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1.
Medicine (Baltimore) ; 100(10): e24960, 2021 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-33725859

RESUMO

INTRODUCTION: (Neo-)adjuvant chemotherapy for breast cancer has a deleterious impact on muscle tissue resulting in reduced cardiorespiratory fitness, skeletal muscle mass and function. Physical exercise during treatment may counteract some of these negative effects. However, the effects of resistance training (RT) alone have never been explored. The present study aims to investigate if heavy-load RT during (neo-)adjuvant chemotherapy counteracts deleterious effects on skeletal muscle in women diagnosed with breast cancer. We hypothesize that (neo-)adjuvant treatment with chemotherapy will reduce muscle fiber size, impair mitochondrial function, and increase indicators of cellular stress and that RT during treatment will counteract these negative effects. We also hypothesize that RT during (neo-)adjuvant chemotherapy will increase muscle and blood levels of potential antitumor myokines and reduce treatment-related side effects on muscle strength and cardiorespiratory fitness. METHODS: Fifty women recently diagnosed with breast cancer scheduled to start (neo-)adjuvant chemotherapy will be randomized to either randomized to either intervention group or to control group.The intervention group will perform supervised heavy-load RT twice a week over the course of chemotherapy (approximately 16-weeks) whereas the control group will be encouraged to continue with their usual activities. Muscle biopsies from m. vastus lateralis will be collected before the first cycle of chemotherapy (T0), after chemotherapy (T1), and 6 months later (T2) for assessment of muscle cellular outcomes. The primary outcome for this study is muscle fiber size. Secondary outcomes are: regulators of muscle fiber size and function, indicators of cellular stress and mitochondrial function, myokines with potential antitumor effects, muscle strength, and cardiorespiratory fitness. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the Regional Ethical Review Board in Uppsala, Sweden (Dnr:2016/230/2). Results will be disseminated through presentations at scientific meetings, publications in peer-reviewed journals, social media, and patient organizations. TRIAL REGISTRATION NUMBER: NCT04586517.


Assuntos
Antineoplásicos/efeitos adversos , Neoplasias da Mama/terapia , Terapia por Exercício/métodos , Fadiga Muscular/fisiologia , Treinamento de Resistência , Adulto , Biópsia , Aptidão Cardiorrespiratória/fisiologia , Quimioterapia Adjuvante/efeitos adversos , Feminino , Seguimentos , Humanos , Mastectomia , Pessoa de Meia-Idade , Fadiga Muscular/efeitos dos fármacos , Força Muscular/efeitos dos fármacos , Força Muscular/fisiologia , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/patologia , Músculo Esquelético/fisiologia , Terapia Neoadjuvante/efeitos adversos , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Resultado do Tratamento
2.
Apunts, Med. esport (Internet) ; 55(208): 137-142, oct.-dic. 2020. tab, ilus
Artigo em Inglês | IBECS | ID: ibc-197957

RESUMO

INTRODUCTION: Two of the main modifiable risk factors for suffering an injury in the anterior cruciate ligament are known to be the Hamstring-to-Quadriceps (H/Q) Ratio and neuromuscular fatigue. The main purpose of this research was to study the effect of neuromuscular fatigue on the H/Q Ratio and the maximum isometric strength of the quadriceps and hamstrings in teenage female basketball and handball players. MATERIAL AND METHODS: This is an experimental, pre-post intervention study with a sample of 19 female basketball players and 11 female handball players (17.02±1.19 yo, 177.8±7.2cm and 68.6±9.3kg). To assess muscle strength, a maximum isometric strength test was performed in a 90° hip and 60° knee position. The H/Q Ratio was then calculated. The 30-15 Intermittent Fatigue Test (30-15 IFT) was used to induce fatigue, measured using the Rating of Perceived Exertion (RPE) scale. A descriptive analysis and a Student's t-test were performed to study the differences in the H/Q Ratio, muscle strength and pre-post intervention fatigue. RESULTS: Although the H/Q Ratio decreased after the 30-15 IFT, the differences were not statistically significant. Regarding strength values, the right and left quadriceps presented strength reductions of 4.52% and 5.55%, respectively. The reduction in strength was statistically significant (p≤0.05), especially in the right hamstring (7.3%) and in the left hamstring (7.5%). The study conclusions suggest that leg muscular strength decreases after a fatigue test and that there is a tendency for the H/Q Ratio to decrease also


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Assuntos
Humanos , Feminino , Adolescente , Adulto Jovem , Músculos Isquiossurais/fisiologia , Fadiga Muscular/fisiologia , Força Muscular , Músculo Quadríceps/fisiologia , Basquetebol/fisiologia , Exercício Físico/fisiologia , Futebol/fisiologia , Estudos Prospectivos , Antropometria/métodos , Atletas/estatística & dados numéricos , Fadiga/fisiopatologia , Mãos/fisiologia , Músculo Esquelético/fisiologia
3.
PLoS One ; 15(12): e0244321, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33338075

