Analysis of Velocity, Power and Skin Temperature in Paralympic Powerlifting Athletes with Fixed and Variable Resistance.

Variable resistance training has been widely used in athletic preparation. OBJECTIVES: To analyze the use of currents (VRT) and the traditional method (TRAD) on speed, power and temperature in a training session. METHODS: Fourteen paralympic powerlifting (PP) athletes took part over three weeks. In week 1, familiarization and 1RM tests took place, and, in weeks 2 and 3, pre- and post-training took place, where the propulsive mean velocity and power and temperatures were assessed before and after, at 24 h and 48 h. RESULTS: There was a difference in the sternal pectoral temperatures before and after VRT (p = 0.040) and at 48 h for TRAD and VRT (p = 0.018); in the clavicular pectoralis before and after VRT and TRAD (p = 0.003); in the anterior deltoid after and at 48 h for TRAD and VRT (p = 0.026 and p = 0.017); and in the triceps after and at 24 h and 48 h between TRAD and VRT (p = 0.005). In the training series, the MPV was significant in TRAD between Set1 and Set5 (p = 0.003), in training (VRT) between Set1 and Set5 (p = 0.001) and in Set5 between the methods (p = 0.047). For power, there was a difference between Set1 and 5 in TRAD (p = 0.016) and VRT (p = 0.002). CONCLUSION: We conclude that training with currents (VRT) promoted greater muscle fatigue when compared to traditional training.

Effects of a mat Pilates-based exercise program for low back pain in helicopter pilots of the Brazilian Air Force: Randomized controlled trial.

INTRODUCTION: Helicopter pilots may present chronic low back pain due to vibration exposure and asymmetric posture during flight. OBJECTIVES: To analyze the effects of a Pilates-based exercise program on low back pain of helicopter pilots of the Brazilian Air Force. METHODS: This is a randomized controlled trial with fifteen helicopter pilots of the Brazilian Air Force, who were assessed for pain intensity (Numerical Pain Rating Scale), disability associated with low back pain, and spine muscle endurance in three positions: trunk extension (Ito test) and left and right lateral bridge. Individuals were randomly distributed into the regular exercises group (REG) (n = 7), oriented to maintain their exercise routine, and Pilates group (PG) (n = 8), which performed an exercise program based on Pilates method twice a week for 12 weeks. Reassessments occurred after 6 and 12 weeks. Data were analyzed on SPSS 20.0 software using a significance level of 5%. RESULTS: PG showed a significant reduction in low back pain after 12 weeks of training compared with REG (mean difference of 3.5 points, p < 0.0001). We also observed increased endurance of trunk extensors (p = 0.002) and right (p = 0.001) and left lateral muscles (p = 0.001) in the PG compared with REG. However, the indexes of disability did not change between groups. CONCLUSION: Pain intensity was significantly reduced while spine muscle endurance increased in PG compared with REG after intervention; thus, Pilates-based exercises should be considered in physical conditioning programs for helicopter pilots.

Fatigue and Performance Rates as Decision-Making Criteria in Pacing Control During CrossFit®.

We investigated fatigue and performance rates as decision-making criteria in pacing control during CrossFit®. Thirteen male regional-level competitors completed conditions of all-out (maximum physical work from beginning to end) and controlled-split (controlled physical work in the first two rounds but maximum work in the third round) pacing throughout the Fight Gone Bad workout separated by one week. We assessed benchmarks, countermovement jumps and ratings of fatigue after each round. Benchmarks were lower in round 1 (99 vs. 114, p < .001) but higher in rounds 2 (98 vs. 80, p < .001) and 3 (97 vs. 80, p < .001) for controlled-split compared with all-out pacing. Reductions in countermovement jumps were higher after rounds 1 (-12.6% vs. 1.6%, p < .001) and 2 (-12.7% vs. -4.0%, p = .014) but similar after round 3 (-13.2% vs. -11.3%, p = .571) for all-out compared with controlled-split pacing. Ratings of fatigue were higher after rounds 1 (7 vs. 5 a.u., p < .001) and 2 (8 vs. 7 a.u, p = .023) but similar after round 3 (9 vs. 9 a.u., p = .737) for all-out compared with controlled-split pacing. During all-out pacing, countermovement jump reductions after round 2 correlated with benchmark drops across rounds 1 and 2 (r = .78, p = .002) and rounds 1 and 3 (r = -.77, p = .002) and with benchmark workout changes between pacing strategies (r = -.58, p = .036), suggesting that the larger the countermovement jump reductions the higher the benchmark drops across rounds and workouts. Therefore, benchmarks, countermovement jumps and ratings of fatigue may assess exercise-induced fatigue as decision-making criteria to improve pacing strategy during workouts performed for as many repetitions as possible.

Acute Effect of Oral Adenosine Triphosphate (ATP) Supplementation on Muscular Performance in Trained Adults.

