Search Results (420)

Objectives: Agonist–antagonist coordination is traditionally defined as simultaneous neural activation assessed by electromyography (EMG). The present study adopts a mechanical perspective, examining twitch-derived contractile ratio indexes between antagonistic muscle groups using tensiomyography (TMG). The aim was to determine whether sport expertise differentiates mechanical agonist–antagonist coordination in karate athletes. Methods: Fifty male participants were divided into four groups: elite karate athletes (EK; n = 7), national team members (NK; n = 14), basically trained karate practitioners (BK; n = 16), and physically active non-athlete controls (CG; n = 13). Bilateral TMG assessment of rectus femoris, vastus lateralis, vastus medialis, biceps femoris, and semitendinosus was performed. Contraction time (Tc), total contraction time (TcT), and rate of muscle tension development (RMTD) were extracted. Twelve twitch-derived contractile ratio indexes (CRI) were calculated separately for dominant (D) and non-dominant (ND) limbs. Results: Significant between-group differences were observed in the temporal coordination of the non-dominant leg. EK demonstrated the lowest index for average contraction time (CRI_Tc_AVG_ND = 17.13%; ANOVA p = 0.005; EK vs. NK p = 0.003) and total contraction time (CRI_TcT_AVG_ND = 9.72%; ANOVA p = 0.003; EK vs. NK p = 0.002). In contrast, velocity-related coordination in the dominant leg was highest in EK (CRI_RMTD_cV_D = 63.66%; ANOVA p = 0.002), differing from NK (p = 0.003), BK (p = 0.002), and CG (p = 0.009). Conclusions: Elite karate athletes exhibit distinct twitch-derived mechanical coordination profiles characterized by highly efficient temporal interplay in the non-dominant (supportive) limb and elevated velocity-related contractile ratio in the dominant (executive) limb. These findings suggest that sport expertise is associated with task-specific mechanical modulation between antagonistic muscle groups detectable through involuntary contractile responses. Full article

Background/Objectives: Understanding how different fatigue contexts influence muscle architecture is essential for optimizing training and recovery strategies in endurance athletes. Ultramarathon running involves prolonged mechanical load and high eccentric demands, which may elicit different acute responses compared to controlled laboratory protocols. This study aimed to examine the effects of time, condition (laboratory vs. race), and muscle on ultrasound-derived muscle architecture in ultratrail runners. Methods: A repeated-measures within-subject design was employed. Forty ultratrail runners completed two fatigue conditions: (1) a standardized laboratory downhill running protocol and (2) an ultramarathon race (CSP 2025; 106 km, +5600 m elevation gain). Muscle thickness and pennation angle of the rectus femoris, vastus lateralis, and medial gastrocnemius were assessed using ultrasound before and after each condition. Linear mixed models were used to evaluate the effects of time, condition, muscle, and their interactions. Results: Forty participants were recruited; 29 completed all assessments. No significant effects of time or condition were observed for muscle thickness, and no interaction effects were detected, indicating that muscle size remained stable across conditions and time points. A significant main effect of muscle was identified (p < 0.001), reflecting inherent morphological differences, with greater thickness in the vastus lateralis compared to the rectus femoris and medial gastrocnemius. In contrast, pennation angle showed a significant main effect of condition (p = 0.031) and a significant condition × muscle interaction (p = 0.005), indicating muscle-specific differences between laboratory and race contexts. No significant effect of time was observed for pennation angle. Conclusions: Muscle thickness appears to remain stable following acute fatigue, regardless of the assessment context. In contrast, pennation angle may be more sensitive to condition-specific and muscle-dependent factors. These findings suggest that ultrasound-derived architectural changes observed immediately after exercise likely reflect acute physiological responses rather than true structural adaptations. Therefore, the interpretation of muscle architecture should consider both contextual factors and methodological constraints. Full article

Muscle size and architecture’s contribution to force and power production in young female acrobatic gymnasts (ACROs) remains unclear. This cross-sectional study examined the associations between quadriceps muscle size and architecture and strength–power performance in young elite female ACROs. Twenty base athletes (12–18 years) underwent ultrasound assessment of rectus femoris (RF) and vastus lateralis (VL) cross-sectional area (CSA), VL muscle volume, VL fascicle length, and VL pennation angle. Participants were additionally classified as pre/mid-pubertal (Tanner stages 1–3) and post-pubertal (Tanner stages 4–5) for descriptive analyses. Performance testing included one-repetition maximum (1RM) squat and hang power clean (HHPC), squat power (Pmax), and countermovement jump (CMJ). In adjusted (Tanner stage and height) linear regression models, VL CSA at 35% and 50% of femur length was positively associated with 1RM squat (β = 2.38–2.31 kg·cm⁻²; p = 0.031–0.011) and Pmax (β = 45.75–38.43 W·cm⁻²; p < 0.001). No associations were observed for CMJ, HHPC, or RF variables. Mid-thigh VL size appears to be an independent predictor of squat strength and power in ACRO. Full article