RESUMO

BACKGROUND: Women involved in repetitive, fatiguing, jobs develop more neck and/or shoulder musculoskeletal disorders than men. Sex differences in the pain response to exercise could contribute to the higher prevalence of neck/shoulder musculoskeletal disorders in women. The objective of this study was to assess sex differences in pain sensitivity following a fatiguing upper limb task. Relationships between measures of fatigue and of the sensitivity to nociceptive and to non-nociceptive stimulations were also explored. METHODS: Thirty healthy adults (15 women) performed a fatiguing repetitive pointing task with their dominant arm. Upper limb electromyography was recorded from the dominant upper trapezius, anterior deltoid and bicep brachii and from the contralateral tibialis anterior. Before and immediately after the repetitive pointing task, pressure pain and light touch sensitivity thresholds were measured over the same muscles. RESULTS: Electromyographic signs of fatigue were observed only in the anterior deltoid and biceps brachii muscles. Pressure pain thresholds over both muscles increased slightly (effect size ≤ 0.34), but no changes occurred over the upper trapezius and the tibialis anterior. Light touch thresholds increased moderately to importantly after the repetitive pointing task over all four muscles (effect sizes = 0.58 to 0.87). No sex differences were observed in any sensory variable. Moreover, no or weak correlations (r = -0.27 to 0.39) were observed between electromyographical signs of fatigue, light touch threshold and pressure pain threshold variables. CONCLUSIONS: We observed sex-independent effects of a repetitive upper limb task on the sensitivity to painful and to nonpainful stimuli. Moreover, the hypoalgesia induced by the repetitive pointing task was weak and localized, and did not directly correlate with the induced muscle fatigue. Results suggest that fatigue-related changes in the sensitivity to noxious and innocuous stimuli could not explain women's greater prevalence of neck/shoulder musculoskeletal disorders.


Assuntos
Transtornos Traumáticos Cumulativos/fisiopatologia , Percepção da Dor/fisiologia , Limiar da Dor/fisiologia , Adulto , Braço/fisiologia , Transtornos Traumáticos Cumulativos/metabolismo , Eletromiografia/métodos , Fadiga/fisiopatologia , Feminino , Humanos , Masculino , Movimento/fisiologia , Contração Muscular/fisiologia , Fadiga Muscular/fisiologia , Pescoço/fisiologia , Caracteres Sexuais , Fatores Sexuais , Ombro/fisiologia , Tato/fisiologia , Extremidade Superior/fisiologia
4.
J Sports Med Phys Fitness ; 60(8): 1057-1064, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32955831

RESUMO

BACKGROUND: Rock climbers are characterized by enhanced forearm fatigue resistance. This study compared the forearm isometric force of rock climbers (RC), strength-matched power lifters (PL) and aerobically trained (AT) athletes to determine the contribution of muscle oxygen desaturation during ischemia. METHODS: Aerobically trained athletes (N.=6, 23±1 years, 77±1 kg), power lifters (N.=7, 24±1 years, 80±3 kg) and rock climbers (N.=8, 25±2 years, 74±2 kg) took part in a controlled forearm ischemic occlusion (5 min) assessment using near infrared spectroscopy. In addition, three fatigue protocols were completed: protocol 1, sustained maximal voluntary contraction (MVC) until exhaustion; protocol 2, sustained 40% MVC for 3 mins duration; protocol 3, an intermittent 40% MVC (5-s contraction, 5-s recovery) for a duration of 3 mins. Forearm contractile fatigue was quantified as the reduction in MVC. RESULTS: MVC was equivalent between groups (P>0.05). Sustained MVC force (time to decline 50% MVC) was longer in the RC versus AT (AT: 35±5, PL: 46±6, RC: 54±4 s, P<0.05) and both AT and PL for sustained 40% MVC (AT: 56±9, RT: 62±8, RC: 87±7 s, P<0.05). Reduction in MVC was less in RC post intermittent 40% contractions (P<0.05). Oxygen desaturation half-time was longer in the RC versus AT (AT: 65±9, RT: 86±7, RC: 99±7 s, P<0.05) and this was associated with time to 50% MVC (P<0.05, r2=0.53) and time to 40% MVC task failure (P<0.05, r2=0.32). CONCLUSIONS: Rock climbers' enhanced isometric fatigue-resistance and ability to maintain MVC was associated with a lower oxygen consumption of the forearm flexors during the ischemic state. This suggests a training adaptation involving intracellular oxygen consumption.


Assuntos
Antebraço/fisiologia , Montanhismo/fisiologia , Fadiga Muscular/fisiologia , Músculo Esquelético/fisiologia , Adaptação Fisiológica , Adulto , Dedos/fisiologia , Antebraço/irrigação sanguínea , Antebraço/diagnóstico por imagem , Humanos , Contração Isométrica/fisiologia , Masculino , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/diagnóstico por imagem , Consumo de Oxigênio , Condicionamento Físico Humano/fisiologia , Espectroscopia de Luz Próxima ao Infravermelho , Levantamento de Peso/fisiologia , Adulto Jovem
5.
PLoS One ; 15(9): e0239505, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32991582

