Search Results (169)

This study aims to investigate asymmetries in muscle activation and co-contraction of main lower limb muscles during flamenco Zap-3 footwork with consideration of the footwork speed and dancer proficiency. Twelve flamenco dancers participated, including six professionals and six amateurs. Each participant performed the Zap-3 sequence under three speed conditions: 160 beats per minute (bpm), 180 bpm and the fastest speed level (F). The normalized surface electromyography was recorded in the gastrocnemius medialis (GM), biceps femoris (BF), tibialis anterior (TA) and rectus femoris (RF) in the dominant (DL) and non-dominant leg (NDL). The co-contraction index was also calculated for selected muscle pairs. The results showed that significant asymmetries occurred only in professional dancers and exclusively at the F speed level. Specifically, the value of the GM in the NDL was higher than that of the DL (p < 0.05, d = 1.97); the value of the BF in the DL was higher than that of the NDL (p < 0.05, d = 1.86) and the co-contraction index of BF/RF in the DL was higher than that of the NDL (p < 0.05, d = 1.87). Understanding these asymmetries may help to inform individualized training strategies aimed at optimizing performance and reducing potential risks. Full article

Background: This study aimed to examine the effects of an 8-week plyometric training program on lower-limb explosive strength, jump performance, musculotendinous stiffness, reactive strength index (RSI), and multidirectional speed in elite Polish badminton players. Methods: Twenty-four athletes were randomly assigned to either an experimental group (n = 15), which supplemented their regular badminton training with plyometric exercises, or a control group (n = 15), which continued standard technical training. Performance assessments included squat jump (SJ), countermovement jump (CMJ), single-leg jumps, sprint tests (5 m, 10 m), lateral movements, musculotendinous stiffness, and RSI measurements. Results: The experimental group showed statistically significant improvements in jump height, power output, stiffness, and 10 m sprint and lateral slide-step performance (p < 0.05), with large effect sizes. No significant changes were observed in the control group. Single-leg jump improvements suggested potential benefits for addressing lower-limb asymmetries. Conclusions: An 8-week plyometric intervention significantly enhanced lower-limb explosive performance and multidirectional movement capabilities in young badminton players. These findings support the integration of targeted plyometric training into regular training programs to optimize physical performance, improve movement efficiency, and potentially reduce injury risk in high-intensity racket sports. Full article

Background and Objective: This study presents a combined osteometric and biomechanical analysis of a Korean female cadaver exhibiting bilateral lower limb bone asymmetry with abnormal curvature and callus formation on the left femoral midshaft. Methods: To investigate bilateral bone length differences, osteometric measurements were conducted at standardized landmarks. Additionally, we developed three gait models using Meta Motivo, an open-source reinforcement learning platform, to analyze how skeletal asymmetry influences stride dynamics and directional control. Results: Detailed measurements revealed that the left lower limb bones were consistently shorter and narrower than their right counterparts. The calculated lower limb lengths showed a bilateral discrepancy ranging from 39 mm to 42 mm—specifically a 6 mm difference in the femur, 33 mm in the tibia, and 36 mm in the fibula. In the gait pattern analysis, the normal model exhibited a straight-line gait without lateral deviation. In contrast, the unbalanced, non-learned model demonstrated compensatory overuse and increased stride length of the left lower limb and a tendency to veer leftward. The unbalanced, learned model showed partial gait normalization, characterized by reduced limb dominance and improved right stride, although directional control remained compromised. Conclusions: This integrative approach highlights the biomechanical consequences of lower limb bone discrepancy and demonstrates the utility of virtual agent-based modeling in elucidating compensatory gait adaptations. Full article

This study aimed to investigate the effects of mental fatigue on physical and cognitive performance (lower-limb power, isometric and handgrip strength, and psychomotor vigilance). Twenty-two physically active young adults (12 males, 10 females; M_age = 20.82 ± 1.47) were randomly assigned to either a Mental Fatigue (MF) or Control group (CON). The MF group showed a statistically significant (p = 0.019) reduction in non-dominant handgrip strength, declining by approximately 2.3 kg (about 5%), while no such change was observed in the CON group or in dominant handgrip strength across groups. Reaction time (RT) was significantly impaired following the mental fatigue protocol: RT increased by 117.82 ms, representing an approximate 46% longer response time in the MF group (p < 0.001), whereas the CON group showed a smaller, non-significant increase of 32.82 ms (~12% longer). No significant differences were found in squat jump performance, indicating that lower-limb explosive power may be less affected by acute mental fatigue. These findings demonstrate that mental fatigue selectively impairs fine motor strength and cognitive processing speed, particularly reaction time, while gross motor power remains resilient. Understanding these effects is critical for optimizing performance in contexts requiring fine motor control and sustained attention under cognitive load. Full article

