Search Results (1,378)

Background: Neurological disease may lead to malnutrition through disease-related complications, underscoring the need for accurate muscle assessment. This study aims to evaluate an AI-based tool for quantifying and characterizing muscle ultrasound images, comparing its performance with the usual techniques of muscle mass and function. Methods: This was a prospective, open-label, longitudinal observational study of 117 adults with neurological disorders at high nutritional risk, designed to evaluate nutritional status and clinical evolution. The clinical assessment integrated anthropometry, bioelectrical impedanciometry, handgrip strength, dysphagia testing, and rectus femoris quadriceps ultrasound. Ultrasound images were evaluated through an AI-based platform to extract muscle quantity (rectus femoris muscle area (RFMA) and rectus femoris muscle thickness (RFMT) and quality biomarkers (percentage of low-echogenicity areas (Mi), interpreted as muscle; percentage of medium-echogenicity areas (FATi), interpreted as intramuscular fat). Patients were followed for two years to record mortality. Results: The sample included 117 adults with neurological disorders (52.1% women), with a mean age of 63.01 (16.14) years. A total of 77 patients (65.8%) had a condition with direct neuromuscular involvement. According to Global Leadership Initiative on Malnutrition (GLIM) criteria, 73 patients (62.4%) had malnutrition, while 30 patients (25.6%) had severe malnutrition. There were no differences in muscle mass parameters, but patients with neuromuscular involvement (NM) had lower values of percentage of Mi (NM: 42.44 (9.09%) vs. 47.36 (7.74)%; p < 0.01), and higher values of FATi (41.91 (5.71)% vs. 39.15 (4.89)%). The prevalence of mortality was 26 patients (22.2%). In the multivariate analysis, FATi (above median) (OR = 5.11 (IC95%: 1.26–20.67)) increased risk of death, adjusted by age, neuromuscular involvement, sex, and Mi. Conclusions: Patients with neuromuscular disorders showed a markedly lower proportion of Mi and a higher presence of FATi compared to those with non-neuromuscular conditions. Mortality was associated with greater FATi on AI-based ultrasound analysis. These findings suggest AI-enhanced imaging captures clinically relevant tissue alterations with potential prognostic value; however, given the observational data and heterogeneity of neurological conditions, these implications should be interpreted cautiously. Full article

Background: To compare the clinical and ultrasonographic effects of pulsed therapeutic ultrasound (US) and pulsed shortwave diathermy (SWD) in patients with mild-to-moderate carpal tunnel syndrome (CTS). Methods: In this randomized controlled trial, 40 patients with electrophysiologically confirmed mild-to-moderate CTS were randomly allocated into two groups. Both groups received wrist splinting and tendon–nerve gliding exercises. The US group received 15 sessions of pulsed ultrasound therapy (3 MHz, 0.8 W/cm²), whereas the SWD group received 15 sessions of pulsed shortwave diathermy (80 Hz, 19.2 W). Outcomes were assessed at baseline, 1 month, and 3 months using ultrasonographic median nerve cross-sectional area (MNCSA) (primary outcome), Boston Carpal Tunnel Questionnaire (BCTQ), Visual Analog Scale (VAS) for pain, Douleur Neuropathique 4 (DN4), and handgrip strength. Results: Baseline demographic characteristics, including age (mean ± SD) and sex distribution, were comparable between groups (p > 0.05), although BCTQ Functional Status and Total scores differed significantly at baseline. Repeated-measures analyses demonstrated significant time effects for MNCSA and all secondary clinical outcomes, including BCTQ scores, VAS pain, DN4 scores, and grip strength (all p < 0.001; partial η² range: 0.51–0.75), indicating moderate-to-large effect sizes. Both the US and SWD groups showed sustained improvements at the 1- and 3-month follow-ups, with no significant differences between treatment modalities (all group × time interaction p > 0.05). Conclusions: In patients with mild-to-moderate CTS, both US and SWD administered alongside splinting and exercise were associated with significant clinical and ultrasonographic improvements over 3 months. No significant difference was observed between the two modalities. Both treatments may be considered adjunctive options within conservative management, although further controlled studies are needed to clarify modality-specific effects. Full article