Among lower-body techniques in karate, the Mawashi Geri Jodan is regarded as the most frequently applied, technically sophisticated, and potentially hazardous skill. Yet, whether karate athletes of varying proficiency levels exhibit differential mastery of this technique remains empirically unexamined. This study aimed to reveal movement control strategies of elite athletes by comparing kinematic and surface electromyography (sEMG) characteristics of Mawashi Geri Jodan between elite and sub-elite female karate practitioners. A total of eight female karate athletes (4 elite, 4 sub-elite) were recruited. During the execution of the dominant-leg Mawashi Geri Jodan, they struck a karate punching bag positioned at head height, while kinematic and sEMG data were synchronously collected. Analyzed metrics included phase durations, center of mass (COM) displacement, joint angles/angular velocities, and integral electromyography (IEMG) with muscle work percentage of 8 lower limb muscles. Independent-sample t-tests were used for intergroup comparisons (α = 0.05). Compared with the sub-elite group, elite athletes completed the full Mawashi Geri Jodan in significantly less time (0.825 ± 0.07 s vs. 1.030 ± 0.05 s, p < 0.01) and exhibited a shorter core striking phase (p < 0.05). Kinematically, elite athletes showed smaller vertical COM displacement during the striking phase (p < 0.05) and greater hip joint range of motion (p < 0.05). sEMG data revealed significantly higher activation of lower limb prime movers (vastus lateralis, gastrocnemius) during the striking phase and greater rectus femoris contribution during the recovery phase in elite athletes. Elite female karate practitioners demonstrate superior movement efficiency, body stability, and neuromuscular coordination in Mawashi Geri Jodan. Technical training should prioritize hip joint flexibility and stability, synergistic explosive force generation of the lower limb kinetic chain during the striking phase, and active rectus femoris activation during the recovery phase to enhance execution precision and efficiency. Full article

Background/Objectives: Osgood–Schlatter disease (OSD) is a common overuse condition in adolescents characterized by increased stiffness of the rectus femoris muscle, which contributes to pain and functional limitations around the knee. We investigated whether repeating 10 min passive joint movements of the hip and knee produces additional immediate reductions in elevated rectus femoris (RF) stiffness in adolescents with OSD. Methods: Fifteen patients (10–14 years of age) diagnosed with bilateral OSD were included. The legs of the participants were randomly assigned to either the intervention or the non-intervention side (control). The intervention side received two sets of 10 min of passive joint movement to the hip and knee, while the control side rested. RF stiffness was measured before the intervention and immediately after one and two sets of passive joint movements. Results: On the intervention side, RF stiffness decreased significantly from pre to post-1 and from pre to post-2; however, RF stiffness did not differ significantly between post-1 and post-2. None of the parameters changed significantly on the control side (rest condition). Conclusions: Passive joint exercise beyond one repetition (one set for 10 min) did not result in a further decrease in RF stiffness and is likely unnecessary for RF muscle stiffness due to OSD. Full article

Background/Objectives: Malnutrition and altered body composition are frequent in chronic heart failure (HF) and are associated with worse functional status and prognosis. Bioelectrical impedance analysis (BIA) is increasingly used in nutritional assessment, although its interpretation may be confounded by fluid overload. This study aimed to evaluate the association between BIA-derived parameters and clinical and biochemical markers of disease severity in ambulatory patients with chronic heart failure. Methods: This cross-sectional study included adult outpatients with chronic HF consecutively assessed in a specialised HF unit. Nutritional evaluation comprised anthropometry, handgrip strength, rectus femoris muscle ultrasound and BIA. Phase angle (PA) and hydration-related parameters were analysed in relation to New York Heart Association (NYHA) functional class and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels. Multivariable regression models adjusted for relevant clinical and BIA variables were applied. Results: A total of 115 patients were included (mean age 68.2 ± 12.6 years; 71.3% men). Mean PA was 4.6 ± 1.1°. Lower PA was independently associated with greater dyspnoea severity (p = 0.026) and higher NT-proBNP concentrations (p = 0.014). Higher total body water was positively associated with symptom burden (p = 0.013) and NT-proBNP levels (p < 0.001) and showed good discriminatory performance for identifying patients in the highest NT-proBNP quartile. Conclusions: In ambulatory patients with chronic HF, BIA-derived parameters reflecting cellular integrity and hydration status are independently associated with clinical and biochemical markers of disease severity. BIA may provide complementary information in nutritional assessment, although hydration-related confounding should be carefully considered. Future longitudinal studies should determine whether these bioimpedance-derived parameters can improve risk stratification and nutritional assessment in chronic heart failure. Full article