In this study, the effects of walking speed on lower limb muscle activity and gait parameters during over-ground walking were investigated in individuals with chronic stroke. Twenty-four patients with chronic stroke participated in a cross-sectional repeated-measures study, walking 20 m at three different speeds: slow (80% of self-selected speed), self-selected, and maximal speed. Surface electromyography was used to measure muscle activity in five paretic-side muscles (rectus femoris, biceps femoris, tibialis anterior, gastrocnemius, and gluteus medius), while gait parameters, including stride length, stance and swing phases, single-limb support time, and the gait asymmetry index were assessed using a triaxial accelerometer. As walking speed increased, activity in the rectus femoris, biceps femoris, and gastrocnemius muscles significantly increased during the stance and swing phases (p < 0.05), whereas the gluteus medius activity tended to decrease. Stride length on the paretic and non-paretic sides significantly increased with faster walking speed (p < 0.05); however, no significant improvements were observed in other gait parameters or gait asymmetry. These findings suggest that although increasing walking speed enhances specific muscle activities, it does not necessarily improve overall gait quality or symmetry. Therefore, rehabilitation programs should incorporate multidimensional gait training that addresses speed and neuromuscular control factors such as balance and proprioception. Full article

Background: Anterior cruciate ligament reconstruction (ACLr) often leads to asymmetries between limbs, with variable return-to-performance rates in athletes. The single-leg countermovement jump (SLCMJ) is commonly used to assess postoperative knee function. However, limited research has explored deficits specifically during the unweighting phase of the jump. Methods: This study assessed 53 recreational athletes (11 females, 42 males) between 6 and 9 months post-ACLr using a dual force plate system (1000 Hz). Each participant performed three maximal-effort SLCMJs per limb. Outcome measures included jump height, negative peak velocity, minimum force, and center of mass (COM) displacement. Paired t-tests and Wilcoxon tests were used to compare the ACLr limb with the contralateral limb. Results: Compared to the healthy limb, the ACLr limb showed significantly lower negative peak velocity (−0.80 ± 0.40 m/s vs. −0.94 ± 0.40 m/s, p < 0.001), higher minimum force (36.75 ± 17.88 kg vs. 32.05 ± 17.25 kg, p < 0.001), and reduced COM displacement (−17.62 ± 6.25 cm vs. −19.73 ± 5.34 cm, p = 0.014). Eccentric phase duration did not differ significantly. Conclusions: Athletes post-ACLr demonstrate altered neuromuscular control during the early SLCMJ phase. These findings highlight the importance of rehabilitation strategies targeting eccentric strength and symmetry restoration. Full article

Given the high neuromechanical demands and frequent asymmetries in badminton, this study investigated the impact of a four-week asymmetry-targeted intervention on single-leg hop performance in elite junior badminton players and examined whether asymmetry-based indices could predict training responsiveness. Twenty-two national-level athletes (aged 15–18) were randomized into an experimental group (EG) undergoing neuromechanical training with EMG biofeedback or a control group (CG) following general plyometric exercises. Key performance metrics—Jump Height, Reactive Strength Index (RSI), Peak Power, and Active Stiffness—were evaluated pre- and post-intervention. Two novel composite indices, Force Efficiency Ratio (FER) and Asymmetry Impact Index (AII), were computed to assess force production efficiency and asymmetry burden. The EG showed significant improvements in Jump Height (p = 0.030), RSI (p = 0.012), and Peak Power (p = 0.028), while the CG showed no significant changes. Contrary to initial hypotheses, traditional asymmetry metrics showed no significant correlations with performance variables (r < 0.1). Machine learning models (Random Forest) using FER and AII failed to classify responders reliably (AUC = 0.50). The results suggest that targeted interventions can improve lower-limb explosiveness in youth athletes; however, both traditional and composite asymmetry indices may not reliably predict training outcomes in small elite groups. The results highlight the need for multidimensional and individualized approaches in athlete diagnostics and training optimization, especially in asymmetry-prone sports like badminton. Full article

Maintaining body symmetry in sports characterized by high lateralization is crucial for optimizing long-term athletic performance and mitigating injury risk. This study aimed to evaluate the extent of morphological asymmetry in anthropometric features among elite professional fencers. Additionally, the presence of functional asymmetry and its associations with morphological asymmetry were assessed. Thirty-two Polish adult female fencers, aged 18–33 yrs, were examined. Data collection involved a questionnaire survey, anthropometric measurements, calculation of anthropological indices, and assessment of functional asymmetry. For the 24 bilateral anthropometric features, small differences were found in seven characteristics: foot length, subscapular skinfold thickness, upper arm circumference, minimum and maximum forearm circumference, upper limb length, and arm circumference in tension. Morphological asymmetry index did not exceed 5%. Left-sided lateralization of either the upper or lower limbs was associated with significantly high asymmetry, specifically indicating larger minimum forearm circumferences in the right limb. Continuous, individualized monitoring of morphological asymmetry and its direction in athletes is essential, demanding concurrent consideration of functional lateralization. This ongoing assessment establishes a critical baseline for evaluating training adaptations, reducing injury susceptibility, and optimizing rehabilitation strategies. Deeper investigation of symmetry within non-dominant limbs is warranted to enhance our understanding. Full article

