative spine assessments in patients with LSS.

STUDY DESIGN/SETTING

Cross-sectional design.

PATIENT SAMPLE

Seventy patients with neurogenic claudication caused by LSS, receiving outpatient physical therapy.

OUTCOME MEASURES

Cross-sectional area (CSA) and functional CSA (FCSA) of the multifidus, erector spinae, and psoas muscles, the severity of stenosis, disc degeneration, and endplate abnormalities were evaluated by magnetic resonance imaging, as well as sagittal spinopelvic alignment by X-ray. Objective physical assessments included pedometry and claudication distance. Patient-reported outcomes included the numerical rating scale of low back pain, leg pain, and leg numbness, and the Zurich Claudication Questionnaire.

METHODS

To assess the impact of LSS on paraspinal muscles, FCSA and FCSA/CSA were compared between the dominant and nondominant sides based on the patients' neurogenic symptoms, and multivariable regression analyses adjusted for age, sex, height, and weight were performed; p<.05 was considered significant.

RESULTS

Seventy patients were analyzed. At one level below the maximum stenotic level, erector spinae FCSA on the dominant side was significantly lower than that on the nondominant side. In the multivariable regression analyses, at one level below the symptomatic level, disc degeneration, endplate abnormalities, and lumbar spinopelvic alignment, such as decreased lumbar lordosis and increased pelvic tilt, were negatively associated with multifidus FCSA and FCSA/CSA ratio. A significant association was observed between dural sac CSA and erector spinae FCSA. Throughout L1/2 to L5/S, disc degeneration, endplate abnormalities, and lumbar spinopelvic alignment were negatively associated with multifidus and erector spinae FCSA or FCSA/CSA.

CONCLUSIONS

Lumbar paraspinal muscle asymmetry caused by LSS was observed only in erector spinae. Disc degeneration, endplate abnormalities, and lumbar spinopelvic alignment, rather than spinal stenosis and LSS symptoms, were more associated with paraspinal muscle atrophy or fat infiltration.

Risk Factors in Patients with Low Back Pain Under 40 Years Old: Quantitative Analysis Based on Computed Tomography and Magnetic Resonance Imaging mDIXON-Quant

Purpose

While low back pain (LBP) constitutes a global life disorder cause, the contribution of paraspinal muscles to its pathogenicity remains elusive. We characterized the paraspinal muscles of patients with LBP using lumbar three-dimensional computed tomography (CT) and magnetic resonance imaging (MRI) mDIXON-Quant, and evaluated the risk factors combined with clinical data.

Methods

A retrospective study involving 181 patients (10-40 years) who underwent lumbar 3D-CT and MRI mDIXON from January 1, 2021 to December 31, 2022, and divided into normal, non-chronic LBP [non-CLBP], and CLBP groups. Clinical data, paraspinal muscle cross-sectional area, Hounsfield unit for CT values, and fat fraction derived from mDIXON-Quant were compared. Three readers analyzed the images independently; intra- and interobserver agreement was measured. Spearman analysis and multiple logistic regression were used to analyze the correlation between clinical data, radiologic and paraspinal muscle parameters. A nomogram was constructed for individualized prediction.

Results

Correlation analysis revealed that body mass index, visual analog scale score, Pfirrmann grade, annulus fibrosus tear, lumbar lordosis (LL), and Modic changes correlated with LBP (all P<0.05). The Pfirrmann grade and annulus fibrosus tear showed positive correlation (r=0.673, 0.559), whereas LL was negatively correlated (r=-0.469). The multifidus CT values were negatively correlated with LBP at L4-5/L5-S1; the multifidus fat fraction was positively correlated at L4-5/L5-S1 (r=0.734, r=0.584, P<0.001). The multiple logistic regression showed that L4-5 multifidus fat fraction (P=0.046, OR=1.167), Pfirrmann grade (P=0.017, OR=0.063), LL (P=0.002, OR=0.828) and annulus fibrosus tear (P=0.005, OR=0.024) were risk factors for predicting LBP in the non-CLBP group; in the CLBP group, BMI (P=0.048 OR=1.225), L4-5 multifidus fat fraction (P=0.001 OR=1.299), LL (P=0.003, OR=0.841) and Pfirrmann classification (P=0.009, OR=0.046) were risk factors.

