Search Results (171)

The investigation of the neuromuscular components of fatigue in team sports, especially in developmental ages, is limited. This study aimed to examine the neuromuscular fatigue and recovery patterns in prepubertal and adult female handball players, focusing on the soleus (SOL) and tibialis anterior (TA) muscles. Fifteen prepubertal (11.1 ± 0.9 years) and fourteen adult (22.0 ± 3.4 years) females performed a sustained isometric plantar flexion at 25% of maximal voluntary contraction (MVC) until exhaustion. The electromyographic (EMG) activity of the SOL and TA, torque, and central activation ratio (CAR) were recorded throughout the experiment. Endurance time was similar between groups (girls: 104 ± 93.5 s; women: 94.4 ± 30.2 s, p > 0.05), and both demonstrated progressive increases in muscle activation, without significant group differences for SOL and TA EMG (p > 0.05). Following fatigue, the torque and soleus (SOL) EMG activity decreased significantly compared to the pre-fatigue values in both groups (p < 0.001) and recovered (p > 0.05) in prepubertal and adult females within the first 3 and 6 min, respectively. The CAR remained unchanged over time, without significant differences observed between age groups (p > 0.05). These findings suggest that neuromuscular responses to fatigue are comparable between prepubertal and adult females, but recovery is significantly faster in prepubertal girls. Consequently, these findings underscore the need for age-specific recovery strategies in training programs, with tailored exercise-to-rest ratios to enhance performance and reduce fatigue during handball-specific activities. Full article

Background/Objectives: In recent years, scientific literature has illustrated the growing interest in telerehabilitation after ACL reconstruction. The aim of this study is to compare the effectiveness of remotely supervised rehabilitation with traditional supervised rehabilitation after ACLR, focusing on objective postoperative functional assessment outcomes. Methods: A retrospective analysis of prospectively collected data was carried out, selecting patients that underwent arthroscopic ACLR by a single surgeon. Functional assessments of the patients were carried out at 1 and 2 weeks and 1, 2 and 3 months after surgery, including range of motion (ROM), maximal voluntary isometric contractions (MVICs) of extensor and flexor muscles, the sit-to-stand test and the countermovement jump. Intergroup statistics were carried out using a non-inferiority hypothesis. Results: A total of 251 patients were included in this study (supervised rehabilitation n = 165; remotely supervised rehabilitation n = 86). Functional assessment improved over time in both groups. The extension ROM deficit decreased to 0 difference 30 days after surgery. The median flexion ROM ILD at 60 days was significantly different among the groups, with a residual 10° ILD in the Group R compared with 0° ILD in group S (p = 0.01). All other assessments did not achieve statistical significance. Conclusions: The results support the integration of a digital rehabilitation tool in post-ACLR recovery programs. The results suggest that remotely supervised rehabilitation can be a viable alternative to traditional supervised rehabilitation for early-stage recovery. However, more research is needed to optimize protocols and to identify patients who may benefit most from this approach. Full article

