The purpose of this study was to compare the shoulder resultant joint moment (RJM) during a shoulder internal rotator exercise using elastic resistance employing four different movement strategies and two different starting elastic strains. Methods: Ten subjects aged 27.4 ± 2.6 yr (5 female and 5 male) with no previous shoulder pathology performed four sets of six repetitions of shoulder rotation though 180° using elastic resistance (Thera-Band® elastic band, blue) during two acceleration (medium and low) and two cadence (2s:2s, <1s:1s) strategies at 0% elastic starting strain. The acceleration movement strategies were also performed with starting strain of 30%. A mathematical model using Newtonian mechanics was used to compute the RJM. Elastic band recoil force was measured with a force transducer. Forearm acceleration was determined by a miniature uniaxial accelerometer secured at the wrist. Electrogoniometer data were collected to determine the range of motion (ROM) as well as the angle between the forearm and band which was used to determine elastic moment arm. Paired t-tests were used to identify joint angle specific RJM differences between conditions. Results: Angle specific comparisons revealed that RJM in the moderate acceleration movement strategy was significantly different from RJM in the low acceleration movement strategy through 150° (83%) of range of motion (p<0.05). Shoulder RJM was up to 111% higher in the moderate acceleration strategy (P < 0.01). Angle specific comparisons revealed RJM in the <1:1 cadence strategy was significantly different from RJM in the 2:2 cadence through 108° (60%) of the range of motion (p<0.05). RJM was up to 47% higher in the <1:1 cadence (p<0.01). RJM in the low acceleration strategy was significantly greater with 30% elastic start strain relative to 0% elastic start strain through 180º of angular excursion (p<0.001). The pattern and magnitude of neuromuscular loading was significantly different in higher acceleration movement strategies (moderate acceleration and fast cadence). Conclusions: These findings indicate that differential limb acceleration as a result of movement strategy significantly affects shoulder load during elastic resistance exercise. The pattern and magnitude of load was different in each movement strategy and could result in differential neuromuscular adaptation through training. Clinicians and exercise professionals should consider movement strategy/acceleration as an important factor when prescribing elastic resistance exercise for safety and efficacy. / October 2006

The purpose of this study was to compare the shoulder resultant joint moment (RJM) during a shoulder internal rotator exercise using elastic resistance employing four different movement strategies and two different starting elastic strains. Methods: Ten subjects aged 27.4 ± 2.6 yr (5 female and 5 male) with no previous shoulder pathology performed four sets of six repetitions of shoulder rotation though 180° using elastic resistance (Thera-Band® elastic band, blue) during two acceleration (medium and low) and two cadence (2s:2s, <1s:1s) strategies at 0% elastic starting strain. The acceleration movement strategies were also performed with starting strain of 30%. A mathematical model using Newtonian mechanics was used to compute the RJM. Elastic band recoil force was measured with a force transducer. Forearm acceleration was determined by a miniature uniaxial accelerometer secured at the wrist. Electrogoniometer data were collected to determine the range of motion (ROM) as well as the angle between the forearm and band which was used to determine elastic moment arm. Paired t-tests were used to identify joint angle specific RJM differences between conditions. Results: Angle specific comparisons revealed that RJM in the moderate acceleration movement strategy was significantly different from RJM in the low acceleration movement strategy through 150° (83%) of range of motion (p<0.05). Shoulder RJM was up to 111% higher in the moderate acceleration strategy (P < 0.01). Angle specific comparisons revealed RJM in the <1:1 cadence strategy was significantly different from RJM in the 2:2 cadence through 108° (60%) of the range of motion (p<0.05). RJM was up to 47% higher in the <1:1 cadence (p<0.01). RJM in the low acceleration strategy was significantly greater with 30% elastic start strain relative to 0% elastic start strain through 180º of angular excursion (p<0.001). The pattern and magnitude of neuromuscular loading was significantly different in higher acceleration movement strategies (moderate acceleration and fast cadence). Conclusions: These findings indicate that differential limb acceleration as a result of movement strategy significantly affects shoulder load during elastic resistance exercise. The pattern and magnitude of load was different in each movement strategy and could result in differential neuromuscular adaptation through training. Clinicians and exercise professionals should consider movement strategy/acceleration as an important factor when prescribing elastic resistance exercise for safety and efficacy.