Background: Falls are a leading cause of injury and mortality worldwide. Higher physical activity levels in young adults may increase exposure to fall-related situations. Understanding their neuromuscular adaptations is critical for balance control research and perturbation-based training. This study examined proactive and reactive adaptations in lower-limb muscle activity during repeated simulated trips among young adults. Methods: Twenty participants experienced five treadmill-induced standing-trips. Bilateral electromyography (EMG) activities of the rectus femoris (RF), vastus lateralis (VL), tibialis anterior (TA), medial gastrocnemius (MG), and biceps femoris (BF) were recorded. Muscle activity magnitude at perturbation onset (ON), EMG peak amplitude, and time-to-peak from ON were extracted and compared across trials. Results: Proactive activation at ON increased across trials in TA and RF on the recovery side (p = 0.012–0.023) and in TA, VL, and BF on the stance side (p = 0.002–0.034). Reactive peak amplitudes decreased in RF, VL, and BF on the recovery side (p < 0.001–0.014) and in RF, VL, and BF on the stance side (p < 0.001–0.016). Time-to-peak shortened in MG, RF, VL, and BF on the recovery side (p < 0.001–0.030) and in RF, VL, TA, and BF on the stance side (p < 0.001–0.050). Conclusions: Repeated simulated trips elicited proactive adaptations in muscle activity and reactive changes in time-to-peak, which may suppress the need for increased reactive muscle activations to recover balance post-perturbation over trials in young adults. The findings augment our understanding of the intercorrelation between proactive and reactive adaptations to repeated perturbations. Full article

Background: Age-related differences in neuromuscular coordination during multi-joint tasks are reported, but phase-specific evidence during maximal sprinting is limited. Aim: The aim of this study was to investigate phase-specific age differences in agonist–antagonist coordination of the biarticular thigh muscles during 50 m sprinting. Methods: Thirty-eight healthy trained track athletes (Adults: n = 21, age = 23.32 ± 2.98 years; Adolescents: n = 17, age = 13.65 ± 0.76 years) performed maximal 50 m sprints over force plates. Bilateral rectus femoris (RF) and biceps femoris (BF) sEMG and ground reaction forces were recorded; each stride was segmented into seven phases, and an RF–BF co-contraction index (CCI) was calculated per phase. Between-group differences in phase mean CCI were tested (α = 0.05) and quantified with Hedges’ g. Speed- and frequency-dependent modulation of CCI was evaluated using linear mixed-effects models (LME; random intercepts for participant) with Frequency × Group and Speed × Group interaction terms; ordinary least squares (OLS) fits on stride cycle-level group means were descriptive. Linear and single-breakpoint segmented models were compared using the corrected Akaike information criterion (AICc) and Akaike weights. Results: Adolescents showed higher CCI in contact (right: Adults 0.09 ± 0.05 vs. Adolescents 0.13 ± 0.07, g = 0.68; left: Adults 0.08 ± 0.04 vs. Adolescents 0.12 ± 0.06, g = 0.84) and propulsive phases (right: Adults 0.08 ± 0.05 vs. Adolescents 0.13 ± 0.08, g = 0.68; left: Adults 0.07 ± 0.04 vs. Adolescents 0.12 ± 0.07, g = 0.84; p < 0.05 for both legs in both phases). LME identified Frequency × Group interactions in the stride cycle (ΔSlope = 0.10, p < 0.001) and late swing (ΔSlope = 0.12, p < 0.05) and a Speed × Group interaction in mid swing (ΔSlope = 0.01, p < 0.05). Mid swing showed a positive CCI–speed/frequency relationship in both groups, whereas across most other phases Adults downregulated CCI as speed/frequency increased while Adolescents tended to increase CCI. Model selection supported phase-dependent single-breakpoint patterns, with breakpoints around 2.19–2.21 Hz and 6.11–9.51 m·s⁻¹ in Adults and around 2.11 Hz and 7.13–7.59 m·s⁻¹ in Adolescents. Conclusions: Maximal sprinting revealed phase-specific age differences in BF–RF co-contraction and its scaling with speed/frequency, which may help guide age-informed monitoring and training considerations in developing athletes. Full article

