RESUMEN
The aim of this study was to compare the acute effects of compression contrast therapy (CT) and dry needling therapy (DN) on muscle tension (MT), muscle strength (Fmax), pressure pain threshold (PPT), and perfusion (PU) following fatigue of forearm muscles (e.g., flexor carpi radialis) in combat sports athletes. A single-blind randomized controlled trial was employed. Participants first underwent muscle fatigue induction, which involved sustaining an isometric handgrip at 60% of their maximum voluntary contraction in 5-second cycles. This was followed by exposure to one of the regenerative therapies. Forty-five participants were randomly assigned to one of three groups: CT/DN (n = 15), CT/ShDN (n = 15), and ShCT/DN (n = 15). The sham condition (Sh) involved a simulated version of the technique. Measurements were taken at four time points: (i) at rest; (ii) immediately after exercise that led to a state of fatigue; (iii) 5 minutes after therapy (PostTh5min); and (iv) 24 hours after therapy (PostTh24h). Each participant was exposed to one experimental condition and one control condition, thereby undergoing evaluation in two sessions. Significant differences between groups were found in MT during the PostTh5min (p = 0.005), as well as in PU during the PostTh5min (p < 0.001) and PU during the PostTh24h (p < 0.001). All groups showed significant improvements at 5 minutes post-therapy compared to immediately post-muscle fatigue. As conclusions, CT/DN seems to be significantly better for enhancing MT and PU after 5 minutes of muscle fatigue induction. Using either CT, DN, or both combined is recommended to enhance the recovery of muscle functionality and properties, favoring recovery and potentially speeding up performance enhancement.
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Punción Seca , Antebrazo , Contracción Isométrica , Fatiga Muscular , Músculo Esquelético , Umbral del Dolor , Humanos , Método Simple Ciego , Fatiga Muscular/fisiología , Adulto Joven , Masculino , Músculo Esquelético/fisiología , Umbral del Dolor/fisiología , Punción Seca/métodos , Adulto , Fuerza de la Mano/fisiología , Fuerza Muscular/fisiología , Artes Marciales/fisiología , FemeninoRESUMEN
The human neck is a unique mechanical structure, highly flexible but fatigue prone. The rising prevalence of neck pain and chronic injuries has been attributed to increasing exposure to fatigue loading in activities such as prolonged sedentary work and overuse of electronic devices. However, a causal relationship between fatigue and musculoskeletal mechanical changes remains elusive. This work aimed to establish this relationship through a unique experiment design, inspired by a cantilever beam mechanical model of the neck, and an orchestrated deployment of advanced motion-force measurement technologies including dynamic stereo-radiographic imaging. As a group of 24 subjects performed sustained-till-exhaustion neck exertions in varied positions-neutral, extended, and flexed, their cervical spine musculoskeletal responses were measured. Data verified the occurrence of fatigue and revealed fatigue-induced neck deflection which increased cervical lordosis or kyphosis by 4-5° to 11°, depending on the neck position. This finding and its interpretations render a renewed understanding of muscle fatigue from a more unified motor control perspective as well as profound implications on neck pain and injury prevention.
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Fatiga Muscular , Dolor de Cuello , Cuello , Humanos , Masculino , Adulto , Femenino , Fatiga Muscular/fisiología , Dolor de Cuello/fisiopatología , Dolor de Cuello/etiología , Vértebras Cervicales/diagnóstico por imagen , Fenómenos Biomecánicos , Músculos del Cuello/fisiología , Rango del Movimiento Articular , Adulto Joven , Lordosis/fisiopatologíaRESUMEN
BACKGROUND: Inspiratory muscle fatigue has been shown to have effects on limbs blood flow and physical performance. This study aimed to evaluate the influence of an inspiratory muscle fatigue protocol on respiratory muscle strength, vertical jump performance and muscle oxygen saturation in healthy youths. METHODS: A randomized and double-blinded controlled clinical trial, was conducted. Twenty-four participants aged 18-45 years, non-smokers and engaged in sports activity at least three times a week for a minimum of one year were enrolled in this investigation. Participants were randomly assigned to three groups: Inspiratory Muscle Fatigue (IMFG), Activation, and Control. Measurements of vertical jump, diaphragmatic ultrasound, muscle oxygen saturation, and maximum inspiratory pressure were taken at two stages: before the intervention (T1) and immediately after treatment (T2). RESULTS: The IMFG showed lower scores in muscle oxygen saturation and cardiorespiratory variables after undergoing the diaphragmatic fatigue intervention compared to the activation and control groups (p < 0.05). For the vertical jump variables, intragroup differences were found (p < 0.01), but no differences were shown between the three groups (p > 0.05). CONCLUSIONS: Inspiratory muscle fatigue appears to negatively impact vertical jump performance, muscle oxygen saturation and inspiratory muscle strength in healthy youths. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT06271876. Date of registration 02/21/2024. https://clinicaltrials.gov/study/NCT06271876 .
