Search Results (618)

Background: Muscle strength asymmetries between limbs are common in physically active populations and may influence performance and injury risk. This study aimed to: (i) analyze the reliability of the seated unilateral cable row exercise using a functional electromechanical dynamometer (FEMD) and to examine differences in reliability between sides and contraction types; (ii) investigate the relationship between the dominant and non-dominant sides, as well as between the dynamic and static force production of the back muscles; and (iii) quantify force output and assess interlimb asymmetries. Methods: Twenty-nine young physically active athletes completed two sets of four repetitions of a seated unilateral cable row at 0.30 m·s⁻¹ using the FEMD, followed by a 6-s isometric contraction. Two testing sessions were conducted seven days apart. Reliability was assessed using paired t-tests, the effect size, the coefficient of variation (CV), the standard error of measurement, and the intraclass correlation coefficient (ICC), with 95% confidence intervals. Results: Peak and average force values showed very high to extremely high relative reliability (ICC = 0.86–0.96) and acceptable absolute reliability (CV ≈ 10%). Differences between dominant and non-dominant sides varied depending on contraction type. While group-level asymmetries did not exceed 10%, individual analysis revealed that 14%, 32%, and 7% of participants had asymmetries greater than 15% in isometric, concentric, and eccentric force, respectively. Conclusions: This test demonstrates strong reliability and provides a practical method for assessing upper limb asymmetries in physically active individuals, with potential applications in performance monitoring and injury prevention. Full article

Introduction: Nowadays, there is evidence regarding a beneficial effect of heat on neuromuscular strength and muscle hypertrophy development. The aim of this study is to evaluate the effects of a 4-week passive sauna bathing program to extreme heat (100 ± 2 °C) as a support for a resistance strength training program on maximal strength and body composition. Methods: 30 young male subjects participated in the study. They were randomly assigned to a Hyperthermia group (HG, n = 14; age: 20.48 (19.12–22–30) years; weight: 76.30 (71.00–79.00) Kg; BMI: 23.92 (22.93–24.87) Kg/m²), or to a Normothermia group (NG, n = 15; age: 19.95 (19.10–21–94) years; weight: 61.70 (59.45–72.90) Kg; BMI: 21.56 (20.42–23.26) Kg/m²). All participants followed the same lower limb strength training program (2 exercises; 4 sets of 10 repetitions at 75% 1RM with progressive loading). Additionally, HG underwent two weekly sessions of exposure to extreme heat in a sauna (100 ± 2 °C and 24 ± 1% relative humidity, four sets of 10 min, 2 days per week). The intervention lasted for 4 weeks, followed by a 4-week deconditioning period. Maximum isometric knee flexion-extension strength, maximum counter-resistance strength, as well as body composition and anthropometric variables were assessed. Results: The HG group significantly increased body weight (p < 0.05) and muscle mass (p < 0.05), while their sum of six skinfolds (Σ6 skinfolds) significantly decreased (p < 0.05). Both groups improved their 1RM squat performance following the intervention program (p < 0.05; HG: r = 0.86; NG: r = 0.89). However, only the HG group continued to improve their squat 1RM after the deconditioning period (p < 0.001; r = 0.93), as well as their leg press 1RM (p < 0.01; r = 0.94). Maximal isometric strength increased only in the NG group at the end of the training program, with a significant increase in knee flexion torque (p < 0.05; r = 0.76). In contrast, the HG group showed significant increases in isometric strength after the deconditioning period in both knee extension (p < 0.05; r = 0.76) and knee flexion (p < 0.05; r = 0.75). Conclusions: A four-week period of passive sauna bathing at extreme heat appears to alter the chronology of strength responses. It also seems to induce favorable responses in terms of strength development and body composition. Full article

Optimizing the neuromechanical determinants of explosive performance remains a key objective in sports science. This study compared the effects of an eight-week movement-pattern-based training program (MPT) with an isometric strength training protocol (ITG) on countermovement jump (CMJ) mechanics in competitive track and field athletes. Thirty-four athletes (19 men, 15 women) with ≥7 years of training experience were randomly allocated to the MPT or ITG. Pre- and post-intervention assessments were conducted using dual force plates to evaluate jump height, musculotendinous stiffness, concentric and eccentric impulses, contraction time, eccentric-to-concentric force ratio, and rate of force development (RFD). The MPT elicited significant gains in stiffness (Δ = +840.94 ± 1302.21 N/m; p = 0.002), maintained concentric peak force, and reduced contraction time (Δ = –64.53 ± 190.32 ms; p = 0.01), suggesting improved elastic efficiency and neuromuscular timing. Conversely, ITG was associated with reductions in concentric peak force (Δ = –66.18 ± 77.45 N; p = 0.003) and stiffness (Δ = –691.94 ± 1414.41 N/m) and an increase in the eccentric-to-concentric force ratio (Δ = +1.99%; p = 0.006). The RFD changes were inconsistent across both groups. These findings indicate that dynamic multi-joint training confers superior neuromechanical adaptations compared to isolated isometric loading. From a performance perspective, programming strategies should prioritize movement-specific dynamic tasks to enhance the explosive qualities critical for sprinting, jumping, and multidirectional field sports. Full article