Background: Older adults are highly heterogeneous, spanning from robust to frail. Older adults aged ≥80 years (older 80+ group) admitted to an intensive care unit (ICU) present with greater severity and face higher risks of functional decline and mortality than younger ICU patients. Objective: This study compared the trajectory of skeletal muscle mass, strength, and functional status between ICU patients aged 60–75 years and those in the older 80+ group. Methods: A non-concurrent prospective observational study was conducted in older adults who were admitted to an ICU. Skeletal muscle mass, muscle strength and functional status from ICU admission to discharge were assessed. Results: Regarding muscle mass, no differences were observed at ICU admission in patients aged 60–75 years and those in the older 80+ group. However, both groups experienced a decrease in quadriceps muscle thickness (Time Effect: vastus intermedius (VI): p < 0.001; rectus femoris (RF): p < 0.001; and total quadriceps (TQ): p < 0.001) during their ICU stay. No differences were observed at awakening in handgrip strength (HS), Medical Research Council Sum Score (MRC-SS) and Functional Status Score for the Intensive Care Unit (FSS-ICU) between groups. However, HS, MRC-SS, and the FSS-ICU scale all increased from awakening to ICU discharge (Time Effect HS: p = 0.002; MRC-SS: p < 0.001; and FSS-ICU: p < 0.001). Conclusions: Both older adult groups admitted to the ICU experience a decline in skeletal muscle mass, muscle strength, and functional status during their ICU stay, with a tendency for the decline to be greater in the older 80+ group. In addition, critically ill older groups recover muscle strength and functional status from awakening to ICU discharge, with a tendency for the recovery to be smaller in the older 80+ group. These conclusions are based on trends observed in an exploratory study and require confirmation in larger trials. Full article

Background and Objectives: Sarcopenia is a common yet underrecognized condition in cancer patients and is associated with increased treatment-related toxicity, functional decline, and poor clinical outcomes. Practical, rapid, and bedside-applicable tools are needed to detect sarcopenia early in routine oncology practice. This study aimed to evaluate the diagnostic value of rectus femoris muscle ultrasonography within an integrated clinical assessment combining handgrip strength and bioelectrical impedance analysis for the detection of sarcopenia in cancer patients. Materials and Methods: In this prospective cross-sectional study, 147 adult patients with malignancy were evaluated using a multimodal sarcopenia assessment framework. Muscle strength was assessed by handgrip dynamometry, muscle mass was estimated using bioelectrical impedance analysis (BIA)-derived appendicular skeletal muscle mass index (ASMI), and muscle morphology was evaluated using ultrasonographic measurements of the rectus femoris and biceps brachii muscles. Sarcopenia was defined and classified according to the EWGSOP2 criteria. Associations between clinical variables, BIA parameters, and ultrasonographic measurements were analyzed. Receiver operating characteristic (ROC) curve analyses were performed to assess the diagnostic performance of muscle ultrasonography for sarcopenia detection. Results: The mean age of the study population was 60.2 ± 11.2 years, and 51% of participants were male. Confirmed sarcopenia was identified in 12.2% of patients, while 27.2% were classified as having probable sarcopenia. Sarcopenic patients were significantly older (68.5 ± 7.6 vs. 59.0 ± 11.2 years, p = 0.001) and had lower handgrip strength (15.8 ± 6.0 vs. 24.3 ± 8.4 kg, p < 0.001) and ASMI values (5.96 ± 0.64 vs. 7.23 ± 1.18 kg/m², p < 0.001). Rectus femoris muscle thickness was significantly reduced in patients with sarcopenia (6.40 ± 1.42 vs. 8.19 ± 2.21 mm, p = 0.001). Rectus femoris muscle thickness demonstrated good diagnostic performance for sarcopenia detection (AUC = 0.752; 95% CI: 0.650–0.853; p = 0.001), with an optimal cut-off value of ≤7.59 mm (sensitivity 83.3%, specificity 61.2%). Conclusions: Rectus femoris muscle ultrasonography is a practical, rapid bedside assessment for detecting sarcopenia in cancer patients. When integrated with handgrip strength and BIA, this multimodal approach provides a feasible, radiation-free strategy for early sarcopenia screening in routine oncology practice. Full article