Background: Sarcopenia, the age-related loss of muscle mass and strength, affects over 20% of older adults in Taiwan and contributes to frailty and functional decline. Nutritional supplementation offers a promising strategy for those unable to engage in structured exercise, yet multi-ingredient MCT–leucine–creatine-based interventions remain understudied in clinically defined sarcopenic populations. Methods: We conducted an 8-week randomized, double-blind, placebo-controlled trial at National Taiwan University Hospital (ClinicalTrials.gov NCT06376266). Seventy-three older adults (mean age 77.3 ± 7.7 years) meeting AWGS 2019 sarcopenia criteria were randomized to TLN-01 (a multi-ingredient supplement containing whey protein, branched-chain amino acids, medium-chain triglycerides, creatine, resveratrol, and vitamin D₃, n = 34) or isocaloric placebo (n = 39). Primary outcomes were changes in appendicular skeletal muscle mass (ASM) assessed by DXA and handgrip strength. Targeted plasma amino acid metabolomics (LC-MS) was performed as an exploratory endpoint. Results: ASM increased significantly in the TLN-01 group (+0.42 kg, +3.2%; p < 0.001) but remained unchanged in controls (p = 0.785), with a significant between-group difference (ANCOVA p < 0.01); this absolute change was below the commonly cited minimal clinically important difference. Handgrip strength did not differ significantly between groups (p = 0.32); within-group analysis showed a significant decline in the placebo group (−7.0%; p < 0.001) that was not observed in the intervention group (p = 0.537). Metabolomic analysis revealed reductions in plasma taurine and 1-methylhistidine and an increase in kynurenine; given the absence of clear separation on PCA/PLS-DA, these findings are considered exploratory and hypothesis-generating rather than confirmatory evidence of altered amino acid utilization or proteolysis. No clinically significant adverse metabolic or renal events occurred. Conclusions: Eight weeks of this multi-ingredient MCT–leucine–creatine-based supplement induced a modest increase in muscle mass and attenuated the decline in handgrip strength observed in the placebo group among sarcopenic older adults without a structured exercise program, supporting further investigation as a safe and practical nutritional adjunct in geriatric care. Full article

Isometric resistance training (IRT) has emerged as a promising non-pharmacological intervention for blood pressure (BP) management. Although current hypertension guidelines primarily recommend aerobic and dynamic resistance exercise, growing evidence indicates that IRT is an effective, feasible, and time-efficient alternative. This narrative review summarizes the current evidence on the efficacy, physiological mechanisms, and clinical applications of IRT. We reviewed randomized controlled trials, systematic reviews, and meta-analyses evaluating the effects of different IRT modalities, including isometric handgrip (IHG), isometric wall squat (IWS), and isometric leg extension (ILE), on BP in normotensive individuals, patients with hypertension, and those with cardiovascular disease. IRT consistently reduces resting systolic BP by approximately 5–8 mmHg and diastolic BP by 3–4 mmHg; these effects may approach those reported with first-line antihypertensive therapy and potentially be equivalent to those of other exercise modalities. These benefits have been demonstrated across normotensive and hypertensive populations and appear largely independent of age, sex, medication use, and the muscle groups involved. Preliminary evidence also supports the feasibility and safety of appropriately prescribed IRT in selected patients with ischemic heart disease and heart failure with preserved ejection fraction. Proposed mechanisms include improvements in endothelial function, nitric oxide bioavailability, autonomic regulation, oxidative stress, arterial baroreflex sensitivity, and myocardial efficiency. IRT has emerged as an effective, safe, and practical adjunct to lifestyle modification for BP control, particularly in older adults and individuals with limited ability to perform conventional exercise. However, current evidence derives from relatively small studies with limited follow-up; further large-scale randomized trials are needed to define the optimal exercise prescription, clarify the underlying mechanisms, and establish the role of IRT in patients with cardiovascular disease. Full article

Background: Although dual-energy X-ray absorptiometry (DXA) is the reference method for measuring appendicular skeletal muscle mass (ASMM) and diagnosing sarcopenia, seated bioelectrical impedance analysis (BIA) may represent a practical alternative. As its validity remains still insufficiently documented in specific populations, the objective is to evaluate the agreement between seated BIA and DXA, and examine associations between phase angle (PhA) and physical performance in old adults. Methods: Fifty-nine old adults (75 ± 7 years) underwent DXA and seated BIA (Biody XpertZM3). ASMM was estimated using the Kyle and Sergi equations. Agreement with DXA was assessed using Lin’s concordance correlation coefficient (CCC), Bland–Altman analysis, root mean square error (RMSE) and mean absolute error (MAE). Associations between PhA, handgrip strength, and five-times sit-to-stand (5-STS) performance were evaluated. Results: Both equations showed good agreement with DXA, but the Sergi equation performed better, with higher concordance (CCC = 0.942 vs. 0.898), lower bias (0.44 vs. 1.11 kg), and lower RMSE (1.33 vs. 1.96 kg). PhA correlated positively with handgrip strength (r = 0.315, p = 0.015) but was not associated with 5-STS. Conclusions: Seated BIA provides clinically acceptable estimates of ASMM in older adults. The Sergi equation demonstrated superior accuracy, supporting population-specific equations. PhA may provide additional information on muscle quality and sarcopenia. Full article