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Inhalación , Fatiga Muscular , Fuerza Muscular , Músculos Respiratorios , Humanos , Músculos Respiratorios/fisiología , Fatiga Muscular/fisiología , Fuerza Muscular/fisiología , Masculino , Adolescente , Adulto Joven , Femenino , Adulto , Inhalación/fisiología , Saturación de Oxígeno/fisiología , Persona de Mediana Edad , Diafragma/fisiología , Método Doble CiegoRESUMEN
The measurement of skeletal muscle fatigue in response to cycling exercise is commonly done in isometric conditions, potentially limiting its ecological validity, and creating challenges in monitoring the time course of muscle fatigue across an exercise bout. This study aimed to determine if muscle fatigue could be reliably assessed by measuring quadriceps twitch force evoked while pedaling, using instrumented pedals. Nine participants completed three laboratory visits: a step incremental test to determine power output at lactate threshold, and on separate occasions, two constant-intensity bouts at a power output 10% above lactate threshold. Femoral nerve electrical stimulation was applied to elicit quadriceps twitch force both while pedaling (dynamic) and at rest (isometric). The test-retest reliability of the dynamic twitch forces and the agreement between the dynamic and isometric twitch forces were evaluated. Dynamic twitch force was found to have excellent reliability in an unfatigued state (intraclass correlation coefficient (ICC) = 0.920 and mean coefficient of variation (CV) = 7.5%), and maintained good reliability at task failure (ICC = 0.846 and mean CV = 11.5%). When comparing dynamic to isometric twitch forces across the task, there was a greater relative decline in the dynamic condition (P = 0.001). However, when data were normalized to the 5 min timepoint when potentiation between conditions was presumed to be more similar, this difference disappeared (P = 0.207). The reliability of this method was shown to be commensurate with the gold standard method utilizing seated isometric dynamometers and offers a new avenue to monitor the kinetics of muscle fatigue during cycling in real time.
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Ciclismo , Estimulación Eléctrica , Contracción Isométrica , Fatiga Muscular , Músculo Cuádriceps , Humanos , Fatiga Muscular/fisiología , Ciclismo/fisiología , Músculo Cuádriceps/fisiología , Reproducibilidad de los Resultados , Masculino , Adulto Joven , Adulto , Contracción Isométrica/fisiología , Nervio Femoral/fisiología , Femenino , Prueba de Esfuerzo/métodosRESUMEN
BACKGROUND: Anterior cruciate ligament (ACL) injuries may correlate with lower limb angles and biomechanical factors in both dominant and non-dominant legs at initial contact (IC) post-landing. This study aims to investigate the correlation between ankle angles in three axes at IC and knee and hip joint angles during post-spike landings in professional volleyball players, both pre- and post-fatigue induction. RESEARCH QUESTION: To what extent does fatigue influence lower limb joint angles, and what is the relationship between ankle joint angles and hip and knee angles at IC during the landing phase following a volleyball spike? METHODS: Under conditions involving the peripheral fatiguing protocol, the lower limb joint angles at IC following post-spike landings were measured in 28 professional male volleyball players aged between 19 and 28 years, who executed the Bosco fatigue protocol both before and after inducing fatigue. A paired t-test was utilized to compare the joint angles pre- and post-fatigue in both dominant and non-dominant legs. Furthermore, Pearson's correlation test was conducted to explore the relationship between ankle angles at IC and the corresponding knee and hip joint angles. RESULTS: The findings of the study revealed that fatigue significantly increased hip external rotation and decreased knee joint flexion and external rotation in both the dominant and non-dominant legs (p < 0.05). Additionally, correlation analysis demonstrated that the ankle joint's positioning in the frontal and horizontal planes was significantly associated with hip flexion and external rotation at the IC, as well as with knee flexion and rotation (0.40 < r < 0.80). CONCLUSION: Fatigue increased hip external rotation and ankle internal rotation, weakening the correlation between these joints while strengthening the ankle-knee relationship, indicating a reduced hip control in jumps. This suggests a heightened ACL injury risk in the dominant leg due to the weakened ankle-hip connection, contrasting with the non-dominant leg.