Background/Objectives: Muscle wasting is often observed in the acute phase after spinal cord injury (SCI). We aim to investigate the factors determining rectus femoris muscle thickness and echo intensity on discharge for patients who had acute incomplete spinal cord injury undergoing inpatient rehabilitation. Methods: This is a prospective exploratory observational cohort study, conducted in a standalone inpatient multi-specialty tertiary rehabilitation center in Singapore. Forty-five patients with incomplete SCI, defined as American Spinal Injury Association Impairment Scale (AIS) B–D were recruited from January 2020 to October 2021. Variables including clinico-demographic data, lower limb spasticity, Lower Extremity Muscle Score (LEMS), Functional Independence Measure (FIM) motor score on admission were collected. Muscle ultrasound of the rectus femoris thickness and echo intensity were obtained at 6 weeks after acute SCI via standardized protocols. Stepwise multiple regression analyses were performed to identify the factors that were significant for rectus femoris muscle thickness and echo intensity on discharge. Results: The mean age of participants was 59.6 ± 16.6 years, with patients having AIS of B (11.1%), C (28.9%) or D (60.0%). Rectus femoris muscle thickness on discharge had a significant association with body mass index (B = 4.62; CI = 1.77, 7.47; p = 0.002) and onset of mobilization (B = −4.97; CI = −9.46, −0.484; p = 0.031). The significant variables associated with rectus femoris echo intensity on discharge were age (B = 0.546; CI = 0.126, 0.967; p = 0.012) and onset of mobilization (B = 2.49; CI = 0.439, 4.53; p = 0.019). Conclusions: Our findings suggest that age, body mass index and a delayed onset of mobilization may have significant impact on muscle ultrasound parameters. Patients with incomplete SCI may benefit from early mobilization and nutritional assessment for improved muscle strength and function. Full article

Background: Although numerous exercises are prescribed for quadriceps femoris (QF) injury prevention and rehabilitation, few studies have compared QF muscle activation across commonly used bodyweight strength tasks. This study compared EMG activity of the rectus femoris proximal (RFP), rectus femoris medial (RFM), vastus lateralis (VL), and vastus medialis (VM) during seven bodyweight exercises with different stance positions. Methods: Twenty healthy male amateur football players performed three staggered-stance exercises (Split Squat, Bulgarian Split Squat, Backward Lunge), three parallel-stance exercises (Half-Squat, Russian Belt, Reverse Nordic), and one single-leg stance exercise (Lateral Step-Down). Surface EMG signals were recorded, and mean peak EMG values for each exercise were averaged and normalized to maximal isometric voluntary contraction (MVIC). Results: The highest VM and VL activation occurred during the Bulgarian Split Squat (VM: 85.4%; VL: 67.6% MVIC) and Backward Lunge (VM: 74.5%; VL: 59.9% MVIC). RFP and RFM showed the greatest activation during the Russian Belt (RFP: 49.8%; RFM: 39.6% MVIC) and Backward Lunge (RFP: 40.4%; RFM: 31.4% MVIC). VM and VL activation were significantly higher than RFP and RFM activation for all exercises except for Russian Belt and Reverse Nordic (p < 0.005). Conclusions: Exercises imposing greater knee stability demands preferentially activated VM and VL, whereas exercises with longer knee extensor lever arms maximized rectus femoris activation. Full article

