O processo de envelhecimento se caracteriza por uma grande perda de massa muscular, processo esse chamado de sarcopenia. Esse processo acarreta em uma redução da área de seção transversa e do comprimento das fibras musculares, com redução da capacidade de produção de força máxima e da velocidade máxima de encurtamento, tornando as respostas musculares mais lentas entre a população idosa. O exercício excêntrico, por outro lado, pode devolver ao músculo mais rapidamente essas suas características estruturais perdidas a partir do aumento da espessura muscular e aumento do comprimento das fibras musculares. Entretanto, o exercício excêntrico máximo produz essas adaptações por meio de microlesões que, no caso dos idosos, poderia acarretar na necessidade de um tempo maior de recuperação entre os dias consecutivos de treinamento excêntrico, o que poderia retardar o processo desejado de rápida adaptação do sistema neuromuscular. Visto que há uma carência na literatura sobre estudos que analisem a temporalidade das adaptações agudas ao exercício excêntrico em idosos, o trabalho apresentado a seguir teve como objetivo principal analisar como a musculatura dos idosos responde a esse tipo de exercício de forma aguda, assim como analisar a temporalidade das adaptações musculares ao longo de 3 dias após a intervenção excêntrica. Além das propriedades mecânicas musculares como a força e potência, foram analisados outros indicadores do dano muscular, como a ecogenicidade e a dor muscular tardia. Para isso, um grupo de idosos saudáveis realizou uma sessão de exercício excêntrico em dinamômetro isocinético e, ao longo de 3 dias subsequentes, foram avaliados quais os efeitos dessa sessão de exercício sobre a dor muscular tardia, ecogenicidade, torque máximo isométrico, torque máximo excêntrico, torque total excêntrico e ângulo do pico de torque excêntrico. Como principais resultados encontramos maiores níveis de dor muscular tardia, redução nos níveis de força isométrica, torque máximo excêntrico, torque total excêntrico e trabalho total excêntrico. Não foram encontradas diferenças nas variáveis algometria de pressão, ecogenicidade e ângulo de pico de torque excêntrico. A presença dos sintomas de redução da força máxima isométrica e excêntrica, trabalho excêntrico e aumento da dor muscular tardia mesmo 72 horas após o exercício, sugere que, em programas de treinamento excêntrico seja respeitado um intervalo mínimo de 72 horas para que o nível de dano muscular não seja deletério em idosos sedentários. / The aging process is characterized by a great loss of muscle mass, a process called sarcopenia. This process leads to a reduction in cross-sectional area and length of the muscle fibers, reducing the capacity of maximum power output and maximum shortening speed, making slower muscle responses in the elderly population. Eccentric exercise, on the other hand, can return quickly to the muscle their structural characteristics such as increasing muscle thickness and increasing the length of the muscle fibers. However, the maximum eccentric exercise produces these adjustments by means of microdamage, in the case of the elderly, would result in the need for a longer recovery time between consecutive days eccentric training, which could retard the desired process to rapidly adapt the neuromuscular system. Since there is a lack in the literature on studies that analyze the temporality of acute adaptations to eccentric exercise in the elderly, the presented study aimed to analyze how the muscles of older people respond to this type of exercise acutely, and to analyze temporality of the muscular adjustments over 3 days after the eccentric intervention. In the muscular mechanical properties such as strength and power were analyzed other indicators of muscle damage, such as echointensity, the DOMS. For this, a group of healthy elderly conducted an eccentric workout using an isokinetic dynamometer and over 3 subsequent days, were assessed what the effects of this workout on DOMS, echointensity, isometric maximum torque, eccentric maximum torque, eccentric total torque and angle of the peak eccentric torque. The main results found higher levels of DOMS, reduction in the levels of isometric strength, maximum eccentric torque, eccentric total torque and eccentric total work. No differences were found in the algometry variables, echointensity and peak angle cam torque. The presence of symptoms of reduced maximal isometric and eccentric force, eccentric work and increased DOMS even 72 hours after exercise, suggesting that in eccentric training programs is respected a minimum of 72 hours for the level of damage muscle is not deleterious in sedentary elderly.

