Objectives: To determine the force-length relationship, muscle thickness (MT), pennation angle (PA) and echo-intensity (EI) of the medial gastrocnemius (MG) in HSD/hEDS compared to healthy controls. Methods: The maximal MG force-length relationship was determined throughout ankle passive ROM in 11 individuals with HSD/hEDS and 11 healthy age- and sex-matched controls. MG fascicle length (FL), MT, PA and EI were measured using ultrasonography. MG force was calculated from plantarflexion moments and MG FL. Sarcomere lengths (SL) were estimated from changes in FL and assuming an optimal SL of 2.64 μm at optimal fascicle length. Results: HSD/hEDS were 36% weaker across the ankle ROM (p = 0.047). Optimal FL was significantly shorter in HSD/hEDS (34.8 ± 8.1 mm) compared to controls (43.6 ± 6.9 mm; p = 0.013). A shallower descending limb of the force-length relationship was seen in HSD/hEDS (p < 0.001). MT, PA, and EI were similar between groups (p > 0.05). Conclusion: HSD/hEDS were weaker at all measured fascicle lengths, despite similar muscle architecture (MT, PA) and quality (EI) suggesting that reduced neuromuscular activation may contribute to muscle weakness in this population. Rehabilitation interventions should consider addressing joint-angle specific strength deficits in HSD/hEDS.

Objectives: The reliability of handgrip strength measurements and their relationship with muscle power in older adults is not well understood. This study aimed to determine the reliability and correlations between handgrip strength measurements and muscle power in older women. Methods: Twenty older healthy women (67.8±5.8 years) participated in two separate testing sessions. During each session, handgrip contractions were performed to evaluate strength, specifically measuring peak force and rate of force development (RFD) across various time intervals. Muscle power was assessed by measuring sit-to-stand peak power and seated medicine ball throw distance. Results: Handgrip strength measurements, sit-to-stand peak power, and seated medicine ball throw distance demonstrated good test-retest reliability. The intraclass correlation coefficients were between 0.930 and 0.978. The coefficients of variation were between 2.7 and 8.0%. There were significant correlations between handgrip strength measurements and both sit-to-stand peak power (r = 0.485-0.533, P = 0.015-0.030) and seated medicine ball throw distance (r = 0.457-0.634, P = 0.003-0.043). Conclusions: Our study showed good reliability for handgrip strength measurements, sit-to-stand peak power, and seated medicine ball throw distance in older women. The significant correlations we observed suggest that handgrip peak force and RFD may be important variables associated with one’s muscle power.

Objectives: This prospective pilot study in healthy children aimed to evaluate the effect of whole-body vibration therapy (WBVT) on hip girdle muscle activation and identify the optimal amplitude and frequency settings that replicate the effects of walking or running without causing discomfort. Methods: A prospective pilot study involving 20 healthy children was conducted to evaluate muscle activation during WBVT at amplitudes of 1, 2, and 3 mm and frequencies of 5–20 Hz. Surface electromyography of the gluteus medius, tensor fascia lata, iliopsoas, and rectus femoris was recorded during walking, running, and WBVT trials, and steady-state 10-s epochs were extracted for analysis. Results: Although dose–response analyses showed no statistically significant increases beyond 10 Hz within WBVT conditions, the reported thresholds specify the vibration settings at which WBVT-induced activation exceeded the RMS values observed during walking or running, rather than indicating significant within-WBVT frequency differences. When “optimal setting” was defined as the highest activation within tolerable ranges, the 3 mm/ 10 Hz setting met these criteria. Conclusions: WBVT produced short-term increases in hip-girdle muscle activation under tolerable conditions. While not indicative of therapeutic benefit, these data provide hypothesis-generating insights for future clinical studies involving children with movement limitations.

Objectives: Vosoritide, a C-type natriuretic peptide analog, is the first approved pharmacological treatment for achondroplasia that targets the overactive FGFR3 pathway and promotes longitudinal bone growth. As increased body height may improve biomechanical leverage and influence muscle function, this retrospective, monocentric, observational study aimed to evaluate changes in muscle performance parameters during long-term vosoritide treatment. Methods: Nineteen (19) children with achondroplasia treated with vosoritide for at least 12 months were included. Muscle function was assessed via two-legged jump tests on a ground reaction force plate at baseline, month 12, 24 and 36. Jumping parameters, 6-minute walking distances and auxological measurements were converted to z-scores. Longitudinal changes were detected using a linear mixed-effects model. Results: Vosoritide treatment resulted in significant gains in height z-scores over 36 months (p < 0.001). Raw values of jumping parameters increased numerically over time for all parameters except relative force; however, no significant changes were observed in z-scores. Similarly, no significant changes were detected in 6-minute walking distances. Conclusions: While vosoritide produced significant height gains, no significant changes in muscle function z-scores were observed in this cohort. These findings are exploratory and suggest that muscle function may develop in parallel with that of unaffected children.