Background: Osteoporosis and sarcopenia frequently coexist in older adults and jointly contribute to increased risk of falls and fragility fractures. While adherence to the Mediterranean diet (MD) has been broadly associated with favorable health outcomes, its potential role in modulating muscle-related functional status and, indirectly, fracture risk remains incompletely understood. Objective: To investigate the association between adherence to MD and SARC-F-assessed functional status, and to explore their interplay with FRAX-estimated fracture probability in postmenopausal women evaluated for osteoporosis. Methods: Adherence to the MD was assessed using the Medi-Lite questionnaire. Muscle-related functional status was evaluated through the SARC-F questionnaire and objectively measured by handgrip strength. Fracture probability was estimated using the FRAX tool. Correlation and multivariable analyses were performed to evaluate associations among study variables. In addition, an exploratory indirect-effect analysis was conducted to investigate whether functional status might represent a potential intermediate pathway linking MD adherence and FRAX-estimated fracture probability. Results: A total of 96 participants (median age 66 years) were consecutively recruited. Greater adherence to the MD was associated with lower SARC-F scores (r = −0.292; p = 0.005), indicating better muscle-related functional status. SARC-F scores were inversely correlated with handgrip strength (r = −0.264; p = 0.013) and positively correlated with the estimated 10-year probability of major osteoporotic fractures (r = 0.289; p = 0.005) and hip fractures (r = 0.277; p = 0.008). No significant associations were observed between MD adherence and FRAX-estimated fracture probability, bone mineral density, or prevalent fractures. In the exploratory indirect-effect analysis, a significant indirect association between MD adherence and FRAX-estimated fracture probability through SARC-F score was observed, whereas the direct association was not significant. Conclusions: In postmenopausal women referred for osteoporosis evaluation, greater adherence to the MD was associated with better self-reported muscle-related functional status but not directly with FRAX-estimated fracture probability. These findings are consistent with the hypothesis that functional status may represent an intermediate link between dietary habits and estimated fracture risk. However, because dietary adherence, functional status, and fracture risk were assessed simultaneously, no causal or temporal inferences can be drawn. Consequently, the indirect-effect findings should be regarded as exploratory and hypothesis-generating, requiring confirmation in adequately powered longitudinal and mechanistic studies. Full article

Background: Device-independent, lifestyle-integrated active pursed-lip diaphragmatic breathing (PLDB) may overcome respiratory rehabilitation barriers in chronic heart failure (CHF). This retrospective real-world study evaluated its prognostic association with functional capacity, quality of life (QoL), and major adverse cardiovascular events (MACE). Methods: A total of 58 CHF patients (NYHA II–IV) were categorized by 6-month post-discharge PLDB adherence into a Respiratory Training Group (RTG; n = 20) and Control Group (n = 38). Functional, structural, QoL metrics, and MACE outcomes were analyzed. Results: After 6 months, the RTG demonstrated significant intra-group improvements in 6 min walk test (6MWT) distance (302.00 [243.60, 408.15] m to 386.00 [339.50, 439.00] m, p = 0.006; baseline-adjusted between-group gain: +76.16 m), handgrip strength (p = 0.046), LVEF (p = 0.003), and scores on the Minnesota Living with Heart Failure Questionnaire (MLHFQ) (p < 0.001), Generalized Anxiety Disorder-7 (GAD-7) (p = 0.010), and Self-rating Somatic Symptom Scale-China (SSS-CN) (p = 0.004). Post-intervention, the RTG outperformed controls in handgrip strength (p = 0.012), MLHFQ (p = 0.001) and SSS-CN (p = 0.020). The RTG exhibited a significantly lower MACE incidence (5.0% vs. 42.1%, p = 0.003) and superior MACE-free survival (log-rank p = 0.005). Multivariable Cox regression confirmed high PLDB adherence was independently associated with a lower MACE risk (adjusted HR = 0.103, 95% CI: 0.014–0.779, p = 0.028). Conclusions: High adherence to a 6-month lifestyle-integrated PLDB program correlates with clinically meaningful improvements in exercise capacity, cardiac function, and QoL, and is independently associated with a lower risk of short-term MACE in CHF patients. Full article

