Age-related site-specific muscle wasting of upper and lower extremities and trunk in Japanese men and women

The Plateau in Muscle Growth with Resistance Training: An Exploration of Possible Mechanisms

It is hypothesized that there is likely a finite ability for muscular adaptation. While it is difficult to distinguish between a true plateau following a long-term training period and short-term stalling in muscle growth, a plateau in muscle growth has been attributed to reaching a genetic potential, with limited discussion on what might physiologically contribute to this muscle growth plateau. The present paper explores potential physiological factors that may drive the decline in muscle growth after prolonged resistance training. Overall, with chronic training, the anabolic signaling pathways may become more refractory to loading. While measures of anabolic markers may have some predictive capabilities regarding muscle growth adaptation, they do not always demonstrate a clear connection. Catabolic processes may also constrain the ability to achieve further muscle growth, which is influenced by energy balance. Although speculative, muscle cells may also possess cell scaling mechanisms that sense and regulate their own size, along with molecular brakes that hinder growth rate over time. When considering muscle growth over the lifespan, there comes a point when the anabolic response is attenuated by aging, regardless of whether or not individuals approach their muscle growth potential. Our goal is that the current review opens avenues for future experimental studies to further elucidate potential mechanisms to explain why muscle growth may plateau.

Muscle ultrasound and its application to point-of-care ultrasonography: a narrative review

Technological advances of hand-held ultrasound devices and educational programmes for their use, such as point-of-care ultrasonography (POCUS) training, have contributed to the increasing application of these devices in clinical practice. With the greater impact of frailty and sarcopenia in aging societies, attention is being focused on the use of ultrasound for skeletal muscle assessment. In this narrative review, we discuss how ultrasound can be applied to skeletal muscle assessment, especially that of the quadriceps muscle, in clinical practice. Muscle thickness by ultrasound has been shown to have good reliability and validity for the evaluation of muscle size, and echo intensity has been used to evaluate muscle quality. Muscle ultrasound has not only been useful to diagnose sarcopenia in various settings, but has also been validated to predict health-related outcomes such as death and functional disability. Recommended methods for muscle ultrasound was published recently, and the results of future studies are expected to be comparable. Although several challenging issues with muscle ultrasound remain, if it could be incorporated into educational programmes such as POCUS training, more clinicians may be able to use ultrasound for skeletal muscle assessment in the future.KEY MESSAGESThe evolution of hand-held ultrasound devices enables physicians to perform ultrasound at the bedside as part of regular medical examinations.Muscle ultrasound is considered an effective tool for evaluating muscle size and quality, and has been studied in various settings.More clinicians may be able to evaluate skeletal muscle assessment with the development of educational programmes on muscle ultrasound in the future.

Superimposed electromyostimulation of the thigh muscles during passive isokinetic cycling increases muscle strength without effort

Objectives

This study was designed to investigate the effects of a completely passive isokinetic cycle (PIC) exercise with electromyostimulation (EMS) on improving muscle strength and the changes in kinesthesia during daily activities.

Methods

Twenty-nine sedentary females were divided into three groups. The EMS anterior and whole groups performed the PIC exercise without EMS 3 times a week for 3 weeks, followed by a 1-week break, and then performed it with EMS applied to the anterior and entire thigh muscles, respectively, 3 times a week for 3 weeks. The control group did not perform any training.

Results

The PIC exercise with EMS significantly increased the 30s chair stand test scores by 12-16% and the maximum isometric knee extension and flexion torques by 38-68% in both EMS-applied groups. The participants found its exercise easy and felt more comfortable with daily physical activities. The exercise without EMS did not show similar improvements. Muscle soreness was significantly greater in the EMS anterior group than in the EMS whole group; however, it was not severe.

Conclusions

The PIC exercise with EMS resulted in significant increases in muscle strength, facilitating a perceived ease of daily physical activities, while minimizing difficulties, effort, and notable muscle soreness.

Muscle performance in octogenarians: Factors affecting dynapenia

BACKGROUND

The muscle performance is associated with several health outcomes in adults, however modifiable and non-modifiable risk factors in octogenarians have not yet been fully investigated. The aim of this study was to analyze the potential risk factors that negatively affect muscle strength in octogenarians.

METHODS

This observational, descriptive, cross-sectional study included 87 older adult participants (56 women and 31 men) attending a geriatric clinic. General anthropometrics, health history, and body composition data were collected. Muscle strength was assessed by handgrip strength (HGS), appendicular skeletal muscle mass (ASMM) and the percentage of body fat were identified by Dual Energy X-ray Absorptiometry, and muscle quality index (MQI) was defined as the ratio of HGS by upper limbs ASMM. Multiple linear regression was conducted to determine predictive factors of the muscle strength.

RESULTS

Females had lower HGS (1.39 kg) than male participants (p = 0.034). An increase of one unit MQI was associated with an increase of 3.38 kg in the HGS (p = 0.001). Each additional year of age was associated with a decrease of 0.12 kg in the HGS (p = 0.047). Regarding ASMM, an increase of one unit was associated with an increase of 0.98 kg in the HGS (p = 0.001). There was no association between dynapenia, body fat percentage, diseases and polypharmacy (p > 0.05).

CONCLUSION

The gender, age, MQI, and ASMM influenced muscle strength of octogenarians. These intrinsic and extrinsic factors are relevant to improve our understanding of age-related complications and outline treatment guidance by healthcare professionals.

Value of conventional ultrasound and shear wave elastography in the assessment of muscle mass and function in elderly people with type 2 diabetes

OBJECTIVES

We assessed muscle mass and function using ultrasound (US) and shear wave elastography (SWE) for sarcopenia in elderly patients with type 2 diabetes.

METHODS

There were 84 patients with type 2 diabetes enrolled in this study; of these, 30 had sarcopenia and 54 did not. We measured appendicular skeletal muscle mass index (ASMI), handgrip strength, calf circumference, 6-m walking speed, and 5-time chair stand test. All patients were in the supine position with their knees in straight and bent poses in turn. The US-derived thickness (Tstraight, Tbent), cross-sectional area (CSAstraight, CSAbent), and SWE (SWEstraight, SWEbent) of the rectus femoris muscle (RFM) were measured and the differences (ΔT, ΔCSA, ΔSWE) were calculated. We assessed the correlations of clinical indicators with US and SWE features. We then compared the clinical indicators and US and SWE features between patients with and without sarcopenia to determine independent predictors. Diagnostic models were established based on these independent predictors.

RESULTS

The ASMI was correlated with Tbent (r = 0.57, p < 0.001) and CSAbent (r = 0.50, p < 0.001). Handgrip strength was correlated with Tbent (r = 0.53, p < 0.001) and CSAbent (r = 0.51, p < 0.001). Between patients with and without sarcopenia, the indicators of age, ΔCSA, and ΔSWE were statically different (all p ≤ 0.001). Based on these results, a diagnostic model for sarcopenia was established with 83.3% sensitivity, 83.3% specificity, and 83.3% accuracy.

CONCLUSIONS

In elderly people with type 2 diabetes, sarcopenia patients had smaller muscle CSA and less stiffness than non-sarcopenia patients. US and SWE might be useful to screen them.

KEY POINTS

• Sarcopenia is common in elderly people with type 2 diabetes. • Ultrasound and shear wave elastography might be useful methods for quantitatively assessing muscle mass and strength. • Ultrasound and shear wave elastography might be useful methods for screening sarcopenia in elderly patients with type 2 diabetes.

The effects of proprioceptive weighting changes on posture control in patients with chronic low back pain: a cross-sectional study

Introduction

Patients with chronic low back pain (CLBP) exhibit changes in proprioceptive weighting and impaired postural control. This study aimed to investigate proprioceptive weighting changes in patients with CLBP and their influence on posture control.