Background: Knee osteoarthritis (KOA) often results in reduced physical activity. This exploratory study evaluated lower limb muscle activity across three e-cycling assistance levels and examined e-cycling’s influence on kinesiophobia, stress and exercise motivation in individuals with KOA. Methods: Ten participants cycled with no, low and high assistance on an e-bike. Muscle activity and knee kinematics were measured using surface electromyography and inertia measurement units. A subset of four participants completed questionnaires assessing kinesiophobia (TSK-17), perceived stress (PSS), and exercise motivation (BREQ-3). Muscle activity across the three levels of assistance was analysed using a linear mixed-effects model. Results: Peak and mean muscle activity of rectus femoris (p = 0.01; 0.039), vastus medialis oblique (p = 0.0002; 0.001) and biceps femoris (p = 0.002; 0.03) were lower during high-assistance compared to the no-assistance cycling. No significant differences were observed in mean muscle activity between no- and low-assistance cycling. Reported exertion and pain were low during e-cycling, with kinesiophobia (M = 35.8 ± 2.5 to 33.3 ± 3.5) decreasing following e-cycling, whereas perceived stress (M = 14 ± 5.7 to 14.5 ± 3.3) increased marginally in our small sample. In the small subgroup of participants, the Behaviour Regulation Exercise Questionnaire outcomes increased in four out of six subscores post-exercise. Conclusions: Considering the differences in muscle activity recorded, and given that this is a pilot study, we propose that e-cycling may be an ideal way of introducing graded exercise to KOA patients, potentially allowing them to maintain physical activity and self-management of their disease. Full article

Background/Objectives: This study investigated the biomechanics of a hip exoskeleton during sit-to-stand transitions. Methods: Eleven participants performed the task under three conditions: without the exoskeleton (No Exo), wearing the exoskeleton without assistance (Exo Off), and wearing it with hip extension assistance (Exo On). Results: The analyses revealed that joint angles (hip, knee, and ankle) and vertical ground reaction forces were comparable across all conditions. However, Exo Off significantly increased transition time, whereas Exo On did not differ significantly from No Exo. Additionally, both exoskeleton conditions led to increased integrated EMG (iEMG) activity in the rectus femoris, vastus medialis, and gluteus maximus—likely due to the added device mass. Notably, iEMG analysis revealed a significant reduction in gluteus maximus activity in Exo On compared to Exo Off. Conclusions: Despite providing only moderate torque assistance (0.12 Nm/kg), the results suggest that well-timed exoskeleton support can partially reduce the physical demands of sit-to-stand transitions. However, the observed reduction in gluteus maximus activity was limited, likely reflecting the combined effects of the assistance strategy, including its magnitude and timing, user adaptation and training, postural demands due to device weight and external torques, and mechanical constraints such as potential joint misalignment. Further research is needed to optimize hip exoskeleton support for daily activities. Full article

Background and Objectives: Rapid physiological decline in terminal cancer is frequently accompanied by accelerated skeletal muscle loss. Although bedside ultrasonography (US) is practical and feasible in palliative care settings, the prognostic relevance of short-term muscle change remains unclear. This study aimed to evaluate whether the rate of muscle loss over a 10-day period, assessed by serial ultrasound, is associated with survival duration in terminally ill cancer patients. Materials and Methods: This single-center retrospective cohort study included 87 inpatients with end-stage cancer who underwent bedside ultrasound measurements of the biceps brachii (BB) and rectus femoris (RF). Baseline US was performed within the first three days of admission, followed by a repeat assessment 10 days after baseline (day-10 follow-up ultrasound). Muscle thickness (MT) measurements were normalized by height squared (m²), and 10-day changes were calculated as delta (Δ) indices, defined as baseline minus day-10 values. Because the exposure of interest (Δ) can only be determined after completion of the day-10 assessment, survival timing analyses were anchored to this prespecified landmark. Survival duration was defined as the number of days from the day-10 follow-up ultrasound to death among patients who died within one year. Associations between muscle changes and survival duration were evaluated using correlation analyses and multivariable linear regression adjusted for age, sex, body mass index, Eastern Cooperative Oncology Group (ECOG) performance status, and nutritional risk. The primary analyses focused on survival timing among decedents. Results: Significant muscle loss was observed over the 10-day interval between baseline and 10 days after baseline. Among the 58 patients who died within one year, greater short-term biceps muscle loss, reflected by higher Δ BB muscle thickness index (Δ BB MT-I), was moderately associated with shorter survival duration (r = −0.437, p = 0.0006). In multivariable linear regression analysis, Δ BB MT-I remained independently associated with survival duration (β = −701.19; 95% CI: −1102 to −301; p = 0.0006), whereas RF muscle changes and baseline clinical variables were not statistically significant. Conclusions: Short-term biceps muscle loss assessed by serial ultrasound, as reflected by Δ BB MT-I, is associated with shorter survival duration in terminally ill cancer patients. These findings suggest that dynamic muscle changes, rather than single-time-point measurements, may provide clinically meaningful insight into short-term survival timing. Serial bedside muscle ultrasound may serve as a low-burden adjunct for prognostic communication in palliative care, although prospective time-to-event studies are required for validation. Full article