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Articulación del Tobillo , Lesiones del Ligamento Cruzado Anterior , Articulación de la Cadera , Articulación de la Rodilla , Voleibol , Humanos , Masculino , Articulación de la Cadera/fisiopatología , Articulación de la Cadera/fisiología , Lesiones del Ligamento Cruzado Anterior/fisiopatología , Articulación del Tobillo/fisiopatología , Articulación del Tobillo/fisiología , Adulto Joven , Adulto , Fenómenos Biomecánicos , Articulación de la Rodilla/fisiopatología , Voleibol/fisiología , Rango del Movimiento Articular/fisiología , Fatiga Muscular/fisiología , RotaciónRESUMEN
When fatigued, the wrist extensors, which are the primary wrist stabilizers, impair distal upper limb motor performance in a surprisingly similar way as when fatiguing the wrist flexors. It is possible that the wrist extensors are so active as antagonists that they develop an equal degree of fatigue during wrist flexion contractions, making it difficult to truly isolate their impact on performance. Thus, the purpose of this study was to examine how wrist flexion/extension forces are impaired following either agonist or antagonist sustained submaximal wrist contractions. 13 male participants attended four laboratory sessions. In these sessions, fatigue was induced via a sustained submaximal isometric contraction of either wrist flexion or extension. These contractions were held for up to 10 min at 20% of the participant's baseline maximal voluntary contraction (MVC) force. Throughout the sustained contraction, intermittent agonist (matching the sustained contraction) or antagonist (opposing the sustained contraction) MVCs were performed. Unsurprisingly, agonist MVC forces decreased significantly more than antagonist (Agonist: 58.5%, Antagonist: 86.5% of MVC, P < 0.001). However, while there were no differences in antagonist wrist extension and flexion MVC decreases (Wrist Flexion: 87.5%, Wrist Extension: 85.5%, P = 0.41), wrist extension MVCs did decrease significantly more than wrist flexion MVCs when forces were expressed relative to the agonist (P = 0.036). These findings partially support the hypothesis that the wrist extensors may be more susceptible to developing fatigue when functioning as antagonists than the wrist flexors. This work will help equip future research into the motor control of the upper limb and the prevention of forearm-related musculoskeletal disorders.
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Contracción Isométrica , Fatiga Muscular , Músculo Esquelético , Muñeca , Humanos , Masculino , Contracción Isométrica/fisiología , Fatiga Muscular/fisiología , Adulto , Adulto Joven , Muñeca/fisiología , Músculo Esquelético/fisiología , Articulación de la Muñeca/fisiología , Rango del Movimiento Articular/fisiología , Fenómenos Biomecánicos/fisiología , ElectromiografíaRESUMEN
BACKGROUND: The present study aimed to investigate whether head and neck cooling (at 18 °C next to the skin) and fatiguing submaximal exercise at a thermoneutral ambient temperature can induce peripheral and central responses in healthy men and those with multiple sclerosis (MS). METHODS: A local head-neck cooling (at 18 °C next to the skin) intervention in men with a relapsing-remitting form of MS (n = 18; age 30.9 ± 8.1 years) and healthy men (n = 22; age 26.7 ± 5.9 years) was assessed. Men in both groups performed 100 intermittent isometric knee extensions with 5 s contractions and 20 s of rest. The primary variables were measured before exercise, after 50 and 100 repetitions, and 1 h after recovery. The central activation ratio, maximal voluntary contraction, electrically induced force, electromyography, contractile properties, blood markers, muscle temperature, and perception of effort were measured. RESULTS: Compared with noncooled conditions, head and neck cooling increased the central capacity to activate exercising muscles but resulted in greater exercise-induced peripheral fatigue in men with MS (p < 0.05). Local cooling did not affect motor accuracy or the amplitude of electromyography signals; however, these factors were related to the intensity of the motor task (p > 0.05). The changes in central and peripheral fatigability induced by local cooling during submaximal exercise were more pronounced in men with MS than in healthy men (p < 0.05). CONCLUSION: Head and neck cooling enhances central activation of muscles during exercise, leading to improved exercise performance compared with noncooled conditions in men with MS.
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Estudios Cruzados , Cabeza , Cuello , Humanos , Masculino , Adulto , Cuello/fisiopatología , Adulto Joven , Cabeza/fisiología , Cabeza/fisiopatología , Esclerosis Múltiple Recurrente-Remitente/fisiopatología , Esclerosis Múltiple Recurrente-Remitente/sangre , Fatiga Muscular/fisiología , Electromiografía , Ejercicio Físico/fisiología , Contracción Isométrica/fisiología , Músculo Esquelético/fisiopatología , Músculo Esquelético/fisiología , Hipotermia InducidaRESUMEN
Emerging research suggests that muscular and kinematic responses to overhead work display a high degree of variability in fatigue-related muscular and kinematics changes, both between and within individuals when evaluated across separate days. This study examined whether electromyographic (EMG), kinematic, and kinetic responses to an overhead drilling task performed until volitional fatigue were comparable to those of a repeated identical exposure of the task completed 1 week later. Surface EMG and intramuscular EMG, sampled from 7 shoulder muscles, and right upper limb kinematics and kinetics were analyzed from 15 male and 14 female participants. No significant day-to-day changes in EMG mean power frequency (MPF) were observed, though serratus anterior displayed significantly less fatigue-related increase in EMG root-mean-squared (RMS) signal amplitude on day 2. Unfatigued upper kinematics on day 2 featured an increase in thoracohumeral elevation, elbow flexion, and decrease in wrist ulnar deviation compared to unfatigued state on day 1. Fatigue-related changes in shoulder joint flexion moment that were present on day 1 were reduced on day 2, suggesting that a more efficient overhead work strategy was learned and preserved across successive days. Day-to-day changes in upper limb joint angle variability, quantified by median absolute deviation (MdAD), were joint dependent. Despite yielding a variable fatigue-related kinetic strategy on both days, kinematic and kinetic fatigue-related changes on a second day of completing an overhead drilling task suggested a potential kinematic learning effect.