Background: Klippel–Trenaunay syndrome (KTS) is a congenital vascular malformation syndrome characterized by low-flow vascular anomalies, including venous malformation (VM) and lymphatic involvement. These anomalies may lead to limb asymmetry due to soft tissue and/or bone overgrowth. Compression therapy using elastic garments is considered a conservative and minimally invasive first-line treatment option for KTS. However, the benefits of compression therapy for low-flow vascular malformations, particularly limb VMs, have not been sufficiently evaluated. This prospective, multi-center study assessed the efficacy and safety of compression therapy for KTS with VM. Methods: After measuring the affected limb, a custom-made elastic garment providing 30 mmHg of compression was manufactured (THUASNE, France). A total of 20 patients (7 male, 13 female; mean age: 10.9 years) underwent compression therapy for 26 weeks at four nationwide institutions in Japan. The primary outcome was the change in lower limb circumference. Secondary outcomes included pain, modified Rankin Scale (mRS) score, body water content, vital signs, changes in garment elasticity, and adverse events. Results: All 20 patients completed the study. At the study endpoint, the circumference ratio of the affected to unaffected limbs was significantly reduced at the superior end of the tibial tuberosity (p = 0.02) and the thinnest part of the ankle (p < 0.001). The elastic force of the garment declined by approximately 50% over 26 weeks. No serious adverse events related to the intervention were reported. Conclusions: Compression therapy using a custom-made elastic garment appears to be a safe and effective approach for managing limb overgrowth in patients with KTS and VM. To maintain the therapeutic effect, garment replacement is recommended at least every six months. Full article

This study aimed to (1) determine and compare the magnitude and direction of asymmetry in lower limbs neuromuscular properties, range of motion, strength and muscle electrical activity (EMG) in well-trained male road cyclist across categories (elite, under-23 and junior); (2) establish test- and age-specific asymmetry thresholds for these variables to enable individualized classification; and (3) examine the relationship between these lateral asymmetries and performance in a maximal incremental cycle ergometer test. Fifty-five well-trained road cyclists were assessed through tensiomyography (TMG), active knee extension test (AKE), leg press and EMG of vastus lateralis (VL-EMG) during a maximal incremental cycling test. Junior cyclists showed lower asymmetry in VM than elite cyclists, but greater asymmetry in AKE. No significant differences were found in strength or VL-EMG during the maximal incremental cycle ergometer test. The magnitude and direction of lateral asymmetry differs between tests (TMG: 11.3–21.3%; AKE: 2.3%; leg-press: 9.8–31.9%; VL-EMG: 20.8–22.7%). Multiple linear regression revealed a significant predictive model for maximal incremental cycling ergometer performance based on lateral asymmetry in AKE, leg press and VL and rectus femoris contraction time (R²_a = 0.23). These reference data can support trainers in monitoring and managing lateral asymmetry throughout the cyclists’ season. Full article

Objective: This study aimed to evaluate the effects of cold-water immersion (CWI) on post-training recovery in Kung Fu athletes. Methods: In a 3-week crossover design, 16 Kung Fu athletes (22.00 ± 5.95 years, 76.90 ± 9.74 kg) were divided into two conditions: CWI and passive recovery as a control (CON) measure. Through the study, muscle damage markers (creatine kinase [CK], lactate dehydrogenase [LDH], aspartate aminotransferase [AST] and alanine aminotransferase [ALT]), physical performance tests (upper limbs power, SJ and CMJ), skin temperature (from lower and upper limbs), and skin temperature asymmetries were measured. Results: CWI resulted in a higher reduction of CK concentration than CON 24 h after the intervention (−21.32%; p < 0.001). The SJ height 24 h after the intervention was higher in the CWI than in the CON (p < 0.001). Both CWI and CON resulted in skin temperature returning to baseline levels 24 h after intervention. Conclusions: CWI was effective in restoring muscle power, reducing muscle damage and reducing body temperature (BT) in Kung Fu athletes. Cold water recovery showed better muscle power and strength 24 and 48 h after training when compared to the passive method. CK and skin temperature were better 24 h after cold water recovery. Full article