The purpose of this study was to compare the shoulder resultant joint moment (RJM) during a shoulder internal rotator exercise using elastic resistance employing four different movement strategies and two different starting elastic strains. Methods: Ten subjects aged 27.4 ± 2.6 yr (5 female and 5 male) with no previous shoulder pathology performed four sets of six repetitions of shoulder rotation though 180° using elastic resistance (Thera-Band® elastic band, blue) during two acceleration (medium and low) and two cadence (2s:2s, <1s:1s) strategies at 0% elastic starting strain. The acceleration movement strategies were also performed with starting strain of 30%. A mathematical model using Newtonian mechanics was used to compute the RJM. Elastic band recoil force was measured with a force transducer. Forearm acceleration was determined by a miniature uniaxial accelerometer secured at the wrist. Electrogoniometer data were collected to determine the range of motion (ROM) as well as the angle between the forearm and band which was used to determine elastic moment arm. Paired t-tests were used to identify joint angle specific RJM differences between conditions. Results: Angle specific comparisons revealed that RJM in the moderate acceleration movement strategy was significantly different from RJM in the low acceleration movement strategy through 150° (83%) of range of motion (p<0.05). Shoulder RJM was up to 111% higher in the moderate acceleration strategy (P < 0.01). Angle specific comparisons revealed RJM in the <1:1 cadence strategy was significantly different from RJM in the 2:2 cadence through 108° (60%) of the range of motion (p<0.05). RJM was up to 47% higher in the <1:1 cadence (p<0.01). RJM in the low acceleration strategy was significantly greater with 30% elastic start strain relative to 0% elastic start strain through 180º of angular excursion (p<0.001). The pattern and magnitude of neuromuscular loading was significantly different in higher acceleration movement strategies (moderate acceleration and fast cadence). Conclusions: These findings indicate that differential limb acceleration as a result of movement strategy significantly affects shoulder load during elastic resistance exercise. The pattern and magnitude of load was different in each movement strategy and could result in differential neuromuscular adaptation through training. Clinicians and exercise professionals should consider movement strategy/acceleration as an important factor when prescribing elastic resistance exercise for safety and efficacy.

A resistência elástica é aplicada amplamente em programas de fortalecimento muscular nos processos de reabilitação física. No entanto, as conseqüências biomecânicas para o músculo exercitado com esta forma de sobrecarga são pouco estudadas. A ausência de fundamentação científica no que tange a aplicação da resistência elástica fez com que surgissem algumas suposições a respeito de sua caracterização biomecânica. Uma delas sugere que o exercício com resistência elástica pode ser caracterizado como sendo isocinético. Neste contexto, o objetivo global deste trabalho foi o de caracterizar o comportamento biomecânico do músculo quadríceps femoral frente ao exercício com resistência elástica. Tal caracterização foi realizada através da utilização de um modelo biomecânico bidimensional da articulação do joelho. O seu comportamento mioelétrico também foi avaliado. Conclui-se de uma forma geral, que o desenvolvimento deste estudo permitiu um entendimento a respeito da interação biomecânica entre o músculo e a resistência elástica durante o exercício. Permitindo dessa forma elucidar algumas questões ligadas a aplicação clínica desta modalidade de exercício / The elastic resistance is applied in programs of muscular fortification in processes of physical rehabilitation. However, the biomechanicals consequences for the muscle exercised with this resistance form aren’t very studied. The low scientific fundamentation for the application of the elastic resistance, results in some suppositions about its biomechanic characterization. One of them suggests that the exercise with elastic resistance can be characterized as isokinetic. In this context, the global objective of this work was characterizing the biomechanic behavior of the quadriceps muscle front to the exercise with elastic resistance. Such characterization was accomplished through the use of a bidimensional biomechanic model of the knee joint. The electromiographic behavior was also evaluated. In a general conclusion, the development of this study allowed an understanding of the biomechanic interaction between the muscle and the elastic resistance during the exercise. Allowing to elucidate some subjects of the clinical application of this exercise modality

