Neuromuscular dysfunction might represent a key, yet underexplored, contributor to exercise intolerance in patients with heart failure (HF). The objective of this study was to investigate the magnitude of activity and the spatial distribution pattern of activation in the vastus lateralis muscle using High-density surface electromyography (HD-EMG) during various measurement tasks in HF patients. This study included hospitalized patients diagnosed with HF and age-matched elderly individuals without cardiac disease (control group). HD-EMG signals from the vastus lateralis muscle were recorded during isometric contractions at 20%, 40%, and 60% maximal voluntary contraction. HD-EMG signals from the vastus lateralis muscle were detected the root mean square (RMS), modified entropy, and coefficient of variation (CV). The generalized linear mixed-effects model revealed a did not differ significantly main effect of group (HF vs. control) on RMS and CV. In contrast, a significant group effect of group was observed for entropy, with HF patients showing higher entropy values than controls. Our results suggests that the temporal structure of motor unit activity is more monotonous and exhibits less variability in patients with heart failure. In other words, although the muscular output appears similar in patients with heart failure, the flexibility and diversity of their control strategies may be impaired. Entropy revealed differences in temporal and structured neural control that were not detectable by quantitative variability metrics such as CV.

The Osteoporosis Self-Assessment Tool for Asians (OSTA) is a tool that can assess osteoporosis risk based on age and weight. Bone quality, including bone microstructure, as well as bone mineral density (BMD), is important for bone strength. The purpose of this study was to investigate the associations between the OSTA and bone strength indices other than BMD. A total of 111 postmenopausal women with osteoporosis who had undergone high-resolution peripheral quantitative computed tomography in our outpatient clinic were included. The OSTA was calculated using the age and weight, and other techniques were used to evaluate the participants' bones. To investigate the relationship between the OSTA and bone microstructure, comparisons of two groups based on OSTA and multiple regression analysis was performed. Women with OSTA below -4 had poor values for many parameters, including bone microstructural parameters. Multiple regression analysis showed that tibial microstructural parameters were associated with OSTA score independently of femoral neck BMD. OSTA was developed as a screening tool for osteoporosis, however it was found to be related to the microstructure parameters of the tibia when evaluated in postmenopausal women with osteoporosis. Among patients with osteoporosis, those with low OSTA may have deteriorated bone quality in the lower limbs.

BACKGROUND:The readmission rate in patients with heart failure (HF) has risen worldwide. One reason for the lack of reduction in readmission rates may be the absence of standardized evaluation methods tailored to the readmission period. Therefore, this study aimed to examine the influence of nutritional status and physical functions on readmission after discharge in patients with HF according to the readmission period. METHODS:This study was a scoping review. We conducted a comprehensive search for observational studies using the electronic databases PubMed, MEDLINE, CINAHL, and NPO Japan Medical Abstracts Society. RESULTS:The search resulted in a total of 452 selected articles, we finally selected 12 articles. The results of this scoping review showed that patients with HF who were readmitted from 3 months to 1 year after discharge exhibited significantly worse nutritional status and muscle strength compared with patients who were not readmitted. Patients with HF readmitted from 6 months to 1 year after discharge showed significantly worse postural balance function compared with patients who were not readmitted. Exercise tolerance was significantly worse in patients with HF readmitted from 6 months to 1 year and more than 1 year after discharge as compared with patients who were not readmitted. Malnutrition influenced readmissions from 3 to 6 months, 6 months to 1 year, and more than 1 year after discharge. Muscle weakness influenced readmissions from 3 months to 1 year after discharge. Low exercise tolerance influenced readmissions from 6 months to more than 1 year after discharge. CONCLUSION:Malnutrition may influence readmissions over a wide range of periods, from 3 months to more than 1 year after discharge. Muscle weakness may influence short- to mid-term readmissions within 1 year after discharge, whereas low exercise tolerance may influence mid- to long-term readmissions occurring after 6 months.