Background/Objectives: Dominant leg use in badminton may contribute to lower limb asymmetry, potentially affecting performance and injury risk. This study investigated the effects of a 12-week integrated neuromuscular training (NMT) program on sports performance. Methods: Twenty-four well-trained male badminton players (age: 13.5 ± 1.15 years) were randomly assigned to groups based on maturation status (pre-peak height velocity [pre-PHV] and post-peak height velocity [post-PHV]; n = 12 each). All participants completed two NMT sessions weekly. Pre- and post-training assessments included a 20 m sprint, countermovement jump (CMJ), agility t-text, hexagon test, and Y-balance test. Results: Both groups improved significantly across most tests. The post-PHV group (ES: 0.70–1.35) showed greater improvements in sprinting, CMJ, and agility, while the pre-PHV group (ES: 0.39–1.23) improved more in balance and asymmetry. Conclusions: These results underscore the need for age- and maturity-specific training strategies to optimize performance and address asymmetries in youth athletes. Full article

Background and Objectives: This cross-sectional study investigates the association between fatigue and upper limb (UL) function in people with Multiple Sclerosis (PwMS). Methods: Adult PwMS were recruited from five Italian MS centers. Fatigue was evaluated using the Modified Fatigue Impact Scale (MFIS), while UL function was assessed through the Box and Block Test (BBT), Nine-Hole Peg Test (9HPT), and Hand-Grip Strength (HGS). Data analysis included Spearman rank correlations and Mann–Whitney U tests. Results: A total of 261 participants were involved. Significant correlations were found between fatigue severity, UL function, and patient-reported manual ability. Physical and cognitive aspects of fatigue were independently related to functional impairments. Participants with clinically relevant fatigue demonstrated lower subjective UL function, poorer BBT and HGS performance, and greater HGS asymmetry. Discussion: The study underscores the complex relationship between fatigue and functional impairments in MS. The findings suggest both strength and dexterity contribute to the perception of clinically relevant fatigue in PwMS, highlighting the importance of incorporating both domains to complement neurological assessment. Conclusion: Fatigue in PwMS is linked to both subjective and objective measures of UL function. Assessing strength and dexterity alongside fatigue may enhance clinical understanding and inform targeted rehabilitation strategies. Full article

Background: Repeated short maximal sprints induce high blood lactate concentrations and may influence neuromuscular coordination, but the relationship between lactate accumulation and inter-limb asymmetry in elite athletes remains unclear. Objectives: This study sought to investigate how blood lactate dynamics during repeated sprint efforts relate to sprint performance and inter-limb muscle asymmetry in elite female sprinters. Methods: Eight elite women (21.3 ± 5.4 y; 54.2 ± 5.1 kg; 165.4 ± 4.3 cm) performed four sets of five all-out 50 m sprints (1 min rest between reps; 5 min between sets). Sprint times were electronically timed. Capillary lactate was measured at rest and 1 min/4 min post-set. Quadricep, hamstring, and gluteal asymmetry was assessed via textile electromyography. Nonparametric statistics (Spearman’s ρ, Friedman test) were applied. Results: From Set 1 to Set 4, sprint time fell from 7.25 ± 0.13 s to 7.07 ± 0.16 s (p = 0.044), 1 min lactate rose from 8.51 ± 2.65 to 15.60 ± 2.66 mmol/L (p < 0.001), and 4 min lactate from 7.16 ± 2.32 to 13.64 ± 2.76 mmol/L (p = 0.002). Muscle group asymmetries decreased (p < 0.01), with lactate at 1 min, correlating negatively with quadriceps (ρ = −0.59) and gluteal (ρ = −0.48) asymmetry. Conclusions: In elite female sprinters, progressive lactate accumulation during repeated 50 m bouts is linked to faster times and reduced muscle asymmetry, suggesting that lactate may enhance neuromuscular coordination under fatigue. Full article

Background: Lower limb asymmetry is a critical factor influencing performance and injury risk in football players. Despite the increasing popularity of women’s football, limited research has examined how asymmetry varies across different age categories. This study aimed to investigate countermovement jump (CMJ) and horizontal jump (HJ) asymmetry in female football players across four age categories (U14, U16, U18, and +18). Methods: Seventy-six female football players from the same club participated in the study. Players performed unilateral CMJ and HJ tests to assess inter-limb asymmetry. A one-way ANOVA and Chi-square tests were conducted to examine age-related differences in asymmetry levels. Results: CMJ asymmetry significantly varied across age groups (p < 0.001), with the highest asymmetry observed in U14 and the lowest in +18. In contrast, HJ asymmetry remained consistently low across all age groups (p = 0.113). No significant correlation was found between CMJ and HJ asymmetry. Additionally, asymmetry levels in CMJ were significantly associated with age (p = 0.003), whereas no such association was observed for HJ. Conclusions: CMJ asymmetry is more prevalent in younger female football players and tends to decrease with age, suggesting that neuromuscular development plays a role in reducing asymmetry over time. These findings highlight the importance of monitoring asymmetry levels across different age groups to optimize training interventions and injury prevention strategies. Full article