Tem sido documentado que uma desvantagem do uso de pesos livres e máquinas de musculação é que há um efeito resultante da aceleração sobre a massa dos implementos usados durante a realização de exercícios dinâmicos. Como conseqüência, a carga externa assume valores ora acima, ora abaixo da carga escolhida durante a amplitude total de movimento (ADM). Apesar disso, há uma escassez de estudos que tenham definido a metodologia de aplicação dos materiais elásticos nos exercícios realizados em máquinas ou que tenham avaliado os efeitos crônicos do uso combinado de tubos elásticos (TEs) e máquinas, sobre parâmetros de força muscular. Desse modo, os objetivos do presente estudo foram desenvolver uma metodologia de implementação dos materiais elásticos às máquinas de musculação e comparar os efeitos crônicos do uso de exercício dinâmico adaptado com TEs com uso de exercícios dinâmico sem TEs, sobre os ganhos de força muscular. Dois estudos foram desenvolvidos. No primeiro estudo, com auxílio de sistema de dinamometria e cinemetria, testes preliminares foram realizados para definir a posição articular e a magnitude da resistência que o TE deveria fornecer para compensar a queda da carga externa durante a realização do exercício de extensão de joelho (EJ) em uma máquina de musculação. Foi determinado que os TEs deveriam oferecer resistência a partir de um ângulo correspondente a um terço do final da fase concêntrica. Ademais, um percentual de queda da carga externa em diferentes velocidades foi obtido e usado para escolher entre os TEs previamente calibrados o que melhor era capaz de compensar a queda da carga externa. No segundo estudo, 22 sujeitos, divididos em grupo com TEs anexados à máquina (CTE) e grupo sem TEs (STE), foram submetidos a um protocolo de treinamento progressivo com exercício de EJ realizado três vezes por semana, com duração de 14 semanas. Em três ocasiões distintas, os sujeitos foram submetidos a realização de teste de uma repetição máxima, teste de contração voluntária máxima isométrica em quatro posições articulares distintas, salto sem contramovimento (SSC) e teste de contração voluntária máxima isocinética. Foram consideradas como variáveis dependentes a força máxima isométrica (FMiso), a força máxima dinâmica isotônica (FMdin), o torque máximo isocinético (TMcin), a potência muscular e a altura do salto (avaliados por meio do SSC). Como variáveis independentes foram considerados os grupos (CTE e STE) e o tempo de treinamento. ANOVA de dois caminhos (grupo e tempo) com medidas repetidas no tempo foi usada pra verificar os efeitos principais e interações entre as variáveis. (α = 0,05). Como resultado, foi observado que o grupo CTE apresentou valores de força máxima isométrica no final da ADM cerca de 40% maiores quando comparado ao grupo STE. Entretanto, não foram observados efeitos principais ou interações nos demais parâmetros de força avaliados. Como aplicação prática, o uso de TEs combinados ao exercício de EJ na máquina avaliada pode ser útil quando o objetivo do treinamento é obter maiores ganhos de força isométrica na porção final da ADM ou ainda obter maior controle da carga escolhida durante uma maior porção do movimento dinâmico. / It has been documented that a disadvantage of the use free weights or exercise machines is that there is a resultant acceleration effect on the mass of the implement used during the dynamic exercises, which modifies the magnitude of the external load. The consequence of this is that the chosen load for the exercise may fluctuate above or below that intended load during the range of motion (ROM). However, there is a scarcity of studies that defined the methodology of application of elastic tubing (ET) in exercise machines or that verified the chronic effect of the use of ET and exercise machines on muscular strength parameters. Thus, the aims of the study were to develop a methodology of implementation to ET at exercises machines and to compare the effects of use of dynamic exercise adapted with ET with use of dynamic exercise without ET on the muscular strength during a strength training program. Two studies were performed. In the first study, using dynamometric and cinematic system, tests were performed earlier to define the magnitude of resistance which ET should offer so that compensates the decrease in the external load. As a result, it was determined that ET should offer resistance from the degree corresponding to third at the end of the concentric phase. Nevertheless, a percentage of decrease in the external load in relation to chosen load at different velocities was obtained and used to choose between the calibrated ET which one that was able to compensate the decrease in the external load. In the second study, twenty two subjects from both sexes, divided between into group with ET attached at machine (ETA) and group without ET attached to machine (WET) were submitted to the progressive training protocol using exercise of knee extension, performed 3 times per week, during 14 weeks. In three distinct situation (0, 7 and 14 weeks) the subjects was submitted to performing of the one repetition maximum, maximum voluntary contraction isometric at four different angles of knee flexion, vertical jump without a countermovement movement (SJ) and maximum voluntary contraction isokinetic. The dependent variables used in this present study were the maximal isometric strength, the maximal dynamic strength, the maximal torque isokinetic, the power strength and height of jump (available during the SJ). The independent variables were the group (ETA and WET) and the training time. ANOVA - two ways (group and time) with repeated measures in time was used to verify the main effects and interactions between the variables (α = 0.05). As a main result, it was observed that the group ETA presented values of maximal strength isometric in the end of the ROM about 40% greater when it was compare with the group STE. However, it was no found main effects or interactions between other parameters of strength. As the practical application, the combining elastic tubing with exercise of knee extension in a specific machine can be use when the goal of training program is obtain greater strength in the final portion of extension knee or obtain better control of the chosen load during greater portion of dynamic movement.