INTRODUCTION: Adenosine Triphosphate is a molecule with the function of generating energy, where high levels are directly related to cellular and muscular health. Oral supplementation appears as a possibility to guarantee such levels, and is normally consumed in capsules, which can be acute or chronic. OBJECTIVES: To verify the influence of a dose of ATP on muscular performance in adults. METHODS: This is an acute, crossover, randomized, double-blind, placebo-controlled intervention study. 18 trained men were recruited, with an average age of 27.95 years. Two visits were made to the laboratory, where each of the protocols consisted of randomized supplementation of 400 mg of Peak ATP® or placebo, and 30 min later, five series were performed, where the first consisted of five repetitions and the following four of ten repetitions at 60° per second in knee extension and flexion on a Biodex® 4.0 isokinetic dynamometer, where the volunteers' muscle strength and resistance to fatigue were measured. For data analysis, data normality was assessed using Shapiro Wilk, the ANOVA repeated measures test with Bonferroni post hoc. To identify the size of the effect, the Cohen test was performed, and the statistical package used was SPSS 25 with an applied significance of p < 0.05. RESULTS: Acute supplementation was unable to achieve significant improvements in muscle strength indicators. The supplement delays drops in strength as the exercise progresses in knee extension compared to the placebo. CONCLUSIONS: An acute dose of 400 mg of ATP did not improve the volunteers' muscle strength indicators, but it was able to reduce fatigue levels as the exercise progressed, enabling greater performance for longer.

Changes related to muscle autophagy after exhaustive exercise and blunt trauma / Cambios relacionados con la autofagia muscular tras ejercicio exhaustivo y traumatismo contuso / Alterações relacionadas à autofagia muscular após exercício exaustivo e trauma contuso

ABSTRACT Objective: To study the temporal changes of autophagy related factors in skeletal muscle of rats after exhaustive exercise and blunt trauma. Methods: Forty-two male SD rats were divided into 7 groups with 6 rats in each group: Quiet control group (C), immediately after exhaustive exercise (E0), 24 hours after exhaustive exercise (E24), 48 hours after exhaustive exercise (E48), immediately after blunt trauma (D0), 24 hours after blunt trauma (D24), 48 hours after blunt trauma (D48). All groups of rats were killed and samped respectively at different time points specified above, and the right gastrocnemius muscle was taken, which was divided into two parts, one for mRNAs of, Lamp-2, BNIP3 and NIX by real-time fluorescent quantitative PCR, and the other for p62 protein by Western blotting. Results: (1) Compared with group C, mRNA levels of p62, Lamp-2 and NIX in group E48 were significantly increased after exhaustive exercise(P<0.05), suggesting that autophagy increased in 48h after exhaustive exercise. (2) Compared with group C, p62mRNA and Lamp-2 mRNA levels were significantly increased immediately after blunt trauma(P<0.05) and decreased significantly in 48h after blunt trauma(P<0.05), suggesting that autophagy activity was enhanced immediately after blunt trauma and decreased in 48h after injury. Conclusions: Generally, there were differences at each recovery phase between blunt trauma and exhausted exercise models, and the basal autophagy factors and mitochondrial autophagy factors were also inconsistent. Basal autophagy factors p62 and Lamp-2 increased significantly 48 hours after eccentric exhaustive exercise and immediately after blunt trauma. Mitochondrial autophagy factor BNIP3 did not increase after exhaustive exercise and blunt trauma, but NIX only increased after exhaustive exercise. Its molecular mechanism needs to be further studied. Level of Evidence III; Therapeutic Studies Investigating the Results of Treatment.

RESUMEN Objetivo: Estudiar los cambios temporales de los factores relacionados con la autofagia en el músculo esquelético de ratas tras el ejercicio exhaustivo y el traumatismo contuso. Métodos: Se dividieron 42 ratas SD macho en 7 grupos con 6 ratas en cada grupo: grupo de control silencioso (C), inmediatamente después del ejercicio exhaustivo (E0), 24 horas después del ejercicio exhaustivo (E24), 48 horas después del ejercicio exhaustivo (E48), inmediatamente después de un traumatismo contuso (D0), 24 horas después de un traumatismo contuso (D24), 48 horas después de un traumatismo contuso (D48). Todos los grupos de ratas fueron sacrificados y rotulados, respectivamente, en diferentes momentos especificados anteriormente, y se extrajo el músculo gastrocnemio derecho, dividido en dos partes, una para los ARNm Lamp-2, BNIP3 y NIX mediante PCR cuantitativa fluorescente en tiempo real, y la otra para la proteína p62 mediante Western blotting. Resultados: (1) En comparación con el grupo C, los niveles de ARNm de p62, Lamp-2 y NIX en el grupo E48 aumentaron significativamente tras el ejercicio exhaustivo (P<0,05), lo que sugiere que la autofagia aumentó en las 48 horas posteriores al ejercicio exhaustivo. (2) En comparación con el grupo C, los niveles de ARNm de p62 ARNm y Lamp-2 aumentaron significativamente inmediatamente después del traumatismo contuso (P<0,05) y disminuyeron significativamente a las 48 horas después del traumatismo contuso (P<0,05), lo que sugiere que la actividad de autofagia aumentó inmediatamente después del traumatismo contuso y disminuyó a las 48 horas después de la lesión. Conclusión: En general, hubo diferencias en cada fase de recuperación entre los modelos de traumatismo contuso y ejercicio exhaustivo, y los factores de autofagia basal y los factores de autofagia mitocondrial también fueron inconsistentes. Los factores de autofagia basal p62 y Lamp-2 aumentaron significativamente 48 horas después del ejercicio excéntrico exhaustivo e inmediatamente después del traumatismo contuso. El factor de autofagia mitocondrial BNIP3 no aumentó tras el ejercicio exhaustivo y el traumatismo contuso, pero NIX sólo aumentó tras el ejercicio exhaustivo. Su mecanismo molecular debe investigarse con más detalle. Nivel de Evidencia III; Estudios Terapéuticos que Investigan los Resultados del Tratamiento.