Desde seu desenvolvimento na década de 60, a fototerapia têm sido utilizada no tratamento de diversas condições patológicas, havendo um considerável corpo de evidências acerca de sua ação regenerativa, analgésica e anti-inflamatória. Tais efeitos terapêuticos podem ser explicados pela capacidade que a energia luminosa possui de ser absorvida pelos tecidos e estimular ou inibir processos intracelulares. Estudos recentes têm apresentado resultados promissores desta terapia também sobre a redução da fadiga e do dano muscular induzido pelo exercício. A fadiga muscular é um fenômeno multifacetado caracterizado por uma progressiva redução da capacidade de produção de força do músculo. O dano muscular, causado principalmente pelas ações excêntricas do exercício, é caracterizado pela desorganização da estrutura microscópica do músculo e redução da capacidade contrátil deste tecido. Assim, o objetivo do presente trabalho foi verificar o efeito da fototerapia aplicada imediatamente antes do exercício sobre: (1) a fadiga muscular de extensores de joelho submetidos a exercício isocinético concêntrico; (2) o dano muscular de extensores de joelho submetidos a exercício isocinético excêntrico. No primeiro estudo, 17 homens saudáveis e fisicamente ativos participaram de um desenho experimental cruzado no qual foram submetidos a 30 repetições concêntricas máximas de flexo-extensão do joelho, precedidas de tratamento com fototerapia ou placebo. A fototerapia foi aplicada através de um equipamento de light emitting diodes therapy (LEDT) composto por 35 diodos infravermelhos de 850 nm e 34 diodos vermelhos de 660 nm. O tratamento foi realizado em três pontos do quadríceps com aplicação de uma dose total de 125,1 J. Mensurações da função muscular dos extensores de joelho foram realizadas antes e imediatamente após o exercício através de contrações voluntárias máximas (CVM) de extensores de joelho a 60º de flexão da articulação. Como resultado, observou-se que os voluntários apresentaram um decréscimo de torque significativamente menor quando tratados com fototerapia em comparação ao tratamento placebo. No segundo estudo, 36 homens saudáveis e fisicamente ativos foram randomizados em grupo fototerapia (n=18) e grupo placebo (n=18), e submetidos a cinco séries de 15 contrações excêntricas máximas de extensores de joelho. Avaliações de dor muscular e níveis séricos das enzimas lactato desidrogenase (LDH) e creatina kinase (CK) foram mensuradas pré-exercício, 24 e 48 horas pós-exercício. Avaliações da função muscular (CVM de extensores de joelho) foram realizadas pré-exercício, imediatamente após, 24 e 48 horas após o exercício. Um equipamento de low level laser therapy (LLLT) composto por cinco diodos infravermelhos de 810 nm foi utilizado para aplicar o tratamento em seis pontos do quadríceps e transmitir uma dose total de 180 J. Como resultado, observou-se que o grupo fototerapia apresentou: (1) menores incrementos de LDH 48 horas após o exercício; (2) menores incrementos de CK 24 e 48 horas após o exercício; e (3) menor decréscimo do torque de extensores de joelho imediatamente após, 24 e 48 horas após o exercício, em comparação ao grupo placebo. Os achados destes estudos permitem concluir que o tratamento com fototerapia foi capaz de atenuar os efeitos da fadiga e do dano muscular induzidos por exercício em dinamômetro isocinético. / Since its development in the 60’s, phototherapy has been used in the treatment of several pathological conditions, with a considerable body of evidence with respect to its regenerative, analgesic and anti-inflammatory action. These therapeutic effects may be explained by the capacity that the light energy has of being absorbed by soft tissues and stimulate or inhibit intracellular processes. Recent studies have also shown promising results regarding the reduction of muscle fatigue and exercise induced muscle damage. Muscle fatigue is