OBJECTIVE:Previous studies have demonstrated that the cerebral cortex is involved in the postural responses to static standing and disturbances. However, the role of the cortex in postural stabilization remains unclear. This study aimed to clarify cortical activity during postural stabilization. METHODS:Thirteen healthy adult subjects performed a transition from the double-leg stance to the single-leg stance. The tasks were classified as -1-0 s (T1) to 3-4 s (T5), and the relationship between the power spectrum of the alpha and beta bands of the electroencephalogram (EEG) and the center of pressure (COP) or time to stabilization (TTS) was examined. The subjects were also divided into the low-TTS and high-TTS groups based on TTS, and EEG findings were compared between groups. RESULTS:While COP parameters showed no significant correlation with EEG findings, TTS shortening was associated with a decrease in the alpha power at T2 (0-1 s) and an increase in the beta power at T5. Low-TTS group also showed a decrease in the alpha power compared with high-TTS group. Furthermore, low-TTS group showed an increase in beta power at T5 compared with T1, and high-TTS group showed a decrease in beta power at T5 compared with T3 (1-2 s). CONCLUSION:Our findings indicate that the cerebral cortex contributes to faster postural stabilization. Furthermore, the results suggest that the decrease in alpha power is the cortical activity that stabilizes the posture, and the increase in beta power is the cortical activity that maintains a stable posture.

OBJECTIVES:In recent years, the number of elderly heart failure patients with multiorgan failure has been increasing. Furthermore, the combination of heart failure and decreased hepatic reserve can cause severe skeletal muscle impairment and decreased survival rates. This study investigated whether the degree of improvement in the five repetitions of sit-to-stand (5STS) and walking speed (WS) differs depending on hepatic reserve in elderly heart failure patients. METHODS:The patients were divided into the following two groups: good hepatic reserve (albumin-bilirubin score [ALBI score] ≤-2.25) and poor hepatic reserve (ALBI score >-2.25). Propensity score matching was performed using the brain natriuretic peptide level. A two-way analysis of variance (ANOVA) was performed to examine the main effects of the hepatic reserve and time points (admission or discharge). RESULTS:After propensity score matching, 28 out of the 33 (84.8%) patients in the good hepatic reserve (age, 83.74 ± 9.25 years and ALBI score, -2.55 ± 0.19 points) and 27 out of 40 (67.5%)patients in the poor hepatic reserve (age, 85.85 ± 7.53 years and ALBI score, -1.93 ± 0.26 points) were analyzed. Two-way ANOVA showed that the 5STS (p = 0.04) and WS (p = 0.01) in poor hepatic reserve tended to be worse than in good hepatic reserve. Furthermore, the 5STS (p = 0.04) and WS tended to improve at discharge in both groups. However, the improvement in WS was not significant (p = 0.15). CONCLUSIONS:Our study suggests that the hepatic reserve in elderly heart failure patients may be an important factor in the assessment of physical functions.

Shoulder kinematics and muscle activity vary depending on the elevation plane of the upper limb. However, how muscle coordination, which plays a crucial role in controlling shoulder kinematics, differs among elevation planes remains unclear. This study compared shoulder kinematics, muscle synergies, and muscle activation levels across different elevation planes to better understand the neuromuscular mechanisms underlying shoulder kinematics. Shoulder kinematics and muscle activity were recorded during three upper limb elevation tasks (sagittal, scapular, and frontal plane elevation) in 12 subjects (7 males and 5 females). Muscle synergies were extracted using nonnegative matrix factorization, and individual muscle activity levels were calculated as a percentage of maximum voluntary contraction. Glenohumeral elevation was greatest during the sagittal plane elevation task and smallest during the frontal plane elevation task (maximum difference of 14.1°). The differences in kinematics among these elevation planes were suggested to be attributable to the early-stage activity level during elevation of one of the two extracted muscle synergies—specifically, the synergy believed to contribute to humeral head stabilization—and the activation amplitude of the anterior deltoid. Differences in scapular kinematics among three elevation plane tasks could not be explained by variations in muscle synergies but were instead suggested to result primarily from differences in the activation amplitudes of the three parts of the trapezius. To results suggest that shoulder kinematics are controlled by subtle changes in muscle synergy activation patterns and individual muscle activation levels.