Spatial reasoning ability plays a critical role in predicting academic outcomes, particularly in STEM (science, technology, engineering, and mathematics) education. According to the Cattell–Horn–Carroll (CHC) theory of human intelligence, spatial reasoning is a general ability including various specific attributes. However, most spatial assessments focus on testing one specific spatial attribute or a limited set (e.g., visualization, rotation, etc.), rather than general spatial ability. To address this limitation, we created a mixed spatial test that includes mental rotation, object assembly, and isometric perception subtests to evaluate both general spatial ability and specific attributes. To understand the complex relationship between general spatial ability and mastery of specific attributes, we used a higher-order linear logistic model (HO-LLM), which is designed to simultaneously estimate high-order ability and sub-attributes. Additionally, this study compares four spatial ability classification frameworks using each to construct Q-matrices that define the relationships between test items and spatial reasoning attributes within the HO-LLM framework. Our findings indicate that HO-LLMs improve model fit and show distinct patterns of attribute mastery, highlighting which spatial attributes contribute most to general spatial ability. The results suggest that higher-order LLMs can offer a deeper and more interpretable assessment of spatial ability and support tailored training by identifying areas of strength and weakness in individual learners. Full article

This study aimed to examine the proximal effects of blood flow restriction (BFR) training on shoulder muscle function and subjective discomfort during low-intensity external rotation exercise. Twenty-four healthy adults were randomly assigned to a BFR group or a control group and performed shoulder stabilization exercises with or without BFR. Outcome measures included shoulder external rotation range of motion, maximal isometric strength, muscle endurance, electromyographic activity of the rotator cuff muscles, and perceived discomfort. Both groups demonstrated significant within-group improvements in all outcomes except posterior deltoid and supraspinatus activity (p < 0.05). Between-group comparisons showed significantly greater gains in maximal strength and infraspinatus and teres minor activation in the BFR group than in the control group (p < 0.05), while discomfort and fatigue scores were also higher in the BFR group (p < 0.05). These findings suggest that BFR applied at the proximal upper arm can enhance the strength and activation of key rotator cuff muscles even when cuff placement near the shoulder is limited by anatomy. Proximal BFR may serve as an effective intervention for improving shoulder function when high-intensity exercise is contraindicated, although strategies to minimize discomfort are needed to improve clinical feasibility. Full article

Background: Hamstring tendon autografts are frequently used for anterior cruciate ligament reconstruction (ACLR), but they are associated with persistent hamstring strength deficits and delayed functional recovery. Current rehabilitation guidelines often delay open kinetic chain (OKC) hamstring exercises due to safety concerns, despite the limited supporting evidence. This uncontrolled, underpowered, and exploratory study aimed to evaluate the safety and effectiveness of introducing OKC hamstring strengthening exercises as early as three weeks after ACLR. Methods: An exploratory retrospective observational study was conducted at a single physiotherapy center on 13 patients (aged 18–35) who underwent primary ACLR with semitendinosus–gracilis grafts. Participants followed a standardized rehabilitation program including isometric leg curls at 60° and 90° knee flexion and long-lever glute bridges twice weekly, starting from postoperative week 3. Safety was assessed through predefined “safety flags” (pain > 4/10, hematoma, clinical hamstring strain). Strength outcomes, including isometric knee flexion strength at 60° and 90°, limb symmetry index (LSI), and endurance tests, were assessed at 6 and 12 weeks. Results: All participants completed the program without major adverse events. Pain remained consistently low (median 2.5/10), with only one transient episode exceeding the threshold. No other complications were recorded. Isometric knee flexion strength significantly improved between week 6 and week 12 at both 60° (p = 0.018) and 90° (p = 0.003), with large effect sizes. LSI at 90° also increased significantly (p = 0.006), whereas improvements at 60° did not reach significance. Endurance testing showed functional gains as early as 6 weeks. Conclusions: The early introduction of OKC hamstring strengthening exercises three weeks after ACLR with hamstring autografts appears safe and promotes clinically meaningful improvements in strength and endurance. These findings, while from a small uncontrolled study, challenge conservative rehabilitation protocols and support the reconsideration of early hamstring loading. Given the retrospective, uncontrolled, and underpowered design, these findings are hypothesis-generating and not generalizable beyond young adults with hamstring autografts; larger randomized trials are required. Full article