RESUMO Objetivo: Estudar as alterações temporais dos fatores relacionados à autofagia no músculo esquelético de ratos após exercício exaustivo e trauma contuso. Métodos: Quarenta e dois ratos machos SD foram divididos em 7 grupos com 6 ratos em cada grupo: Grupo de controle silencioso (C), imediatamente após o exercício exaustivo (E0), 24 horas após o exercício exaustivo (E24), 48 horas após o exercício exaustivo (E48), imediatamente após o trauma contuso (D0), 24 horas após o trauma contuso (D24), 48 horas após o trauma contuso (D48). Todos os grupos de ratos foram mortos e rotulados, respectivamente, em diferentes momentos especificados acima, e o músculo gastrocnêmio direito foi retirado, dividido em duas partes, uma para mRNAs de Lamp-2, BNIP3 e NIX por PCR quantitativo fluorescente em tempo real, e a outra para a proteína p62 por imunotransferência. Resultados: (1) Em comparação com o grupo C, os níveis de mRNA de p62, Lamp-2 e NIX no grupo E48 aumentaram significativamente após o exercício exaustivo (P<0,05), sugerindo que a autofagia aumentou em 48 horas após o exercício exaustivo. (2) Em comparação com o grupo C, os níveis de mRNA de p62mRNA e Lamp-2 foram significativamente aumentados imediatamente após o trauma contuso (P<0,05) e diminuíram significativamente em 48 horas após o trauma contuso (P<0,05), sugerindo que a atividade de autofagia foi aumentada imediatamente após o trauma contuso e diminuiu em 48 horas após a lesão. Conclusão: Houve, via de regra, diferenças em cada fase de recuperação entre os modelos de trauma contuso e de exercício exaustivo, sendo que os fatores de autofagia basal e os fatores de autofagia mitocondrial também foram inconsistentes. Os fatores de autofagia basal p62 e Lamp-2 aumentaram significativamente 48 horas após o exercício excêntrico exaustivo e imediatamente após o trauma contuso. O fator de autofagia mitocondrial BNIP3 não aumentou após o exercício exaustivo e o trauma contuso, mas o NIX aumentou somente após o exercício exaustivo. Seu mecanismo molecular precisa ser investigado com mais detalhes. Nível de Evidência III; Estudos Terapêuticos que Investigam os Resultados do Tratamento.

Effects of photobiomodulation therapy on the functional performance of healthy individuals: a systematic review with meta-analysis.

The aim of this study is to assess the effect of photobiomodulation therapy (PBMT) on functional performance concerning strength, fatigue, and functional capacity in healthy individuals. This systematic review with meta-analysis involved searches on data platforms and active searches of randomized clinical trials, focusing on PBMT as the sole intervention. Primary outcomes assessed included strength, fatigue, and functional capacity. Three reviewers screened studies by title and abstract using Rayyan, and data were extracted using a specific form. Bias risk was assessed using RoB2, and confidence in the evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). The RevMan was used for meta-analysis. Sixteen studies were included, totaling 340 individuals (183 males and 157 women). Most articles presented a low risk of bias. Variability was observed in device types and application domains, including wavelengths (655-905 nm), power (10-200 nW), energy (0.6-30 J per point), and time (30-100 s per point). PBMT improved fatigue recovery (mean difference: 5.87; 95% CI 3.83, 7.91). There was no enhancement in strength (peak torque: mean difference 12.40; 95% CI -5.55, 30.55; one-repetition maximum test: mean difference 39.97, 95% CI -2.44, 82.38; isometric and isokinetic strength: mean difference 2.77, 95% CI -14.90, 20.44) nor improvement in short-term (mean difference 0.67, 95% CI -0.58, 1.91) and long-term (mean difference 18.44, 95% CI -55.65, 92.54) functional capacity. PBMT may aid in favoring fatigue recovery in healthy individuals; however, there's no evidence to support PBMT enhancing strength or improving functional capacity.