Tem sido documentado que uma desvantagem do uso de pesos livres e máquinas de musculação é que há um efeito resultante da aceleração sobre a massa dos implementos usados durante a realização de exercícios dinâmicos. Como conseqüência, a carga externa assume valores ora acima, ora abaixo da carga escolhida durante a amplitude total de movimento (ADM). Apesar disso, há uma escassez de estudos que tenham definido a metodologia de aplicação dos materiais elásticos nos exercícios realizados em máquinas ou que tenham avaliado os efeitos crônicos do uso combinado de tubos elásticos (TEs) e máquinas, sobre parâmetros de força muscular. Desse modo, os objetivos do presente estudo foram desenvolver uma metodologia de implementação dos materiais elásticos às máquinas de musculação e comparar os efeitos crônicos do uso de exercício dinâmico adaptado com TEs com uso de exercícios dinâmico sem TEs, sobre os ganhos de força muscular. Dois estudos foram desenvolvidos. No primeiro estudo, com auxílio de sistema de dinamometria e cinemetria, testes preliminares foram realizados para definir a posição articular e a magnitude da resistência que o TE deveria fornecer para compensar a queda da carga externa durante a realização do exercício de extensão de joelho (EJ) em uma máquina de musculação. Foi determinado que os TEs deveriam oferecer resistência a partir de um ângulo correspondente a um terço do final da fase concêntrica. Ademais, um percentual de queda da carga externa em diferentes velocidades foi obtido e usado para escolher entre os TEs previamente calibrados o que melhor era capaz de compensar a queda da carga externa. No segundo estudo, 22 sujeitos, divididos em grupo com TEs anexados à máquina (CTE) e grupo sem TEs (STE), foram submetidos a um protocolo de treinamento progressivo com exercício de EJ realizado três vezes por semana, com duração de 14 semanas. Em três ocasiões distintas, os sujeitos foram submetidos a realização de teste de uma repetição máxima, teste de contração voluntária máxima isométrica em quatro posições articulares distintas, salto sem contramovimento (SSC) e teste de contração voluntária máxima isocinética. Foram consideradas como variáveis dependentes a força máxima isométrica (FMiso), a força máxima dinâmica isotônica (FMdin), o torque máximo isocinético (TMcin), a potência muscular e a altura do salto (avaliados por meio do SSC). Como variáveis independentes foram considerados os grupos (CTE e STE) e o tempo de treinamento. ANOVA de dois caminhos (grupo e tempo) com medidas repetidas no tempo foi usada pra verificar os efeitos principais e interações entre as variáveis. (α = 0,05). Como resultado, foi observado que o grupo CTE apresentou valores de força máxima isométrica no final da ADM cerca de 40% maiores quando comparado ao grupo STE. Entretanto, não foram observados efeitos principais ou interações nos demais parâmetros de força avaliados. Como aplicação prática, o uso de TEs combinados ao exercício de EJ na máquina avaliada pode ser útil quando o objetivo do treinamento é obter maiores ganhos de força isométrica na porção final da ADM ou ainda obter maior controle da carga escolhida durante uma maior porção do movimento dinâmico. / It has been documented that a disadvantage of the use free weights or exercise machines is that there is a resultant acceleration effect on the mass of the implement used during the dynamic exercises, which modifies the magnitude of the external load. The consequence of this is that the chosen load for the exercise may fluctuate above or below that intended load during the range of motion (ROM). However, there is a scarcity of studies that defined the methodology of application of elastic tubing (ET) in exercise machines or that verified the chronic effect of the use of ET and exercise machines on muscular strength parameters. Thus, the aims of the study were to develop a methodology of implementation to ET at exercises machines and to compare the effects of use of dynamic exercise adapted with ET with use of dynamic exercise without ET on the muscular strength during a strength training program. Two studies were performed. In the first study, using dynamometric and cinematic system, tests were performed earlier