a multifaceted phenomenon characterized by a progressive reduction in muscle force production capacity. Muscle damage, mainly caused by eccentric exercise, is characterized by the microscopic disorganization of muscle structure and reduction of the contractile capacity of this tissue. Thus, the purpose of this study was to verify the effect of phototherapy applied immediately before exercise on: (1) knee extensors muscle fatigue after isokinetic concentric exercise; (2) knee extensor muscle damage after isokinetic eccentric exercise. In the first study 17 healthy and physically active male subjects participated of a cross-over design trial. Subjects were subjected to 30 maximal concentric repetitions of knee flexion-extension, preceded by placebo or phototherapy treatment. Phototherapy was applied with a light emitting diodes therapy (LEDT) equipment composed by 35 infrared diodes of 850 nm wavelength and 34 red diodes of 660 nm. Treatment was applied in three different points of the quadriceps muscle with a total dose of 125.1 J. Measurements of knee extensor muscle function were obtained before and immediately after exercise by maximal voluntary contractions (MVC) at a knee angle of 60º of joint flexion. Subjects showed a significant smaller decrease in torque when treated with phototherapy compared to placebo treatment. On the second study, 36 healthy and physically active male subjects were randomized into a phototherapy (n=18) and a placebo (n=18) group, and subjected to five series of 15 maximal knee extensor eccentric contractions. Measurements of pain and serum levels of lactate dehydrogenase (LDH) and creatine kinase (CK) enzymes were obtained pre-exercise, 24 and 48 hours postexercise. Evaluations of muscle function (knee extensor MVC) were obtained preexercise, immediately after, and 24 and 48 hours after exercise. A low level laser therapy (LLLT) equipment composed by five infrared diodes of 810 nm wavelength was used to apply the treatment on six different points of the quadriceps muscle with a total dose of 180 J. The phototherapy group showed: (1) smaller increments of LDH 48 hours after exercise; (2) smaller increments of CK 24 and 48 hours after exercise; and (3) smaller decrease on knee extensor torque immediately after, 24 and 48 hours after exercise compared to the placebo group. These findings allow us to conclude that the phototherapy treatment was able to attenuate the effects of fatigue and muscle damage induced by isokinetic exercise.

Com este projeto obteve-se informações sobre o comportamento de pilares submetidos à compressão excêntrica, executados com concreto de alta resistência, com resistência média à compressão de 80 MPa. Os pilares tinham seção transversal retangular de 15 cm x 30 cm, com altura livre de 174 cm. A excentricidade da força foi de 38 cm com plano de ação do momento paralelo ao menor lado. Foram ensaiados seis pilares, onde as variáveis foram as taxas de armaduras transversais e longitudinais. Os pilares foram ensaiados sob a ação de duas forças aplicadas de modos independentes, para maior precisão e controle do posicionamento da força excêntrica. Uma força era aplicada na direção do eixo longitudinal do pilar e outra, paralela a esse, com excentricidade definida. Foram montados dispositivos de vinculações e mecanismos de transferências de forças nos pilares, procurando aproximar as situações de ensaios às do modelo teórico pretendido. As rotações eram liberadas nas extremidades dos pilares, e a seção localizadas na meia altura comportava-se sob flexo compressão reta com pequena excentricidade. Os pilares com menor taxa de armadura transversal, tiveram ruptura frágil da seção transversal central com flambagem das barras das armaduras longitudinais. Os pilares com maior taxa de armadura transversal, apresentaram ruptura com boa ductilidade e esmagamento do concreto do lado mais comprimido. As