Methods

Sixteen patients with CLBP and 16 healthy controls were recruited. All participants completed the joint reposition test sense (JRS) and threshold to detect passive motion test (TTDPM). The absolute errors (AE) of the reposition and perception angles were recorded. Proprioceptive postural control was tested by applying vibrations to the triceps surae or lumbar paravertebral muscles while standing on a stable or unstable force plate. Sway length and sway velocity along the anteroposterior (AP) and mediolateral (ML) directions were assessed. Relative proprioceptive weighting (RPW) was used to evaluate the proprioception reweighting ability. Higher values indicated increased reliance on calf proprioception.

Results

There was no significant difference in age, gender, and BMI between subjects with and without CLBP. The AE and motion perception angle in the CLBP group were significantly higher than those in the control group (JRS of 15°: 2.50 (2.50) vs. 1.50 (1.42), JRS of 35°: 3.83 (3.75) vs. 1.67 (2.00), p_JRS < 0.01; 1.92 (1.18) vs. 0.68 (0.52), p_TTDPM < 0.001). The CLBP group demonstrated a significantly higher RPW value than the healthy controls on an unstable surface (0.58 ± 0.21 vs. 0.41 ± 0.26, p < 0.05). Under the condition of triceps surae vibration, the sway length (p_stable < 0.05; p_unstable < 0.001), AP velocity (p_stable < 0.01; p_unstable < 0.001) and ML velocity (p_unstable < 0.05) had significant group main effects. Moreover, when the triceps surae vibrated under the unstable surface, the differences during vibration and post vibration in sway length and AP velocity between the groups were significantly higher in the CLBP group than in the healthy group (p < 0.05). However, under the condition of lumbar paravertebral muscle vibration, no significant group main effect was observed.

Conclusion

The patients with CLBP exhibited impaired dynamic postural control in response to disturbances, potentially linked to changes in proprioceptive weighting.

Association of Sonographic Sarcopenia and Falls in Older Adults Presenting to the Emergency Department

BACKGROUND AND OBJECTIVE

To determine the association between point-of-care-ultrasonography (POCUS)-measured sarcopenia and grip strength, as well as the history of prior-year falls among older adults admitted to the emergency department observation unit (EDOU).

MATERIALS AND METHODS

This cross-sectional observational study was conducted over 8 months at a large urban teaching hospital. A consecutive sample of patients who were 65 years or older and admitted to the EDOU were enrolled in the study. Using standardized techniques, trained research assistants and co-investigators measured patients' biceps brachii and thigh quadriceps muscles via a linear transducer. Grip strength was measured using a Jamar Hydraulic Hand Dynamometer. Participants were surveyed regarding their history of falls in the prior year. Logistic regression analyses assessed the relationship of sarcopenia and grip strength to a history of falls (the primary outcome).

RESULTS

Among 199 participants (55% female), 46% reported falling in the prior year. The median biceps thickness was 2.22 cm with an Interquartile range [IQR] of 1.87-2.74, and the median thigh muscle thickness was 2.91 cm with an IQR of 2.40-3.49. A univariate logistic regression analysis demonstrated a correlation between higher thigh muscle thickness, normal grip strength, and history of prior-year falling, with an odds ratio [OR] of 0.67 (95% conference interval [95%CI] 0.47-0.95) and an OR of 0.51 (95%CI 0.29-0.91), respectively. In multivariate logistic regression, only higher thigh muscle thickness was correlated with a history of prior-year falls, with an OR of 0.59 (95% CI 0.38-0.91).

CONCLUSIONS

POCUS-measured thigh muscle thickness has the potential to identify patients who have fallen and thus are at high risk for future falls.

Narrative Review of Sex Differences in Muscle Strength, Endurance, Activation, Size, Fiber Type, and Strength Training Participation Rates, Preferences, Motivations, Injuries, and Neuromuscular Adaptations

ABSTRACT

Nuzzo, JL. Narrative review of sex differences in muscle strength, endurance, activation, size, fiber type, and strength training participation rates, preferences, motivations, injuries, and neuromuscular adaptations. J Strength Cond Res 37(2): 494-536, 2023-Biological sex and its relation with exercise participation and sports performance continue to be discussed. Here, the purpose was to inform such discussions by summarizing the literature on sex differences in numerous strength training-related variables and outcomes-muscle strength and endurance, muscle mass and size, muscle fiber type, muscle twitch forces, and voluntary activation; strength training participation rates, motivations, preferences, and practices; and injuries and changes in muscle size and strength with strength training. Male subjects become notably stronger than female subjects around age 15 years. In adults, sex differences in strength are more pronounced in upper-body than lower-body muscles and in concentric than eccentric contractions. Greater male than female strength is not because of higher voluntary activation but to greater muscle mass and type II fiber areas. Men participate in strength training more frequently than women. Men are motivated more by challenge, competition, social recognition, and a desire to increase muscle size and strength. Men also have greater preference for competitive, high-intensity, and upper-body exercise. Women are motivated more by improved attractiveness, muscle "toning," and body mass management. Women have greater preference for supervised and lower-body exercise. Intrasexual competition, mate selection, and the drive for muscularity are likely fundamental causes of exercise behaviors in men and women. Men and women increase muscle size and strength after weeks of strength training, but women experience greater relative strength improvements depending on age and muscle group. Men exhibit higher strength training injury rates. No sex difference exists in strength loss and muscle soreness after muscle-damaging exercise.

Knee Muscles Composition Using Electrical Impedance Myography and Magnetic Resonance Imaging

We evaluated the correlation of electrical impedance myography (EIM) measurements of knee muscles composition using Skulpt ChiselTM with MRI data retrieved from muscles segmentation. A total of 140 patients (71 females, 52 ± 21 years) underwent knee MRI, EIM with Skulpt®, and clinical evaluation (SARC-F questionnaire). MRIs were reviewed to assess the cross-sectional area (CSA) and skeletal muscle index (SMI = CSA/height2) of vastus medialis, vastus lateralis, biceps, semimembranosus, and sartorius. We tested the correlations of EIM-derived parameters [body fat-percentage (BF%) and muscle quality] with total CSA, CSA of each muscle, SMI, and SARC-F scores (0−10) using Pearson correlation coefficient. We found medium negative correlation of BF% with SMI (r = −0.430, p < 0.001) and total CSA (r = −0.445, p < 0.001), particularly with biceps (r = −0.479, p < 0.001), sartorius (r = −0.440, p < 0.001), and semimembranosus (r = −0.357, p < 0.001). EIM-derived muscle quality showed small-to-medium positive correlation with MRI measurements, ranging from r = 0.234 of biceps (p = 0.006) to r = 0.302 of total CSA (p < 0.001), except for vastus lateralis (r = 0.014, p = 0.873). SARC-F scores showed small correlations with EIM and MRI data, ranging from r = −0.132 (p = 0.121) with EIM muscle quality to r = −0.288 (p = 0.001) with CSA of vastus medialis. Hence, we observed small-to-medium correlations of muscle parameters derived from Skulpt ChiselTM with SARC-F scores and MRI parameters. We recommend using Skulpt ChiselTM with caution for assessing knee skeletal muscles composition.

Is handgrip strength a marker of muscle and physical function of the lower limbs? Sex differences in older adults with obesity

BACKGROUND AND AIMS

In this cross-sectional study we investigate the association between handgrip strength (HGS) and muscle function of the lower limbs and the predictors of the appendicular lean mass index (ALMI) in older adults with obesity of both sexes.

METHODS AND RESULTS

Eighty-four older (67 ± 5 years) men (N = 44) and women (N = 40) with obesity (body mass index (BMI) 33 ± 4 kg/m²) performed: the HGS, isokinetic knee extensors (KE) and flexors (KF) muscle strength and power and Short Physical Performance Battery (SPPB). The correlation between HGS and lower limbs muscle function was evaluated, and four multiple hierarchical linear models were built to assess the contribution of each ALMI predictor (i.e., HGS, BMI, SPPB, muscle strength and power). In men, HGS was weakly-to-moderately associated (p < 0.05) with KE, KF muscle function and physical performance. In women, HGS showed a weak association (p < 0.05) with KE muscle function. The significant predictors of ALMI were only the BMI in women, whereas in the group of men BMI, KE maximal strength and power better explain the variance in ALMI than HGS alone.