RESUMO

Evidence suggests that the application of Kinesio Tape (KT) on patients with chronic non-specific low back pain (CNLBP) is inconclusive. Dynamic tape (DT) is a relatively new treatment technique, which is increasingly being used as an adjunctive method to treat musculoskeletal problems. To our knowledge, no study has investigated the application of DT in individuals with CNLBP. To compare the immediate and short-term effects of DT versus KT and no tape among patients with CNLBP on pain, endurance, disability, mobility, and kinesiophobia. Forty-five patients with CNLBP were randomly assigned to 1 of 3 groups. Outcomes were measured at baseline, immediately, and on the third day post-application of tapes. The primary outcomes of pain, endurance, and disability were measured through the visual analog scale (VAS), Biering-Sorensen test, and Oswestry disability index (ODI), respectively. Secondary outcome measures of mobility and kinesiophobia were measured using the modified-modified Schober test and the Tampa Scale of Kinesiophobia, respectively. No significant immediate and short-term differences were found between DT and KT in pain, disability, mobility, and kinesiophobia. Improved back extensor endurance was observed for the DT group than KT (p = 0.023) and control group (p = 0.006). The application of DT may result in improvements only in back extensor endurance among individuals with CNLBP. This finding suggests that DT controls the processes that lead to back muscle fatigue.


Assuntos
Fita Atlética , Dor Lombar/fisiopatologia , Dor Lombar/terapia , Medição da Dor/métodos , Resistência Física/fisiologia , Adulto , Músculos do Dorso/fisiopatologia , Avaliação da Deficiência , Pessoas com Deficiência , Humanos , Masculino , Fadiga Muscular/fisiologia , Amplitude de Movimento Articular/fisiologia
6.
Rev. int. med. cienc. act. fis. deporte ; 20(79): 551-566, sept. 2020. ilus, tab
Artigo em Espanhol | IBECS | ID: ibc-197054

RESUMO

Las transiciones en triatlón afectan al rendimiento y riesgo de lesión. El objetivo fue determinar la fatiga neuromuscular inducida por 40 km de ciclismo y la eficacia del entrenamiento pliométrico en la fatiga y rendimiento de la carrera a pie. Participaron doce triatletas, 5 realizaron un entrenamiento pliométrico y 7 continuaron su entrenamiento habitual. Se realizaron tests de salto antes y después de 40 km de ciclismo para determinar la fatiga y se registró el ritmo de 5 km de carrera. Se observaron diferencias significativas en la altura de salto (p < 0,05) indicando que 40 km de ciclismo inducen fatiga en la extremidad inferior. Tras el entrenamiento pliométrico se observaron mejoras significativas en el test Squat Jump posterior al ciclismo (p = 0,038) y en el ritmo del primer kilómetro (p = 0,015). El entrenamiento pliométrico parece ser más eficaz que el entrenamiento habitual para mejorar la fatiga neuromuscular y el ritmo del primer kilómetro


The transition between the different phases of triathlon affects both athletic performance and risk of injury. The aim was to determine the neuromuscular fatigue induced by 40 km cycling and the plyometric training efficacy in order to improve such fatigue and running performance. Twelve triathletes participated, 5 of them did specific plyometric training versus 7 who continued with their usual training. Different jump tests were carried out before and after 40 km cycling in order to determine the fatigue, the 5km-running pace was also recorded. Significant differences were observed in the jump height (p < 0,05) post-cycling, showing that 40 km cycling induces leg neuromuscular fatigue. After the plyometric training, significant improves were observed in the Squat Jump Test post-cycling (p = 0,038) and in the first kilometre running pace (p = 0,015). The plyometric training seems to be more effective than usual training to improve cycling induced neuromuscular fatigue and the first kilometre running pace


Assuntos
Humanos , Masculino , Feminino , Adulto Jovem , Adulto , Fadiga Muscular/fisiologia , Esportes/fisiologia , Projetos Piloto , Desempenho Atlético , Ciclismo/fisiologia , Corrida/fisiologia , Atletas/estatística & dados numéricos , Estudos Longitudinais
7.
Exerc Sport Sci Rev ; 48(4): 209-216, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32658041

RESUMO

This review discusses evidence suggesting that group III/IV muscle afferents affect locomotor performance by influencing neuromuscular fatigue. These neurons regulate the hemodynamic and ventilatory response to exercise and, thus, assure appropriate locomotor muscle O2 delivery, which optimizes peripheral fatigue development and facilitates endurance performance. In terms of central fatigue, group III/IV muscle afferents inhibit motoneuronal output and thereby limit exercise performance.


Assuntos
Exercício Físico/fisiologia , Neurônios Motores/fisiologia , Músculo Esquelético/inervação , Neurônios Aferentes/fisiologia , Resistência Física/fisiologia , Fadiga/fisiopatologia , Hemodinâmica , Humanos , Fadiga Muscular/fisiologia , Músculo Esquelético/metabolismo , Consumo de Oxigênio , Respiração
8.
Exerc Sport Sci Rev ; 48(4): 163-169, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32658042

RESUMO

The prolonged impairment in muscle strength, power, and fatigue resistance after eccentric exercise has been ascribed to a plethora of mechanisms, including delayed muscle refueling and microvascular and mitochondrial dysfunction. This review explores the hypothesis that local heat therapy hastens functional recovery after strenuous eccentric exercise by facilitating glycogen resynthesis, reversing vascular derangements, augmenting mitochondrial function, and stimulating muscle protein synthesis.