Background: Sarcopenia (loss of muscle mass) and dynapenia (loss of strength) are prevalent in older adults aged 70 years and over. Both have an impact on their functional ability and quality of life, with type II muscle fibres being particularly affected. Although traditional resistance training (TRT) is effective, it presents technical difficulties and an increased risk of injury among this vulnerable population. Isometric strength training (IST) is a potentially safer, more accessible and more effective alternative. Objective: To describe the protocol of a single-arm, pre-post intervention trial designed to evaluate the efficacy and applicability of a 16-week IST programme on muscle strength, skeletal muscle mass, quality of life and applicability (safety, acceptability, perceived difficulty) in 18 older adults aged 70 years and above with a diagnosis of sarcopenia and dynapenia. The influence of genetic and environmental factors on the variability of response to IST will also be explored. Methodology: The participants, who have all been diagnosed with sarcopenia according to EWGSOP2 (European Working Group on Sarcopenia in Older People 2) criteria, will perform two IST sessions per week for 16 weeks. Each 30-min session will consist of one progressive set (total duration 45 s to 90 s) for each of the eight major muscle groups. This series will include phases at 20% and 40% of individual Maximal Voluntary Isometric Contraction (MVIC), culminating in 100% Maximal Effort (ME), using the CIEX SYSTEM machine with visual feedback. The primary outcome variables will be: change in knee extensor MVIC and change in Appendicular Skeletal Muscle Mass Index (ASMMI). Secondary variables will be measured (other components of sarcopenia, quality of life by EQ-5D-5L, use of Likert scales, posture and physiological variables), and saliva samples will be collected for exploratory genetic analyses. The main statistical analyses will be performed with t-tests for related samples or their non-parametric analogues. Discussion: This protocol details a specific IST intervention and a comprehensive evaluation plan. The results are expected to provide evidence on the feasibility and effects of IST among older adults with sarcopenia and dynapenia. Understanding individual variability in response, including genetic influence, could inform the design of more personalised and effective exercise strategies for this population in the future. Full article

Static stretching (SS) is widely used in clinical and sports settings. However, the acute effects on neuromuscular control during dynamic tasks remain unclear. This study aimed to examine the immediate effects of SS on force control using a randomized crossover design. Seventeen healthy young males performed low-range (10–30% of maximal voluntary isometric contraction: MVIC) and high-range (40–60% MVIC) isometric force tracking tasks. In the SS condition, the ankle plantar flexors were stretched for 60 s; in the control condition, the participants remained at rest. The primary outcomes included ankle dorsiflexion range of motion (ROM), musculotendinous stiffness, and the root mean square error (RMSE) of force tracking. Compared to the control group, SS significantly increased dorsiflexion ROM and reduced musculotendinous stiffness. A significant reduction in the RMSE was observed during the force release phase when participants smoothly decreased force output in the high-range task following SS (p = 0.030, d = 0.79), but no significant changes were found during the force generation phase in the high-range task or during either phase (generation or release) in the low-range task. These findings suggest that a brief SS intervention may acutely refine the dynamic force control under high neuromuscular demands. Therefore, SS may enhance motor control in tasks that involve submaximal force modulation. Full article

Background: Lower limb motor output contributes to determining functional performance in many motor tasks. This study investigated the effects of non-invasive spinal cord transcutaneous stimulation (scTS) applied during an exercise-based priming protocol on lower limb muscle force and power generation. Methods: Twelve young, physically active male volunteers (age: 22.7 ± 2.1 years) participated in this randomized crossover, sham-controlled study. The maximal voluntary contraction and low-level torque steadiness of knee extensors, as well as the maximal explosive extension of lower limbs, were assessed before and after the priming protocol with scTS or sham stimulation over a total of four experimental sessions. Further, characteristics of evoked potentials to scTS related to spinal circuitry excitability were assessed in the supine position before and after the scTS priming protocol. The exercise component of the ~25 min priming protocol consisted of low-volume, low- and high-intensity lower limb motor tasks. Results: scTS priming protocol tended to increase or maintain maximum isometric torque during knee extension (4.7%) as well as peak force (0.2%) and rate of force development (6.0%) during explosive lower limb extensions, whereas sham priming protocol tended to decrease them (−4.3%, −3.3%, and −15.1%, respectively). This resulted in significant interactions (p = 0.001 to 0.018) and medium–large differences between scTS and sham protocols. These findings were associated with meaningful trends of some neurophysiological variables. Conversely, priming protocols did not affect low-level torque steadiness. Conclusions: scTS counteracted the unexpected fatigue induced by the exercise-based priming protocol, supporting lower limb performance during maximal efforts. Future studies are warranted to assess the implementation of scTS with optimized exercise-based priming protocols during training and rehabilitation programmes that include high-intensity neuromuscular efforts. Full article