Unaccustomed eccentric exercise is well established to induce exercise-induced muscle damage (EIMD), characterized by transient strength loss, delayed onset muscle soreness (DOMS), reduced range of motion, and proprioceptive disturbances. While limb dominance has been proposed as a potential modulator of susceptibility to EIMD, evidence remains inconclusive. This exploratory study aimed to compare alterations in muscle damage indices between dominant and non-dominant knee extensors 48 h after eccentric isokinetic exercise. Eighteen physically active young women (23 ± 2 years) completed two eccentric exercise sessions (5 × 15 maximal contractions at 60°/s), one per limb, with sessions separated by 24–30 days. For all participants, testing was conducted during the early follicular phase. Muscle strength (isometric and eccentric peak torque), DOMS (palpation and pain pressure threshold), range of motion, fatigue index, and position sense were assessed pre- and 48 h post-exercise. Significant reductions in isometric and eccentric peak torque, increased DOMS, impaired position sense, and altered fatigue index were observed 48 h post-exercise in the exercised limb (p < 0.001), with no differences between dominant and non-dominant limbs across all indices. These findings demonstrate that limb dominance does not influence the magnitude of EIMD in knee extensors of young women. Practical implications include equal consideration of both limbs in eccentric training, rehabilitation, and injury prevention programs. Full article

Background: Taekwondo (TKD) and Tai Chi (TC) are promising interventions for enhancing health and physical function in older people, yet few studies have compared their effects across multiple domains. This study aimed to compare the effects of TKD versus TC on health status in independent older women. Methods: A randomized controlled trial was conducted with two parallel groups: TKD (n = 11) and TC (n = 10). Both groups trained three times per week for 8 weeks. Pre- and post-intervention assessments included anthropometry, submaximal CPX, 2-min step test, Timed Up-and-Go (TUG), isometric mid-thigh pull (IMTP), maximal isometric handgrip strength (MIHS), 30 s chair stand, 30 s arm curl, sit-and-reach, and back scratch. Results: Compared with TC, the TKD group showed significantly greater improvements in several cardiorespiratory outcomes, including VO₂ at VT1 and VT2, power output, VO₂/HR, OUES, and VE/VCO₂ slope (p < 0.05 to p < 0.001; d = 0.69–1.29). TKD participants also exhibited superior gains in maximal and relative IMTP, MIHS, relative MIHS, 30 s arm curl repetitions, and TUG performance (p < 0.05 to p < 0.001; d = 0.61–1.26). Both groups improved similarly in the 30 s chair stand test (p < 0.05). Flexibility outcomes diverged, with TKD improving sit-and-reach and TC showing greater gains in the back scratch test (p < 0.05). Conclusions: TKD was more effective than TC in improving cardiorespiratory fitness, muscle strength, and balance in older women and may represent a valuable health-oriented training strategy for this population. Full article

Background and Objectives: Developmental dysplasia of the hip (DDH) in children can result in long-term skeletal complications, including a reduced bone mineral density (BMD) and an increased risk of osteoporosis. This study aimed to evaluate BMD in children with DDH and to identify clinical, functional, and nutritional factors associated with reduced BMD. Materials and Methods: A cross-sectional study was conducted on 25 children aged 5–10 years with confirmed DDH. Bone mineral density was measured at the total body, subtotal, and lumbar spine using dual-energy X-ray absorptiometry (DXA), and Z-scores were calculated. Functional assessments included isometric muscle strength, weight-bearing symmetry, and physical activity measured via accelerometry. Demographic data and daily calcium intake were recorded. Correlation and multiple linear regression analyses were performed to determine predictors of BMD. Results: Most participants exhibited normal growth and mobility, with mild asymmetries in limb strength and length. The mean total BMD was within normative ranges, whereas the lumbar spine Z-score (−1.41 ± 1.72) was mildly reduced. BMD positively correlated with age, anthropometric measures, weight-bearing capacity, and calcium intake, and negatively correlated with a family history of osteoporosis. Multiple regression analysis identified the muscle strength symmetry index as the strongest independent predictor of BMD across all sites (subtotal Z-score: β = 1.000, p < 0.001; total Z-score: β = 0.425, p = 0.023; lumbar Z-score: β = 0.499, p = 0.014). Physical activity levels showed no significant associations with BMD. Conclusions: Children with DDH generally demonstrate preserved overall BMD; however, mild lumbar spine deficits may occur. Muscle strength symmetry appears to be the most influential modifiable factor for optimizing bone health in this population, highlighting the importance of targeted physiotherapy interventions. Full article