deformações lidas nas barras das armaduras do lado mais comprimido, no instante da ruptura, ficaram entre 2,3% e 3%. Utilizaram-se modelos teóricos propostos na literatura para obter os valores estimados das forças normais últimas e momentos fletores últimos, comparando-os com os encontrados experimentalmente. / This work presents a study of the behavior of high strength columns under eccentric compression, with concrete cylinder compressive strength of around 80 MPa. The columns studied had cross section area of 15 cm x 30 cm at the test region, and an effective length of 174 cm. The eccentricity of the load was 380 mm and the plan of action of the moment was parallel to the smallest side of the cross section. Six columns were tested. The main variables were the stirrup volumetric ratio and the longitudinal steel ratio. The columns were tested under the action of two independent loads, an axial load and an eccentric load, so that could be precise the positioning of the eccentric load and the control of this action. The axial load was applied on of the longitudinal axis of the columns and the eccentric load was applied with the defined eccentricity. Articulation devices and load application devices were mounted such as to approach the proposed theoretical model as much as possible. The rotations were liberated in the extremities of the columns, and the section behaved under eccentric compression. The columns with smaller stirrup volumetric ratio showed a brittle mode of failure occurring at the central cross section accompanied by the buckling of the longitudinal reinforcement. On the other hand, the columns with larger stirrup volumetric ratio presented ductile failure accompanied by crushing on the most compressed side of the column. The measured longitudinal reinforcement strain on the most compressed side of the columns at the instant of failure were between 2,3% and 3%.Theoretical models proposed in literature were used to obtain values of the maximum axial load and ultimate flexural moment and the result compared with experimental results obtained in the tests.

This study examined the kinetic and kinematic differences between accentuated eccentric loading (AEL) and cluster sets in trained male subjects (age = 26.1 ± 4.1 years, height = 183.5 ± 4.3 cm, body mass = 92.5 ± 10.5 kg, and back squat to body mass ratio = 1.8 ± 0.3). Four load condition sessions consisted of traditionally loaded (TL) “straight sets,” TL cluster (TLC) sets, AEL cluster (AEC) sets, and AEL “straight sets” where only the first repetition had eccentric overload (AEL1). An interrepetition rest interval of 30 seconds was prescribed for both TLC and AEC. Concentric intensity for all load conditions was 80% 1 repetition maximum (1RM). Accentuated eccentric loading was applied to repetitions using weight releasers with total eccentric load equivalent to 105% of concentric 1RM. Traditionally loaded cluster had statistically greater concentric outputs than TL. Furthermore, statistically greater eccentric and concentric outputs were observed during AEC compared with TL with the exception of peak power. Statistically greater concentric characteristics were observed in TLC compared with AEL1, but statistically greater eccentric outputs were observed in AEL1. In the 2 cluster set conditions, statistically greater concentric rate of force development (RFDCON) (d = 0.470, p < 0.001) and average velocity (vavg) (d = 0.560, p < 0.001) in TLC compared with AEC were observed. However, statistically greater eccentric work (WECC) (d = 2.096, p < 0.001) and eccentric RFD (RFDECC) (d = 0.424, p < 0.001) were observed in AEC compared with TLC. Overall, eccentric overload demonstrated efficacy as a means of increasing eccentric work and RFD, but not as a means of potentiating concentric output. Finally, interrepetition rest seems to have the largest influence on concentric power output and RFD.