Objectives:This study aimed to clarify the impact of cachexia on physical function recovery during hospitalization among patients with heart failure using the new Asian Working Group for Cachexia criteria and to identify the characteristics of heart failure patients with cachexia. Methods:Cachexia at discharge was defined by low body mass index combined with one or more of the following: low handgrip strength, elevated C-reactive protein, or anorexia. Physical function was assessed at admission and discharge. Two-way analysis of variance (ANOVA) was performed to examine the interaction and main effects of the presence of cachexia and duration factors (admission and discharge) on physical function. Hierarchical logistic regression analysis was performed to explore factors associated with the presence of cachexia. Results:Of the 96 patients analyzed, 26 were heart failure patients with cachexia, and 70 were heart failure patients without cachexia. The results of the 2-way ANOVA indicated that heart failure patients without cachexia exhibited improved physical function at discharge compared to that at admission. In contrast, heart failure patients with cachexia showed no improvement in physical function during hospitalization. Hierarchical logistic regression analysis revealed that a low geriatric nutritional risk index (GNRI) and low muscle power were associated with the presence of cachexia in patients with heart failure. Conclusions:Our results suggest that heart failure patients with cachexia experience poor recovery of physical function during hospitalization, and that reduced muscle power and deterioration in nutritional status, as indicated by a low GNRI, were associated with the presence of cachexia.

BACKGROUND AND AIMS:Studies reported that knee extension strength on the operated side in patients with hip fractures was not recovered to the level on the non-operated side 6 months after surgery or later. In a cross-sectional study, we revealed that a reduction in isometric knee extension muscle strength on the operated side in patients with hip fractures approximately 6 months after surgery was associated with not only a reduction in skeletal muscle mass but also a reduction in muscle quality, characterized by a reduction in the phase angle (PhA). Furthermore, the mechanisms of knee extension strength improvement can be clarified in more detail using the minimal significant change as the index of recovery. However, no longitudinal studies have examined the factors for knee extension strength improvement based on the minimal significant change in patients with hip fractures 6 months after surgery. This study aimed to longitudinally examine the factors influencing the recovery of knee extension strength based on the minimal significant change in patients with hip fractures between 2 weeks and approximately 6 months after surgery.METHODS:In this study, the outcomes used were basic and medical information, PhA, skeletal muscle index (SMI), pain, one-leg standing time, movement control during one-leg standing, and walking speed. For PhA, SMI, pain, one-leg standing time, movement control during one-leg standing, and walking speed, the amount of change was calculated by subtracting the data at 2 weeks from the data at 6 months. Group classification was determined by dividing the patients into two groups using a previous study as a reference: recovery group if the knee extension strength value approximately 6 months after surgery minus that 2 weeks after surgery was ≥3.3 kgf and non-recovery group if the value was <3.3 kgf. Logistic regression analysis was performed to explore the association between the recovery and non-recovery groups.RESULTS:The recovery group contained 55 patients, while the non-recovery group comprised 35 patients. The only significant factor associated with knee extension muscle strength in the recovery group was the amount of change in PhA. The odds ratio for the amount of change in PhA was 2.26. The discrimination rate of the model was 62.5%.CONCLUSIONS:Our results suggest that recovery of knee extension strength in patients with hip fractures after surgery was mainly because of improvements in muscle quality, not improvements in muscle mass or pain.

OBJECTIVES:The current study sought to investigate whether physical function and activity were associated with hip structural analysis (HSA) parameters on the non-fracture side of patients with hip fractures. METHODS:Participants were patients with unilateral hip fracture treated by surgery. HSA of the proximal femur was conducted based on dual-energy x-ray absorptiometry data. HSA parameters in the narrow neck region included cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), section modulus (SM), and buckling ratio (BR). Hierarchical multiple regression analysis was conducted to identify predictors of HSA. RESULTS:Except for the adjustment variables, age, gender and BMI, other variables were extracted. Hierarchical multiple regression analysis (standardised partial regression coefficients) identified movement control during one-leg standing on the non-fractured side (0.15) as factors associated with CSA. Hierarchical multiple regression analysis (standardised partial regression coefficients) identified hand grip (0.12, 0.23) as factors associated with CSMI and SM, respectively. Hierarchical multiple regression analysis (standardised partial regression coefficients) identified presence of steroid (0.23) and cerebrovascular disease (0.19) as factors associated with BR. The coefficients of determination adjusted for degrees of freedom (R2) were 0.545, 0.331, 0.401, and 0.148 for CSA, CSMI, SM, and BR, respectively. CONCLUSIONS:Our results indicate that movement control during 1-leg standing and muscle strength may be important for maintaining and improving bone strength.