to define the magnitude of resistance which ET should offer so that compensates the decrease in the external load. As a result, it was determined that ET should offer resistance from the degree corresponding to third at the end of the concentric phase. Nevertheless, a percentage of decrease in the external load in relation to chosen load at different velocities was obtained and used to choose between the calibrated ET which one that was able to compensate the decrease in the external load. In the second study, twenty two subjects from both sexes, divided between into group with ET attached at machine (ETA) and group without ET attached to machine (WET) were submitted to the progressive training protocol using exercise of knee extension, performed 3 times per week, during 14 weeks. In three distinct situation (0, 7 and 14 weeks) the subjects was submitted to performing of the one repetition maximum, maximum voluntary contraction isometric at four different angles of knee flexion, vertical jump without a countermovement movement (SJ) and maximum voluntary contraction isokinetic. The dependent variables used in this present study were the maximal isometric strength, the maximal dynamic strength, the maximal torque isokinetic, the power strength and height of jump (available during the SJ). The independent variables were the group (ETA and WET) and the training time. ANOVA - two ways (group and time) with repeated measures in time was used to verify the main effects and interactions between the variables (α = 0.05). As a main result, it was observed that the group ETA presented values of maximal strength isometric in the end of the ROM about 40% greater when it was compare with the group STE. However, it was no found main effects or interactions between other parameters of strength. As the practical application, the combining elastic tubing with exercise of knee extension in a specific machine can be use when the goal of training program is obtain greater strength in the final portion of extension knee or obtain better control of the chosen load during greater portion of dynamic movement.

Tem sido documentado que uma desvantagem do uso de pesos livres e máquinas de musculação é que há um efeito resultante da aceleração sobre a massa dos implementos usados durante a realização de exercícios dinâmicos. Como conseqüência, a carga externa assume valores ora acima, ora abaixo da carga escolhida durante a amplitude total de movimento (ADM). Apesar disso, há uma escassez de estudos que tenham definido a metodologia de aplicação dos materiais elásticos nos exercícios realizados em máquinas ou que tenham avaliado os efeitos crônicos do uso combinado de tubos elásticos (TEs) e máquinas, sobre parâmetros de força muscular. Desse modo, os objetivos do presente estudo foram desenvolver uma metodologia de implementação dos materiais elásticos às máquinas de musculação e comparar os efeitos crônicos do uso de exercício dinâmico adaptado com TEs com uso de exercícios dinâmico sem TEs, sobre os ganhos de força muscular. Dois estudos foram desenvolvidos. No primeiro estudo, com auxílio de sistema de dinamometria e cinemetria, testes preliminares foram realizados para definir a posição articular e a magnitude da resistência que o TE deveria fornecer para compensar a queda da carga externa durante a realização do exercício de extensão de joelho (EJ) em uma máquina de musculação. Foi determinado que os TEs deveriam oferecer resistência a partir de um ângulo correspondente a um terço do final da fase concêntrica. Ademais, um percentual de queda da carga externa em diferentes velocidades foi obtido e usado para escolher entre os TEs previamente calibrados o que melhor era capaz de compensar a queda da carga externa. No segundo estudo, 22 sujeitos, divididos em grupo com TEs anexados à máquina (CTE) e grupo sem TEs (STE), foram submetidos a um protocolo de treinamento progressivo com exercício de EJ realizado três vezes por semana, com duração de 14 semanas. Em três ocasiões distintas, os sujeitos foram submetidos a realização de teste de uma repetição máxima, teste de contração voluntária máxima isométrica em quatro posições articulares distintas, salto sem contramovimento (SSC) e teste de