Background: To determine the role of muscle mass in sex-dependent differences in power output during flywheel resistance training (FRT). Methods: Twenty recreationally active (≥ 2 resistance exercise bouts per week), subjects (10 M, 10 F) completed 2 bouts of resistance exercise using a flywheel resistance training (FRT) device (Exxentric kbox 4 Pro) separated by at least one week. Each session consisted of 3 sets of 4 exercises (squat, bent-over row, Romanian deadlift, and biceps curl) with varying moments of inertia (0.050, 0.075, and 0.100 kg/m2, respectively) in random order. Each set consisted of 5 maximal effort repetitions with 3-minute recovery between sets. Average power, peak concentric and peak eccentric power were recorded and normalized to whole-body skeletal muscle mass (as calculated from bioelectrical impedence analysis). Additionally, linear regression analysis was used to determine the association between muscle mass and highest power output observed among all three inertial loads. Results: Absolute average, peak concentric and peak eccentric power for all lifts was significantly higher for males compared to females except for peak eccentric power for biceps curl which showed no significant difference. After normalizing to skeletal muscle mass, power output remained significantly higher for men in Row average power and peak concentric power as well as average power for biceps curl. A significant main effect of inertial load was noted for both absolute and relative power output for all exercises except for squat average power and peak concentric power. Regression analysis revealed that power output increases linearly with skeletal muscle mass (R2 = 0.37-0.77). Conclusions: Differences in power output between sexes during resistance exercise can largely be explained by differences in muscle mass. Indeed, muscle mass accounts for approximately 37-77% of the variance in power output during FRT depending on the exercise. Increasing inertial load tends to decrease power output during FRT.

Background: Training to increase muscular power is essential for improving athletic performance in most sports. Weight training (WT) is a common means for training muscular power. Another modality, flywheel resistance training (FRT), may be superior for improving muscular power. However, few studies have examined if FRT is kinematically similar to WT, or if FRT kinematics change with increasing inertial load. The purposes of this study were to determine how sagittal plane joint kinematics are affected by increasing inertial load during FRT squats, and to determine how FRT squat joint kinematics compare to WT squat joint kinematics. Methods: Subjects (n=9) completed three visits for this study. On the first visit subjects completed squat 1 repetition maximum (1RM) testing. The second visit served as a full FRT familiarization session in which subjects performed one set of 5 maximal effort FRT squats at each inertial load (0.050, 0.075, and 0.100 kgm2). On the third visit, subjects were videoed in the sagittal plane while performing the FRT squat protocol. Subjects then completed 5 maximal velocity repetitions of WT squats with the barbell loaded according to the Kansas Squat Test (KST) protocol. Kinematic differences between inertial loads were determined via 1-way repeated measures ANOVAS while differences between FRT and WT were determined with paired T-tests. Results: There were no differences in peak sagittal plane knee, trunk-hip, trunk (absolute) or ankle angles between inertial loads. Peak and mean joint angular velocities decreased with increasing inertial loads at the knee and trunk-hip. Mean joint angular velocities decreased at the ankle with increasing inertial loads, while peak and mean trunk (absolute) angular velocities were unaffected. No statistical analyses were conducted for FRT and WT comparison as not enough subjects met the criteria (n=3). Conclusions: Sagittal plane joint kinematics are largely maintained despite increasing inertial load during FRT squats. Lower extremity joint angular velocities decreased with increasing inertial load. If training for muscular power and knee extensor velocity is the goal, then the inertia of 0.050 kgm2 is most suitable.

Abstract not available

Doctor of Philosophy / In this thesis, three experiments were conducted to monitor: (i) muscle oxygenation and electromyographic activity of the biceps brachii after exercise-induced muscle damage (ii) muscle oxygenation after downhill walking-induced muscle damage, and, (iii) muscle oxygenation following a bout of vigorous concentric exercise. Maximal eccentric exercise (EE) of biceps brachii resulted in significantly increased mean resting oxygen saturation and decreased deoxyhaemoglobin. During isometric contractions at 50% and 80% of subjects’ maximum voluntary torque (MVT), oxygen desaturation and resaturation kinetics and volume were significantly decreased after EE, and these declines were significantly prevalent over the following 6 days. Additionally, a significant shift in median frequency intercept (measured by electromyography; EMG) towards lower frequencies was observed during isometric contractions at both 50% and 80% MVT after EE in the exercised arm. After an exhaustive session of downhill walking, another form of EE, resting total haemoglobin and oxyhaemoglobin decreased. Furthermore, during isometric contractions at 30%, 50% and 80% of MVT, prolonged and significant increases were observed in oxygen desaturation and resaturation kinetics and volumes after ambulatory EE. In contrast to the two EE experiments, concentric contractions did not evoke any prolonged changes in muscle oxygenation. Collectively, the findings of this thesis revealed significant and prolonged changes in muscle oxygenation at rest and during exercise, following sessions of strenuous eccentric exercise. Although not clear, the possible mechanism responsible for the changes in muscle oxygenation after EE could be increased resting muscle oxygen utilization due to probable muscle damage and a subsequent requirement of energy demanding repair processes. Concentric exercise resulted in fatigue, but it did not affect muscle oxygenation. Although a prolonged reduction in EMG median frequency intercept was observed after EE, this was not closely time-associated with the biochemical, anthropometric or functional markers of muscle damage.