Assuntos
Exercício Físico/fisiologia , Temperatura Alta/uso terapêutico , Músculo Esquelético/lesões , Mialgia/terapia , Adaptação Fisiológica , Animais , Glicogênio/biossíntese , Humanos , Microcirculação , Mitocôndrias Musculares/fisiologia , Fadiga Muscular/fisiologia , Proteínas Musculares/biossíntese , Força Muscular/fisiologia , Músculo Esquelético/irrigação sanguínea , Mialgia/etiologia
9.
Am J Physiol Regul Integr Comp Physiol ; 319(3): R296-R314, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32697655

RESUMO

The present study aimed to simultaneously examine the age-related, muscle-specific, sex-specific, and contractile mode-specific changes in isolated mouse skeletal muscle function and morphology across multiple ages. Measurements of mammalian muscle morphology, isometric force and stress (force/cross-sectional area), absolute and normalized (power/muscle mass) work-loop power across a range of contractile velocities, fatigue resistance, and myosin heavy chain (MHC) isoform concentration were measured in 232 isolated mouse (CD-1) soleus, extensor digitorum longus (EDL), and diaphragm from male and female animals aged 3, 10, 30, 52, and 78 wk. Aging resulted in increased body mass and increased soleus and EDL muscle mass, with atrophy only present for female EDL by 78 wk despite no change in MHC isoform concentration. Absolute force and power output increased up to 52 wk and to a higher level for males. A 23-36% loss of isometric stress exceeded the 14-27% loss of power normalized to muscle mass between 10 wk and 52 wk, although the loss of normalized power between 52 and 78 wk continued without further changes in stress (P > 0.23). Males had lower power normalized to muscle mass than females by 78 wk, with the greatest decline observed for male soleus. Aging did not cause a shift toward slower contractile characteristics, with reduced fatigue resistance observed in male EDL and female diaphragm. Our findings show that the loss of muscle quality precedes the loss of absolute performance as CD-1 mice age, with the greatest effect seen in male soleus, and in most instances without muscle atrophy or an alteration in MHC isoforms.


Assuntos
Envelhecimento/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Atrofia Muscular/fisiopatologia , Animais , Diafragma/fisiopatologia , Camundongos , Fadiga Muscular/fisiologia , Doenças Musculares/fisiopatologia
10.
J Sports Sci ; 38(18): 2063-2070, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32508221

RESUMO

The effects of acute ingestion of nitrate on short-duration repeated sprint performance (RSP) are unclear. This study investigated the effect of acute ingestion of beetroot juice on a test of RSP in team sport athletes. Sixteen male team sport athletes undertook four trials using a 40 m maximum shuttle run test (MST), which incorporates 10 × 40 m shuttle sprints with 30 s between the start of each sprint. Two familiarisation trials, followed by nitrate-rich beetroot juice (BR; ~6 mmol nitrate) and nitrate-depleted beetroot juice (PLA; ~0.0034 mmol nitrate) trials were completed in a randomised, double-blind manner. Ingestion of beetroot juice 3 h prior to exercise elevated plasma nitrate concentrations ~6-fold in BR (BR, 413 ± 56 µM; PLA, 69 ± 30 µM; P < 0.001). RSP, assessed by sprint performance decrement (Sdec; %), did not differ (P = 0.337) between BR (5.31 ± 2.49%) and PLA (5.71 ± 2.61%). There was no difference between trials for total sprint time (P = 0.806), fastest sprint (P = 0.341), slowest sprint (P = 0.787), or post-exercise blood lactate concentration (BR, 11.8 ± 2.5 mM; PLA, 12.2 ± 2.3 mM; P = 0.109). Therefore, acute ingestion of beetroot juice did not improve a test of short-duration RSP in team sport athletes.


Assuntos
Desempenho Atlético/fisiologia , Suplementos Nutricionais , Sucos de Frutas e Vegetais , Nitratos/administração & dosagem , Corrida/fisiologia , Estudos Cross-Over , Método Duplo-Cego , Ingestão de Alimentos , Frequência Cardíaca , Humanos , Ácido Láctico/sangue , Masculino , Fadiga Muscular/fisiologia , Nitratos/sangue , Adulto Jovem
11.
J Sports Sci ; 38(16): 1877-1885, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32508286

RESUMO

With potential implications for recovery and conditioning practices, the aim of this study was to assess the cumulative and residual response of angle specific eccentric knee flexor (eccKF) strength indices following soccer-specific activity. Thirteen semi-professional soccer players were therefore required to complete a 90-minute soccer-specific treadmill running. with eccKF isokinetic strength assessments completed pre-trial, immediately post-trial, and 48 hours post-trial. The strength assessments comprised the completion of 5 repetitions at angular velocities of 60 and 300 deg·s-1. Isokinetic data was analysed for measures of peak torque (PT), angle of peak torque (APT), functional range (FR), and angle specific torque (AST). Significant post-trial impairments were observed for measures of slow velocity PT60 (6.6%) and AST300 (12.5%). Further significant differences were observed 48 hours post-trial for PT300 (10.7%) and PT60 (12.8%) PT, APT60 (~15°), and AST300 (>13.6%). These data have implications for post exercise recovery monitoring and the prescription of recovery modalities and conditioning practices in the 2 days following match-play. The AST and APT responses highlight the importance of analysis of the entire strength-angle curve and at a range of angular velocities.