CONCLUSION

Our results suggest that HGS should not be used alone as a marker of lower muscle nor physical function. Sex differences exist with the BMI that is a contributor of ALMI both in men and women. However, at least in the group of men, markers related to strength and power of the lower limbs can better describe variations in ALMI compared to HGS in this kind of population.

CLINICAL TRIAL REGISTRATION

NA.

Relationship of creatinine cystatin C ratio with muscle mass and grip strength in memory clinic outpatients

OBJECTIVES

The purpose of this study was to examine the relationship of the serum creatinine/cystatin C ratio (CCR) with hand grip strength (HGS), total body muscle mass, trunk muscle mass, and skeletal muscle mass index (SMI) in patients attending a memory clinic.

DESIGN

This cross-sectional study enrolled outpatients of a memory clinic in Japan from October 2010 to July 2017.

SETTING AND PARTICIPANTS

We enrolled 1945 participants aged 60 years or older with measured skeletal muscle mass, HGS, and serum creatinine and serum cystatin C levels.

MEASURES

Linear multiple regression analysis was performed for men and women using total body muscle mass, trunk muscle mass, and SMI as objective variables. The exposure variables were selected from previous reports if they were strongly linked to muscle mass. Total body muscle mass and trunk muscle mass were corrected by dividing by body weight. Multiple regression analysis was also conducted for men and women using HGS as an objective variable. Because cognitive function and HGS are strongly related, we also conducted sensitivity analysis by excluding participants with a Mini-Mental State Examination score < 24 to alleviate any concern that we did not fully adjust for the effect of cognitive dysfunction.

RESULTS

In men, CCR was significantly associated with total body muscle mass, trunk muscle mass, and SMI (P = 0.013, P = 0.008, and P < 0.001, respectively). In women, CCR was significantly associated with total body muscle mass and trunk muscle mass (P = 0.013 and P < 0.001, respectively), but not with SMI (P = 0.932). On the other hand, CCR was significantly associated with grip strength in both men and women (P < 0.001 and P < 0.001, respectively).

CONCLUSIONS

CCR was associated with both muscle mass and muscle strength. This study suggests that CCR is a useful marker not only for muscle mass but also for muscle strength.

Predictors of Step Length from Surface Electromyography and Body Impedance Analysis Parameters

Step length is a critical hallmark of health status. However, few studies have investigated the modifiable factors that may affect step length. An exploratory, cross-sectional study was performed to evaluate the surface electromyography (sEMG) and body impedance analysis (BIA) parameters, combined with individual demographic data, to predict the individual step length using the GAITRite® system. Healthy participants aged 40−80 years were prospectively recruited, and three models were built to predict individual step length. The first model was the best-fit model (R2 = 0.244, p < 0.001); the root mean square (RMS) values at maximal knee flexion and height were included as significant variables. The second model used all candidate variables, except sEMG variables, and revealed that age, height, and body fat mass (BFM) were significant variables for predicting the average step length (R2 = 0.198, p < 0.001). The third model, which was used to predict step length without sEMG and BIA, showed that only age and height remained significant (R2 = 0.158, p < 0.001). This study revealed that the RMS value at maximal strength knee flexion, height, age, and BFM are important predictors for individual step length, and possibly suggesting that strengthening knee flexor function and reducing BFM may help improve step length.

Muscle Ultrasound as Imaging Domain of Frailty

Introduction

Frailty is a geriatric syndrome, a clinical state of vulnerability for developing dependency and/or death. Due to its multidimensional nature, Comprehensive Geriatric Assessment (CGA) constitutes the best strategy to evaluate frailty in older patients. Accumulation of deficits model synthesizes the global assessment of geriatric domains in the Frailty Index (FI) score. Muscle Ultrasound (MUS) has been employed to evaluate muscle mass wasting as tool to assess sarcopenia in late life. The present study aims to evaluate the association between CGA-based FI and MUS measures in a population of hospitalized older adults.

Methods

Patients aged ≥65 years underwent CGA for the evaluation of the domains of health and functional status, psycho-cognition, nutritional status, socio-environmental condition. Following standard procedure, a CGA-based FI was elaborated, taking into account 38 multidimensional items. Muscle thicknesses (MT) of rectus femoris plus vastus intermedius were measured through MUS axial cross-section. Multivariable regression analysis was employed to determine factors associated with FI.

Results

The study population consisted of 136 older patients, 87 men (63.9%), with median age of 74 (70–81) years, FI of 0.3 (0.21–0.46), and MT of rectus femoris plus vastus intermedius 29.27 (23.08–35.7) mm. At multivariable regression analysis, FI resulted significantly and independently associated with age and MT.

Conclusion

Muscle thicknesses of rectus femoris plus vastus intermedius, measured through MUS, resulted to be significantly related to FI in a population of hospitalized older patients. In the CGA-based assessment of frailty, MUS may constitute an additional imaging domain.

Usefulness of Muscle Ultrasound to Study Sarcopenic Obesity: A Pilot Case-Control Study

Background and objectives: Sarcopenic obesity (SO) is an emerging problem, especially in candidates for bariatric surgery (BS). We hypothesized that musculoskeletal ultrasound (MUS), a simple and accessible method, could be a reliable index of SO. Materials and Methods: A cross-sectional pilot study including 122 subjects (90 cases and 32 controls, 73% female, mean age: 51.2 years) who underwent BS was conducted at University Hospital Mútua Terrassa. The lean mass (LM) was calculated by bioelectrical impedance analysis (BIA) and the thigh muscle thickness (TMT) by MUS. To identify the subjects with SO by BIA, we used skeletal muscle index (SMI). The validity of MUS was determined using the ROC curve. Results: The mean BMI in the obesity group was 44.22 kg/m2. We observed a correlation between the LM and SMI assessed by BIA and the TMT assessed by MUS (R = 0.46, p < 0.001). This correlation was maintained at significant levels in the SO group (n = 40): R = 0.79; p = 0.003). The TMT assessed by MUS was able to predict SMI using BIA (AUC 0.77; 95% CI: 0.68242 to 0.84281). The optimal cut-off point for maximum efficiency was 1.57 cm in TMT (sensitivity = 75.6% and specificity = 71.1%). Conclusions: The TMT of the quadriceps assessed by US is a useful tool for identifying subjects with SO. Larger studies to validate this simple low-cost screening strategy are warranted.

Muscle Mass Measurement Using Machine Learning Algorithms with Electrical Impedance Myography

Sarcopenia is a wild chronic disease among elderly people. Although it does not entail a life-threatening risk, it will increase the adverse risk due to the associated unsteady gait, fall, fractures, and functional disability. The import factors in diagnosing sarcopenia are muscle mass and strength. The examination of muscle mass must be carried in the clinic. However, the loss of muscle mass can be improved by rehabilitation that can be performed in non-medical environments. Electronic impedance myography (EIM) can measure some parameters of muscles that have the correlations with muscle mass and strength. The goal of this study is to use machine learning algorithms to estimate the total mass of thigh muscles (MoTM) with the parameters of EIM and body information. We explored the seven major muscles of lower limbs. The feature selection methods, including recursive feature elimination (RFE) and feature combination, were used to select the optimal features based on the ridge regression (RR) and support vector regression (SVR) models. The optimal features were the resistance of rectus femoris normalized by the thigh circumference, phase of tibialis anterior combined with the gender, and body information, height, and weight. There were 96 subjects involved in this study. The performances of estimating the MoTM used the regression coefficient (r²) and root-mean-square error (RMSE), which were 0.800 and 0.929, and 1.432 kg and 0.980 kg for RR and SVR models, respectively. Thus, the proposed method could have the potential to support people examining their muscle mass in non-medical environments.

Association of age-related decrease in intracellular-to-total water ratio with that in explosive strength of the plantar flexors: a cross-sectional study

Background

We aimed to investigate the association of age-related differences in the intracellular-to-total water ratio with explosive strength of the plantar flexors.