contração voluntária máxima isocinética. Foram consideradas como variáveis dependentes a força máxima isométrica (FMiso), a força máxima dinâmica isotônica (FMdin), o torque máximo isocinético (TMcin), a potência muscular e a altura do salto (avaliados por meio do SSC). Como variáveis independentes foram considerados os grupos (CTE e STE) e o tempo de treinamento. ANOVA de dois caminhos (grupo e tempo) com medidas repetidas no tempo foi usada pra verificar os efeitos principais e interações entre as variáveis. (α = 0,05). Como resultado, foi observado que o grupo CTE apresentou valores de força máxima isométrica no final da ADM cerca de 40% maiores quando comparado ao grupo STE. Entretanto, não foram observados efeitos principais ou interações nos demais parâmetros de força avaliados. Como aplicação prática, o uso de TEs combinados ao exercício de EJ na máquina avaliada pode ser útil quando o objetivo do treinamento é obter maiores ganhos de força isométrica na porção final da ADM ou ainda obter maior controle da carga escolhida durante uma maior porção do movimento dinâmico. / It has been documented that a disadvantage of the use free weights or exercise machines is that there is a resultant acceleration effect on the mass of the implement used during the dynamic exercises, which modifies the magnitude of the external load. The consequence of this is that the chosen load for the exercise may fluctuate above or below that intended load during the range of motion (ROM). However, there is a scarcity of studies that defined the methodology of application of elastic tubing (ET) in exercise machines or that verified the chronic effect of the use of ET and exercise machines on muscular strength parameters. Thus, the aims of the study were to develop a methodology of implementation to ET at exercises machines and to compare the effects of use of dynamic exercise adapted with ET with use of dynamic exercise without ET on the muscular strength during a strength training program. Two studies were performed. In the first study, using dynamometric and cinematic system, tests were performed earlier to define the magnitude of resistance which ET should offer so that compensates the decrease in the external load. As a result, it was determined that ET should offer resistance from the degree corresponding to third at the end of the concentric phase. Nevertheless, a percentage of decrease in the external load in relation to chosen load at different velocities was obtained and used to choose between the calibrated ET which one that was able to compensate the decrease in the external load. In the second study, twenty two subjects from both sexes, divided between into group with ET attached at machine (ETA) and group without ET attached to machine (WET) were submitted to the progressive training protocol using exercise of knee extension, performed 3 times per week, during 14 weeks. In three distinct situation (0, 7 and 14 weeks) the subjects was submitted to performing of the one repetition maximum, maximum voluntary contraction isometric at four different angles of knee flexion, vertical jump without a countermovement movement (SJ) and maximum voluntary contraction isokinetic. The dependent variables used in this present study were the maximal isometric strength, the maximal dynamic strength, the maximal torque isokinetic, the power strength and height of jump (available during the SJ). The independent variables were the group (ETA and WET) and the training time. ANOVA - two ways (group and time) with repeated measures in time was used to verify the main effects and interactions between the variables (α = 0.05). As a main result, it was observed that the group ETA presented values of maximal strength isometric in the end of the ROM about 40% greater when it was compare with the group STE. However, it was no found main effects or interactions between other parameters of strength. As the practical application, the combining elastic tubing with exercise of knee extension in a specific machine can be use when the goal of training program is obtain greater strength in the final portion of extension knee or obtain better control of the chosen load during greater portion of dynamic movement.