Background: The diagnostic criteria for respiratory sarcopenia have been recently reported. However, no studies have clarified the characteristics of skeletal muscle impairment of the limbs in subjects with respiratory sarcopenia. This study aimed to explore the factors, including skeletal muscle, associated with probable respiratory sarcopenia in elderly subjects. Methods: Subjects were classified into the probable respiratory sarcopenia group and nonrespiratory sarcopenia group. Probable respiratory sarcopenia was defined as the concurrent presence of respiratory muscle weakness (as less than the predicted value calculated from age, sex, and height) and low skeletal muscle mass ( <7.0 kg/m(2) in males and 5.7 kg/m(2) in females). The following factors were measured: respiratory muscle strength, skeletal muscle mass index, muscle thickness and echo intensity of the rectus femoris, extracellular-to-intracellular water ratio, hand grip strength, 5 sit-to-stand, knee extension strength, bone mineral density, age, sex, body mass index, degree of frailty, presence or absence of medical history, presence or absence of habitual exercise, period of time since the start of exercise, and number of hours of exercise at a time. The association subjects with probable respiratory sarcopenia were analyzed using hierarchical logistic regression analysis. Results: Twenty-six with probable respiratory sarcopenia and 54 with nonrespiratory sarcopenia were included. Hierarchical logistic regression analysis revealed that echo intensity was a significant predictor of probable respiratory sarcopenia. The odds ratio for echo intensity was 2.54 (95% confidence interval: 1.04 -6.23). Conclusions: Our results suggest that a decrease in muscle quality in the lower extremity is associated with probable respiratory sarcopenia.

This study aimed to classify subgroups of healthy young adults based on foot stiffness and related kinetic parameters during gait, as well as to analyze intra-foot sagittal kinematics within each subgroup. Data were collected from 25 males and 24 females using a 3D motion capture system, which measured the rearfoot, midfoot, and forefoot segments. Cluster analysis identified three subgroups based on the following variables: the truss coefficient, windlass coefficient, forward component of ground reaction force (F-GRF), and ankle plantar flexion power. Group 1 demonstrated the highest foot stiffness, as indicated by the largest truss coefficient, while Groups 2 and 3 exhibited lower stiffness, characterized by greater dorsiflexion of the midfoot and forefoot relative to the rearfoot during the stance phase. Additionally, the kinematic coordination patterns between the rearfoot-midfoot and midfoot-forefoot of Groups 2 and 3 during the early and late stance phases showed significant variation. Group 3, in particular, exhibited lower F-GRF and ankle plantar flexion power than Groups 1 and 2. These results suggest that midfoot movement during the late stance phase is critical in generating foot stiffness, with a midfoot-dominant kinematic pattern potentially serving as a key contributor. The study underscores the importance of understanding intersegmental coordination for managing foot stiffness, which could have implications for improving gait mechanics and preventing injuries. Further research is needed to explore how these findings can be applied to individuals with various foot conditions or pathologies.

Background There is limited research on the factors influencing frailty improvement and on whether exercise therapy is effective in the general population with heart failure. We aimed to examine the factors and interventions that affect the improvement of frailty in older patients with heart failure during hospitalization. Methods This multicentre prospective cohort study included patients with heart failure admitted and treated in the participating hospitals. Cox regression analysis was done to determine factors and interventions that affect improvement of frailty. After the Cox regression analysis, the receiver operating characteristic (ROC) curve was calculated for significant predictors to assess the cut-off point. Results The factors that affect improvement of frailty were the high short physical performance battery (SPPB) chair-stand test and hand grip strength values. The results of the ROC analysis revealed that the cut-off values of the SPPB chair-stand test and hand grip strength were 2 points and 13.7 kg, respectively. Interventions that affect frailty improvement were use of dobutamine, low resting heart rate, early days to start until aerobic exercise, and light intensity or higher of aerobic exercise. Moreover, the cut-off values of the resting heart rate, number of days to start until aerobic exercise, and intensity of aerobic exercise were 80 beats per minute, 7 days, and 31.6%, respectively. Conclusions Our results suggest that pharmacotherapy and exercise will be effective to improve frailty in patients with heart failure. In particular, early exercise therapy, including aerobic exercise, started within 7 days, may be effective to improve frailty in older patients with heart failure with low resting heart rate, depending on their condition on admission.