Conclusion

BMI, L4-5 multifidus fat fraction, LL, and Pfirrmann grade are risk factors for CLBP in patients under 40; whereas annulus fibrosus tear is an independent risk factor for non-CLBP, nomograms derived from these parameters can help predict LBP and MRI mDIXON-Quant is recommended for quantitatively analyzing paraspinal muscle fat infiltration.

Changes of the posterior paraspinal and psoas muscle in patients with low back pain: a 3-year longitudinal study

PURPOSE

This study aimed to investigate the changes of the posterior paraspinal muscles (PPM) and psoas muscle in patients with low back pain (LBP) over time.

METHODS

Patients with LBP who had a repeat lumbar MRI with a minimum of 3-years apart at a tertiary referral center were analyzed. MRI-based quantitative assessments of the PPM and the psoas muscle were conducted for the baseline and follow-up MRI. The cross sectional area (CSA), the functional cross sectional area (fCSA) and the fat area (FAT) were calculated using a dedicated software program. The fatty infiltration (FI,%) of the regions of interest was calculated. Differences between the 1st and 2nd MRI were calculated for all assessed muscular parameters.

RESULTS

A total of 353 patients (54.4%female) with a median age of 60.1 years and BMI of 25.8 kg/m2 at baseline were analyzed. The mean time between the 1st and 2nd MRI was 3.6 years. The fCSAPPM declined in both sexes significantly from the 1st to the 2nd MRI, whereas the FATPPM increased. In line with this result, the FIPPM increased in both males (29.9%) and females (19.4%). Females had a higher FIPPM and FIPsoas than males in both MRIs. In females, no significant changes were found for the psoas muscle. The CSAPsoas and fCSAPsoas in males were significantly smaller in the 2nd MRI. With increasing age, a significant trend in a decrease in ∆FIPPM was observed for both sexes.

CONCLUSION

The study revealed significant quantitatively muscular changes in males and females, especially in the posterior paraspinal muscles in only three years' time.

Are serum thyroid hormone, parathormone, calcium, and vitamin D levels associated with lumbar spine degeneration? A cross-sectional observational clinical study

PURPOSE

Low back pain (LBP) impairs the quality of life and rises healthcare costs. The association of spine degeneration and LBP with metabolic disorders have been reported, previously. However, metabolic processes related with spine degeneration remained unclear. We aimed to analyze whether serum thyroid hormones, parathormone, calcium, and vitamin D levels were associated with lumbar intervertebral disc degeneration (IVDD), Modic changes, and fatty infiltration in the paraspinal muscles.

METHODS

We cross-sectionally analyzed a retrospective database. Patients who visited internal medicine outpatient clinics with suspect of endocrine disorders and chronic LBP were searched. Patients with biochemistry results within 1 week before lumbar spine magnetic resonance imaging (MRI) were included. Age- and gender-matched cohorts were made-up and analyzed.

RESULTS

Patients with higher serum free thyroxine levels were more likely to have severe IVDD. They were also more likely to have fattier multifidus and erector spinae at upper lumbar levels, less fatty psoas and less Modic changes at lower lumbar levels. Higher PTH levels were observed in patients with severe IVDD at L4-L5 level. Patients with lower serum vitamin D and calcium levels had more Modic changes and fattier paraspinal muscles at upper lumbar levels.

CONCLUSION

Serum hormone, vitamin D, and calcium levels were associated with not only IVDD and Modic changes but also with fatty infiltration in the paraspinal muscles, mainly at upper lumbar levels in patients with symptomatic backache presenting to a tertiary care center. Complex inflammatory, metabolic, and mechanical factors present in the backstage of spine degeneration.