Background/Objectives: This study evaluated whether phase angle (PhA) was associated more strongly with nutritional and functional vulnerability than with postoperative morbidity. Methods: This cohort included 207 adults undergoing colorectal cancer surgery. Primary outcomes were malnutrition defined according to the Global Leadership Initiative on Malnutrition (GLIM) criteria, low handgrip strength and impaired Short Physical Performance Battery (SPPB) scores; postoperative complications, readmissions and length of stay were exploratory outcomes. PhA was measured by 50 kHz bioelectrical impedance vector analysis. Analyses estimated areas under the curve (AUCs) with 95% confidence intervals and Youden cut-offs; models adjusted for age, sex and body mass index. Results: PhA was lower in participants with nutritional vulnerability than in those without it (4.57 ± 0.62° vs. 5.20 ± 0.69°; p < 0.001). Discrimination was excellent for handgrip strength <10th percentile (AUC 0.803) and acceptable for SPPB < 10 (AUC 0.785), SPPB ≤ 6 (AUC 0.761) and GLIM-defined malnutrition (AUC 0.728) but showed no discrimination for any postoperative complication (AUC 0.507). After adjustment, PhA ≤ 4.7° remained associated with GLIM-defined malnutrition, handgrip strength < 10th percentile and SPPB < 10 but not with any postoperative complication. Conclusions: PhA was more strongly associated with nutritional and functional vulnerability than with postoperative morbidity. Thresholds require external validation; PhA may complement, not replace, GLIM, body composition, handgrip strength and SPPB. Full article

Background: This study aimed to determine the prevalence of osteosarcopenia and evaluate the diagnostic performance of phase angle, derived from bioelectrical impedance analysis, in identifying osteosarcopenia among older adults with type 2 diabetes mellitus. Method: A cross-sectional study was conducted with 147 participants aged 60 years or older, recruited from an outpatient clinic in Thailand between during 2024. Osteosarcopenia was diagnosed when criteria for both sarcopenia, defined by low skeletal muscle mass and either reduced handgrip strength or impaired physical performance, and osteoporosis, defined by a T-score of −2.5 or lower on dual-energy X-ray absorptiometry, were met. Participant characteristics, physical function, laboratory values, and body composition data were collected. Univariable Firth’s penalized logistic regression identified low body mass index and a lower phase angle as independent predictors of osteosarcopenia. Results: The overall prevalence of osteosarcopenia was 7.5 percent. Receiver operating characteristic curve analysis showed strong diagnostic performance of phase angle, with an area under the curve of 0.865. A cutoff value of less than 4.0 degrees achieved 100% sensitivity, 62.5% specificity, and 100% negative predictive value. These findings suggest that phase angle may be a practical, noninvasive screening tool for identifying older adults with type 2 diabetes mellitus who are at risk for osteosarcopenia. Its application in routine clinical settings could enable earlier intervention and reduce long-term complications associated with musculoskeletal decline in this vulnerable population. Full article

Objective: To evaluate the effects of virtual reality (VR) and whole-body vibration (WBV) training on muscle strength and balance-related functional outcomes in older adults. Methods: PubMed, Web of Science, the Cochrane Library, CNKI, and Embase were searched from inception to March 2026. Randomised controlled trials assessing VR or WBV training in samples with a mean participant age of ≥60 years were included. Outcomes were the Timed Up and Go (TUG) test, handgrip strength, Tinetti score, five-times sit-to-stand test, and gait speed. Pooled mean differences (MDs) with 95% confidence intervals (CIs) were calculated. Subgroup analyses and Bucher-adjusted indirect comparisons were used to explore potential relative effects. Results: Thirty-two trials involving 1359 participants were included. VR training reduced TUG completion time (MD = −1.13, 95% CI −1.70 to −0.55, p = 0.0001) and improved handgrip strength (MD = 3.49, 95% CI 0.46 to 6.52, p = 0.02), Tinetti scores (MD = 0.84, 95% CI 0.46 to 1.21, p < 0.0001), and gait speed (MD = 0.16, 95% CI 0.07 to 0.24, p = 0.0003). WBV training reduced TUG completion time (MD = −3.92, 95% CI: −6.36 to −1.48, p = 0.002) and five-times sit-to-stand completion time (MD = −1.20, 95% CI −2.03 to −0.38, p = 0.004). Conclusions: VR and WBV training may improve functional mobility and dynamic balance in older adults, although their effects may vary across functional domains. Because direct head-to-head trials are lacking, comparative findings should be interpreted as exploratory evidence. Full article