Background/Purpose: The prevalence of sarcopenia is high in patients with medical diseases and after fractures and is particularly high in heart failure patients among patients with medical diseases and hip fracture patients among patients with fractures. In 2019, the European Working Group of Sarcopenia in Older People 2 reported that muscle quality assessment is important for the diagnosis of sarcopenia. However, it is unknown whether sarcopenia in heart failure and hip fracture patients is significantly associated with poor muscle quality. This study aimed to determine whether muscle quality is associated with sarcopenia in heart failure and hip fracture patients. Methods: Basic medical information, extracellular water (ECW) / intracellular water (ICW) ratio as muscle quality, and physical functions were assessed. Hierarchical multinomial logistic regression analysis was performed to investigate factors associated with three groups (i.e., healthy elderly participants, patients with heart failure and sarcopenia, and patients with hip fracture and sarcopenia). Results: Participants included in the analysis were 21 healthy elderly participants, 15 in patients with heart failure and sarcopenia, and 21 in patients with hip fracture and sarcopenia. The results of hierarchical multinomial logistic regression analysis revealed that high total ECW/ICW ratio was a significant predictor for sarcopenia in patients with heart failure and hip fracture. The odds ratios for total ECW/ICW ratio were 11.47 in patients with heart failure and sarcopenia and 30.91 in patients with hip fracture and sarcopenia, respectively. Conclusion: This study suggested that poor muscle quality were associated with sarcopenia in patients with heart failure and hip fracture.

Objective: Scapular dyskinesis is one of the causes of shoulder disorders and involves muscle weakness in the serratus anterior. This study investigated whether motor unit (MU) recruitment and firing property, which are important for muscle exertion, have altered in serratus anterior of the individuals with scapular dyskinesis. Methods: Asymptomatic adults with (SD) and without (control) scapular dyskinesis were analyzed. Surface electromyography (sEMG) waveforms were collected at submaximal voluntary contraction of the serratus anterior. The sEMG waveform was decomposed into MU action potential amplitude (MUAP(AMP)), mean firing rate (MFR), and recruitment threshold. MUs were divided into low, moderate, and high thresholds, and MU recruitment and firing properties of the groups were compared. Results: Highthreshold MUAP(AMP) was significantly smaller in the SD group than in the control group. The control group also exhibited recruitment properties that reflected the size principle, however, the SD group did not. Furthermore, the SD group had a lower MFR than the control group. Conclusions: Individuals with scapular dyskinesis exhibit altered MU recruitment properties and lower firing rates of the serratus anterior; this may be detrimental to muscle performance. Thus, it may be necessary to improve the neural drive of the serratus anterior when correcting scapular dyskinesis.

Background/Purpose We aimed to investigate whether there is an interaction between life-space assessment (LSA) and movement control during one-leg standing on bone strength on the non-fractured side in patients with hip fracture. Methods Two-way analysis of variance (ANOVA) was applied for osteoporosis parameter to examine the interaction and main effects of LSA and movement control during one-leg standing. Results Two-way ANOVA revealed significant interaction and main effects of LSA and movement control during one-leg standing on bone mineral density (BMD) and Z-score. In parameters of hip structural analysis (HSA), the interaction and main effect of movement control during one-leg standing were detected only in cross-sectional area (CSA). Conclusion The results of this study suggest that both high LSA and good movement control during one-leg standing are necessary to maintain or improve some parameters of bone strength, such as BMD (neck and total hip), Z-score (neck and total hip), and CSA.