This study investigated the effect of wearable ultrasound-imaging-based visual feedback (UVF) on assisting paretic ankle dorsiflexion training of chronic stroke survivors. Thirty-three participants with unilateral hemiplegia performed maximal isometric contractions on an isokinetic dynamometer in randomized conditions with and without UVF that provided by a wearable ultrasound imaging system. Torque parameters (mean, peak, percentage of maximal voluntary contraction) and tibialis anterior muscle thickness were analyzed across different contraction phases. Statistical comparisons were conducted using paired t-tests or Wilcoxon tests. Correlation analyses were performed using Pearson’s or Spearman’s tests. Results demonstrated that UVF significantly improved torque output, as evidence by the increased percentage of maximal voluntary contraction (%MVC) during entire contractions (p = 0.007), increased mean (p ≤ 0.022) and peak (p ≤ 0.044) torque and the %MVC (p ≤ 0.004) during mid and end phases, and larger muscle thickness during mid contraction (p = 0.045). Moderate correlations were found between torque and muscle thickness (r ≥ 0.30, p ≤ 0.049). These findings preliminarily supported the positive outcomes of real-time wearable UVFs in enhancing paretic ankle dorsiflexion strength and force control during isometric contractions in chronic stroke survivors. While the developed and validated new training protocol may potentially serve as a practical adjunct to existing rehabilitation approaches, further investigations emphasizing the functional outcomes and clinical translations are still needed to verify the clinical utility. Full article

Background: Short sessions of isometric exercise have been shown to reduce blood pressure (BP) in normotensive and hypertensive subjects. However, there are few data in hypertensive patients with underlying ischemic heart disease (IHD). In the present study, we compared post-exercise hypotension (PEH) induced by isometric versus combined, aerobic plus dynamic resistance exercise in IHD patients. Methods: Twenty-five stable patients with established IHD and with treated hypertension were enrolled. The study had a cross-over design. All patients performed in a random order and on different days: (1) isometric exercise session (IES) consisting of bilateral knee extension, performed at 20% of maximal voluntary contraction and lasting 20 min; (2) combined exercise session (CES) including moderate-intensity continuous exercise at and dynamic resistance exercise performed at 60% of one repetition maximum, and lasting 60 min and (3) control session (no exercise). BP was measured at rest, immediately after the training and then every 15 min up to 90 min. Results: The repeated measures ANOVA analysis showed that systolic BP significantly decreased after the CES session compared to the control (F = 6.2; p 0.001) and IES (F = 4.4; p 0.004). Systolic BP significantly decreased after IES compared to the control (F = 3.6; p 0.036). Diastolic BP did not show significant changes after CES and IES compared to the control (CES vs. control: F = 2.2; p 0.142; IES vs. control (F = 2.5; p 0.062). There were no significant differences in diastolic BP changes between CES and IES (CES vs. IES: F = 1.8; p 0.156). Conclusions: We observed that CES was more effective than IES in reducing systolic BP; IES was as effective as CES in inducing diastolic PEH in hypertensive patients with underlying IHD. Full article

Introduction: Spinal and bulbar muscular atrophy (SBMA) is an adult-onset, X-linked, progressive neuromuscular disease caused by abnormal CAG trinucleotide expansion in the androgen receptor gene. Patients with SBMA report difficulty with falls on self-reported activities of daily living scales. To our knowledge, no study has examined the relationship between falls and common clinical measures of strength, balance, mobility, and disease biomarkers. We performed a cross-sectional analysis of an SBMA cohort. Objectives: The objectives of this study are as follows: (1) compare demographics, clinical measures, and biomarkers between patients who did and did not fall; (2) determine which measures best discriminate fallers from non-fallers; and (3) identify cutoff scores to detect patients with a higher fall risk. Design: Cross-sectional analysis was used. Outcome Measures: Disease biomarkers included blood serum creatinine, and clinical measures included the Timed Up and Go (TUG), the Adult Myopathy Assessment Tool (AMAT), and posturography, including the Modified Clinical Test of Sensory Interaction on Balance and the Motor Control Test. The Maximal Voluntary Isometric Contractions (MVICs) of four lower extremity muscles were captured via fixed-frame dynamometry. Results: We identified three clinical measures that help detect fall risk in people with SBMA. A post hoc receiver operating characteristic curve analysis helped identify cut scores for each test. Impairments of mobility (TUG > 8 s), muscle endurance (AMAT endurance subscale < 14), and muscle strength (ankle plantar flexion MVIC < 45% of predicted) were different between fallers and non-fallers, via independent t-tests. Conclusions: These three clinical tests can help detect fall risk that may help clinicians implement gait aid use or other fall prevention strategies before catastrophic falls occur. Full article