Intensive Care Unit-Acquired Weakness (ICU-AW) is a secondary neuromuscular disorder diagnosed during a critical illness and related to ICU stay and intensive treatments, once other possible etiologies have been excluded. Micronutrients are essential components of human nutrition that are needed in small amounts to maintain pivotal organ functions, but their role in critical care nutrition and in prevention and treatment of ICU-AW is unclear. This narrative review aimed to provide a synthesis of the current evidence on the potential role of micronutrients in ICU-AW, with a glance at what is known in medical settings outside the ICU. Available evidence is fragmented, showing controversial results. Studies on vitamin K1 and vitamin D suggest potential benefits on handgrip strength, skeletal muscle mass and mobility, while Coenzyme Q10 may have a role in improving skeletal muscle composition. Moreover, zinc homeostasis may influence muscle degradation, whereas copper levels may represent a risk factor. Evidence on iron and carnitine showed uncertain results. Conversely, more robust evidence on muscle weakness is available for medical settings outside the ICU. Larger observational studies and RCTs are needed to further evaluate the possible efficacy of micronutrient supplementation in the critical care setting. Full article

(1) Background/Objectives: Sarcopenia is common in older surgical candidates and may affect perioperative risk and recovery after total hip arthroplasty (THA). Quantifying its burden and severity gradient in THA pathways can inform surgeon-led optimization. (2) Methods: A cross-sectional analysis of baseline preoperative data at a tertiary center (December 2019 to December 2022) was conducted. Consecutive adults with hip osteoarthritis undergoing primary THA were screened. Sarcopenia was staged per EWGSOP2: probable (low handgrip), confirmed (probable and low skeletal muscle index by whole-body DXA), and severe (confirmed and low gait speed). (3) Results: Of 312 screened patients, 203 completed baseline assessment (95 men, 108 women). According to the EWGSOP2 algorithm, 57 patients (28.1%; 95% CI 22.3–34.6%) had low handgrip strength, 30 (14.8%; 95% CI 10.6–20.3%) fulfilled criteria for confirmed sarcopenia, and 21 (10.3%; 95% CI 6.9–15.3%) had severe sarcopenia. No significant association was observed for sex. Sarcopenia diagnosis was associated with older age, lower body mass index (BMI), higher comorbidity burden, lower functional independence, greater cognitive impairment, poorer mental health, and worse hip-related function (all p < 0.05). In multivariable analysis, older age (OR 1.51 per 5-year increase; 95% CI 1.11–2.12), lower BMI (OR 0.88 per kg/m²; 95% CI 0.79–0.98), and lower functional independence (Barthel Index: OR 2.02 per 10-point decrease; 95% CI 1.20–3.60) were independently associated with confirmed sarcopenia. Across EWGSOP2 categories, differences in age, BMI, pain, comorbidity, functional independence, cognition, mental health and hip function showed significant differences (all p < 0.05), with ordered trends in most domains but no uniform monotonic pattern. (4) Conclusions: In THA candidates, sarcopenia is prevalent and is related to older age, lower BMI and lower functional independence. Integrating sarcopenia screening by EWGSOP2 may help to identify THA candidates with greater clinical vulnerability who may warrant further preoperative assessment and targeted optimization strategies. Full article

Background/Objectives: Beetroot juice (BRJ), a dietary nitrate source, may enhance high-intensity intermittent exercise, but its effects on single- and repeated-sprint performance remain unclear. This systematic review and meta-analysis aimed to evaluate the effects of BRJ supplementation on sprint-related performance and neuromuscular, perceptual, and physiological outcomes. Methods: PubMed, Scopus, and Web of Science were searched for trials published from 2014 to June 2026. Eligible studies compared BRJ with placebo or control in healthy adults aged 18–40 years. The review followed PRISMA guidelines. Methodological quality and risk of bias were assessed using the PEDro scale and Cochrane RoB 2 tool. Evidence certainty was assessed using GRADE. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated. Results: Twenty-three randomized trials involving 401 participants were included, and 21 contributed to the meta-analysis. BRJ improved time to peak power in four Wingate-based studies (SMD = −0.92, 95% CI: −1.29 to −0.54, p < 0.001) and handgrip strength (SMD = 0.40, 95% CI: 0.05 to 0.74, p = 0.027). No significant effects were observed for countermovement jump, peak or mean power, 10 m or 20 m sprint performance, perceived exertion, heart rate, or blood lactate. Sex did not significantly moderate the effects, although female data were limited. Certainty was low for most outcomes and very low for 20 m sprint performance and blood lactate. Conclusions: BRJ may improve time to peak power and handgrip strength; however, low- to very-low-certainty evidence does not support its routine use to enhance short-distance or repeated-sprint performance. Full article