A resistência elástica é aplicada amplamente em programas de fortalecimento muscular nos processos de reabilitação física. No entanto, as conseqüências biomecânicas para o músculo exercitado com esta forma de sobrecarga são pouco estudadas. A ausência de fundamentação científica no que tange a aplicação da resistência elástica fez com que surgissem algumas suposições a respeito de sua caracterização biomecânica. Uma delas sugere que o exercício com resistência elástica pode ser caracterizado como sendo isocinético. Neste contexto, o objetivo global deste trabalho foi o de caracterizar o comportamento biomecânico do músculo quadríceps femoral frente ao exercício com resistência elástica. Tal caracterização foi realizada através da utilização de um modelo biomecânico bidimensional da articulação do joelho. O seu comportamento mioelétrico também foi avaliado. Conclui-se de uma forma geral, que o desenvolvimento deste estudo permitiu um entendimento a respeito da interação biomecânica entre o músculo e a resistência elástica durante o exercício. Permitindo dessa forma elucidar algumas questões ligadas a aplicação clínica desta modalidade de exercício / The elastic resistance is applied in programs of muscular fortification in processes of physical rehabilitation. However, the biomechanicals consequences for the muscle exercised with this resistance form aren’t very studied. The low scientific fundamentation for the application of the elastic resistance, results in some suppositions about its biomechanic characterization. One of them suggests that the exercise with elastic resistance can be characterized as isokinetic. In this context, the global objective of this work was characterizing the biomechanic behavior of the quadriceps muscle front to the exercise with elastic resistance. Such characterization was accomplished through the use of a bidimensional biomechanic model of the knee joint. The electromiographic behavior was also evaluated. In a general conclusion, the development of this study allowed an understanding of the biomechanic interaction between the muscle and the elastic resistance during the exercise. Allowing to elucidate some subjects of the clinical application of this exercise modality

Progressive overload through the range of motion (ROM) is important for proper rehabilitation of muscle strength, yet varies across types of resistance for a given exercise. The purpose of this study was to compare strength curves (SC) for shoulder internal (IR) and external rotation (ER) with resistance curves (RC) for two application angles (A and B) of Thera-Band® resistance to determine which application angle best overloads IR and ER through the ROM. Thirty volunteer subjects participated in this study. SCs were obtained experimentally by measuring maximal isometric torque for IR and ER from 30° to 135°. RCs were calculated using regression equations from the literature. Significant differences (p < 0.05) were found between the SCs and RCs for both application angles during IR and ER. The findings of this study indicate that application angles A and B do not provide optimal loading when performing shoulder IR and ER exercises.

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. COPD is a slowly progressive, inflammatory disease in the airways and lungs, caused mainly by smoking. The inflammation leads to a narrowing of the small airways (airway obstruction) and a destruction of tissue in the lungs. This gives a decreased expiratory airflow which leads to dyspnea, the primary symptom of the disease. The chronic airflow limitation also is associated with the development of limb muscle dysfunction. Decreases in both limb muscle strength and endurance have been shown which, in turn, is associated with exercise intolerance, one of the key disabling factors of the disease. Pulmonary rehabilitation including exercise training is the cornerstone of treatment and is strongly recommended. However, it is still unclear how to optimize exercise training for this group of patients. Also how to address the increase in dyspnea which limits the exercise stimulus, and how to assess muscular strength, need further study. Partitioning the exercising muscle mass, known as single limb exercises, is a novel exercise strategy aimed at reducing the negative consequences of chronic airflow limitation in patients with COPD. The aim of this thesis was to study the current evidence of single limb approaches in patients with COPD, to examine the feasibility and effects of a high-repetitive single limb exercise (HRSLE) regimen in patients with COPD and to examine whether elastic resistance could be used to evaluate muscular strength. This thesis is based on five papers. In order to study the evidence on single limb exercises, a systematic review of randomized controlled trials was performed. The review showed that single limb exercises, performed as one-legged cycling appeared to be more effective than two-legged cycling with regard to exercise capacity but not dyspnea, and might be included in exercise programs for patients with COPD (Paper I). Thirty healthy older women and men participated in a validation study comparing elastic resistance maximal strength with isokinetic dynamometry measurements. Excellent levels of agreement and no differences between the two pieces of equipment were found which indicates that elastic resistance could be used to evaluate