Assuntos
Joelho/fisiologia , Força Muscular/fisiologia , Corrida/fisiologia , Futebol/fisiologia , Adulto , Humanos , Masculino , Fadiga Muscular/fisiologia , Dinamômetro de Força Muscular , Músculo Esquelético/fisiologia , Fatores de Tempo , Torque , Adulto Jovem
12.
J Sports Sci ; 38(20): 2279-2290, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32543282

RESUMO

This investigation examined the effect of prior workload on high-intensity football match performance. Player load variables were recorded using a global positioning system and converted into composite variables: rolling season accumulated load (AL), exponentially weighted moving average acute, chronic and acute:chronic workload ratio (A:C). Match-play high-intensity performance-per-minute: accelerations (ACC), sprints, high-speed running (HSR) and high metabolic load (HMLd) distances; and situational and contextual variables were recorded for all games. Partial least squares modelling, and backward stepwise selection determined the most parsimonious model for each performance variable. Quadratic relationships of small to moderate effect sizes were identified for sprint AL and sprint performance, HSR AL and HSR performance, acute HMLd and HMLd performance, acute sprint load and ACC performance and A:C sprint load and ACC performance. Match performance was typically greatest between the mean and +1SD. High chronic HMLd, and combined acceleration and deceleration (ACC+DEC) load exerted small beneficial effects on HMLd and HSR performance, whereas high acute load exerted trivial to moderate negative effects. High sprint A:C exerted a small beneficial effect on sprint performance and playing position exerted small effects on HSR and HMLd performance. Prior workload has trivial to moderate effects on high-intensity match performance in professional players.


Assuntos
Desempenho Atlético/fisiologia , Comportamento Competitivo/fisiologia , Condicionamento Físico Humano/fisiologia , Futebol/fisiologia , Aceleração , Desempenho Atlético/psicologia , Sistemas de Informação Geográfica , Humanos , Masculino , Fadiga Muscular/fisiologia , Corrida/fisiologia , Futebol/psicologia , Estresse Fisiológico , Estresse Psicológico , Estudos de Tempo e Movimento , Adulto Jovem
13.
J Electromyogr Kinesiol ; 53: 102429, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32505088

RESUMO

Unfused tetanic contractions evoked in fast motor units exhibit extra-efficient force production at the onset of contraction, an effect called "boost". Boost is diminished in subsequent contractions if there is a short rest period between contractions, but can be re-established with a longer period of rest. We tested the hypothesis that contractile activity and rest could enhance boost-related metrics. Two sets of 3 unfused tetani were evoked 3 min apart in fast fatigable (FF) and fast fatigue-resistant (FR) motor units of the rat medial gastrocnemius. The greatest changes occurred in the first unfused tetanic contractions. Relative to the first contraction in the first set, the first contraction in the second set exhibited higher peak force during boost in a subset of motor units (76% of FF and 48% of FR). Enhanced force during boost was influenced by interaction of slowing of twitch contraction time (up to 20% and 25%, for FF and FR motor units, respectively), half-relaxation time (up to 37% and 49% for FF and FR motor units, respectively), and potentiation of the first twitch (up to 13% and 5% for FF and FR motor units, respectively). Examination of twitches evoked between sets suggested opportunity for greater enhancement of boost with shorter intervening rest periods. The phenomenon of enhanced boost following motor unit activity may interest sports scientists.


Assuntos
Contração Muscular/fisiologia , Fadiga Muscular/fisiologia , Músculo Esquelético/fisiologia , Recrutamento Neurofisiológico/fisiologia , Descanso/fisiologia , Animais , Estimulação Elétrica/métodos , Feminino , Neurônios Motores/fisiologia , Ratos , Ratos Wistar , Fatores de Tempo
14.
Rev. andal. med. deporte ; 13(2): 87-91, jun. 2020. tab, graf
Artigo em Inglês | IBECS | ID: ibc-194370

RESUMO

OBJECTIVE: The purpose of this study was to examine the effect of pre-fatiguing the triceps brachii on subsequent strength performance and myoelectric activity in the barbell, dumbbell, and Smith machine bench press. METHOD: Nineteen trained men participated of this study (27.9 ± 4.5 years; 1.72 ± 0.1 m; 80.3 ± 9.2 kg). Ten-repetition maximum loads were determined for the triceps extension as well as the barbell barbell, dumbbell and Smith machine bench press. Three experimental protocols were performed in a randomized design. All experimental protocols began with four sets of the triceps extension (performed with a high pulley) to repetition failure followed by four sets to repetition failure for one of three bench press modalities. Two minute-rest intervals were adopted between sets and exercises. Total repetitions (work), training volume and myoelectric activity of pectoralis major, anterior deltoid, biceps brachii, and triceps brachii were recorded during each bench press modality. RESULTS: Significantly greater activity of the biceps brachii was observed during performance of the dumbbell bench press versus barbell and Smith machine bench press. No other significant differences were observed between protocols. CONCLUSION: Therefore, considering the training volume and myoelectric activity of the synergistic muscles, similar performance across bench press modalities can be expected when preceded by performance of a triceps extension