Comparação das respostas neuromusculares e bioquímicas entre pacientes com DPOC e indivíduos saudáveis / Comparison of neuromuscular and biochemical responses between patients with COPD and healthy subjects

Objetivo: Comparar as respostas neuromusculares e bioquímicas do dano e fadiga muscular do quadríceps femoral entre indivíduos com doença pulmonar obstrutiva crônica (DPOC) e saudáveis. Métodos: Estudo observacional, transversal e comparativo. A amostra foi composta por 18 indivíduos alocados em dois grupos distintos: Grupo DPOC (GD) e grupo saudáveis (GS), os quais foram avaliados por meio da espirometria, do desempenho neuromuscular do quadríceps, dos marcadores bioquímicos do dano e fadiga muscular, da fatigabilidade e da dor muscular. Resultados: Observou-se diferença estatisticamente significante na potência média entre o GD e GS (99,9 ± 21,0 vs 145,1 ± 51,5, respectivamente; p= 0,02) e uma tendência das médias de pico de torque (85,7 ± 24,4 vs 104,4 ± 31,0; p= 0,45) e trabalho total (1.305,5 ± 329,9 vs 1.671,5 ± 444,5; p= 0,06) serem menores no GD que no GS, respectivamente. A concentração da LDH imediatamente após o teste isocinético foi significantemente maior no GD que no GS (402,3 ± 33,6 vs 289,4 ± 33,6, respectivamente; p= 0,03). Conclusões: O presente estudo mostrou que pacientes com DPOC tem redução da capacidade de gerar força em um determinado período de tempo quando comparado a indivíduos saudáveis. A dosagem plasmática dos marcadores bioquímicos não permitiu confirmar que os pacientes com DPOC tem maior nível de dano muscular quando realizam exercício que os controles saudáveis.

Objective: To compare neuromuscular and biochemical responses of femoral quadriceps muscle damage and fatigue between chronic obstructive pulmonary disease (COPD) and healthy subjects. Methods: Observational, transversal and comparative study. The sample consisted of 18 subjects assigned to two distinct groups: COPD group (CG) and healthy group (HG), who were assessed by spirometry, quadriceps neuromuscular performance, biochemical markers of muscle damage and fatigue, fatigability and muscle pain. Results: Statistically significant difference was observed in mean power between CG and HG (99.9 ± 21.0 vs. 145.1 ± 51.5, respectively; p= 0.02) and a tendency of mean peak torque (85.7 ± 24.4 vs 104.4 ± 31.0, p= 0.45) and total work (1,305.5 ± 329.9 vs 1.671.5 ± 444.5; p= 0.06) were smaller in the CG than HG, respectively. The LDH concentration immediately after the isokinetic test was significantly higher in the CG than HG (402.3 ± 33.6 vs 289.4 ± 33.6, respectively; p= 0.03). Conclusions: The present study showed that patients with COPD have a reduced ability to generate force over a given period of time when compared to healthy subjects. The plasma levels of biochemical markers did not confirm that patients with COPD have a higher level of muscle damage when exercising than healthy controls.

Data-Driven Approach for Upper Limb Fatigue Estimation Based on Wearable Sensors.

Muscle fatigue is defined as a reduced ability to maintain maximal strength during voluntary contraction. It is associated with musculoskeletal disorders that affect workers performing repetitive activities, affecting their performance and well-being. Although electromyography remains the gold standard for measuring muscle fatigue, its limitations in long-term work motivate the use of wearable devices. This article proposes a computational model for estimating muscle fatigue using wearable and non-invasive devices, such as Optical Fiber Sensors (OFSs) and Inertial Measurement Units (IMUs) along the subjective Borg scale. Electromyography (EMG) sensors are used to observe their importance in estimating muscle fatigue and comparing performance in different sensor combinations. This study involves 30 subjects performing a repetitive lifting activity with their dominant arm until reaching muscle fatigue. Muscle activity, elbow angles, and angular and linear velocities, among others, are measured to extract multiple features. Different machine learning algorithms obtain a model that estimates three fatigue states (low, moderate and high). Results showed that between the machine learning classifiers, the LightGBM presented an accuracy of 96.2% in the classification task using all of the sensors with 33 features and 95.4% using only OFS and IMU sensors with 13 features. This demonstrates that elbow angles, wrist velocities, acceleration variations, and compensatory neck movements are essential for estimating muscle fatigue. In conclusion, the resulting model can be used to estimate fatigue during heavy lifting in work environments, having the potential to monitor and prevent muscle fatigue during long working shifts.

Within- and between-day reliability and repeatability of neuromuscular function assessment in females and males.