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Electromiografía , Fatiga Muscular , Músculo Esquelético , Humanos , Masculino , Femenino , Fatiga Muscular/fisiología , Fenómenos Biomecánicos/fisiología , Adulto Joven , Adulto , Rango del Movimiento Articular/fisiología , Articulación del Hombro/fisiopatología , Extremidad Superior/fisiopatologíaRESUMEN
The study investigated the effects of unilateral and bilateral lower extremity fatigue on both postural stability and postural adjustments. Fourteen young male subjects performed unilateral and bilateral dynamic lower extremity pedaling exercises with 5 sets of 20 times at 50 % maximum voluntary contraction. Center of pressure (COP) signals were recorded before and after the fatigue exercise. Electromyography activities of six trunk and leg muscles were recorded and analyzed during the anticipatory (APAs) and compensatory (CPAs) postural adjustments. The results showed that both fatiguing exercises caused an increase in COP and larger APAs and CPAs in the rectus femoris and tibialis anterior during externally initiated perturbation. However, the observed indicators showed no clear difference between unilateral and bilateral fatigue. These results validated that when enlarged APAs were not sufficient to resist the external perturbation, the central nervous system increased the strength of CPAs to maintain the stability of the body. These findings provided a perspective on the association between APAs and CPAs, which may apply to the athletic training or rehabilitation on postural control.
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Electromiografía , Extremidad Inferior , Fatiga Muscular , Músculo Esquelético , Equilibrio Postural , Humanos , Masculino , Equilibrio Postural/fisiología , Fatiga Muscular/fisiología , Extremidad Inferior/fisiología , Electromiografía/métodos , Adulto Joven , Músculo Esquelético/fisiología , Postura/fisiología , AdultoRESUMEN
The purpose was to determine the impact of both cognitive constraint and neuromuscular fatigue on landing biomechanics in healthy and chronic ankle instability (CAI) participants. Twenty-three male volunteers (13 Control and 10 CAI) performed a single-leg landing task before and immediately after a fatiguing exercise with and without cognitive constraints. Ground Reaction Force (GRF) and Time to Stabilization (TTS) were determined at landing in vertical, anteroposterior (ap) and mediolateral (ml) axes using a force plate. Three-dimensional movements of the hip, knee and ankle were recorded during landing using a motion capture system. Exercise-induced fatigue decreased ankle plantar flexion and inversion and increased knee flexion. Neuromuscular fatigue decreased vertical GRF and increased ml GRF and ap TTS. Cognitive constraint decreased ankle internal rotation and increased knee and hip flexion during the flight phase of landing. Cognitive constraint increased ml GRF and TTS in all three axes. No interaction between factors (group, fatigue, cognitive) were observed. Fatigue and cognitive constraint induced greater knee and hip flexion, revealing higher proximal control during landing. Ankle kinematic suggests a protective strategy in response to fatigue and cognitive constraints. Finally, these two constraints impair dynamic stability that could increase the risk of ankle sprain.