OBJETIVO: Examinar el efecto de la prefatiga del tríceps braquial en el desempeño subsiguiente de la fuerza y actividad mioeléctrica en el supino recto utilizando barra (SRB), mancuernas (SRM) y Smith machine (SMSR). MÉTODO: En el estudio participaron 19 hombres entrenados (27.9 ± 4.5 años, 1.72 ± 0.1 m, 80.3 ± 9.2 kg). Se realizó una prueba de diez repeticiones máximas para la extensión del tríceps, así como para el supino resto utilizando barra, mancuernas y Smith Machine. Se realizaron tres protocolos experimentales en orden aleatorizado. Los protocolos consistieron de cuatro series de repeticiones de extensión del tríceps (realizado con polea alta) hasta la fatiga, seguida de cuatro series de repeticiones hasta la fatiga de una de las tres modalidades de supino. Dos intervalos de descanso de un minuto se realizaron entre series y ejercicios. Las repeticiones totales (trabajo), volumen de entrenamiento y actividad mioeléctrica de pectoral mayor, deltoides anteriores, bíceps braquial y tríceps braquial fueron registradas durante cada modalidad de supino. RESULTADOS: Se observó una actividad significativamente mayor del bíceps braquial durante la realización del supino recto con mancuerna versus barra y Smith Machine. No se observó ninguna diferencia significativa entre los protocolos. CONCLUSIONES: Por lo tanto, considerando el volumen de entrenamiento y la actividad mioeléctrica de los músculos sinérgicos, se puede esperar un rendimiento similar en las diversas modalidades de supino, cuando es precedido por la realización de una extensión de tríceps


OBJETIVO: examinar o efeito da pré-fatiga do tríceps braquial no desempenho subsequente da força e atividade mioelétrica no supino reto utilizando barra, halter e Smith machine. MÉTODO: Participaram do estudo 19 homens treinados (27.9 ± 4.5 anos; 1.72 ± 0.1 m; 80.3 ± 9.2 kg). Foi realizado um teste de dez repetições máximas para a extensão do tríceps, assim como para o SRB, SRH e SMSR. Três protocolos experimentais foram realizados em ordem randomizada. Os protocolos consistiram de quatro séries de repetições do a extensão do tríceps (realizado com polia alta) até a falha seguida de quatro séries de repetições até a falha de uma das três modalidades de supino. Dois intervalos de descanso de um minuto foram adotados entre séries e exercícios. As repetições totais (trabalho), volume de treinamento e atividade mioelétrica de peitoral maior, deltóide anterior, bíceps braquial e tríceps braquial foram registradas durante cada modalidade de supino. RESULTADOS: Observou-se uma atividade significativamente maior do bíceps braquial durante a realização do supino reto halter versus barra e Smith Machine. Nenhuma outra diferença significativa foi observada entre os protocolos. CONCLUSÕES: Portanto, considerando o volume de treinamento e a atividade mioelétrica dos músculos sinérgicos, pode-se esperar um desempenho semelhante em modalidades de supino quando precedido pela realização de uma extensão de tríceps


Assuntos
Humanos , Masculino , Adulto , Adulto Jovem , Treinamento de Resistência/métodos , Músculo Esquelético/fisiologia , Força Muscular/fisiologia , Eletromiografia , Fadiga Muscular/fisiologia , Antropometria
15.
Arch. med. deporte ; 37(197): 183-190, mayo-jun. 2020. graf, tab
Artigo em Espanhol | IBECS | ID: ibc-195230

RESUMO

INTRODUCCIÓN: Tanto la inmersión en agua fría como las prendas de compresión han sido usadas rutinariamente para acelerar la recuperación después del ejercicio, sin embargo, hay una falta de conocimiento del uso de ambas técnicas de forma simultánea. Pressurice Compressport, es una herramienta simple, no farmacológica y carente de efectos secundarios que permite aplicar la crioterapia compresiva (CC). OBJETIVO: Investigar el efecto crónico del Pressurice Compressport, tras cada partido, y sesión de entrenamiento, sobre los marcadores de daño muscular, la fuerza muscular y la fatiga. MÉTODOS: Un diseño de cohorte prospectivo. En 24 jugadores de baloncesto masculinos divididos en dos grupos, recuperación (RP) (n = 12) y control (GC) (n = 12). Los marcadores séricos del metabolismo muscular, la fuerza de cuádriceps (FC) y los valores de esfuerzo percibido (RPE) por escala de Borg CR10, se midieron en 3 momentos del estudio: a) día 1, (T1); b) día 28 (T2) y c) día 56 (T3). La CC se aplicó inmediatamente después de cada partido y entrenamiento. RESULTADOS: Se observó una disminución progresiva de todos los marcadores de daño muscular al final de la pretemporada en el grupo RP. Por el contrario, en el GC aumentaron y fueron significativas para la creatina quinasa (CK) (T1 vs. T3 p < 0,05). El curso temporal de la mioglobina (Mb) en el grupo RP (p > 0,05), siguió un patrón diferente al GC (p < 0,05). En RP los RPE disminuyeron significativamente (p < 0,05) en todos los puntos del estudio. La FC fue mayor en el RP que en el GC, además se obtuvieron ganancias a lo largo de la pretemporada en RP y una disminución en GC. CONCLUSIÓN: La CC es potencialmente capaz de promover la recuperación del daño muscular asociada con la competición y el entrenamiento, con reducciones en los marcadores del daño muscular, mejoras de la fuerza muscular y disminución significativa RPE