The study evaluated the reliability and repeatability of the force and surface electromyography activity (EMG) outcomes obtained through voluntary and electrically evoked contractions of knee extensors in females (n = 18) and males (n = 20) and compared these data between sexes. Maximal isometric voluntary contractions (iMVCs) of knee extensors associated with electrical stimulation of the femoral nerve were performed over 4 days (48-h interval), with the first day involving familiarization procedures, the second involving three trials (1-h interval), and the third and fourth involving just one trial. The intraclass correlation coefficient (ICC), coefficient of variation (CV), and repeatability of outcomes from within- and between-day trials were determined for each sex. Females presented lower maximal voluntary force during iMVC (iMVCForce) and associated vastus lateralis EMG activity (root mean square, RMSVL), force evoked by potentiated doublet high-frequency (Db100Force) and single stimuli (Qtw), and M-wave amplitude than males (P ≤ 0.01, partial eta squared ≥0.94). Voluntary activation (VA) and RMSVL/M-wave amplitude did not differ between sexes. iMVCForce, VA, Db100Force, Qtw, and M-wave amplitude were the most reliable outcomes in within-day trials, with similar results between sexes (ICC > 0.62; CV < 6.4%; repeatability: 12.2%-22.6%). When investigating between-day trials, the iMVCForce, VA, Db100Force, and Qtw were the most reliable (ICC > 0.66; CV < 7.5%; repeatability: 13.2%-33.45%) with similar results between sexes. In conclusion, females presented lower iMVCForce and evoked response than males. Although reliability and repeatability statistics vary between trials, data (e.g., from EMG or force signal), and sexes, most of the outcomes obtained through this technique are reliable in females and males.NEW & NOTEWORTHY Although reliability and repeatability of knee extensors vary according to the type of neuromuscular function outcome (e.g., from force or EMG responses), the trial intervals (i.e., hours or days), and the sex of the participant, most force and EMG outcomes obtained through these neuromuscular assessment protocols present ICC > 0.75, very good CV (<10%), and repeatability <25% in within- and between-day trials in both sexes.

Influence of Breathing Modes and Facial Growth Patterns on Electromyographic Fatigue of Masticatory Muscles in Children.

Introduction Changes in breathing patterns affect the harmonious development of the structures of the craniofacial system, leading to changes in posture, occlusion, and facial growth patterns. However, little is known about how these changes influence the muscle contraction patterns, either at rest or while functioning, and either in a normal or unbalanced condition. Objective To study the masseter and anterior temporal muscles fatigue during mastication in nasal- and mouth-breathing children, also considering their facial growth patterns. Methods: A total of 70 children aged 6 to 12 years old who met the study criteria were assessed. Speech-language-hearing, otorhinolaryngologic, and cephalometric assessments were performed to divide them into groups. In the electromyographic assessment, the children were asked to chew gum following a metronome until they felt fatigued. The median frequency of the muscles was analyzed at 15, 30, 45, and 60 seconds of mastication. The reported time of fatigue perception was recorded. The data were analyzed with analysis of variance (ANOVA) and the Kruskal-Wallis and the Mann-Whitney U tests. Results There were no median frequency decrease patterns nor differences in the myoelectric manifestations and reported time of fatigue between the groups. Conclusion The masticatory muscles did not reveal fatigue in the electromyographic analysis; however, the fatigue time was reported, despite the absence of physiological fatigue. The breathing mode, the facial growth pattern, and the association between them did not interfere with the behavior of the median frequency of the electromyographic signal and the fatigue time perception.

Acute outcomes of acupuncture and dry needling over peripheral acute fatigue in untrained healthy volunteers: A randomized controlled clinical trial.

Peripheral acute fatigue (PAF) is defined as when the skeletal muscle is incapable of generating power. We aimed to investigate the acute effects of traditional Chinese acupuncture (TCA) and dry needling (DN) over PAF induced on the biceps brachii of untrained healthy volunteers. We conducted a randomized, single-blind controlled clinical trial. All volunteers (n = 45) underwent fatigue induction protocols repeated before and after treatment with TCA (TCA group; TCAg; n = 15), DN (DN group; DNg; n = 15), and rest (control group; Cg; n = 15). Assessments of PAF, skin temperature, and exercise time occur before and after each event: 1st fatigue induction (FI), treatment, and 2nd FI. We used repeated measures ANOVA adjusted with Bonferroni post hoc test to determine any change in tested variables (PAF-VAS, PAF-EMG, and skin temperature) at different time points compared to the baseline. Paired Samples t-test was used for the variable exercise times. All statistical tests considered' the significance level at p ≤ 0,05. There was no difference between groups in acute fatigue recovery (p = 0.19). All intragroup analyses were significant (p ≤ 0.05) and all volunteers show a reduction in fatigue perception after treatment (p ≤ 0,05), however, exercise time did not ameliorate after TCA or DN (p > 0.77). A single session of TCA and, DN can equally reduce fatigue, temperature, and exercise time over PAF induced on biceps brachii of untrained healthy volunteers.

Assessing Muscle Fatigue in Multiple Sclerosis using the Sample Entropy of Electromyographic Signals: A Proof of Concept.