Background/Objectives: The cardiometabolic consequences of sarcopenic obesity (SO) remain poorly characterized in Latin America. We hypothesized that SO uniquely concentrates aortic stiffness, metabolic syndrome, and vitamin D deficiency in older Mexican adults, and that handgrip strength exhibits a dose–response relationship with cardiometabolic risk independent of adiposity. Methods: We conducted a cross-sectional analysis of 2087 adults ≥ 50 years from the Mexican Health and Aging Study (MHAS) 2012. Four phenotypes were defined using EWGSOP2 criteria: lean–fit, lean–sarcopenic, obese–non-sarcopenic, and obese–sarcopenic (BMI ≥ 30 kg/m²). Outcomes were pulse pressure (PP, aortic stiffness proxy), metabolic syndrome (modified IDF criteria), and serum 25(OH)D. Normality tests confirmed non-normal distribution (p < 0.001). Given heteroscedasticity (Breusch–Pagan p < 0.001), HC3 robust standard errors were used. Regression models were sex-adjusted and sex-stratified. Results: The sample showed high cardiometabolic burden: mean HbA1c 6.91% (35.3% ≥ 6.5%); metabolic syndrome 57.6%; mean PP 60.7 ± 17.9 mmHg; mean gait speed 0.708 m/s (70.4% slow). Phenotype distribution: lean–fit 12.3%; lean–sarcopenic 47.3%; obese–non-sarcopenic 8.7%; obese–sarcopenic 31.7%. In multivariable models, handgrip strength was an independent protective predictor of PP (beta = −0.09 per kg; 95% CI: −0.17 to −0.01; p = 0.033), with a sex-specific effect in women (beta = −0.13; p = 0.010). Conclusions: SO is highly prevalent in older Mexican adults and associates with an adverse cardiometabolic profile. Handgrip strength shows a protective dose–response association with cardiometabolic risk independent of adiposity, identifying muscle function as a candidate modifiable factor that warrants confirmation in longitudinal and interventional studies. The obese–non-sarcopenic phenotype exhibited the lowest PP, unveiling the sarcopenic obesity paradox: adiposity without muscle function loss does not promote arterial stiffening. Full article

Background: Maintaining adequate physical fitness is essential for preserving functional independence with ageing. Women with fibromyalgia often exhibit reduced fitness levels, and daily sedentary time (ST) and physical activity (PA) may be important contributors to physical fitness. Objectives: To examine (1) the proportion of women with fibromyalgia meeting fitness standards for later-life independence, (2) associations of ST and PA with fitness, and (3) how reallocating ST to PA relates to fitness. Methods: 407 women with fibromyalgia (51.9 ± 8.0 years) participated. Fitness (Senior Fitness Test and handgrip strength) was compared with standards for women aged 60–64 as indicators of later-life independence. ST and PA were measured using triaxial accelerometry. Linear and isotemporal substitution models examined associations and estimated the theoretical associations of replacing ST with light, moderate, or vigorous PA in relation to physical fitness. Results: 13.3% of participants met cardiorespiratory, 7.9% lower-body strength, 29.9% upper-body endurance, and 4.4% agility standards. ST and PA were associated with fitness (all p < 0.05; adj R² < 0.06). Reallocating 30 min of ST to light PA was associated with higher handgrip strength (B = 0.3); with moderate PA, cardiorespiratory fitness (B = 9.0); and with vigorous PA, upper-body muscular endurance (B = 11.1) and cardiorespiratory fitness (B = 104.9), all p < 0.05. Conclusions: Overall, only a small proportion of women met established fitness reference standards for later-life independence. ST was negatively and PA positively associated with fitness, although these associations explained little of its variability. In isotemporal substitution models, estimated replacement of ST with PA was associated with better fitness outcomes, particularly cardiorespiratory fitness and upper-body muscular endurance, with stronger associations at higher PA intensities. Further research is needed to identify additional modifiable determinants of physical fitness and support long-term functional independence. Full article