muscular strength (Paper II). A study protocol was created for a randomized controlled trial designed to identify the effects of HRSLE in combination with COPD-specific patient training (experimental group) in comparison to patient information alone (control group) (Paper III). HRSLE was performed as resistance training, using a single limb at a time, elastic bands as resistance and a high number of repetitions (25 repetitions in 2 sets) with the aim of increasing limb muscle endurance. After eight weeks of exercise, the differences between the groups were in favor of the experimental group on lower- and upper-extremity functional capacity, upper-extremity endurance capacity and muscular function. No differences were seen between the groups on endurance-cycle capacity or health-related quality of life (Paper IV). In patients with COPD, the HRSLE regimen was considered feasible with a high attendance rate, excellent compliance and high relative exercise intensity. No severe adverse events occurred. The physiotherapists conducting the HRSLE in the clinical setting also found it to be feasible (Paper V). This thesis shows that single limb exercises performed as one-legged cycling may be useful and effective for patients with COPD. Eight weeks of HRSLE was feasible and effective with regard to exercise capacity but without effect with regard to health-related quality of life. Elastic resistance could be used as exercise equipment to improve limb muscle function in patients with COPD and to evaluate muscular strength in healthy older adults. / Kroniskt obstruktiv lungsjukdom (KOL) är idag ett stort globalt problem.  KOL är en långsamt fortskridande inflammatorisk sjukdom i luftvägar och lungor, i huvudsak orsakad av cigarrettrökning. Inflammationen leder till en förträngning i de små luftvägarna och förstör vävnaden i lungorna. Detta medför en luftvägsobstruktion där flödet av luft vid utandning är minskat, vilket bidrar till varierande grad av andnöd hos patienten. Luftvägsobstruktionen är relaterad till försämrad muskelfunktion hos patientgruppen. Både nedsatt muskulär styrka och uthållighet har påvisats vilket är relaterat till ett av huvudproblemen vid KOL; nedsatt förmåga till fysisk aktivitet och träning.  Lungrehabilitering inklusive fysisk träning är centralt i behandlingen och starkt rekommenderat. Det är dock inte fastställt hur patientgruppen skall träna för att optimera effekterna av träningen eller hur träningen bäst kan utvärderas. Det är också oklart hur man skall hantera den successivt ökande andfåddheten vid träning. Träning med en arm eller ett ben i taget, så kallad lokal muskelträning är en strategi som syftar till att minska andnöd under träning hos patienter med KOL Syftet med denna avhandling var att undersöka vilken evidens det finns för lokal muskelträning hos patienter med KOL, utvärdera genomförbarhet och effekter av lokal högrepetitiv muskelträning utfört med elastiska träningsband hos patienter med KOL samt att undersöka ifall elastiska träningsband kan användas för att utvärdera muskelstyrka. Avhandlingen består av fem delstudier. För att undersöka evidens för lokal muskelträning genomfördes en systematisk litteraturgranskning av randomiserade kontrollerade studier. Granskningen visade att lokal muskelträning, i form av cykling med ett ben i taget kan vara effektivt, avseende fysisk förmåga, men utan effekt avseende andfåddhet för patienter med KOL (delstudie 1). Trettio friska kvinnor och män, deltog i en valideringsstudie där jämförelser gjordes mellan maximal kraftutveckling utfört med elastiska träningsband och en isokinetisk dynamometer. Ett högt samband mellan de två metoderna och ingen skillnad i maximal kraft, indikerade att elastiska band kan användas för att utvärdera muskelstyrka (delstudie 2). Ett studieprotokoll skapades för en randomiserad kontrollerad studie, som syftade till att undersöka effekterna av lokal högrepetitiv muskelträning i kombination med KOL-specifik patientutbildning (interventionsgrupp) jämfört med enbart KOL-specifik patientutbildning (kontrollgrupp) (delstudie 3). Lokal högrepetitiv muskelträning utfördes i grupp med elastiska träningsband som redskap. Övningarna genomfördes med en arm eller ett ben i taget med 25 repetitioner i 2 set med syfte att påverka muskulaturens uthållighet. Efter åtta veckors träning hade interventionsgruppen bättre muskelfunktion i både övre och nedre extremitet samt en bättre funktionell förmåga jämfört med kontrollgruppen. Inga skillnader i effekt sågs mellan grupperna avseende uthållighet vid test på ergometercykel eller avseende hälsorelaterade utfallsmått, såsom livskvalitet och tilltro till sin egen förmåga (delstudie 4). För patienter med KOL, visade sig lokal högrepetitiv muskelträning vara en genomförbar metod avseende följsamhet och närvaro i träningen. De fysioterapeuter som ledde träningen i klinisk verksamhet ansåg att den var möjlig att genomföra med hög relativ intensitet och utan allvarliga biverkningar (delstudie 5). Sammanfattningsvis visar denna avhandling att lokal muskelträning kan vara en användbar och effektiv metod för patienter med KOL. Åtta veckor med lokal högrepetitiv muskelträning är genomförbart och effektivt avseende fysisk förmåga hos dessa patienter. Elastiska träningsband kan användas som träningsredskap för att förbättra muskelfunktion hos patienter med KOL samt för att utvärdera muskelstyrka hos friska vuxna.