Objective: This study investigated the effects of an eight-week shoulder flexibility exercise program on shoulder range of motion (ROM) and serve accuracy in youth volleyball players. Methods: Thirty-two adolescent players (12–13 years) were randomly assigned to an experimental group (EG, n=16) and a control group (CG, n=16). The EG performed structured flexibility exercises twice weekly in addition to regular training, while the CG continued routine volleyball practice only. Shoulder ROM was assessed with a goniometer, and serve accuracy was evaluated using a standardized scoring protocol (maximum 48 points). Results: Significant improvements were observed over time in both groups for most ROM variables (p < 0.001). However, significant group differences emerged for shoulder external rotation (F_1,29=5.42, p=0.027, ηp²=0.153) and serve accuracy (Time × Group: F=6.73, p=0.015, ηp²=0.183). The adjusted ANCOVA confirmed a significant group effect for external rotation (F_1,29 =4.28, p=0.048, ηp²=0.128). The experimental group improved serve accuracy by +17.2 points (95% CI: 15.6–18.8) versus +11.6 points (95% CI: 9.4–13.8) in the control group. Conclusion: The eight-week flexibility program significantly enhanced serve accuracy and select shoulder ROM parameters in youth volleyball players. Incorporating structured flexibility exercises into training routines may improve technical performance and support shoulder function development during early adolescence.

Objective: This study examined alterations in ankle eversion/inversion strength and postural control in chronic lateral ankle instability (CLAI). Methods: Twenty-three CLAI patients and 14 matched controls underwent isokinetic strength testing at 30°/s, 60°/s, and 90°/s (peak torque/body weight: PT/BW). Postural control was assessed via center-of-pressure (COP) trajectory length and peripheral area during eyes-open and eyes-closed single-leg stance. Results: The CLAI group demonstrated significantly lower eversion PT/BW across all angular velocities versus controls (p<0.05). Inversion PT/BW was not significantly different for the group effect (p>0.05). The eversion-to-inversion strength ratio was consistently lower in CLAI (p<0.05). No between-group differences in COP metrics occurred during eyes-open stance (p>0.05). However, with eyes closed, the CLAI group exhibited significantly longer COP trajectory [107.52 (94.90,118.70) cm vs. 93.75 (83.09,95.25) cm] and larger peripheral area [8.34 (5.73,12.90) cm² vs. 5.92 (5.05,6.88) cm²] (p<0.05). Conclusions: CLAI is characterized by eversion muscle weakness and an impaired eversion-to-inversion strength ratio. Postural control deficits manifest primarily under visual deprivation, suggesting proprioceptive impairment, though visual input enables partial compensation during eyes-open conditions.

Objectives: To explore associations between mechanical load, expressed by structural (appendicular lean soft tissue index, ALSTI; ALST/trunk fat mass, TrFM); and functional lean mass (handgrip strength, HGS; HGS/body mass) with the mechanical capacity of bone, represented by whole-body bone mineral density less head (WBLH BMD) and arms/legs BMD imbalance. Methods: We analysed cross-sectional NHANES data from 5,424 adolescents (10–19 years, both sexes) collected between 2011 and 2020. ALST, TrFM and BMD were determined using whole-body dual-energy X-ray absorptiometry, and HGS was assessed with a dynamometer. All variables were standardised by sex and age group (Z-scores), with Z ≤ -1 indicating low or at-risk values. Results: The odds of low WBLH BMD were higher in participants with low ALSTI (girls: OR= 3.9; boys: OR=4.5, p<0.001) or low HGS (girls: OR=3.1; boys: OR=4.5, p<0.001). Boys with low HGS/body mass had 1.8 times higher odds of low arms/legs BMD (p=0.012), while girls with low HGS/body mass had 4.0 times higher odds (p<0.001). Conclusions: Both structural and functional lean mass deficits are associated with reduced WBLH BMD and arms/legs BMD imbalance in adolescents. These findings reinforce the importance of lean soft tissue in bone health monitoring.

