Estimating thigh skeletal muscle volume using multi-frequency segmental-bioelectrical impedance analysis

Universal optimal design in the vertebrate limb pattern and lessons for bioinspired design

This paper broadly summarizes the variation of design features found in vertebrate limbs and analyses the resultant versatility and multifunctionality in order to make recommendations for bioinspired robotics. The vertebrate limb pattern (e.g. shoulder, elbow, wrist and digits) has been proven to be very successful in many different applications in the animal kingdom. However, the actual level of optimality of the limb for each animal application is not clear because for some cases (e.g. whale flippers and bird wings), the basic skeletal layout is assumed to be highly constrained by evolutionary ancestry. This paper addresses this important and fundamental question of optimality by analysing six limbs with contrasting functions: human arm, whale flipper, bird wing, human leg, feline hindlimb and frog hindlimb. A central finding of this study is that the vertebrate limb pattern is highly versatile and optimal not just for arms and legs but also for flippers and wings. One key design feature of the vertebrate limb pattern is that of networks of segmented bones that enable smooth morphing of shapes as well as multifunctioning structures. Another key design feature is that of linkage mechanisms that fine-tune motions and mechanical advantage. A total of 52 biomechanical design features of the vertebrate limb are identified and tabulated for these applications. These tables can be a helpful reference for designers of bioinspired robotic and prosthetic limbs. The vertebrate limb has significant potential for the bioinspired design of robotic and prosthetic limbs, especially because of progress in the development of soft actuators.

Clinical Application of Skeletal Muscle Quantity and Quality Assessment Using Bioelectrical Impedance and Ultrasound Images

A decline in muscle strength is a key factor responsible for physical dysfunction in older individuals. Both loss of muscle quantity and quality are associated with muscle strength decline. While the gold standard method for evaluating muscle mass and quality is magnetic resonance imaging, it is not suitable for clinical settings because of the measurement and analysis costs. Bioelectrical impedance analysis (BIA) and B-mode ultrasonography are clinically useful alternatives for skeletal muscle assessment owing to their feasibility and noninvasiveness. The recent advancements in the techniques for BIA and ultrasonography have improved their accuracy in assessing skeletal muscle quantity and quality, making them useful in detecting age-related and disease-specific alterations. This review comprehensively analyzes the advantages of using BIA and ultrasound imaging for assessing skeletal muscle quantity and quality and detecting muscle degeneration. We summarize the recent findings regarding age-related changes in muscle characteristics and the associations of muscle degeneration with physical dysfunction in patients with knee osteoarthritis. Furthermore, we discuss the clinical application of skeletal muscle assessment using BIA and ultrasound for evaluating training effects and exercise prescription.

The extracellular-to-total body water ratio reflects improvement in the activities of daily living in patients who experienced acute stroke

OBJECTIVES

To determine the relationship between bioelectrical impedance analysis (BIA) parameters, including the extracellular water-to-total body water ratio (ECW/TBW), and the activities of daily living (ADL) improvement, in patients who experienced acute stroke.

MATERIALS AND METHODS

This retrospective cohort study included 307 patients (mean age, 72 years; 39 % female) who experienced acute stroke and were admitted to the stroke unit of the Nippon Medical School Hospital (Bunkyo-ku, Tokyo, Japan) between April 2021 and March 2022. The Functional Independence Measure (FIM) was assessed at initial rehabilitation and discharge, and FIM effectiveness was calculated as ADL improvement in the participating acute care hospitals. BIA markers included the skeletal muscle mass index (SMI), phase angle (PhA), and ECW/TBW. Multiple linear regression models were used to estimate the relationship between the FIM effectiveness and each BIA marker.

RESULTS

The mean (±SD) FIM effectiveness was 0.45 ± 0.36. The proportions of low SMI (male, <7.0 kg/m2; female, <5.7 kg/m2) and low PhA (male <5.36 degrees, female <3.85 degrees), were 48.9 % and 43.3 %, respectively. In addition, the proportions of of low (<0.36), normal (0.36-0.40), and high (>0.4) ECW/TBW ratios were 1.3 %, 78.5 %, and 20.2 %, respectively. After adjustments for demographic and clinical variables, low PhA, low ECW/TBW, and high ECW/TBW were all significantly associated with FIM effectiveness (P < 0.05), with β coefficients of -0.126, -0.089, and -0.117, respectively.