Skeletal muscle atrophy and short-term mortality in patients with acute exacerbation of idiopathic pulmonary fibrosis: an observational cohort study

BACKGROUND

Skeletal muscle atrophy, a common complication of idiopathic pulmonary fibrosis (IPF), and its presence upon diagnosis can indicate a poor prognosis. Patients with IPF frequently experience acute exacerbations (AE), which is associated with a high mortality rate. However, the association between skeletal muscle atrophy and short-term mortality remains unknown.

METHODS

We performed a retrospective, multicenter cohort study of patients admitted for AE-IPF in Japan. The cross-sectional areas of the erector spinae muscle (ESM_CSA) and the pectoralis muscle (PM_CSA) were analyzed via single-slice computed tomography (CT). The primary outcome was 90-day mortality. Survival probability was estimated using the Kaplan-Meier method, and the log-rank test was used between the low and high groups of ESM_CSA and PM_CSA. We used multivariable Cox proportional-hazards models to evaluate the association between ESM_CSA and PM_CSA and prognosis.

RESULTS

Of the 212 patients included, 94 (44%) died during the observation period. The low ESM_CSA group (<25.6 cm²) had a significantly worse prognosis than that of the high ESM_CSA group (≥25.6 cm²) (hazard ratio (HR) [95% confidence interval (CI)]: 1.52 [1.00-2.33], P = 0.049). Multivariable analyses showed that all-cause mortality was associated with low ESM_CSA (model 1, adjusted HR [95% CI]: 1.59 [0.98-2.60]; model 2, 1.55 [0.95-2.56], and model 3, 1.67 [1.00-2.78], respectively). The adjusted HR of low PM_CSA (<20.4 cm²) vs. high PM_CSA (≥20.4 cm²) was 1.39 (95% CI: 0.88-2.20).

CONCLUSIONS

Low ESM_CSA on CT images is associated with a high 90-day mortality rate in patients with AE-IPF.

Human skeletal muscle-specific atrophy with aging: a comprehensive review

Age-related skeletal muscle atrophy appears to be a muscle group-specific process, yet only a few specific muscles have been investigated and our understanding in this area is limited. This review provides a comprehensive summary of the available information on age-related skeletal muscle atrophy in a muscle-specific manner, nearly half of which comes from the quadriceps. Decline in muscle-specific size over ∼50 yr of aging was determined from 47 cross-sectional studies of 982 young (∼25 yr) and 1,003 old (∼75 yr) individuals and nine muscle groups: elbow extensors (-20%, -0.39%/yr), elbow flexors (-19%, -0.38%/yr), paraspinals (-24%, -0.47%/yr), psoas (-29%, -0.58%/yr), hip adductors (-13%, -0.27%/yr), hamstrings (-19%, -0.39%/yr), quadriceps (-27%, -0.53%/yr), dorsiflexors (-9%, -0.19%/yr), and triceps surae (-14%, -0.28%/yr). Muscle-specific atrophy rate was also determined for each of the subcomponent muscles in the hamstrings, quadriceps, and triceps surae. Of all the muscles included in this review, there was more than a fivefold difference between the least (-6%, -0.13%/yr, soleus) to the most (-33%, -0.66%/yr, rectus femoris) atrophying muscles. Muscle activity level, muscle fiber type, sex, and timeline of the aging process all appeared to have some influence on muscle-specific atrophy. Given the large range of muscle-specific atrophy and the large number of muscles that have not been investigated, more muscle-specific information could expand our understanding of functional deficits that develop with aging and help guide muscle-specific interventions to improve the quality of life of aging women and men.

Muscle group-specific skeletal muscle aging: a 5-yr longitudinal study in septuagenarians