Objectives: To examine the relationship between technical reaction time and core stabilization in taekwondo athletes. Methods: Cross-sectional correlational study of healthy male and female taekwondo athletes (n = 41; mean age 12.76 ± 1.07 years). Reaction performance was assessed using FITLIGHT Trainer sensors mounted on a taekwondo striking stand. Core stabilization was assessed using the Stabilizer Pressure Biofeedback Unit (PBU), a device employed to evaluate core muscle stabilization and deep abdominal muscle function. Spearman correlations (non-normal data) and Mann–Whitney U tests (sex comparisons) were applied. Results: Shorter reaction times were associated with a higher number of successful strikes (p<0.05). Higher PBU task performance (time held) of the transversus abdominis muscle and multifidus muscle correlated with higher strike success rates. In unadjusted comparisons, male athletes achieved more successful strikes on both right and left sides and completed tasks with fewer errors; however, after adjusting for age, height, and weight, sex was not a significant predictor of outcomes. Transversus abdominis PBU task performance (time held) was significantly higher in males in unadjusted analyses, indicating superior core stabilization compared to females. Conclusion: These findings suggest that deep core muscles are important not only for postural stability but also for dynamic motor performance.

Objectives: Cervical radiculopathy is a prevalent neuromusculoskeletal disorder which negatively impacts quality of life. Kinetic control concept indicates that the main goals of rehabilitation are to improve motor control and stabilize the cervical spine. The aim of this study was to assess the impact of kinetic control retraining on neck proprioception and function in individuals with cervical radiculopathy. Methods: A total of forty-four participants, aged 40 to 55, diagnosed with chronic unilateral cervical spondylotic radiculopathy, were randomly divided into two equal groups. The study group received kinetic control retraining along with the conventional physical therapy protocol. The control group underwent a conventional physical therapy protocol, comprising three sessions weekly for eight successive weeks. Cervical joint position error was assessed through cervical range of motion, pain levels were measured by the Visual Analogue Scale, neck-related disability was evaluated using Arabic Neck Disability Index scores, and deep neck flexor performance was tested with a pressure-biofeedback device. Results: After eight weeks of intervention, statistically significant differences between groups were observed across all outcome measures, favoring the study group (P < 0.05). Conclusion: Kinetic Control retraining has a useful effect on managing chronic cervical radiculopathy by reducing pain and enhancing proprioception and functional abilities. ClinicalTrials.gov ID:NCT06803134

Objectives: To investigate the relationship between core stability and neuromuscular performance (i.e., sprint velocity and change-of-direction speed) among adolescent male football players. Methods: In this cross-sectional study, sixteen high-level male football players were divided into higher and lower core stability groups based on their performance in a partial range single-leg deadlift (SLD) test, assessed using a smartphone application (OCTOcore© app). Neuromuscular performance was assessed with a 30-m maximal sprint test (with 5-m split intervals) and a V-cut test, and these outcomes were correlated with SLD test results. Results: Statistically significant differences were observed between higher and lower core performance groups in the SLD test (p = 0.001) and between SLD non-dominant and 30-m maximal sprint test (p = 0.001–0.005), while no differences were founded between SLD performance and V-cut test (p > 0.05). A large correlation was found between non-dominant SLD and 10-m sprint performance (r = 0.765, p = 0.001), while moderate correlations were observed for the 15-, 20-, 25-, and 30-m sprints (r = 0.508–0.562, p = 0.023–0.044). No significant correlations between SLD performance and the V-cut test (p>0.05). Conclusion: Core stability appears to be positively associated with sprint performance (0–30 m) but not with change-of-direction speed, suggesting that it plays a greater role in linear acceleration than in multidirectional tasks.

Objectives: Persistent toe walking (TW) in children is often idiopathic but may conceal subtle neuromuscular or metabolic causes. This cross-sectional, retrospective study investigated clinical and genetic characteristics of children carrying PYGM variants to explore potential subclinical phenotypes among heterozygous carriers. Methods: Seventy-two (72) children meeting criteria for idiopathic TW were evaluated using a standardized clinical protocol and a validated 49-gene next-generation sequencing neuromuscular panel. Variants were classified as pathogenic, likely pathogenic, or of uncertain significance according to ACMG/AMP guidelines. Analyses were descriptive. Results: Among 1,300 screened patients, 72 were identified as PYGM variant carriers. Toe walking was bilateral in all cases, with severe dorsiflexion restriction (≤5°) in 80.5%. Pes cavus was observed in 93% of patients, and muscle symptoms—pain, fatigue, or cramps—occurred in approximately one-third. VUS carriers displayed comparable, slightly milder muscle symptom frequencies than P/LP carriers. 12.5% could perform heel walking. Speech difficulties were reported in 56.9% of cases. Conclusions: While causality cannot be inferred, these findings suggest that heterozygous PYGM variants may contribute to subtle neuromuscular phenotypes. Genetic testing can be considered in persistent TW when clinical findings raise suspicion for an underlying neuromuscular/metabolic condition.