INTRODUCTION: Both cold water immersion and compression garments have been routinely used to speed recovery after exercise, however, there is a lack of knowledge of applying both techniques simultaneously. Pressurice Compressport, which is a simple tool, non-pharmacological and free of side effects that allows the application of compressive cryotherapy (CC). OBJECTIVE: To investigate the chronic effect of Pressurice Compressport, after each match and training session, on the markers of muscle damage, muscle strength and fatigue. METHODS: A prospective cohort design. In 24 male basketball players divided into two groups, recovery (RP) (n = 12) and control (GC) (n = 12). Serum markers of muscle metabolism, quadriceps strength (FC) and perceived effort values (RPE) by Borg CR10 scale were measured at 3 times in the study: a) day 1, (T1); b) day 28 (T2) and c) day 56 (T3). The CC was applied immediately after each match and training. Results: A progressive decrease in all markers of muscle damage was observed at the end of the pre-season in the RP group. On the contrary, in the GC they increased significantly for creatine kinase (CK) (T1 vs. T3 p < 0.05). The time course of myoglobin (Mb) in the RP group (p > 0.05) followed a pattern different from that of GC (p < 0.05). In RP, the RPE significantly decreased (p < 0.05) in all points of the study. The HR was higher in the RPE than in the GC, in addition gains were obtained throughout the pre-season in RPE and a decrease in GC. CONCLUSION: CC is potentially capable of promoting recovery from muscle damage associated with competition and training, with reductions in markers of muscle damage, improvements in muscle strength and significant decrease in RPE


Assuntos
Humanos , Masculino , Adolescente , Adulto Jovem , Adulto , Crioterapia/métodos , Traumatismos em Atletas/prevenção & controle , Músculo Esquelético/lesões , Basquetebol/fisiologia , Recuperação de Função Fisiológica/fisiologia , Estudos Prospectivos , Fadiga Muscular/fisiologia , Força Muscular/fisiologia , Bandagens Compressivas , Mioglobina/sangue , Valores de Referência , Fatores de Tempo , Reprodutibilidade dos Testes
16.
Sci Rep ; 10(1): 7728, 2020 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-32382067

RESUMO

To assess if the alteration of neuromuscular properties of knee extensors muscles during heavy exercise co-vary with the SCV ([Formula: see text] slow component), eleven healthy male participants completed an incremental ramp test to exhaustion and five constant heavy intensity cycling bouts of 2, 6, 10, 20 and 30 minutes. Neuromuscular testing of the knee extensor muscles were completed before and after exercise. Results showed a significant decline in maximal voluntary contraction (MVC) torque only after 30 minutes of exercise (-17.01% ± 13.09%; p < 0.05) while single twitch (PT), 10 Hz (P10), and 100 Hz (P100) doublet peak torque amplitudes were reduced after 20 and 30 minutes (p < 0.05). Voluntary activation (VA) and M-wave were not affected by exercise, but significant correlation was found between the SCV and PT, MVC, VA, P10, P100, and P10/P100 ratio, respectively (p < 0.015). Therefore, because the development of the SCV occurred mainly between 2-10 minutes, during which neuromuscular properties were relatively stable, and because PT, P10 and P100 were significantly reduced only after 20-30 minutes of exercise while SCV is stable, a temporal relationship between them does not appear to exist. These results suggest that the development of fatigue due to alterations of neuromuscular properties is not an essential requirement to elicit the SCV.


Assuntos
Exercício Físico/fisiologia , Joelho/fisiologia , Fadiga Muscular/fisiologia , Músculo Esquelético/metabolismo , Oxigênio/metabolismo , Adulto , Eletromiografia , Humanos , Contração Isométrica/fisiologia , Articulação do Joelho/fisiologia , Masculino , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Torque , Adulto Jovem
17.
Int J Sports Med ; 41(11): 709-719, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32365388

RESUMO

This two-part narrative review aims to provide an insight into the age-related mechanical and neuromuscular factors contributing to: (1) decreased maximal muscle strength and power; (2) decreased force control; and (3) increased fatigability. Structural and functional changes from the macro-level of the muscle-tendon unit to the micro-level of the single muscle fibre have been reviewed and are described. At the muscle-tendon unit level, muscle volume, thickness and cross-sectional area, as well as pennation angle and fascicle length all decrease as part of the natural ageing process. These changes negatively affect muscle quality, muscle and tendon stiffness and Young's modulus and account for impairment in motor performance. A progressive age-related alteration in neuromuscular function is also well-established, with reduction in number and firing rate of the motor unit, contractile velocity and specific tension of muscle fibres, and stability of neuromuscular junction. These could be the result of structural alterations in the: (i) motor neuron, with number reduced, size and collateral sprouting increased; (ii) neuromuscular junction, with decreased post-synaptic junctional fold and density of active zones and increased pre-synaptic branching and post-synaptic area; and (iii) muscle fibre, with decreased number and size and increased type I and co-expression of myosin heavy chain.