Background: Multiple sclerosis (MS) is a progressive and neurodegenerative disease of the central nervous system. Its symptoms vary greatly, which makes its diagnosis complex, expensive, and time-consuming. One of its most prevalent symptoms is muscle fatigue. It occurs in about 92% of patients with MS (PwMS) and is defined as a decrease in maximal strength or energy production in response to contractile activity. This article aims to compare the behavior of a healthy control (HC) with that of a patient with MS before and after muscle fatigue. Methods: For this purpose, a static baropodometric test and a dynamic electromyographic analysis are performed to calculate the area of the stabilometric ellipse, the remitting MS (RMS) value, and the sample entropy (SampEn) of the signals, as a proof of concept to explore the feasibility of this test in the muscle fatigue quantitative analysis; in addition, the statistical analysis was realized to verify the results. Results: According to the results, the ellipse area increased in the presence of muscle fatigue, indicating a decrease in postural stability. Likewise, the RMS value increased in the MS patient and decreased in the HC subject and the opposite behavior in the SampEn was observed in the presence of muscle fatigue. Conclusion: Thus, this study demonstrates that SampEn is a viable parameter to estimate muscle fatigue in PwMS and other neuromuscular diseases.

Effects of lower-limb extensors' neuromuscular fatigue on the regularity of running movements: a crossover study.

Neuromuscular fatigue (NMF) reduces the musculoskeletal system's ability to produce force during activities like running. Analysis of motor behaviour's regularity may identify motor system deficits caused by fatigue. The present study investigated whether the NMF of lower limb extensors alters the regularity of running movement and whether this possible effect remains over time. Crossover study with two randomised conditions: NMF and control. Twelve healthy young males participated in this study. Hip, knee, and ankle angles (sagittal plane) and centre of mass (CoM) linear accelerations were assessed during treadmill running at self-selected speed in four assessment conditions: Baseline (pre-NMF), and after NMF (NMF condition) or after rest (control), at the 1st (Time_1), 10th (Time_10) and 20th (Time_20) minutes. Kinematics regularity was measured as Sample Entropy. Repeated measures ANOVAs were used (α = 0.05). NMF reduced regularity of lower limb joints during running, and these effects remained up to 20 minutes. No changes were observed in the CoM accelerations' regularity. The regularity reductions may be an adaptive solution for the motor system to maintain the task performance. The measure of regularity of the lower limb joints' motion is sensitive to NMF and can identify states with deficits in muscles' force production capacity in running.

Can infrared thermography serve as an alternative to assess cumulative fatigue in women?

Muscle fatigue can limit performance both in sports and daily life activities. Consecutive days of exercise without a proper recovery time may elicit cumulative fatigue. Although it has been speculated that skin temperature could serve as an indirect indicator of exercise-induced adaptations, it is unclear if skin temperature measured by infrared thermography (IRT) could be an outcome related to the effects of cumulative fatigue. In this study, we recruited 21 untrained women and induced cumulative fatigue in biceps brachii over two consecutive days of exercise. We measured delayed onset muscle soreness (DOMS, using a numeric rate scale), maximal strength (using a dynamometer), and skin temperature (using IRT) in exercise and non-exercise muscles. Cumulative fatigue reduced muscle strength and increased DOMS. Skin temperature in the arm submitted to cumulative fatigue was higher for minimum and mean temperature, being asymmetrical in relation to the control arm. We also observed that the variations in the minimum and mean temperatures correlated with the strength losses. In summary, skin temperature measured by IRT seems promising to help detect cumulative fatigue in untrained women, being useful to explain strength losses. Future studies should provide additional evidence for the potential applications not only in trained participants but also in patients that may not be able to report outcomes of scales or precisely report DOMS.

Blood Flow Restriction Attenuates Muscle Damage in Resistance Exercise Performed Until Concentric Muscle Failure.

The present study aimed to evaluate whether blood flow restriction (BFR) can prevent exercise-induced muscle damage in resistance exercise (RE) performed until concentric muscle failure (CMF). Twenty healthy volunteers (25 ± 4 years, 80.4 ± 11.8 kg, 175 ± 8 cm) performed three sets of unilateral biceps curl exercise (40% of 1RM) with (RE + BFR) and without (RE) BFR until CMF. A third condition was to perform the same number of repetitions as RE + BFR without using BFR (matched). Performing fewer repetitions, RE + BFR caused muscle fatigue post-exercise as high as that caused by RE. In addition, the range of motion, upper arm circumference, pressure pain threshold, and maximal voluntary contraction were immediately affected by our exercise protocol with BFR, returning rapidly to basal values within 24 h, while in RE, muscle damage markers remained elevated until 48 h post-exercise. The same results were observed concerning serum creatine kinase and lactate dehydrogenase activity. Thus, BFR + RE performed until CMF attenuated muscle damage following similar metabolic stress to RE alone performed until CMF, with less work volume.

Effect of Exergaming on Quality of Life, Fatigue, and Strength and Endurance Muscle in Cancer Patients: A Randomized Crossover Trial.