Introduction: Spinal and bulbar muscular atrophy (SBMA) is an X-linked neuromuscular disorder characterized by progressive muscle weakness, along with muscle cramps, tremors, and sensory neuropathy. Previous research has shown that patients with SBMA have difficulty with dynamic balance and sensory postural control during quiet stance. There have been no reports on automatic postural reactions in SBMA. Objectives: In this study, we aimed (1) to augment previous findings of sensory postural control, (2) to investigate automatic postural reactions in SBMA, and (3) to explore the relationship between strength and balance. Design: A cross-sectional design was used for the analysis. Participants: The participants were fifty male individuals with a confirmed diagnosis of SBMA. Outcome Measures: Balance testing included the NeuroCom modified Clinical Test of Sensory Interaction on Balance (mCTSIB), which measures sway velocity during quiet stance, and the NeuroCom Motor Control Test (MCT), which measures the latency and strength of postural reactions following sudden perturbations. Strength testing included maximal voluntary isometric contractions measured via fixed-frame dynamometry. Results: Forty-seven out of fifty participants were able to complete the mCTSIB test, but only thirty-eight completed the MCT test. Patients who were unable to complete the MCT were significantly weaker in all lower extremity muscles compared to those who were able to complete testing. Compared to normative data, participants showed significantly higher sway velocity during quiet stance across all conditions of the mCTSIB, except when standing on foam with eyes open. They also exhibited significantly slower postural reactions in response to sudden shifts of the force plate on the MCT. Plantarflexor weakness was significantly correlated with poor postural control on the mCTSIB and MCT. Conclusions: This study confirms previously reported abnormalities of sensory postural control in SBMA and highlights patients’ heavy reliance on visual inputs for postural control. Additionally, this study shows that automatic postural corrections are slower than normal in SBMA and provides a unique approach for measuring the combined sensory and motor components of the disease. Both the sensory and automatic balance abnormalities were found to be associated with plantarflexor weakness and may contribute to a higher risk of falls under challenging situations. Therefore, addressing this weakness may be an important step toward fall prevention in this population. Full article

The Pilates breathing technique is theorized to improve neuromuscular efficiency, but its specific effects on peripheral muscles have not been thoroughly investigated. This study evaluated how Pilates breathing influenced the neuromuscular efficiency of the biceps brachii muscle during submaximal elbow flexion in comparison to regular breathing. Fifty-eight healthy adults without prior experience with the Pilates method of exercise performed concentric and eccentric elbow contractions at 20%, 40%, and 60% of their maximal voluntary isometric contraction under two breathing conditions: the specialized Pilates breathing pattern (executing movements exclusively during expiration) and normal breathing patterns. Muscle activity was measured using surface electromyography, with neuromuscular efficiency quantified as the relationship between muscle electrical activity and force production. The results revealed significantly improved neuromuscular efficiency during Pilates breathing at all tested intensity levels, with the most substantial enhancement observed at 60% of maximal effort. The eccentric phase of movement demonstrated greater efficiency gains compared to the concentric phase. These findings indicate that the distinct breathing pattern used in Pilates can independently enhance neuromuscular performance in the biceps brachii. This study suggests that incorporating Pilates breathing techniques could be beneficial in rehabilitation programs and strength training regimens to optimize both muscle function and movement efficiency. Additional research is recommended to examine the long-term effects and practical applications in clinical and athletic settings. Full article