There is some evidence that the age-associated change in skeletal muscle mass is muscle specific, yet the number of specific muscles that have been studied to form our understanding in this area is limited. In addition, few aging investigations have examined multiple muscles in the same individuals. This longitudinal investigation compared changes in skeletal muscle size via computed tomography of the quadriceps (rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius), hamstrings (biceps femoris short and long heads, semitendinosus, and semimembranosus), psoas, rectus abdominis, lateral abdominals (obliques and transversus abdominis), and paraspinal muscles (erector spinae and multifidi) of older individuals from the Health, Aging, and Body Composition (Health ABC) study at baseline and 5.0 ± 0.1 years later (n = 469, 73 ± 3 yr and 78 ± 3 yr, 49% women, 33% black). Skeletal muscle size decreased (P < 0.05) in quadriceps (-3.3%), hamstrings (-5.9%), psoas (-0.4%), and rectus abdominis (-7.0%). The hamstrings and rectus abdominis atrophied approximately twice as much as the quadriceps (P < 0.05), whereas the quadriceps atrophied substantially more than the psoas (P < 0.05). The lateral abdominals (+5.9%) and paraspinals (+4.3%) hypertrophied (P < 0.05) to a similar degree (P > 0.05) over the 5 years. These data suggest that older individuals experience skeletal muscle atrophy and hypertrophy in a muscle group-specific fashion in the eighth decade, a critical time period in the aging process. A broader understanding of muscle group-specific skeletal muscle aging is needed to better guide exercise programs and other interventions that mitigate decrements in physical function with aging.NEW & NOTEWORTHY These longitudinal analyses of six muscle groups in septuagenarians provide novel information on the muscle group-specific aging process. Although the quadriceps, hamstrings, psoas, and rectus abdominis atrophied with different magnitudes, the lateral abdominals and paraspinals hypertrophied over the 5 years. These findings contribute to a better understanding of the skeletal muscle aging process and highlight the need to complete studies in this area with a muscle-specific focus.

Age- and sex-dependent differences in the morphology and composition of paraspinal muscles between subjects with and without lumbar degenerative diseases

BACKGROUND

The quality of the paraspinal muscles has been recommended as a surrogate marker for the evaluation of the severity of the lumbar degenerative diseases (LDD). The purpose of this study is to determine the age- and sex-dependent differences in the morphology and composition of the paraspinal muscles between LDD and asymptomatic subjects.

METHODS

We analyzed data from 370 patients and 327 asymptomatic volunteers aged between 18-85 years. The measurement of the cross-sectional area (CSA) of the erector spinae, multifidus, and psoas at the L4/5-disc level was performed by the magnetic resonance imaging (MRI). The fatty infiltration ratio (FI %) of the multifidus and erector spinae was calculated.

RESULTS

FI % of the lumbar paraspinal muscles were significantly and positively correlated with the severity of LDD instead of the CSA. Males had greater CSA than females, and females showed higher FI % than males in the paraspinal muscles. With the increase of age, the CSA of the lumbar paraspinal muscles gradually decreased, and the psoas showed the most significant decreasing trend. However, the FI % gradually increased in both LDD and asymptomatic groups with aging.

CONCLUSION

Age- and sex-dependent differences were found in the morphology and composition of the paraspinal muscles between subjects with and without LDD. Further long-term follow up investigations and basic studies will continue to confirm the natural history of the paraspinal muscles with aging and their association with LDD.

Influence of Spinal Movements Associated with Physical Evaluation on Muscle Mechanical Properties of the Lumbar Paraspinal in Subjects with Acute Low Back Pain

This research aimed to identify changes in muscle mechanical properties (MMPs) when a standardized sequence of movements is performed and to determine the influence of acute low back pain (LBP) and age on the MMPs. Socio-demographic, clinical variables and MMPs were collected in 33 patients with LBP and 33 healthy controls. A 2 × 2 × 2 (group × age × time) analysis of variance (ANOVA) mixed model was used to determine the effect of the study factors on the different MMPs. There were no significant triple interactions. After the movements, tone and stiffness increased 0.37 Hz and 22.75 N/m, respectively, in subjects <35 years, independent of their clinical status. Relaxation showed differences by age in healthy subjects and creep in LBP subjects. Furthermore, elasticity was higher in <35 years (p < 0.001) without the influence of any other factor. In conclusion, sequenced movements can modify tone and stiffness as a function of age, while age-associated changes in viscoelastic characteristics depends on pain but not on movements. The MMPs should be assessed, not only at the beginning of the physical examination at rest, but also along the patient's follow-up, depending on their pain and age, in a clinical setting.