Objective: To analyze the influence of exergaming (EXE) quality of life, cancer-related fatigue (CRF), electromyography, and strength and endurance muscle in a randomized crossover trial. Methods: We conducted a single-blinded, randomized, and crossover trial, which included 38 cancer volunteers undergoing chemotherapy (Age = 60.07 ± 12.10 years; body mass index = 26.79 ± 5.33 kg/m2). All volunteers were randomized into two intervention moments: EXE and without intervention (WI) and after 1-month washout period of crossing of the evaluated moments. The intervention was performed on an EXE protocol using Xbox 360 Kinect®, with the game "Your Shape Fitness Evolved 2012" two to three times per week for 20 sessions. All volunteers were assessed the CRF and quality-of-life levels through the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) questionnaire, the median frequency (MDF) by surface electromyography, maximal voluntary isometric contraction (MVIC), and the muscle endurance time at 80% MVIC of the dorsiflexors and plantar flexors using dynamometer. Results: In the comparison between EXE and WI moments, were observed increase in the scores for quality of life (P < 0.001), subscale fatigue (P < 0.001), in the MDF values of right lateral gastrocnemius muscles: P = 0.017, muscle endurance time (left dorsiflexion [LDF]: P < 0.001; right dorsiflexion [RDF]: P < 0.001; left plantar flexion [LPF]: P < 0.001; RPF: P = 0.039), and muscle strength (LDF: P < 0.001; RDF: P < 0.001; LPF: P = 0.002). Conclusion: The crossover study, the EXE protocol promoted improvement in cancer-related fatigue (CRF) and quality of life, increased MVIC, endurance time, and MDF values of the dorsiflexor and plantar flexor muscles of cancer volunteers undergoing chemotherapy.

Episodic Binge-like Ethanol Reduces Skeletal Muscle Strength Associated with Atrophy, Fibrosis, and Inflammation in Young Rats.

Binge Drinking (BD) corresponds to episodes of ingestion of large amounts of ethanol in a short time, typically ≤2 h. BD occurs across all populations, but young and sports-related people are especially vulnerable. However, the short- and long-term effects of episodic BD on skeletal muscle function have been poorly explored. Young rats were randomized into two groups: control and episodic Binge-Like ethanol protocol (BEP) (ethanol 3 g/kg IP, 4 episodes of 2-days ON-2-days OFF paradigm). Muscle function was evaluated two weeks after the last BEP episode. We found that rats exposed to BEP presented decreased muscle strength and increased fatigability, compared with control animals. Furthermore, we observed that skeletal muscle from rats exposed to BEP presented muscle atrophy, evidenced by reduced fiber size and increased expression of atrophic genes. We also observed that BEP induced fibrotic and inflammation markers, accompanied by mislocalization of nNOSµ and high levels of protein nitration. Our findings suggest that episodic binge-like ethanol exposure alters contractile capacity and increases fatigue by mechanisms involving atrophy, fibrosis, and inflammation, which remain for at least two weeks after ethanol clearance. These pathological features are common to several neuromuscular diseases and might affect muscle performance and health in the long term.

Energy metabolism and muscle activation heterogeneity explain V ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component and muscle fatigue of cycling at different intensities.

NEW FINDINGS: What is the central question of this study? What are the physiological mechanisms underlying muscle fatigue and the increase in the O2 cost per unit of work during high-intensity exercise? What is the main finding and its importance? Muscle fatigue happens before, and does not explain, the V ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component ( V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ ), but they share the same origin. Muscle activation heterogeneity is associated with muscle fatigue and V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ . Knowing this may improve training prescriptions for healthy people leading to improved public health outcomes. ABSTRACT: This study aimed to explain the V ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component ( V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ ) and muscle fatigue during cycling at different intensities. The muscle fatigue of 16 participants was determined through maximal isokinetic effort lasting 3 s during constant work rate bouts of moderate (MOD), heavy (HVY) and very heavy intensity (VHI) exercise. Breath-by-breath V ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ , near-infrared spectroscopy signals and EMG activity were analysed (thigh muscles). V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ was higher during VHI exercise (∼70% vs. ∼28% of V ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ reserve in HVY). The deoxygenated haemoglobin final value during VHI exercise was higher than during HVY and MOD exercise (∼90% of HHb physiological normalization, vs. ∼82% HVY and ∼45% MOD). The muscle fatigue was greater after VHI exercise (∼22% vs. HVY ∼5%). There was no muscle fatigue after MOD exercise. The greatest magnitude of muscle fatigue occurred within 2 min (VHI ∼17%; HVY ∼9%), after which it stabilized. No significant relationship between V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ and muscle force production was observed. The τ of muscle V ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ was significantly related (R2  = 0.47) with torque decrease for VHI. Type I and II muscle fibre recruitment mainly in the rectus femoris moderately explained the muscle fatigue (R2  = 0.30 and 0.31, respectively) and the V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ (R2  = 0.39 and 0.27, respectively). The V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ is also partially explained by blood lactate accumulation (R2  = 0.42). In conclusion muscle fatigue and O2 cost seem to share the same physiological cause linked with a decrease in the muscle V ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ and a change in lactate accumulation. Muscle fatigue and V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ are associated with muscle activation heterogeneity and metabolism of different muscles activated during cycling.