Background: A comprehensive understanding of variations in physical attributes both between and within young players is crucial for accurately identifying talent based on physical performance. This study aimed to compare maximum strength, jump, and sprint test results among young soccer players from different age categories and playing positions. Secondarily, this study aimed to analyze the association between maximum strength, jump, and sprint performances. Methods: A total of 103 players were categorized as U23, U19, U17, and U16. The players were placed into these age categories based on their football abilities. All participants completed standardized warm-ups, and testing procedures followed protocols established in previous studies. Results: Significant differences were found between age categories regarding the Isometric Mid-Thigh Pull (p < 0.001; η²_p = 0.33), Countermovement Jump (CMJ) (p < 0.001; η²_p = 0.50), Squat Jump (SJ) (p < 0.001; η²_p = 0.29), and sprint (p < 0.001; η²_p = 0.30) tests. No significant differences were detected in Broad Jump results between age categories. Moreover, no significant differences were observed in any physical capacities between playing positions. Furthermore, significant moderate-to-strong correlations (r = 0.30–0.86) were observed between all physical tests. Conclusions: Age categories can distinguish soccer players’ performance in different physical tests while no differences were observed between playing positions. Similar magnitude correlations were observed across all tests with only the CMJ and SJ being strongly correlated. Coaches and strength and conditioning professionals should apply a variety of tests to assess different physical qualities since they have different patterns between age categories. Full article

Background/Objectives: The aim of this study was to assess the effects of cold-water immersion (CWI) post-eccentric muscle contraction exercise on skin temperature, pain score, maximum voluntary isometric contraction (MVIC), muscle damage, and muscle mechanical properties. Methods: Twenty-seven male participants (age 20.6 ± 0.6; body mass 69.4 ± 8.1; body fat % 13.7 ± 4.3) were divided into three treatments: whole-body CWI treatment group (n = 9), lower-body CWI treatment group (n = 9), and control treatment group (n = 9). Results: MVIC did not show a significant interaction effect between group and time but demonstrated a significant main effect for time (p = 0.001). The pain scale demonstrated a significant interaction effect between group and treatment (p = 0.049), in addition to significant main effects for both time and treatment (both p = 0.001). While blood creatine kinase (CK) concentration revealed no significant interaction effect between group and time, a significant main effect was observed for time (p = 0.001). Blood lactate dehydrogenase (LDH) concentration showed both a significant interaction effect between group and time (p = 0.02) and a significant main effect for time (p = 0.001). The tensiomyography (TMG) results for Dm showed a significant interaction effect between group and treatment (p = 0.047), as well as a significant main effect for time (p = 0.001). Conclusions: Lower-body CWI is effective in reducing pain indices and blood LDH levels, a marker of muscle damage. It may serve as an effective method for preventing and minimizing pain and muscle damage, comparable to whole-body CWI. Full article