This study aimed to investigate if there are differences in neck strength between dental students in their fourth and fifth years, with and without neck pain. Neck muscle strength was assessed in flexion, extension, and lateral flexion to both sides using a handheld dynamometer while participants performed maximum voluntary isometric contractions with a make test procedure. Differences between groups were evaluated through a one-way analysis of variance followed by Tukey’s post hoc comparison. Forty-three students (twenty-one fourth-year and twenty-two fifth-year students) participated in the study. Fifth-year students with neck pain (P5) (n = 14) showed less strength (p = 0.018) compared to the no-pain group (NP) (n = 15) in neck flexion and lateral flexion for both sides (p < 0.001). The fourth-year symptomatic students (P4) (n = 14) showed reduced right lateral flexion strength compared to the NP group (p = 0.035). No significant differences were observed in neck extension across all groups (p = 0.085). Our research indicates a progressive decline in neck muscle strength in flexion and lateral flexion among students with neck pain over their training years. Our findings suggest that this may be linked to the increasing mechanical demands of clinical practice during training, potentially affecting muscle balance and cervical function. This pain could be associated with changes in motor behavior and reduced cervical muscle strength. Full article

Objective: This study aimed to evaluate the effects of Cistanche deserticola Y.C. Ma (CD) supplementation on muscle strength and recovery in individuals with and without resistance training experience. Methods: A randomized, double-blind, placebo-controlled trial was conducted with 48 male participants, including 24 resistance-trained and 24 untrained individuals. Participants were stratified by training status and randomly assigned to either the CD or placebo (PLAC) group. All subjects completed a standardized resistance training program three times per week for eight weeks. The CD group received 5 g of CD extract twice daily, while the PLAC group consumed a matched placebo. Assessments included one-repetition maximum (1RM) for bench press and squat, maximal voluntary isometric contraction (MVIC), and repetitions to failure (RTF). Blood biomarkers including serum testosterone, cortisol, C-reactive protein (CRP), and creatine kinase (CK) were also measured. Results: No significant differences in dietary energy intake or macro-nutrient composition were observed based on two 5-day dietary records collected before baseline testing and at the end of the intervention. Among untrained individuals, the CD group showed significantly greater improvements in 1RM bench press and squat compared with the PLAC group (p < 0.05), with MVIC and RTF also significantly increased (p < 0.01). Serum cortisol levels were reduced (p < 0.05), and significant improvements were observed in testosterone, CRP, and CK (p < 0.01). In trained individuals, CD supplementation led to significant increases in 1RM squat and MVIC (p < 0.05), along with improvements in testosterone and cortisol levels (p < 0.05) and marked reductions in CRP and CK (p < 0.01). Conclusions: Daily supplementation with 5 g of CD extract for eight consecutive weeks significantly enhanced muscle strength and endurance in males with different training backgrounds and facilitated post-exercise recovery by modulating hormonal responses and reducing stress levels and inflammation. These findings provide experimental evidence supporting the application of CD in sports nutrition. Full article

Background/Objectives: We investigated whether cervical sensitive nerves (CSN) provide motor input to the trapezius muscle and how this relates to short-term functional outcomes after neck dissection. Methods: A total of 22 neck dissections were performed in 17 patients; the SAN was preserved. CSN roots (C2–C4) were stimulated intraoperatively using IONM. Shoulder and neck function were evaluated preoperatively and at 3 months in 15 operated necks using goniometry, an IMU-based motion analysis system (iSen), trapezius isometric strength, the Modified Constant–Murley Score (MCMS), and the Shoulder Pain and Disability Index (SPADI). Results: CSN-evoked trapezius responses were detected in 10/22 (45.5%) dissections (C2: 6/22, 27.2%; C3: 4/22, 18.2%; C4: 0/22). Postoperatively, neck extension/rotation and shoulder abduction/external rotation decreased significantly within groups; upper and middle trapezius strength and MCMS also declined. Shoulder flexion loss was smaller when CSN motor participation was present. Median shoulder flexion (goniometry) changed from 162°→140° in CSN(+) vs. 170°→131° in CSN(−) (between-group p = 0.024). With iSen, shoulder flexion changed 120°→116° in CSN(+) vs. 122°→97° in CSN(−) (p = 0.033). Conclusions: Approximately half of the neck dissections exhibited CSN-related motor responses. Short-term shoulder flexion was better preserved when CSN motor participation was present, suggesting that documenting CSN motor input intraoperatively may inform early rehabilitation planning. Full article