Assuntos
Envelhecimento/fisiologia , Músculo Esquelético/fisiologia , Humanos , Neurônios Motores/citologia , Neurônios Motores/fisiologia , Fadiga Muscular/fisiologia , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/fisiologia , Força Muscular/fisiologia , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/inervação , Junção Neuromuscular/anatomia & histologia , Junção Neuromuscular/fisiologia , Qualidade de Vida , Tendões/anatomia & histologia , Tendões/fisiologia
18.
Artigo em Inglês | MEDLINE | ID: mdl-32325707

RESUMO

BACKGROUND: This study examined the motor unit (MU) control strategies for non-fatiguing isometric elbow flexion tasks at 40% and 70% maximal voluntary isometric contraction. METHODS: Nineteen healthy individuals performed two submaximal tasks with similar torque levels: contracting against an immovable object (force task), and maintaining the elbow joint angle against an external load (position task). Surface electromyographic (EMG) signals were collected from the agonist and antagonist muscles. The signals from the agonist were decomposed into individual action potential trains. The linear regression analysis was used to examine the MU recruitment threshold (RT) versus mean firing rates (MFR), and RT versus derecruitment threshold (DT) relationships. RESULTS: Both agonist and antagonist muscles' EMG amplitudes did not differ between two tasks. The linear slopes of the MU RT versus MFR and RT versus DT relationships during the position task were more negative (p = 0.010) and more positive (p = 0.023), respectively, when compared to the force task. CONCLUSIONS: To produce a similar force output, the position task may rely less on the recruitment of relatively high-threshold MUs. Additionally, as the force output decreases, MUs tend to derecruit at a higher force level during the position task.


Assuntos
Potenciais de Ação/fisiologia , Eletromiografia , Contração Isométrica/fisiologia , Contração Muscular/fisiologia , Fadiga Muscular/fisiologia , Músculo Esquelético/fisiologia , Recrutamento Neurofisiológico , Adulto , Braço/fisiologia , Articulação do Cotovelo/fisiologia , Eletromiografia/métodos , Humanos , Análise e Desempenho de Tarefas
19.
J Neuroeng Rehabil ; 17(1): 49, 2020 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-32276627

RESUMO

Neuroprostheses that activate musculature of the lower extremities can enable standing and movement after paralysis. Current systems are functionally limited by rapid muscle fatigue induced by conventional, non-varying stimulus waveforms. Previous work has shown that sum of phase-shifted sinusoids (SOPS) stimulation, which selectively modulates activation of individual motor unit pools (MUPs) to lower the duty cycle of each while maintaining a high net muscle output, improves joint moment maintenance but introduces greater instability over conventional stimulation. In this case study, implementation of SOPS stimulation with a real-time feedback controller successfully decreased joint moment instability and further prolonged joint moment output with increased stimulation efficiency over open-loop approaches in one participant with spinal cord injury. These findings demonstrate the potential for closed-loop SOPS to improve functionality of neuroprosthetic systems.


Assuntos
Terapia por Estimulação Elétrica/métodos , Músculo Esquelético/fisiopatologia , Traumatismos da Medula Espinal/reabilitação , Adulto , Retroalimentação , Humanos , Articulação do Joelho/fisiologia , Masculino , Movimento/fisiologia , Fadiga Muscular/fisiologia , Paralisia/etiologia , Paralisia/fisiopatologia , Paralisia/reabilitação , Traumatismos da Medula Espinal/complicações , Traumatismos da Medula Espinal/fisiopatologia
20.
Phys Ther ; 100(6): 897-906, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-32157308

RESUMO

BACKGROUND: Functional outcomes with early rehabilitation in the acute care setting have improved; however, an improved understanding of muscle fatigue using surface electromyography (sEMG) is warranted to better guide patient-centered exercise prescription. OBJECTIVES: The objectives of this study were to assess the safety and feasibility of collecting sEMG at the acute care bedside and to determine differences in muscle fatigue during isometric and dynamic submaximal contractions among patients in the hospital, healthy younger participants, and healthy older participants. DESIGN: The study used an observational cohort design. METHODS: There were 37 participants. Median frequency (Fmed) of the myoelectric signal of the quadriceps femoris muscles and time to task failure (TTTF) were measured using sEMG during an isometric and dynamic fatiguing contraction. Primary analysis compared TTTF between groups for both types of contractions. Secondary analysis compared Fmed at initiation and termination of fatiguing contraction. RESULTS: High-quality sEMG measures were safe and feasible to collect at the acute care bedside with no adverse events. There was a statistically significant difference in TTTF between groups after isometric and dynamic contractions; hospitalized patients fatigued faster than healthy younger and healthy older participants after both contractions. With the exception of the vastus lateralis during a dynamic contraction in healthy younger and hospitalized patients, there was a statistically significant difference between Fmed at initiation and termination of contraction, indicating that subjects' muscles did truly fatigue. LIMITATIONS: A limitation of the study was the small sample size of patients who were hospitalized without matched controls. CONCLUSIONS: sEMG is a lab quantitative technique that was found to be safe and feasible to assess muscle fatigue in the acute care environment. The protocol yielded similar results to previously published literature for healthy younger and healthy older people. Further research is needed to better understand how to integrate sEMG findings into patient-centered exercise prescriptions.


Assuntos
Eletromiografia/métodos , Contração Isométrica/fisiologia , Fadiga Muscular/fisiologia , Músculo Quadríceps/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Eletromiografia/efeitos adversos , Estudos de Viabilidade , Feminino , Voluntários Saudáveis , Hospitalização , Humanos , Masculino , Pessoa de Meia-Idade , Força Muscular , Testes Imediatos , Estatísticas não Paramétricas , Adulto Jovem
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