Background/Objectives: Studies of the effects of anchor schemes (perceived intensity vs. relative intensity) on muscular performance have reported mixed findings. Therefore, the present study examined the effects of different anchor schemes on time-to-task failure (TTF), muscular performance, neuromuscular responses, and potentiated twitch torque (PTT). Methods: On separate days, 15 men (age = 21.5 ± 2.3 yrs) performed forearm flexion maximal voluntary isometric contractions (MVICs) before and after sustained tasks anchored to a rating of perceived exertion of 6 (RPEFT) and with the torque at RPE = 6 (TRQFT). Electromyographic amplitude (EMG AMP) and mean power frequency (EMG MPF) were recorded from the biceps brachii (BB). Supramaximal stimuli were delivered to the motor nerve of the BB following the MVICs to quantify the PTT. Repeated measures ANOVAs assessed the mean differences between anchor schemes for MVIC, neuromuscular, and PTT responses. Paired t-tests compared the magnitude of percent changes for the dependent variables. Results: The TTF for the RPEFT was longer (p < 0.001) than the TRQFT, but the MVIC decreased similarly (12.7 ± 9.5% vs. 20.3 ± 7.9%, p = 0.054). Electromyographic AMP did not change (p = 0.288), while EMG MPF decreased (15.7 ± 10.2%, p < 0.011) for the TRQFT only. Mean decreases in PTT were comparable for both tasks (p < 0.003), although the percent change was greater for the TRQFT (49.6 ± 16.1%, p < 0.001). Conclusions: The differences in TTF, but similar decreases in MVIC suggested that participants reached a sensory tolerance limit. Based on EMG MPF and PTT, the TRQFT caused greater peripheral perturbations to contractile function than the RPEFT. Full article

Low back pain is a major cause of disability worldwide, often associated with deficits in trunk extensor strength control. Accurate assessment of trunk extension strength control is crucial for diagnosing impairments and monitoring interventions. This study evaluated the reliability of a dynamometry-based protocol for isometric trunk extension strength control assessment. Twenty-eight healthy volunteers (9 females, 19 males) completed two sessions, seven days apart. A single-point load cell system, encapsulated within a 3D-printed structure and connected to a Delsys system^® at a sampling frequency of 2000 Hz, was used for data acquisition. Participants performed maximal voluntary contractions (MVC) and submaximal isometric contractions (SMVC) guided by trapezoidal visual feedback. Key outcome variables included peak force, mean force, and force steadiness. Calibration demonstrated high accuracy (R² = 1) with a low root mean square error (0.55 N). Test–retest analysis showed excellent reliability for peak force (ICC = 0.81, SEM = 0.50, MDC = 1.39), mean force (ICC = 0.93, SEM = 0.17, MDC = 1.08), and steadiness (ICC = 0.87, SEM = 0.85, MDC = 2.36), with no significant intersession differences (p > 0.05). This study demonstrates the high reliability of using dynamometry to assess trunk extension strength during MVC and SMVC, endorsing the dynamometer as a tool for functional assessment and the development of personalized rehabilitation and training strategies. Full article

Background: Isometric exercise effectively reduces blood pressure (BP) but its effects on myocardial work have been poorly studied. For the present study, we compared acute changes in myocardial work during two different isometric exercises, namely, bilateral knee extension and handgrip, in patients with hypertension and underlying ischemic heart disease (IHD). Methods: This was a randomized pilot study in which 48 stable, trained patients with hypertension and IHD were enrolled. Patients were randomly assigned to perform a single session of bilateral knee extension (IKE) or handgrip (IHG) exercises or no exercise (control), with a 1:1:1 ratio. Both exercises were performed at 30% of maximal voluntary contraction and lasted three minutes. Echocardiography and BP measurements were performed at rest, during the exercise, and after ten minutes of recovery. Results: Both exercises were tolerated well, and no side effects occurred. During the exercise, the systolic BP increased significantly in the IKE group compared with the IHG and control groups (ANOVA p < 0.001). Left ventricular global longitudinal strain decreased significantly in the IKE group (−21%) compared with the IHG and control groups (ANOVA p 0.002). The global work index increased significantly in the IKE group (+28%) compared with the IHG and control groups (ANOVA p 0.034). Global constructive work and wasted work increased significantly in the IKE group compared with the IHG and control groups (ANOVA p 0.009 and <0.001, respectively). Global work efficiency decreased significantly in the IKE group (−8%) while remaining unchanged in the IHG and control groups (ANOVA p 0.002). Conclusions: Myocardial work efficiency was impaired during isometric bilateral knee extension but not during handgrip, which evoked a limited hemodynamic response. Full article