Methods

A total of 60 young (21–33 years) and older (64–83 years) individuals were recruited. Intracellular- (ICW) and total-water (TW) content within the right leg was evaluated by bioelectrical impedance spectroscopy as indicators of muscle cell mass and whole muscle mass within the segment, respectively. ICW divided by TW (ICW/TW) was calculated as an index of the occupancy of muscle cells within whole muscle. Rate of torque development (RTD) and electromyography (EMG) activity during maximal voluntary isometric plantar flexion were measured as indicators of explosive muscle strength and neuromuscular activity, respectively. RTD was calculated from three time windows of 0–50, 50–100, and 100–200 ms. Time-to-peak torque (TPT) was assessed from evoked twitch contraction.

Results

Compared with young participants, older participants showed lower ICW/TW (−7%, P < 0.001), RTD (−25 to −40%, P = 0.003 to 0.001), and longer TPT (+11%, P < 0.001). ICW/TW associated positively with RTD (r = 0.377 to 0.408, P = 0.004 to 0.001) and negatively with TPT (r = −0.392, P = 0.002), but not with EMG activity. RTD was associated positively with EMG for each time window (r = 0.527 to 0.607, P < 0.001).

Conclusions

These results indicate that ICW/TW may be a useful predictor of the age-related decrease in RTD, and that the decrease in ICW/TW with age may reflect age-associated changes in intrinsic contractile properties.

Rectus Abdominis Muscle Thickness is a Valid Measure of Cross-Sectional Area: Implications for Ultrasound

RATIONALE AND OBJECTIVES

The rectus abdominis muscle exhibits early and significant muscle atrophy, which has largely been characterized using ultrasound measured muscle thickness. However, the validity of rectus abdominis muscle thickness as a metric of muscle size has not been established, limiting precise interpretation of age-related changes. In a heterogeneous cohort of women and men, our objectives were to: (1) evaluate the association between rectus abdominis muscle thickness and cross-sectional area (CSA), and (2) examine if the visceral adipose tissue (VAT) compartment confounds the validity of rectus abdominis muscle thickness.

MATERIALS AND METHODS

Abdominal computed tomography scans of the third lumbar vertebrae from clinical and healthy populations were used to evaluate rectus abdominis thickness and CSA, and VAT CSA. Computed tomography scans were utilized due to the limited field of view of ultrasound imaging to capture the rectus abdominis CSA.

RESULTS

A total of 348 individuals (31% women) were included in this analysis, with a mean ± standard deviation age and body mass index of 51.2 ± 15.4 years and 28.0 ± 5.1 kg/m², respectively. Significant correlations were observed between rectus abdominis thickness and CSA for women (r = 0.758; p < 0.001) and men (r = 0.688; p < 0.001). Independent of age, VAT CSA was negatively associated with rectus abdominis thickness in men (p = 0.011), but not women (p = 0.446).

CONCLUSION

These data support the use of rectus abdominis muscle thickness as a measurement of muscle size in both women and men; however, the VAT compartment may confound its validity to a minor extent in men.

Clinical characteristics of geriatric patients with non-specific chronic low back pain

A comprehensive analysis of clinical information in patients with chronic low back pain (CLBP) was performed to clarify the clinical characteristics of geriatric LBP from the perspective of body composition, spinal alignment, and blood findings related to senescence. We enrolled 203 patients with an average age of 79.0 years (77 men and 126 women), with non-specific CLBP as a single-center prospective cohort study, the patients were compared with age- and sex-matched controls without CLBP using a propensity score-matching. We performed laboratory analysis, radiographic evaluations for global spinal parameter and lumbar degeneration, and body composition analysis using whole-body dual-energy X-ray absorptiometry. We observed a higher red blood cell distribution width (RDW) (p < 0.001), which is an index of aging, as well as a lower vitamin D level (p = 0.002), skeletal muscle mass index (p = 0.045) and a higher fat mass (p = 0.007) in patients with CLBP. Moreover, patients with geriatric CLBP had significantly lower lumbar lordosis (p = 0.024), and higher sagittal vertical axis (p = 0.006) was correlated with lower extremity and trunk muscle mass (p < 0.001), independent of lumbar degeneration. Geriatric patients with CLBP have sarcopenic fat accumulation and spinal sagittal malalignment with senescent status, such as elevated RDW and hypovitaminosis D.

Advanced Glycation End-Products in Skeletal Muscle Aging

Advanced age causes skeletal muscle to undergo deleterious changes including muscle atrophy, fast-to-slow muscle fiber transition, and an increase in collagenous material that culminates in the age-dependent muscle wasting disease known as sarcopenia. Advanced glycation end-products (AGEs) non-enzymatically accumulate on the muscular collagens in old age via the Maillard reaction, potentiating the accumulation of intramuscular collagen and stiffening the microenvironment through collagen cross-linking. This review contextualizes known aspects of skeletal muscle extracellular matrix (ECM) aging, especially the role of collagens and AGE cross-linking, and underpins the motor nerve’s role in this aging process. Specific directions for future research are also discussed, with the understudied role of AGEs in skeletal muscle aging highlighted. Despite more than a half century of research, the role that intramuscular collagen aggregation and cross-linking plays in sarcopenia is well accepted yet not well integrated with current knowledge of AGE’s effects on muscle physiology. Furthermore, the possible impact that motor nerve aging has on intramuscular cross-linking and muscular AGE levels is posited.

Determining the Influence of Habitual Dietary Protein Intake on Physiological Muscle Parameters in Youth and Older Age

Protein ingestion is a potent stimulator of skeletal muscle protein synthesis (MPS). However, older adults demonstrate resistance to anabolic stimuli. Some evidence has demonstrated that a larger acute protein dose is required in older compared to younger adults to elicit the same synthetic response, suggesting that older adults should be consuming higher habitual dietary protein to optimise muscle mass. However, limited research has explored dietary habits in different age groups or the relationship between habitual dietary intake and mechanistic physiological parameters associated with muscle mass and function. This work investigated the effect of habitual dietary intake in young (n = 10, 25.9 (3.2y)) and older (n = 16, 70.2 (3.2y)) community-dwelling adults (16:10 male: female) on physiological muscle parameters. Dietary intake was assessed using four-day diet diaries. Post-absorptive MPS and MPS responses to feeding (4.25x basal metabolic rate; 16% protein) were determined in muscle biopsies of the m. vastus lateralis via stable isotope tracer ([1, 2^-13C₂]-leucine) infusions with mass-spectrometric analyses. Body composition was measured by dual-energy x-ray absorptiometry. Whole body strength was assessed via 1-repetition maximum assessments. No significant differences in habitual dietary intake (protein, fat, carbohydrate and leucine as g.kgWBLM^-1.day^-1) were observed between age groups. Whole-body lean mass (61.8 ± 9.9 vs. 49.8 ± 11.9 kg, p = 0.01) and knee-extensor strength (87.7 ± 28.3 vs. 56.8 ± 16.4 kg, p = 0.002) were significantly higher in young adults. Habitual protein intake (g.kg^-1.day^-1) was not associated with whole-body lean mass, upper-leg lean mass, whole-body strength, knee-extensor strength, basal MPS or fed-state MPS across both age groups. These findings suggest that differences in muscle mass and strength parameters between youth and older age are not explained by differences in habitual dietary protein intake. Further research with a larger sample size is needed to fully explore these relationships and inform on interventions to mitigate sarcopenia development.