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Articulación del Tobillo , Cognición , Inestabilidad de la Articulación , Extremidad Inferior , Fatiga Muscular , Humanos , Masculino , Inestabilidad de la Articulación/fisiopatología , Fenómenos Biomecánicos , Adulto Joven , Articulación del Tobillo/fisiopatología , Articulación del Tobillo/fisiología , Fatiga Muscular/fisiología , Extremidad Inferior/fisiología , Extremidad Inferior/fisiopatología , Cognición/fisiología , Rodilla/fisiología , Rodilla/fisiopatología , Adulto , Ejercicio Pliométrico , Tobillo/fisiología , Tobillo/fisiopatología , Estudios de Tiempo y Movimiento , Movimiento/fisiología , Traumatismos del Tobillo/fisiopatología , Articulación de la Rodilla/fisiología , Articulación de la Rodilla/fisiopatología , Articulación de la Cadera/fisiología , Articulación de la Cadera/fisiopatologíaRESUMEN
BACKGROUND: Work-related musculoskeletal disorders (WMSDs) show a rapid growth trend. It has brought a huge economic burden to the society and become a serious occupational health problem that needs to be solved urgently. This study aimed to analyze the local muscle response under continuous ergonomic load, screen sensitive fatigue-related biomarkers and provide data support for the early prevention of local muscle damage and the exploration of early warning indicators. METHODS: Thirteen male college student volunteers were recruited to perform simulated repetitive manual lifting tasks in the laboratory. The lifting task was designed for 4 periods which lasted for 12 min in each, and then paused for 3 min for sampling. Local muscle fatigue is assesed by the Rating of perceived exertion (RPE) and the Joint analysis of sEMG spectrum and amplitude (JASA). Elbow venous blood was collected and 14 kinds of biomarkers were analyzed, which included Metabolic markers Ammonia (AMM), Lactic acid (LAC), Creatine kinase (CK), Lactate dehydrogenase (LDH), Cartilage oligomeric matrix protein (COMP), C-telopeptide of collagen I and II (CTX-I, CTX-II) and Calcium ion (Ca2+); Oxidative stress marker Glutathione (GSH); Inflammatory markers C-reaction protein (CRP), Prostaglandin E2 (PG-E2), Interleukin-6 (IL-6) and Tumor necrosis factor α (TNF-α); Pain marker Neuropeptide Y (NPY). Repeated measures analysis of variance (Repeated ANOVA), linear regression analysis, t-test and spearman correlation analysis were used to analyze the data. RESULTS: Both subjective and objective fatigue appeared at the same period. Serum AMM, LAC, CK, LDH, COMP, CTX-II, Ca2+ and NPY after fatigue were significantly higher than those before fatigue (p < 0.05). There was a certain degree of correlation between the markers with statistical differences before and after fatigue. CONCLUSIONS: Metabolic markers (serum AMM, LAC, CK, LDH, COMP, CTX-II, Ca2+) and pain markers (serum NPY) can reflect local muscle fatigue to a certain extent in repetitive manual lifting tasks. It is necessary to further expand the research on fatigue-related biomarkers in different types of subjects and jobs in the future.
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Biomarcadores , Elevación , Fatiga Muscular , Humanos , Masculino , Fatiga Muscular/fisiología , Biomarcadores/sangre , Adulto Joven , Elevación/efectos adversos , Trastornos de Traumas Acumulados/sangre , Trastornos de Traumas Acumulados/fisiopatología , Trastornos de Traumas Acumulados/diagnóstico , Adulto , Músculo Esquelético/metabolismoRESUMEN
Loading both lateral and medial compartments is crucial to understanding the effect of muscle fatigue during sidestep cutting. The present study investigated the changes in tibiofemoral contact forces in the medial and lateral compartments and the muscle force contributions during the sidestep-cutting manoeuvre after a handball-specific fatigue protocol. Twenty female handball athletes performed three trials of the sidestep-cutting manoeuvre before (baseline) and after the fatigue protocol. Motion capture and ground reaction forces were measured, and the data were processed in OpenSim. The variables were compared using statistical parametric mapping (SPM), with a significance level of p < 0.05. The results showed a decreased knee flexion angle during fatigue in the early stance phase. In addition, the post-fatigue analysis demonstrated significantly reduced forces in vasti muscles. Similarly, during fatigue, the SPM analysis showed decreased tibiofemoral contact forces in the vertical and anterior directions. Vertical force applied to both medial and lateral condyles demonstrated a significant reduction after the fatigue protocol. These results indicated that forces applied to the tibiofemoral joint were reduced following the fatigue protocol compared to the baseline values. However, no consistent evidence exists that fatigue increases the risk of knee injuries.
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Articulación de la Rodilla , Fatiga Muscular , Humanos , Femenino , Fenómenos Biomecánicos , Fatiga Muscular/fisiología , Adulto Joven , Articulación de la Rodilla/fisiología , Deportes/fisiología , Músculo Esquelético/fisiología , Estudios de Tiempo y Movimiento , Rodilla/fisiología , Movimiento/fisiologíaRESUMEN
Surface electromyogram (EMG) signals find diverse applications in movement rehabilitation and human-computer interfacing. For instance, future advanced prostheses, which use artificial intelligence, will require EMG signals recorded from several sites on the forearm. This requirement will entail complex wiring and data handling. We present the design and evaluation of a bespoke EMG sensing system that addresses the above challenges, enables distributed signal processing, and balances local versus global power consumption. Additionally, the proposed EMG system enables the recording and simultaneous analysis of skin-sensor impedance, needed to ensure signal fidelity. We evaluated the proposed sensing system in three experiments, namely, monitoring muscle fatigue, real-time skin-sensor impedance measurement, and control of a myoelectric computer interface. The proposed system offers comparable signal acquisition characteristics to that achieved by a clinically-approved product. It will serve and integrate future myoelectric technology better via enabling distributed machine learning and improving the signal transmission efficiency.