CONCLUSIONS

Low and High ECW/TBW and low PhA levels were negatively correlated with improvements in ADL. The ECW/TBW ratio may be an additional indicator of rehabilitation trainability in patients who experience acute stroke.

Association of appendicular extracellular-to-intracellular water ratio with age, muscle strength, and physical activity in 8,018 community-dwelling middle-aged and older adults

BACKGROUND

The appendicular extracellular-to-intracellular water ratio (Ap ECW/ICW) has recently gained attention as a non-invasive measurable marker of muscle quality. However, there is a lack of basic evidence regarding age-related changes, sex differences, contribution to muscle strength independent of skeletal muscle mass (SMM), and potential improvement through physical activity (PA) in Ap ECW/ICW.

METHODS

This cross-sectional study enrolled 8,018 middle-aged and older Japanese individuals (aged 45-75 years). The Ap ECW/ICW and SMM were measured using segmental bioelectrical impedance spectroscopy. Muscle strength was evaluated by measuring the handgrip strength (HGS) with a dynamometer, and the PA level (PAL) was measured with an accelerometer. We performed a linear regression analysis of the associations of the Ap ECW/ICW with age, HGS, and PAL.

RESULTS

The Ap ECW/ICW increased by 0.019 for men and 0.014 for women per 5-year increase in age (p < 0.001), and the age-related increase was greater in men than in women (p for interaction <0.001). The Ap ECW/ICW was more strongly associated with the HGS than with the SMM in both men and women (p < 0.001). PAL showed a significant inverse association with the Ap ECW/ICW in both men and women (p < 0.001).

CONCLUSIONS

Ap ECW/ICW is higher with age, and it varies by sex. The Ap ECW/ICW may reflect muscle strength more than the SMM, suggesting that the Ap ECW/ICW may be improved by PA. The findings from this study may provide a framework for further Ap ECW/ICW research.

Evaluation of raw segmental bioelectrical impedance variables throughout anterior cruciate ligament reconstruction rehabilitation

Background.Raw bioelectrical impedance analysis (BIA) variables are related to physical function in healthy and diseased populations. Therefore, BIA may be an insightful, noninvasive method of assessment to track following anterior cruciate ligament reconstruction (ACLR).Objectives.Evaluate phase angle, reactance and impedance at 50 kHz (PhA₅₀, Xc₅₀, andZ₅₀, respectively) in the operative (OP) and non-operative (NOP) limbs during ACLR rehabilitation.Approach.Seventeen patient (12 M, 5 F; 18.8 ± 4.8 years) clinic reports were evaluated prior to ACLR (PRE), two- (2 W), six- (6 W), and twelve-weeks (12 W) post-ACLR and at return to sport testing (RTS).Setting.All observations occurred during the participant's physical therapy visits.Measurements.A multi-frequency BIA device measured segmental PhA, Xc, andZ. Linear mixed effects models were used to assess any leg and time interaction and changes over leg and time, independently. Any interactions or main effects were considered significant atp< 0.05.Main results.Significant legxtime interactions were observed for each variable. PhA₅₀and Xc₅₀of NOP were higher (p< 0.001) than OP at each time point by an average of by 0.9° and 4.9 Ω, respectively. In OP, PhA₅₀and Xc₅₀decreased from PRE to 2 W and increased from 6 to 12 W and 12 W to RTS (p< 0.01, for all). At RTS, PhA₅₀and Xc₅₀were similar to PRE in OP (p> 0.05). ForZ₅₀, the OP leg did not change over time (p> 0.05).Z₅₀was greater in NOP at 2 and 6 W (p< 0.01, for both). There were differences in PhA₅₀in NOP between PRE and 6 W and from 6 W to RTS (p< 0.05 for both). Xc₅₀did not change (p> 0.05), andZ₅₀PRE was lower than at 2 W (p< 0.05).Significance.A multi-frequency BIA device can detect changes in segmental BIA variables following ACLR.