Orbicularis Oculi Muscle Size and Function: Exploring the Influence of Aging and Exercise Training

The orbicularis oculi muscle is the sphincter muscle of the eyelids that blinks and closes the eyes. In this review, our aim was threefold: (1) to introduce the performance characteristics of blinking activity in young and older adults, (2) to discuss the influence of aging on the orbicularis oculi muscle in healthy adults, and (3) to provide information about the effect of facial exercise training on the orbicularis oculi muscle. To achieve the purpose of this review, a search using two electronic databases (PubMed and Scopus) and a search engine (Google Scholar) was conducted. The amplitude and peak velocity of spontaneously blinking behavior, which is an index of muscle function of the orbicularis oculi, appear to be affected by aging. The muscle thickness of the orbicularis oculi tends to be low in older adults, but there are issues that need to be examined further, such as differences in sex and measurement positions. There was no study on the effect of exercise training; however, the results of a highly trained man indicate that the orbicularis oculi muscles might elicit muscle hypertrophy through non-traditional resistance exercise.

Anthropometric and musculoskeletal gender differences in young soccer players

BACKGROUND

This study aimed to clarify potential gender differences across a comprehensive set of anthropometric and musculoskeletal characteristics within a young soccer player population.

METHODS

This study included 227 (121 males and 106 females with mean ages of 19.0 and 17.5 years, respectively) young elite soccer players. Anthropometric measurements were obtained. In addition, general joint laxity tests assessing the wrist, elbow, shoulder, trunk, hip, knee, and ankle were performed. Muscle flexibility tests were performed on the iliopsoas, quadriceps femoris, hamstring, gastrocnemius, and soleus muscles. Moreover, isometric knee extension and flexion strength and isometric hip abduction strength were measured. Single- and double-leg balance tests were also performed.

RESULTS

Male soccer players were taller, heavier, and had lower fat mass and percent body fat, and greater skeletal muscle mass and body minerals than female soccer players. Female soccer players had significantly greater laxity in all tests for general joint laxity. Female soccer players demonstrated significantly better hamstring and soleus flexibility than male soccer players but worse iliopsoas flexibility. Consequently, no significant differences were noticed in the quadriceps and gastrocnemius muscles between the male and female soccer players. However, female soccer players demonstrated significantly weaker knee extension and flexion and hip abduction. The hamstring- quadriceps ratio was significantly lower in female soccer players. Although no significant difference exists in the center of pressure excursion in the double-leg balance test between male and female soccer players, female soccer players displayed a significantly lower center of pressure excursion in the single-leg balance test.

CONCLUSIONS

Young male and female soccer players demonstrate significantly different anthropometric and musculoskeletal profiles.

Simplified morphological evaluation of skeletal muscle mass and maximum muscle strength in healthy young women: Comparison between thigh and calf

Objectives:

The purpose of this study was to examine the prediction of skeletal muscle mass and maximum muscle strength using simplified morphology evaluation in young Japanese women from the thigh and calf perspective.

Methods:

A total of 249 Japanese young women (aged 18–25 years) were used for data analyses in this study. Thigh and calf girths were measured using a tape measure at 50% of thigh length and at 30% proximal of calf length, respectively. Muscle thickness was measured using B-mode ultrasound at the anterior and posterior thigh (at 50% of thigh length) and at the posterior lower leg (at 30% proximal of calf length), respectively. The measurements were carried out on the right side of the body while the participants stood with their elbows extended and relaxed. A stepwise multiple regression analysis (method of increasing and decreasing the variables; criterion set at p < 0.05) was performed for skeletal muscle index (defined by appendicular skeletal muscle mass/height²), handgrip strength, or sit-to-stand test and five variable factors (girth (thigh and calf) and muscle thickness (anterior and posterior thigh and posterior calf)).

Results:

Unlike the sit-to-stand test, skeletal muscle index or handgrip strength was correlated (p < 0.001) with the girth or muscle thickness for both thigh and calf. Unlike the sit-to-stand test, the prediction equations for skeletal muscle index and handgrip strength estimation showed significant correlations with multiple regression analysis of data obtained from the calf girth and muscle thickness. In both skeletal muscle index and handgrip strength, calf girth was adopted as a Step 1, respectively.

Conclusion:

Our results indicated that skeletal muscle index and handgrip strength could be evaluated by the simplified morphology methods, especially that for the calf girth measurement, which may be a good indicator of screening/preventing for sarcopenia in healthy Japanese young women.

Hip Fracture Patients in Geriatric Rehabilitation Show Poor Nutritional Status, Dietary Intake and Muscle Health

The aim of this study was to gain insight into the nutritional status, dietary intake and muscle health of older Dutch hip fracture patients to prevent recurrent fractures and to underpin rehabilitation programs. This cross-sectional study enrolled 40 hip fracture patients (mean ± SD age 82 ± 8.0 years) from geriatric rehabilitation wards of two nursing homes in the Netherlands. Assessments included nutritional status (Mini Nutritional Assessment), dietary intake on three non-consecutive days which were compared with Dietary Reference Intake values, and handgrip strength. Muscle mass was measured using Bioelectrical Impedance Analysis and ultrasound scans of the rectus femoris. Malnutrition or risk of malnutrition was present in 73% of participants. Mean energy, protein, fibre and polyunsaturated fat intakes were significantly below the recommendations, while saturated fat was significantly above the UL. Protein intake was <0.8 in 46% and <1.2 g/(kg·day) in 92%. Regarding micronutrients, mean intakes of calcium, vitamin D, potassium, magnesium and selenium were significantly below the recommendations. The prevalence of low muscle mass, low handgrip strength and sarcopenia were 35, 27 and 10%, respectively. In conclusion, a poor nutritional status, dietary intake and muscle health are common in older hip fracture patients in geriatric rehabilitation wards.

Muscle thickness contribution to sit-to-stand ability in institutionalized older adults

BACKGROUND

Ultrasound is a low-cost, safe and accessible tool to use on muscle mass assessment. The relations between muscle thickness and lower limb function have not been investigated in institutionalized elderly people.

AIM

The purpose of the present study was to investigate the associations among sit-to-stand capacity, ultrasound-measured rectus femoris muscle thickness, hand grip strength and anthropometrics in a population of institutionalized older adults.

METHODS

Twelve older adults (nine women and three men, mean age ± SD 86 ± 7 years, body mass index 24 ± 3 kg/m²) participated in this cross-sectional study. Sit-to-stand capacity using five-repetition sit-to-stand test, rectus femoris muscle thickness using B-mode ultrasonography, handgrip and anthropometric were measured. The relationships of the variables were analyzed using Pearson correlation coefficient and multiple linear regression analysis.

RESULTS

Significant bivariate correlations were found between rectus femoris muscle thickness and sit-to-stand test (p < 0.05). Multiple linear regression analysis showed associations between rectus femoris muscle thickness and sit-to-stand test, after adjusting by body mass index and age (p < 0.0001).

DISCUSSION

Rectus femoris thickness in contraction adjusted by body mass index and age was predictors of physical performance. The independent variables shared 78.6% of variance in the sit-to-stand test.

CONCLUSIONS

Rectus femoris muscle thickness measured with ultrasonography, body mass index and age could explain functionality in institutionalized older adults measured by five-repetition sit-to-stand test.

Postural Sway during Local Vibratory Stimulation for Proprioception in Elderly Individuals with Pre-Sarcopenia

OBJECTIVE

Many studies have demonstrated that the loss of muscle mass (LMM) poses a risk of postural instability in the elderly; however, few studies have shown how LMM decreases proprioception. In this study, we investigated the changes in postural sway among older individuals with LMM induced by application of a local vibratory stimulus.

METHOD

We enrolled 64 older adults (mean age). Postural sway was measured while applying vibration stimuli of 30, 60, and 240 Hz to both the gastrocnemius and lumbar multifidus muscles. We also measured the relative proprioceptive weighting ratio (RPW) of postural sway. The patients were divided into LMM and non-LMM (NLMM) groups. The study subjects were compared in terms of their age, height, weight, body mass index (BMI), lower leg skeletal muscle mass index (LSMI), L4/5 lumbar multifidus cross-sectional area ratio, and RPW at 30, 60, and 240 Hz.

RESULTS

Subjects in the LMM group showed a significantly lower RPW at 60 Hz, LSMI, and BMI than did those in the NLMM group.