Context : Excessive hip adduction and internal rotation are abnormal movements that may lead to the onset and progression of patellofemoral pain. Previous studies have reported that lower dynamic frontal plane hip joint stiffness in the gait of women is associated with the magnitude of hip adduction and internal rotation angles. However, the factors contributing to the lack of dynamic frontal plane hip joint stiffness in the gait of young women are unclear. This study aims to investigate the factors affecting dynamic frontal plane hip joint stiffness during the weight-acceptance phase of the gait of healthy young women. Design : Cross-sectional study. Methods : This study included 30 healthy women between the ages of 18 and 30 years. The pelvic width/femur length ratio was calculated by dividing the pelvic width by the femur length. Data on hip kinematics and kinetics and activation of the gluteus maximus and medius, tensor fasciae latae, and adductor longus muscles during gait were collected using a motion capture system, force plates, and surface electromyography. Stepwise multiple regression analysis was conducted to determine the extent to which each independent factor affected dynamic frontal plane hip joint stiffness. Results : In healthy young women, decreased dynamic frontal plane hip joint stiffness was associated with decreased muscle activity of the gluteus maximus during the gait, as well as greater pelvic width/femur length ratio. Conclusions : Women with a relatively great pelvic width relative to femur length may have more difficulty in producing dynamic frontal plane hip joint stiffness. However, increasing the muscle activity of the gluteus maximus may contribute to increased dynamic frontal plane hip joint stiffness.

This study aimed to examine the interaction effect between the presence of heart failure and the degree of frailty on skeletal muscle mass index (SMI), handgrip strength, and 5 times sit-to-stand (5STS). This study revealed a significant interaction effect between the presence of heart failure and the degree of frailty on SMI, handgrip strength, and 5STS. The study results revealed that the combination of heart failure and frailty has synergistic negative effects on SMI and upper and lower limb muscle strength.

Our results revealed that the decrease in isometric knee extension muscle strength on the operated and nonoperated sides in patients with hip fractures was associated with not only a decrease in skeletal muscle mass but also a decrease in muscle quality, characterized by a decreased PhA. This study aimed to assess the relationship between isometric knee extension muscle strength on the operated or nonoperated sides and PhA in patients with hip fractures at approximately 6 months postoperatively. This study was a cross-sectional study. Skeletal muscle index (SMI), PhA, knee extension muscle strength on the operated and nonoperated sides, and other physical function variables were assessed at approximately 6 months postoperatively. To identify predictors of knee extension muscle strength on the operated and nonoperated sides, hierarchical multiple regression analysis was performed. A total of 90 patients with hip fractures were included (mean age, 80.1 ± 6.9 years). SMI (0.45) and PhA on the operated side (0.27) were the significant associated factors extracted for isometric knee extension muscle strength on the operated side (standardized partial regression coefficients), independent of age, sex, and body mass index (BMI). Movement control during one-leg standing on the nonoperated side (0.26), SMI (0.32), and PhA on the nonoperated side (0.40) were the significant associated factors extracted for isometric knee extension muscle strength on the nonoperated side, independent of age, sex and BMI. Our results revealed that the decrease in isometric knee extension muscle strength on the operated and nonoperated sides in patients with hip fractures at approximately 6 months postoperatively was associated with not only a decrease in skeletal muscle mass but also a decrease in muscle quality, characterized by a decreased PhA.

AbstractScapular dyskinesis results from weakness of the lower trapezius and serratus anterior, but no studies have investigated the motor unit (MU) behavior required for muscle exertion. This study aimed to classify scapular dyskinesis into raising (SDR) and lowering (SDL) phases and investigated the MU behaviors of the lower trapezius and serratus anterior. Fifty healthy young subjects underwent a scapular dyskinesis test and were divided into Normal, SDR, and SDL groups. The subjects performed submaximal voluntary contractions of the lower trapezius and serratus anterior, and surface electromyography signals were decomposed into the MU action potential amplitude (MUAPAMP), mean firing rate (MFR), and recruitment threshold (RT). The average MUAPAMPand MFR and the slopes and y-intercepts of the linear MUAPAMP-RT and MFR-RT were compared. The MUAPAMP-RT slopes in the lower trapezius (p = 0.049,r = 0.420) and serratus anterior were smaller (p = 0.010,r = 0.490) and the MFR-RT y-intercept in the serratus anterior was lower (p = 0.004,r = 0.540) in the SDR group than in the Normal group. Differences in other parameters between the SDL and Normal groups were not significant. Lower trapezius and serratus anterior MU behavioral changes may cause scapular dyskinesis in the raising phase.