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Electromiografía , Diseño de Equipo , Procesamiento de Señales Asistido por Computador , Electromiografía/métodos , Electromiografía/instrumentación , Humanos , Algoritmos , Músculo Esquelético/fisiología , Fatiga Muscular/fisiología , Impedancia Eléctrica , Masculino , Aprendizaje Automático , Reproducibilidad de los Resultados , Interfaz Usuario-Computador , Adulto , Sensibilidad y Especificidad , Antebrazo/fisiología , Contracción Muscular/fisiologíaRESUMEN
The purpose was to clarify the effect of individualised post-exercise blood flow restriction (PE-BFR) on measures of recovery following strenuous resistance exercise. Twenty resistance-trained adults were randomised to a PE-BFR or control (CON) group and completed a fatigue protocol of five sets of 10 repetitions of maximal intensity concentric and eccentric seated knee extension exercise. Participants then lied supine with cuffs applied to the upper thigh and intermittently inflated to 80% limb occlusion pressure (PE-BFR) or 20 mmHg (CON) for 30 min (3 × 5 min per leg). Peak torque (PT), time-to-peak torque (TTP), countermovement jump height (CMJ), muscle soreness (DOMS) and perceived recovery (PR) were measured pre-fatigue, immediately post-fatigue and at 1, 24, 48 and 72 h post-fatigue. Using a linear mixed-effect model, PE-BFR was found to have greater recovery of CMJ at 48 h (mean difference [MD]=-2.8, 95% confidence interval [CI] -5.1, 0.5, p = 0.019), lower DOMS at 48 (MD = 3.0, 95% CI 1.2, 4.9, p = 0.001) and 72 h (MD = 1.95, 95% CI -1.2, 1.5, p = 0.038) and higher PR scores at 24 (MD = -1.7, 95% CI -3.4, -0.1, p = 0.038), 48 (MD = -3.1, 95% CI -4.8, -1.5, p < 0.001) and 72 h (MD = -2.2, 95% CI -3.8, -0.5, p = 0.011). These findings suggest that individualised PE-BFR accelerates recovery after strenuous exercise.
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Mialgia , Flujo Sanguíneo Regional , Entrenamiento de Fuerza , Torque , Humanos , Entrenamiento de Fuerza/métodos , Masculino , Mialgia/fisiopatología , Flujo Sanguíneo Regional/fisiología , Adulto Joven , Femenino , Adulto , Fatiga Muscular/fisiología , Músculo Esquelético/irrigación sanguínea , Músculo Esquelético/fisiología , Terapia de Restricción del Flujo SanguíneoRESUMEN
Plyometric training is characterized by high-intensity exercise which is performed in short term efforts divided into sets. The purpose of the present study was twofold: first, to investigate the effects of three distinct plyometric exercise protocols, each with varying work-to-rest ratios, on muscle fatigue and recovery using an incline-plane training machine; and second, to assess the relationship between changes in lower limb muscle strength and power and the biochemical response to the three exercise variants employed. Forty-five adult males were randomly divided into 3 groups (n = 15) performing an exercise of 60 rebounds on an incline-plane training machine. The G0 group performed continuous exercise, while the G45 and G90 groups completed 4 sets of 15 repetitions, each set lasting 45 s with 45 s rest in G45 (work-to-rest ratio of 1:1) and 90 s rest in G90 (1:2 ratio). Changes in muscle torques of knee extensors and flexors, as well as blood lactate (LA) and ammonia levels, were assessed before and every 5 min for 30 min after completing the workout. The results showed significantly higher (p < 0.001) average power across all jumps generated during intermittent compared to continuous exercise. The greatest decrease in knee extensor strength immediately post-exercise was recorded in group G0 and the least in G90. The post-exercise time course of LA changes followed a similar pattern in all groups, while the longer the interval between sets, the faster LA returned to baseline. Intermittent exercise had a more favourable effect on muscle energy metabolism and recovery than continuous exercise, and the work-to-rest ratio of 1:2 in plyometric exercises was sufficient rest time to allow the continuation of exercise in subsequent sets at similar intensity.