CONCLUSIONS

Decrease in RPW with 60-Hz stimulation concerning the lower leg proprioception is a risk factor for LMM-associated postural instability in the elderly. Consequently, with respect to the gastrocnemius muscles proprioception in LMM, it is necessary to perform assessments using muscle spindle stimuli.

One-repetition submaximal protocol to measure knee extensor muscle strength among older adults with and without sarcopenia: a validation study

Background

Dynamic knee extensor muscle strength is a valid measure among healthy older adults but has not been tested in the sarcopenia condition. This study’s objective was to test the validity of a one-repetition submaximal strength protocol to measure dynamic knee extension strength in older adults with and without sarcopenia.

Methods

Ninety-four physically independent older adults (female: n = 64, 60 to 85 years; male: n = 29, 60 to 85 years) participated in this study in Brazil during 2016–2017. Sarcopenia was classified and isokinetic unilateral knee extension strength was measured at 60°/s. Bilateral dynamic knee extension strength was estimated with an extensor chair using one-repetition submaximal protocol. Validity was determined using Spearman’s correlation with isokinetic muscle strength.

Results

The frequency of sarcopenia was 11.7%. Sarcopenic individuals presented lower body mass, body mass index and skeletal muscle index. Only chronological age was higher among the sarcopenic individuals. A high correlation was found between isokinetic unilateral knee extension strength and bilateral estimated one-repetition with submaximal protocol (r = 0.74; p <  0.001), when the presence (r = 0.71; p = 0.014) and absence of sarcopenia (r = 0.74; p <  0.001) were considered. The validity of the one-repetition submaximal protocol for bilateral knee extension was confirmed.

Conclusions

The estimated measure of bilateral knee extension muscle strength can be used to monitor adaptations promoted by physical exercise for older adults with and without sarcopenia. The validation enable studies that will propose cutoff points to identify sarcopenia with this submaximal protocol. This will enable early diagnosis and better management of sarcopenia, a disease with adverse impacts for older adults.

Age-related degeneration of the lumbar paravertebral muscles: Systematic review and three-level meta-regression

BACKGROUND

Morphological changes of the lumbar spine muscles are not well characterised with ageing. To further the understanding of age-related degeneration of the lumbar spine musculature, normative morphological changes that occur within the paravertebral muscles must first be established.

METHODS

A systematic review and meta-regressions were conducted adhering to PRISMA guidelines. Searches for published and unpublished data were completed in June 2019.

RESULTS

Searches returned 4781 articles. 34 articles were included in the quantitative analysis. Three-level meta-analyses showed age-related atrophy (r = -0.26; 95% CI: -0.33, -0.17) and fat infiltration (r = 0.39; 95% CI: 0.28, 0.50) in the lumbar paravertebral muscles. Degenerative changes were muscle-specific and men (r = -0.32; 95% CI: -0.61, 0.01) exhibited significantly greater muscle atrophy than women (r = -0.24; 95% CI: -0.47, 0.03). Imaging modality, specifically ultrasound, also influenced age-related muscle atrophy. Measurements taken across all lumbar levels revealed the greatest fat infiltration with ageing (r = 0.58, 95% CI: 0.35, 0.74). Moderators explained a large proportion of between-study variance in true effects for muscle atrophy (72.6%) and fat infiltration (79.8%) models.

CONCLUSIONS

Lumbar paravertebral muscles undergo age-related degeneration in healthy adults with muscle, lumbar level and sex-specific responses. Future studies should use high-resolution imaging modalities to quantify muscle atrophy and fat infiltration.

Effects of Progressive Walking and Stair-Climbing Training Program on Muscle Size and Strength of the Lower Body in Untrained Older Adults

The purpose of the present study was to investigate the effect of the progressive walking program on lower limb muscle size and strength and evaluated whether the stair-climbing exercise provided additional training effects when combined with the walking program. Fifteen elderly subjects (age 69 ± 1 years, height 1.63 ± 0.02 m, body weight 64.5 ± 2.0 kg) were randomly assigned to a walking group or a walking and stair-climbing group. The progressive walking program comprised continuous (week 1-8) and interval (week 9-17) exercises. The walking and stair-climbing group also performed stair climbing. Muscle thickness, strength, and walking performance were evaluated before and 8 and 17 weeks after the start of the program. The muscle thickness of the anterior and posterior parts of the thigh significantly (p < 0.05) increased in both groups. There was also a significant (p < 0.01) main effect of time in isometric maximal strength and the values expressed relative to body mass for both knee extension and flexion. However, no group × time interactions were noted. Furthermore, the percentage change of knee flexion strength after the training period was significantly (p < 0.01) correlated with the pre-intervention value. Seventeen weeks of the progressive walking program can increase thigh muscle size and strength for older adults; however, an added stair-climbing exercise may not provide additional training effects. Furthermore, the magnitude of improvement in knee flexion strength would depend on the pre-intervention value.

The Influence of Facial Muscle Training on the Facial Soft Tissue Profile: A Brief Review

In this review, we summarize recent literature investigating facial-exercise-induced changes in facial soft tissue. A literature search was performed in PubMed for the terms facial exercise, rejuvenation, muscle, skin, and aging. Four studies were identified from the search and were subject to further assessment. Four studies were included in our analysis. Two of the four studies included compared the experimental (training) group to a control group. The other two studies had no control group. The participants were mainly middle-aged women. Training conditions varied; neuromuscular electrical stimulation (NMES) was used in two studies, the other two studies used an oscillatory movement device and voluntary facial isometric exercise. Two studies measured facial muscle size using ultrasonography before and after 12 weeks of NMES or 8 weeks of oscillatory movement of the face. One study assessed the changes in facial skin elasticity in a single group following 8 weeks of facial isometric exercise, while one study measured strength of labial and lingual muscles before and following 4 weeks of NMES. We found two studies that reported facial-exercise-induced increases in facial muscle size in middle-aged women. It was also reported that facial skin function may improve following facial isometric exercise. Future research is needed to clarify how these changes link with facial rejuvenation. Compared to extremity muscles, the facial muscles are small in size, their shapes are complex, and the boundaries with other tissues may be unclear. Future study is also necessary to examine the reliability of measurements of the facial muscles.

Relationship Between L4/5 Lumbar Multifidus Cross-Sectional Area Ratio and Fall Risk in Older Adults with Lumbar Spinal Stenosis: A Retrospective Study

Various factors, including spinal deformities and trunk muscle atrophy, greatly affect the fall risk among older adults with lumbar spinal stenosis (LSS). However, the etiology of falls in older adults with degenerative LSS and trunk muscle atrophy is poorly understood. We investigated the association between trunk muscle atrophy and falls in older LSS patients. This retrospective study included 99 hospitalized older adults with LSS. Participants completed self-reported fall score questionnaires and were divided into the fall risk (n = 30) and non-fall risk (n = 69) groups. The patients' low back pain visual analog scale score, Geriatric Depression Scale score, sagittal vertical axis, L4/5 lumbar multifidus cross-sectional area ratio (LMCSAR), and center of pressure (COP) values during quiet standing were evaluated. The fall risk group had a lower L4/5 LMCSAR (p = 0.002) and increased COP excursion (p = 0.034) than the non-fall risk group. No significant differences were observed in the other measured variables between the two groups. The L4/5 LMCSAR (p < 0.001) and COP (p = 0.024) were related to fall risk and may be useful in fall risk assessment in such populations. Strategies aimed at enhancing controlled lumbar segmental motion and improving trunk muscle stability or mass may decrease the fall risk in this cohort.

Ultrasound imaging for sarcopenia, spasticity and painful muscle syndromes

PURPOSE OF REVIEW

On the basis of its various advantages and the relevant awareness of physicians, ultrasound imaging has overwhelmingly taken its place in the scientific arena. This is true both from the side of daily clinical applications and also from the side of research. Yet, ultrasound provides real-time (diagnostic) imaging and (interventional) guidance for a wide spectrum of muscle disorders. In this regard, this review aims to discuss the potential/actual utility of ultrasound imaging in particular muscle disorders, that is, sarcopenia, spasticity and fibromyalgia/myofascial pain syndrome.