Background: Respiratory efficiency is considered important in karate due to its role in sustaining muscular performance during high-intensity actions. This study examined the association between pulmonary function and isometric muscle strength in national-level karate athletes. Methods: A total of 23 elite karate athletes (mean age: 23.0 ± 2.3 (mean ± SD) years) participated in the study. Pulmonary function was assessed using a digital spirometer, while isometric handgrip, lower back, and leg strength were measured using a dynamometer. The correlation between pulmonary function and isometric strength was analyzed, and linear regression was employed to examine the predictive capacity of pulmonary parameters for muscle strength. Results: The results revealed significant correlations, ranging from large to very large, between pulmonary function and isometric muscle strength, with correlation coefficients from 0.639 to 0.812 (p < 0.01). Pulmonary function was strongly associated with isometric strength, accounting for 27% to 67% of the variance (p < 0.05). Multiple regression analysis revealed that pulmonary function parameters accounted for 71% of the variance in handgrip strength, 47% in leg strength, and 71% in back strength (p < 0.05). Conclusions: These findings highlight the strong associations between pulmonary function and isometric muscle strength in elite karate athletes. The results emphasize the importance of pulmonary health and respiratory muscle function in athletic performance, particularly for sports requiring high-intensity, dynamic movements like karate. Future longitudinal studies are needed to explore the mechanisms underlying the association and potential implications, and for training and performance optimization. Full article

This study aimed to evaluate the effects of jump rope training on cardiovascular capacity, assessed with the Ruffier test, and muscular strength, measured using isometric dynamometry (BioFET Mustec, Almere, The Netherlands), within a university physical education program. A total of 52 undergraduate students from non-specialist faculties at the University of Oradea were randomly assigned to either an experimental group (EG) or a control group (CG). Over eight weeks, the EG performed a ten-minute jump rope training session once per week in combination with cardiovascular exercises, while the CG participated only in cardiovascular exercises. Statistical analyses revealed a significant group effect on cardiovascular response (Ruffier Index: p = 0.019; Cohen’s d = −0.271) and a substantial increase in right lower limb strength (p = 0.003; d = 1.026) in the EG compared to the CG. Furthermore, improvements were observed in upper limb strength (left arm: p = 0.010; d = 0.922) and left lower limb strength (p = 0.027; d = 0.779). These findings suggest that incorporating jump rope training into university physical education classes may represent an effective and low-cost strategy to enhance both cardiovascular efficiency and muscular strength in young adults. Given its simplicity and affordability, jump rope training appears feasible for implementation in schools and universities, even where resources are limited. Future research should investigate its long-term effects across different populations. Full article

Introduction: Acute neuromuscular fatigue impairs athletic performance and increases the risk of musculoskeletal injury. Recovery strategies such as manual massage (MM) and intermittent pneumatic compression (IPC) have been proposed to mitigate these effects, although their efficacy in elite youth soccer remains under debate. Objective: To compare the acute effects of MM and IPC on muscle damage recovery, lower limb strength, and power in Brazilian Under-20 soccer athletes. Methods: A randomized crossover study was conducted with twenty male youth athletes (18.65 ± 0.67 years) from the under-20 category of Paysandu Sport Club—Brazil. Each athlete underwent both MM and IPC interventions, separated by a seven-day washout. Variables assessed included serum creatine kinase (CK), quadricep and hamstring isometric voluntary contraction (IVC), and vertical jump (VJ). Results: MM resulted in a CK reduction of Δ = −77.1 U/L (p = 0.042; d = 0.37), indicating a moderate effect size, while IPC induced a larger reduction of Δ = −138.0 U/L (p = 0.160; d = 1.41), with a very large effect size despite the lack of statistical significance. Neither intervention produced significant changes in quadricep or hamstring IVC, nor in VJ height (p > 0.05). Conclusions: Both MM (statistical difference) and IPC (clinical difference) were viable recovery strategies for attenuating acute serum CK without impairing neuromuscular performance in elite under-20 soccer players. Full article