Effects of exercise training combined with acupuncture and moxibustion on fatigue / Efeitos do treinamento de exercício combinado à acupuntura e moxabustão sobre a fadiga / Efectos del entrenamiento físico combinado con acupuntura y moxibustión sobre la fatiga

ABSTRACT Introduction: Muscle fatigue bothers athletes, affecting training level and competitive performance, it also has a great impact on the physical health of athletes, predisposing them to accidents and an early termination of their career. Relieving sports fatigue is the focus of research in the field of sports health nowadays. Objective: Study the effect of acupuncture and moxibustion rehabilitation combined with physical training on sports fatigue. Methods: A controlled experiment was used. The experimental group used acupuncture and moxibustion combined with exercise training, while the control group used acupuncture and moxibustion. The same group of doctors performed the acupuncture and moxibustion treatment according to the actual situation of the patients, and they tested the changes in VAS pain score and PRI pain score. Results: The VAS pain score in the experimental group was 7.88 points before the procedure and 2.96 points after the sixth week of the procedure. The control group score was 7.67 before the start and 5.03 after training. The total PRI pain score in the experimental group was 6.52 points before training and 2.05 points in the sixth week of training. The control group scored 6.66 before the procedure and 3.89 in the sixth week. Conclusion: The combination of training and exercises can achieve a better rehabilitation effect compared to the isolated treatment of acupuncture and moxibustion. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

RESUMO Introdução: A fadiga muscular incomoda os atletas, afetando o nível de treinamento e o desempenho competitivo, também tem um grande impacto sobre a saúde física dos atletas, predispondo a acidentes e a um término precoce da carreira. Aliviar a fadiga esportiva é o foco da pesquisa no campo da saúde esportiva nos dias de hoje. Objetivo: Estudar o efeito de reabilitação pela acupuntura e moxabustão combinada com o treinamento físico sobre a fadiga esportiva. Métodos: Foi utilizado um experimento controlado. O grupo experimental usou acupuntura e moxabustão combinadas com treinamento com exercícios, enquanto o grupo de controle usou acupuntura e moxabustão. O mesmo grupo de médicos realizou o tratamento de acupuntura e moxabustão de acordo com a situação real dos pacientes, e testaram as alterações do escore de dor VAS e do escore de dor PRI. Resultados: A pontuação de dor VAS no grupo experimental foi de 7,88 pontos antes do procedimento e 2,96 pontos após a sexta semana de procedimento. A pontuação do grupo de controle foi 7,67 antes do início e 5,03 após o treinamento. A pontuação total de dor PRI no grupo experimental foi 6,52 pontos antes do treinamento e 2,05 pontos na sexta semana de treinamento. A pontuação do grupo de controle foi de 6,66 antes do procedimento e 3,89 na sexta semana. Conclusão: A combinação do treinamento com exercícios pode alcançar um melhor efeito de reabilitação em comparação com o tratamento isolado de acupuntura e moxabustão. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

RESUMEN Introducción: La fatiga muscular molesta a los deportistas, ya que afecta al nivel de entrenamiento y al rendimiento competitivo, además de tener un gran impacto en la salud física de los atletas, predisponiendo a accidentes y al cese prematuro de la carrera. En la actualidad, el alivio de la fatiga deportiva es objeto de investigación en el campo de la salud deportiva. Objetivo: Estudiar el efecto de la rehabilitación mediante acupuntura y moxibustión combinada con entrenamiento físico sobre la fatiga deportiva. Métodos: Se utilizó un experimento controlado. El grupo experimental utilizó acupuntura y moxibustión combinadas con entrenamiento físico, mientras que el grupo de control utilizó acupuntura y moxibustión. El mismo grupo de médicos realizó el tratamiento de acupuntura y moxibustión de acuerdo con la situación real de los pacientes, y comprobó los cambios en la puntuación del dolor según VAS y la puntuación del dolor según PRI. Resultados: La puntuación VAS del dolor en el grupo experimental fue de 7,88 puntos antes del procedimiento y de 2,96 puntos después de la sexta semana del procedimiento. La puntuación del grupo de control fue de 7,67 antes del inicio y de 5,03 después del entrenamiento. La puntuación total del dolor PRI en el grupo experimental fue de 6,52 puntos antes del entrenamiento y de 2,05 puntos en la sexta semana de entrenamiento. La puntuación del grupo de control era de 6,66 antes del procedimiento y de 3,89 a la sexta semana. Conclusión: La combinación de entrenamiento con ejercicios puede lograr un mejor efecto rehabilitador en comparación con el tratamiento aislado de acupuntura y moxibustión. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.