RECENT FINDINGS

Due to the aging population worldwide and the importance of functionality in the older population, mounting interest has been given to the diagnosis and management of sarcopenia in the recent literature. Likewise, several articles started to report that ultrasound imaging can be used conveniently and effectively in the early diagnosis and quantification of sarcopenia.For spasticity, aside from ultrasound-guided botulinum toxin injections, intriguing attention has been paid to sonographic evaluation of muscle architecture, echogenicity and elasticity in the follow-up of these chronic conditions.As regards painful muscle syndromes, quantitative ultrasound techniques have been shown to detect statistically significant differences between healthy controls and patients with myofascial pain syndrome.

SUMMARY

Ultrasound imaging seems to be a promising tool that indisputably deserves further research in the management of a wide range of muscle disorders. VIDEO ABSTRACT: http://links.lww.com/COSPC/A17.

Regional and total muscle mass, muscle strength and physical performance: The potential use of ultrasound imaging for sarcopenia

OBJECTIVE

To evaluate the relationship between the regional and total muscle mass, muscle strength and physical performance, and also to investigate the affected muscles, their strength and physical performance with aging.

METHODS

A total of 145 healthy subjects were included for the cross-sectional descriptive study. Demographic data were obtained, and body composition was consecutively assessed by anthropometric methods, bioelectrical impedance analysis and ultrasound (muscle thickness, fascicule length and pennation angle). Functional status was assessed using hand grip strength and gait speed measurements.

RESULTS

Abdominal and thigh muscles were thinner and triceps muscle was thicker in older subjects when compared with younger ones. Age and grip strength were significant predictors for physical performance. Gait speed, grip strength and regional muscle measurements decreased with age at higher rates (26-28%), skeletal muscle mass index was affected at a lower rate (15%).

CONCLUSIONS

Low muscle strength and regional muscle measurements should be used to confirm the diagnosis of sarcopenia.

Assessing sarcopenia with vastus lateralis muscle ultrasound: an operative protocol

BACKGROUND

Muscle ultrasound (MUS) has so far not been implemented for sarcopenia assessment in clinical geriatric practice due to allegedly low reproducibility of results in the absence of standardization of procedures. However, rigorous and standardized application of this technique yields highly reproducible results. Its application, especially if integrated with clinical evaluation and comprehensive geriatric assessment, proofs very useful for rapidly obtaining information on muscle mass and architecture.

OBJECTIVE

Here, we present a standardized protocol for performing right vastus lateralis (RVL) MUS and measuring parameters of muscle size and architecture.

METHODS

RVL muscle thickness (MT), fascicle length (FL), pennation angle (PA), echo-intensity (EI) and cross-sectional area (CSA) can be assessed with this protocol. A portable instrument equipped with a 5-cm long 3-11 mHz linear probe should be used with both B-mode real-time and extended-field-of-view (EFOV) techniques. Longitudinal B-mode and transverse EFOV images should be acquired during each exam, and analyzed with NIH-ImageJ software.

CONCLUSIONS

This operative protocol represents a good compromise between the feasibility of MUS in clinical settings and the need of obtaining precise measurements of muscle parameters. Future studies should verify the reproducibility of the proposed technique, and its correlation with appendicular lean mass and parameters of muscle function.

Fascia thickness, aging and flexibility: is there an association?

The morphology of the connective tissue may play an important role in locomotor mechanics. Recent research has revealed an association between increased fascia thickness and reduced joint flexibility in patients with chronic pain. The present study aimed to examine the relationship of both factors in healthy individuals, additionally testing the hypothesis that older subjects display a higher fascia thickness. Young (n = 18, 22 ± 1 years) and old (n = 17, 69 ± 4 years) healthy females were recruited for a quasi-experimental, cross-sectional trial. All participants underwent standardized ultrasound-based thickness measurements of the deep fasciae of the trunk and lower limb. Flexibility was assessed using sit and reach testing (hamstring extensibility) and the Schober test (lumbar flexion and extension). Systematic between-group differences of fascia thickness and variable associations (i.e. fascia thickness and flexibility) were detected using non-parametric data analyses. Young adults exhibited higher fascia thickness of the anterior and posterior lower leg, anterior thigh and abdominal wall (+12.3-25.8%, P < 0.05). Conversely, older participants showed higher thickness in the lumbar spine (+40.0-76.7%, P < 0.05). Correlations of both body mass and fascia thickness (τ = 0.45-0.75, P < 0.05), as well as flexibility and fascia thickness (τ = 0.38-0.42, P < 0.05) were found. Age-related changes in fascia thickness may be a contributing factor of restrictions in joint range of motion. Further study delineating the cause-effect triangle of body mass index, flexibility and fascia thickness is necessary.

Muscle Thickness and Echo Intensity of the Abdominal and Lower Extremity Muscles in Stroke Survivors

Background and Purpose

This study compared the muscle thickness (MT) and echo intensity (EI) of the abdominal, thigh, and lower leg muscles between the paretic and nonparetic sides in chronic stroke survivors.

Methods

Thirty-two stroke survivors living in the community participated in this study. The MT and EI, which are indicators of muscle mass and intramuscular fat or connective tissue, were assessed in the rectus abdominis, external oblique, internal oblique, transversus abdominis, rectus femoris, vastus intermedius, vastus lateralis, vastus medialis, tibialis anterior, gastrocnemius, and soleus via transverse ultrasound imaging. In addition, a possible indicator of physical activity—the frequency of going out per week—was evaluated.

Results

All quadriceps muscles and the tibialis anterior were significantly thinner and the EI values of the vastus intermedius, vastus lateralis, vastus medialis, and soleus were significantly higher in the paretic limb than the nonparetic limb. The MT and EI values of abdominal muscles did not differ significantly between the two sides. The MT values of the paretic rectus femoris, vastus lateralis, and vastus medialis were significantly associated with the frequency of going out after adjusting confounding factors. The MT of the nonparetic vastus lateralis was significantly associated with latency from stroke onset after adjusting confounding factors.

Conclusions

Our results indicate that quantitative and qualitative changes on the paretic side in stroke survivors were the most robust in the thigh muscles, whereas such changes might not occur in the abdominal muscles.

Comparison of bedside screening methods for frailty assessment in older adult trauma patients in the emergency department

BACKGROUND

Frailty is linked to poor outcomes in older patients. We prospectively compared the utility of the picture-based Clinical Frailty Scale (CFS9), clinical assessments, and ultrasound muscle measurements against the reference FRAIL scale in older adult trauma patients in the emergency department (ED).

METHODS

We recruited a convenience sample of adults 65 yrs. or older with blunt trauma and injury severity scores <9. We queried subjects (or surrogates) on the FRAIL scale, and compared this to: physician-based and subject/surrogate-based CFS9; mid-upper arm circumference (MUAC) and grip strength; and ultrasound (US) measures of muscle thickness (limbs and abdominal wall). We derived optimal diagnostic thresholds and calculated performance metrics for each comparison using sensitivity, specificity, predictive values, and area under receiver operating characteristic curves (AUROC).

RESULTS

Fifteen of 65 patients were frail by FRAIL scale (23%). CFS9 performed well when assessed by subject/surrogate (AUROC 0.91 [95% CI 0.84-0.98] or physician (AUROC 0.77 [95% CI 0.63-0.91]. Optimal thresholds for both physician and subject/surrogate were CFS9 of 4 or greater. If both physician and subject/surrogate provided scores <4, sensitivity and negative predictive value were 90.0% (54.1-99.5%) and 95.0% (73.1-99.7%). Grip strength and MUAC were not predictors. US measures that combined biceps and quadriceps thickness showed an AUROC of 0.75 compared to the reference standard.

CONCLUSION

The ED needs rapid, validated tools to screen for frailty. The CFS9 has excellent negative predictive value in ruling out frailty. Ultrasound of combined biceps and quadriceps has modest concordance as an alternative in trauma patients who cannot provide a history.