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Fatiga Muscular , Fuerza Muscular , Ejercicio Pliométrico , Descanso , Humanos , Masculino , Descanso/fisiología , Fatiga Muscular/fisiología , Adulto , Fuerza Muscular/fisiología , Ejercicio Pliométrico/métodos , Adulto Joven , Músculo Esquelético/fisiología , Ácido Láctico/sangre , Amoníaco/sangre , Ejercicio Físico/fisiologíaRESUMEN
ABSTRACT: Díaz-García, J, López-Gajardo, MÁ, Parraca, JA, Batalla, N, López-Rodríguez, R, and Ring, C. Brain endurance training improves and maintains chest press and squat jump performance when fatigued. J Strength Cond Res 38(9): 1568-1575, 2024-Mental fatigue can impair resistance exercise performance. Brain endurance training (BET)-the addition of demanding cognitive tasks to standard exercise training-improves endurance exercise performance more than standard training. Although BET has yet to be evaluated with resistance exercise, it is expected to improve performance, particularly when the performer feels mentally fatigued. The study employed a pretest (week 0), midtest (week 3), posttest (week 6), and follow-up (week 9) design, with subjects randomized to BET ( n = 46) or control (exercise training) ( n = 45) groups. In testing sessions, subjects performed chest press and squat jump exercises to failure before (feeling fresh) and after (feeling tired) a 30-minute cognitively demanding Stroop task. Training comprised 5 BET or control training sessions per week for 6 weeks. In each training session, subjects completed 4 sets of each exercise to failure, with each exercise set preceded by a 3-minute cognitive task (BET) or rest (control). Exercise performance (number of repetitions to failure) and mental fatigue markers were assessed. In pretesting, exercise performance did not differ between the groups. In midtesting and posttesting, BET performed more chest press and squat jump repetitions when fatigued by the 30-minute Stroop than control. The mental fatigue elicited by the Stroop task gradually declined with training in BET compared with control. In conclusion, BET enhanced resistance exercise performance compared with standard training when tested subsequent to a mentally fatiguing cognitive task. These benefits were maintained weeks after training ended. Brain endurance training is an effective method to mitigate the deleterious effects of mental fatigue on resistance exercise performance.
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Entrenamiento Aeróbico , Entrenamiento de Fuerza , Humanos , Masculino , Adulto Joven , Adulto , Entrenamiento de Fuerza/métodos , Entrenamiento Aeróbico/métodos , Fatiga Mental , Femenino , Resistencia Física/fisiología , Encéfalo/fisiología , Rendimiento Atlético/fisiología , Test de Stroop , Fatiga Muscular/fisiologíaRESUMEN
Neuromuscular fatigue (NMF) induces temporary reductions in muscle force production capacity, affecting various aspects of motor function. Although studies have extensively explored NMF's impact on muscle activation patterns and postural stability, its influence on motor adaptation processes remains less understood. This article investigates the effects of localized NMF on motor adaptation during upright stance, focusing on reaching tasks. Using a force-field perturbation paradigm, participants performed reaching movements while standing upright before and after inducing NMF in the ankle dorsiflexor muscles. Results revealed that despite maintained postural stability, participants in the NMF group exhibited larger movement errors during reaching tasks, suggesting impaired motor adaptation. This was evident in both initial and terminal phases of adaptation, indicating a disruption in learning processes rather than a decreased adaptation rate. Analysis of electromyography activation patterns highlighted distinct strategies between groups, with the NMF group showing altered activation of both fatigued and nonfatigued muscles. In addition, differences in coactivation patterns suggested compensatory mechanisms to prioritize postural stability despite NMF-induced disruptions. These findings underscore the complex interplay between NMF, motor adaptation, and postural control, suggesting a potential role for central nervous system mechanisms in mediating adaptation processes. Understanding these mechanisms has implications for sports performance, rehabilitation, and motor skill acquisition, where NMF may impact the learning and retention of motor tasks. Further research is warranted to elucidate the transient or long-term effects of NMF on motor adaptation and its implications for motor rehabilitation interventions.NEW & NOTEWORTHY We assessed motor adaptation during force-field reaching following exercise-induced neuromuscular fatigue (NMF) on postural muscles. NMF impaired adaptation in performance. Similarly, diverging activation strategies were observed in the muscles. No effects were seen on measures of postural control. These results suggest the remodulation of motor commands to the muscles in the presence of NMF, which may be relevant in settings where participants could be exposed to NMF while learning, such as sports and rehabilitation.