Graduation date: 2006 / We hypothesized that calpain activity is elevated in response to muscle damage. To test this hypothesis, we examined the degradation of α-fodrin into its 150 and 145 kDa fragments following either 20 eccentric or isometric contractions. In addition, experiments were performed in the presence or absence of E-64-d, a calpain inhibitor. Both EDL and SOL muscles displayed significant differences (p<0.003 and p<0.002 respectively) between the raw and normalized 150 and 145 kDa α-fodrin fragments of the DMSO + E-64-d compared to the other bath treatments. Based on our model of exercise-induced muscle damage, we expected to see greater levels of 150 and 145 kDa α-fodrin fragments in those muscles that performed the eccentric protocol. However, there was no evidence that eccentric muscle damage increased the levels of 150 and 145 kDa α-fodrin fragments over the levels observed in the isometric trials. These findings suggest that the magnitude of damage was insufficient to activate calpains.

Chronic painful tendinopathies are common, not only in sports and recreationally active people, but also among people with a sedentary lifestyle. Both the lower and upper limbs are affected. There is lack of knowledge about the etiology and pathogenesis to tendinopathy, and many different treatments options have been presented. Unfortunately, most treatments have not been tested in scientific studies. Conservative (non-surgical) treatment has since long shown unsatisfactory results and surgical treatment is known to give unpredictable results. The aim of this thesis was to evaluate new models of painful eccentric training for the conservative treatment of different chronic tendinopathies. After promising results in a pilot study, using painful eccentric calf muscle training in patients with chronic mid-portion Achilles tendinopathy, we investigated if these results could be reproduced in a larger group of patients with both mid-portion and insertional Achilles tendinopathy (study I). After 12 weeks, 89% of the patients with pain from the mid-portion were satisfied and back in previous activities. In the group with insertional Achilles tendinopathy the results were poor. A new model for eccentric training was designed for patients with insertional Achilles tendinopathy. The eccentric calf muscle training was done from tip-toe to floor level (study II). With this new regimen 67% of the patients were satisfied and back in previous activities. The next step was to investigate the effects of painful eccentric quadriceps training on patients with jumper´s knee/patellar tendinopathy (study III). Two different training protocols were used. Eccentric training performed on a 250 decline board showed promising results with reduced pain and a return to previous activities, while eccentric training without the decline board had poor results. In a following prospective study, patients with jumper´s knee/patellar tendinopathy were randomised to either concentric or eccentric painful quadriceps training on a 250 decline board (study IV). After 12 weeks of training, there were significantly better results in the group that did eccentric training. In a pilot study (study V), we investigated painful eccentric deltoideus and supraspinatus muscle training on a small group of patients on the waiting list for surgical treatment of subacromial impingement syndrome. After 12 weeks of training, 5 out of 9 patients were satisfied with the results of treatment and withdrew from the waiting list for surgery. In conclusion, the present studies showed good clinical results with low risks of side effects and low costs. Thus, we suggest that painful eccentric training should be tried in patients with Achilles and patellar tendinopathy before intratendinous injections and surgery are considered. For patients with chronic painful impingement syndrome, the results of our small pilot study are interesting, and stimulates to randomised studies on larger materials.