Age-related reduction of trunk muscle torque and prevalence of trunk sarcopenia in community-dwelling elderly: Validity of a portable trunk muscle torque measurement instrument and its application to a large sample cohort study

Trunk muscle weakness and imbalance are risk factors for postural instability, low back pain, and poor postoperative outcomes. The association between trunk muscle strength and aging is poorly understood, and establishing normal reference values is difficult. We aimed to establish the validity of a novel portable trunk muscle torque measurement instrument (PTMI). We then estimated reference data for healthy young adults and elucidated age-related weakness in trunk muscle strength. Twenty-four university students were enrolled to validate values for PTMI, and 816 volunteers from the general population who were recruited to the Iwaki Health Promotion Project were included to estimate reference data for trunk muscle strength. Trunk flexion and extension torque were measured with PTMI and KinCom, and interclass correlation coefficients (ICC) were estimated to evaluate the reliability of PTMI values. Furthermore, from the young adult reference, the age-related reduction in trunk muscle torque and the prevalence of sarcopenia among age-sex groups were estimated. The ICC in flexion and extension torque were 0.807 (p<0.001) and 0.789 (p<0.001), respectively. The prevalence of sarcopenia increased with age, and the prevalence due to flexion torque was double that of extension torque. Flexion torque decreased significantly after 60 years of age, and extension torque decreased after 70 years of age. In males over age 80, trunk muscle torque decreased to 49.1% in flexion and 63.5% in extension. In females over age 80, trunk muscle torque decreased to 60.7% in flexion and 68.4% in extension. The validity of PTMI was confirmed by correlation with KinCom. PTMI produced reference data for healthy young adults, and demonstrated age-related reduction in trunk muscle torque. Trunk sarcopenia progressed with aging, and the loss of flexion torque began earlier than extension torque. At age 80, trunk muscle torque had decreased 60% compared with healthy young adults.

Skeletal muscle mass in human athletes: What is the upper limit?

OBJECTIVES

To examine the amount of absolute and relative skeletal muscle mass (SM) in large sized athletes to investigate the potential upper limit of whole body muscle mass accumulation in the human body.

METHODS

Ninety-five large-sized male athletes and 48 recreationally active males (control) had muscle thickness measured by ultrasound at nine sites on the anterior and posterior aspects of the body. SM was estimated from an ultrasound-derived prediction equation. Body density was estimated by hydrostatic weighing technique, and then body fat percentage and fat-free mass (FFM) were calculated. We used the SM index and FFM index to adjust for the influence of standing height (ie, divided by height squared).

RESULTS

Ten of the athletes had more than 100 kg of FFM, including the largest who had 120.2 kg, while seven of the athletes had more than 50 kg of SM, including the largest who had 59.3 kg. FFM index and SM index were higher in athletes compared to controls and the percentage differences between the two groups were 44% and 56%, respectively. The FFM index increased linearly up to 90 kg of body mass, and then the values leveled off in those of increasing body mass. Similarly, the SM index increased in a parabolic fashion reaching a plateau (approximately 17 kg/m² ) beyond 120 kg body mass.

CONCLUSIONS

SM index may be a valuable indicator for determining skeletal muscle mass in athletes. A SM index of approximately 17 kg/m² may serve as the potential upper limit in humans.

Differences in 100-m sprint performance and skeletal muscle mass between elite male and female sprinters

BACKGROUND

The sex difference in 100-m sprint performance between the world's best athletes is approximately 10%. We hypothesized that skeletal muscle mass (SM) relative to body mass may be a major factor contributing to this difference. The aim of this study was to examine the sex difference in absolute and relative SM and sprint performance in male and female sprinters.

METHODS

We analyzed the SM of male (N.=37) and female (N.=26) 100-m sprinters; the sample was divided into two subgroups within each sex according to personal best 100-m time: 10.00-10.90 s (M10; N.=22) and 11.00-11.70 s (M11; N.=15) for males and 11.00-11.90 s (F11, N.=14) and 12.00-13.50 s (F12, N.=12) for females. SM was estimated from ultrasound-measured muscle thickness (MT) using prediction equations.

RESULTS

There was an approximate 10% difference in 100-m sprint time between sexes, whereas absolute and relative values of SM for female sprinters were 70-71% and 79-84% of the male sprinters, respectively. No differences were observed within each male/female subgroup for fat-free mass, absolute and relative SM, excepting that leg SM index of M10 was higher than M11. The 100-m time was not different (0.27 s, P=0.051) between M11 and F11 subgroups, but absolute and relative values of SM and MT were higher and percent body fat was lower in the M11 than in the F11 subgroup.

CONCLUSIONS

Our results suggest that differences in muscle mass may not play a large role in determining successful performance in elite male and female sprinters.

Muscle Mass, Quality, and Composition Changes During Atrophy and Sarcopenia

Skeletal muscle mass (SMM) and muscle strengh reach their peak in 20s to 40s of age in human life and then decrease with advancing age. The decrease rate of muscle strength or power was twice to four times as large as that of the SMM. Thus, the normalized muscle force (muscle strength divided by SMM) also decreases in aging. It depends on the number of factors in skeletal muscle tissues and neuromuscular system. In human study, SMM cannot be measured directly without dissection so that all of the methodologies are indirect methods to assess SMM, even computing tomography or magnetic resonance imaging. Dual-energy X-ray absorptiometry, ultrasonography, anthropometry, and bioelectrical impedance analysis (BIA) are used as secondary indirect methods to estimate SMM. Recent researches show muscle composition changes in aging, and in particular, the ratio of muscle cell mass (MCM) against SMM decrease and relative expansion of extracellular water (ECW) and extracellular space is observed with advancing age and/or decrease of physical function. The intracellular water (ICW) and ECW estimated by segmental bioelectrical impedance spectroscopy or multifrequency BIA are good biomarkers of the ratio of MCM against SMM in limbs. The BIS and other state-of-the-art technology for assessment of muscle mass, quality, and composition are useful to fully understand the muscle atrophy in a living organism.

DXA-Rectified Appendicular Lean Mass: Development of Ultrasound Prediction Models in Older Adults

OBJECTIVE

Dual-energy X-ray absorptiometry (DXA)-derived appendicular lean soft tissue mass (aLM) is used to diagnose sarcopenia. However, DXA-derived aLM includes non-skeletal muscle components, such as fat-free component of adipose tissue fat cell. These components, if not accounted for, could falsely inflate the aLM in individuals with a high amount of adipose tissue mass. B-mode ultrasound accurately measures muscle size in older adults. We sought to develop regression-based prediction equations for estimating DXA-rectified appendicular lean tissue mass (i.e. DXA-derived aLM minus appendicular fat-free adipose tissue (aFFAT); abbreviated as aLM minus aFFAT) using B-mode ultrasound.

DESIGN

Cross-sectional study.

MEASUREMENTS

Three hundred and eighty-nine Japanese older adults (aged 60 to 79 years) volunteered in the study. aLM was measured using a DXA, and muscle thickness (MT) was measured using ultrasound at nine sites. An ordinary least-squares multiple linear regression model was used to predict aLM minus aFFAT from sex, age and varying muscle thicknesses multiplied by height. Based on previous studies, we chose to use 4 MT sites at the upper and lower extremities (4-site MT model) and a single site (1-site MT model) at the upper extremity to develop prediction models.

RESULTS

The linear prediction models (4 site MT model; R2 = 0.902, adjusted R2 = 0.899, and 1-site MT model; R2 = 0.868, adjusted R2 = 0.866) were found to be stable and accurate for estimating aLM minus aFFAT. Bootstrapping (n=1000) resulted in optimism values of 0.0062 (4-site MT model) and 0.0036 (1-site MT model).

CONCLUSION

The results indicated that ultrasound MT combined with height, age and sex can be used to accurately estimate aLM minus aFFAT in older Japanese adults. Newly developed ultrasound prediction equations to estimate aLM minus aFFAT may be a valuable tool in population-based studies to assess age-related rectified lean tissue mass loss.