Asunto(s)
Adaptación Fisiológica , Electromiografía , Fatiga Muscular , Músculo Esquelético , Equilibrio Postural , Postura , Humanos , Fatiga Muscular/fisiología , Masculino , Músculo Esquelético/fisiología , Adaptación Fisiológica/fisiología , Equilibrio Postural/fisiología , Femenino , Adulto Joven , Adulto , Postura/fisiología , Electromiografía/métodos , Extremidad Inferior/fisiología , Movimiento/fisiologíaRESUMEN
Neuromuscular fatigue induces superior migration of the humeral head in individuals with subacromial pain. This has been attributed to weakness of rotator cuff muscles and overactive deltoid muscles. Investigation of common inputs to motoneuron pools of the rotator cuff and deltoid muscles offers valuable insight into the underlying mechanisms of neuromuscular control deficits associated with subacromial pain. This study aims to investigate intermuscular coherence across the rotator cuff and deltoid muscles during a sustained submaximal isometric fatiguing contraction in individuals with and without subacromial pain. Twenty symptomatic and 18 asymptomatic young adults participated in this study. Surface electromyogram (EMG) was recorded from the middle deltoid (MD) and infraspinatus (IS). Intramuscular EMG was recorded with fine-wire electrodes in the supraspinatus (SS). Participants performed an isometric fatiguing contraction of 30° scaption at 25% maximum voluntary contraction (MVC) until endurance limit. Pooled coherence of muscle pairs (SS-IS, SS-MD, IS-MD) in the 2-5 Hz (delta), 5-15 Hz (alpha), and 15-35 Hz (beta) frequency bands during the initial and final 30 s of the fatigue task were compared. SS-IS and SS-MD delta-band coherence increased with fatigue in the asymptomatic group but not the symptomatic group. In the alpha and beta bands, SS-IS and SS-MD coherence increased with fatigue in both groups. IS-MD beta-band coherence was greater in the symptomatic than the asymptomatic group. Individuals with subacromial pain failed to increase common drive across rotator cuff and deltoid muscles and have altered control strategies during neuromuscular fatigue. This may contribute to glenohumeral joint instability and subacromial pain experienced by these individuals.NEW & NOTEWORTHY Through the computation of shared neural drive across glenohumeral muscles, this study reveals that individuals with subacromial pain were unable to increase shared neural drive within the rotator cuff and across the supraspinatus and deltoid muscles during neuromuscular fatigue induced by sustained isometric contraction. These deficits in common drive across the shoulder muscles likely contribute to the joint instability and pain experienced by these individuals.
Asunto(s)
Músculo Deltoides , Electromiografía , Contracción Isométrica , Fatiga Muscular , Manguito de los Rotadores , Humanos , Fatiga Muscular/fisiología , Masculino , Músculo Deltoides/fisiopatología , Músculo Deltoides/fisiología , Femenino , Manguito de los Rotadores/fisiopatología , Adulto , Contracción Isométrica/fisiología , Adulto Joven , Dolor de Hombro/fisiopatologíaRESUMEN
Sustained low-intensity muscle fatigue (SULMF) refers to the phenomenon that skeletal muscle continues to contract at less than 10% of maximum voluntary contraction during work activities, resulting in decreased muscle contractile function, which is one of the main causes of occupational neck, shoulder, waist and back discomfort and pain symptoms. Although surface electromyography is a key physiological technique for assessing the efficiency of neuromuscular activity, its effectiveness in objectively detecting SULMF remains controversial. Therefore, this paper describes the neurophysiological mechanism and related hypotheses of SULMF, and reviews the research progress of electromyography detection indicators and detection methods of SULMF, which is of great significance for the early prevention and accurate detection of work-related musculoskeletal disorders.
Asunto(s)
Electromiografía , Fatiga Muscular , Humanos , Electromiografía/métodos , Fatiga Muscular/fisiología , Músculo Esquelético/fisiología , Músculo Esquelético/fisiopatología , Contracción Muscular/fisiologíaRESUMEN
Few studies have explored the kinetics of performance and perceived fatigability during high-intensity interval training, despite its popularity. We aimed to characterize the kinetics of fatigability and recovery during an 8 × 4-min HIIT protocol, hypothesizing that most muscle function impairment would occur during the initial four intervals. Fifteen healthy males and females (mean ± standard deviation; age = 26 ± 5 years, VÌO2max = 46.8 ± 6.1 mL·kg-1·min-1) completed eight, 4-min intervals at 105% of critical power with 3 min of rest. Maximal voluntary knee extension contractions (MVCs) coupled with electrical nerve stimulation were performed at baseline and after the first, fourth, and eighth intervals. MVC, potentiated twitch force (Pt), and Db10:100 ratio all declined throughout HIIT (p < 0.05). MVC sharply declined after interval 1 (-15 ± 9% relative to baseline; p < 0.05) and had only further declined after interval 8 (-26 ± 11%; p < 0.05), but not interval 4 (-19 ± 13%; p > 0.05). Pt and Db10:100 also sharply declined after interval 1 (Pt: -18 ± 13%, Db10:100: -14 ± 20%; p < 0.05) and further declined after interval 4 (Pt: -35 ± 19%, Db10:100: -30 ± 20%; p < 0.05) but not interval 8 (Pt: -41 ± 19%; Db10:100: -32 ± 18%; p > 0.05). Voluntary activation did not significantly change across the HIIT protocol (p > 0.05). Evoked force recovery was significantly blunted as more intervals were completed: after interval 1, Pt recovered by 7 ± 11% compared to -6 ± 7% recovery after interval 8 (p < 0.05). Ratings of perceived effort, fatigue, and leg pain rose throughout the session (p < 0.05 for each) and were greater (effort and fatigue) for females (p < 0.05). Otherwise, males and females exhibited similar performance fatigability kinetics, with contractile function declines blunted in response to additional intervals.