Objectives: Osteoporosis (OP) is a prevalent bone disease characterized by reduced bone mass and increased fracture risk, in part due to impaired osteogenic differentiation of bone marrow–derived mesenchymal stromal cells (BMSCs). Loss of AT-rich interactive domain–containing protein 2 (ARID2) attenuates BMSC osteogenesis, but the underlying mechanism remains to be elucidated. Methods: Human BMSCs were induced to undergo osteogenic or adipogenic differentiation. Lentiviral transduction was used to silence ARID2 and/or overexpress serine/threonine kinase 39 (STK39). Effects on BMSC fate were assessed by quantitative reverse-transcription PCR (qRT-PCR), MTT assay, alkaline phosphatase (ALP) staining, Alizarin Red S (ARS) staining, Oil Red O staining, and western blotting. Results: ARID2 expression increased over time during osteogenic induction. ARID2 silencing reduced BMSC proliferation and osteogenic differentiation while favoring adipogenesis. Conversely, STK39 overexpression enhanced proliferation and osteogenic differentiation and attenuated nuclear factor κB (NF-κB) signaling during osteogenic induction; these effects were reversed by ARID2 silencing. Conclusion: The STK39–ARID2 axis promotes osteogenic differentiation and suppresses adipogenic differentiation of BMSCs, at least in part via inhibition of NF-κB signaling. These findings highlight a potential molecular target for therapeutic strategies in OP.

Objective: To elucidate the role and mechanism of HOXA7 in osteoporosis (OP), with the goal of informing future research directions in OP. Methods: We assessed HOXA7 gene and protein expression; the effect of HOXA7 on osteogenic differentiation in human bone marrow–derived mesenchymal stem cells (hBMSCs); and proliferation, apoptosis, and autophagy in MC3T3-E1 cells. We also evaluated p38 MAPK/JNK pathway–associated proteins in hBMSCs and MC3T3-E1 cells. Cells were transfected with si-HOXA7 and cultured with or without the JNK inhibitor SP600125 or the p38 inhibitor SB203580, after which cell viability, apoptosis, and autophagy were re-assessed. Results: HOXA7 overexpression inhibited osteogenic differentiation of hBMSCs, reduced OPG, OPN, and RUNX2 expression in hBMSCs, and decreased proliferation while promoting apoptosis in MC3T3-E1 cells. In vitro, HOXA7 modulated autophagy markers in MC3T3-E1 cells. Phosphorylated JNK and p38 (p-JNK, p-p38) were increased in hBMSCs following osteogenic induction, whereas HOXA7 upregulation significantly suppressed p-JNK and p-p38 in MC3T3-E1 cells. SP600125 and SB203580 attenuated the effects of HOXA7 silencing on proliferation, apoptosis, and autophagy in MC3T3-E1 cells. Conclusion: HOXA7 reduces osteogenesis and osteoblast proliferation and promotes osteoblast apoptosis via the p38 MAPK/JNK pathway, suggesting potential therapeutic avenues against OP.

Objectives: Human nucleus pulposus cells (HNPCs), the primary cellular constituents of the intervertebral disc, are central to the pathogenesis of intervertebral disc degeneration (IVDD). Oxidative stress–induced mitochondrial dysfunction leads to intracellular metabolic imbalance and has been implicated in IVDD. This study investigated the role and molecular mechanism of glutamate dehydrogenase 1 (GLUD1) in hydrogen peroxide (H₂O₂)–challenged HNPCs relevant to IVDD. Methods: HNPCs were exposed to H₂O₂ to establish an oxidative stress model. Cell viability was assessed using the CCK-8 assay. Mitochondrial function was evaluated by measuring the oxygen consumption rate (OCR) and mitochondrial membrane potential. GLUD1 expression was quantified by qRT-PCR and Western blotting. The regulatory relationship between METTL3 and GLUD1 was examined by MeRIP-qPCR and a luciferase reporter assay. Results: H₂O₂ treatment decreased OCR and mitochondrial membrane potential in HNPCs and reduced alpha-ketoglutarate (α-KG) levels and GLUD1 expression. GLUD1 knockdown exacerbated H₂O₂-induced mitochondrial dysfunction, whereas GLUD1 overexpression alleviated it. METTL3 regulated GLUD1 mRNA stability by inducing GLUD1 m6A modification via YTHDF2, thereby modulating H₂O₂-induced mitochondrial dysfunction. Conclusion: GLUD1 protects HNPCs from H₂O₂-induced mitochondrial dysfunction through the glutamate/α-KG metabolic axis.