This thesis presents the development and experimental testing of a lower-limb exoskeleton system. The device supplies assistive torque at the knee joint to alleviate the loading at the knee, and thus reduce the muscular effort required to perform activities of daily living. The hypothesis is that the added torque would facilitate the execution of these movements by people who previously had limited mobility. Only four specific movements were studied: level-waking, gradient-walking, sit-to-stand-to-sit and ascending stairs. All three major components of the exoskeleton system, i.e. the exoskeleton actuators and actuator control system, the user intention estimation algorithm, and the mechanical construction of the exoskeleton, were investigated in this work. A leg brace was fabricated in accordance with the biomechanics of the human lower-limb. A single rotational degree of freedom at the knee and ankle joints was placed to ensure that the exoskeleton had a high kinematic compliance with the human leg. The position of the pneumatic actuators and sensors were also determined after significant deliberation. The construction of the device allowed the real-world testing of the actuator control algorithm and the user intention estimation algorithms. Pneumatic artificial muscle actuators, that have high power to weight ratio, were utilized on the exoskeleton. An adaptive fuzzy control algorithm was developed to compensate for the inherent nonlinearities in the pneumatic actuators. Experimental results confirmed the effectiveness of the adaptive controller. The user intention estimation algorithm is responsible for interpreting the user's intended movements by estimating the magnitude of the torque exerted at the knee joint. To accomplish this, the algorithm utilizes biological signals that emanate from the knee extensor and flexor muscles when they are activated. These signals combined with the knee angle data are used as inputs to the estimation algorithm. The output is the magnitude and direction of the estimated torque. This value is then scaled by an assistance ratio, which determines the intensity of the assistive torque provided to the user. The experiments conducted verify the robustness and predictability of the proposed algorithms. Finally, experimental results from the four activities of daily living, affirm that the desired movements could be performed successfully in cooperation with the exoskeleton. Furthermore, muscle activity recorded during the movements show a reduction in effort when assisted by the exoskeleton.

The aim of the study was to examine the muscle activities of fifteen male participants (23.44 ±2.63 years) during unilateral hockey bag load carrying of different weights (10%, 20%, and 30% bodyweight) and sizes (small and large). Walking without a hockey bag was the control condition. The results showed that increased peak and integrated EMG occurred with an increased load weight in the semitendinosus, gastrocnemius, rectus abdominis, and vastus medialis. The left rectus femoris and left semitendinosus were both significantly greater than the right corresponding muscle. Carrying the large hockey bag produced greater peak EMG in the right rectus abdominis and the right rectus femoris, whereas the right vastus medialis showed a larger peak EMG in the small hockey bag. It was concluded that the posterior-lateral carrying style of hockey bag load carriage explained the results being similar to both backpack and side pack load carriage studies.

Master of Science / Department of Animal Sciences and Industry / John M. Gonzalez / Pigs fed ractopamine-HCl (RAC) are more prone to fatigue and exhaustion when improperly handled. Wireless electromyography (EMG) can be used to directly measure median power frequency (MdPF) and root mean square (RMS) as indicators of action potential conduction velocity and muscle fiber recruitment, respectively. The objectives of this study were to determine the effect of RAC on exhaustion, EMG measures, and muscle fiber type characteristics when barrows were subjected to increased levels of activity. Thirty-four barrows were assigned to one of two treatments: a commercial finishing diet containing 0 mg/kg (CON) RAC or a diet formulated to meet the requirements of finishing barrows fed 10 mg/kg RAC (RAC+) for 35 d. After 32 d of feeding, barrows were walked around a circular track at 0.79 m/s until subjective exhausted was reached. Time, distance, and speed were measured. Wireless surface EMG sensors were affixed to the Deltoideus (DT), Triceps brachii lateral head (TLH), Tensor fasciae latae (TFL), and Semitendinosus (ST) muscles. After harvest, samples of each muscle were collected for fiber type, succinate dehydrogenase, and capillary density analysis. Speed was not different (P = 0.82) between treatments, but RAC+ barrows reached subjective exhaustion quicker and covered less distance than CON barrows (P < 0.01). The end-point MdPF was not affected by the RAC diet. The RAC diet did not change end-point RMS values in the DT or TLH; however, the RAC+ barrows tended to have decreased ST and increased TFL end-point RMS values (P < 0.07). The percentage of type I fibers tended to be greater (P = 0.07) in RAC+ barrows, but the RAC diet tended to increase (P = 0.07) size of type I fibers and increase (P = 0.03) the size of type IIA fibers. Succinate dehydrogenase was not different between treatments. The RAC+ barrows had more (P = 0.03) capillaries per fiber than CON barrows. A diet containing RAC contributes to increased onset of subjective exhaustion, possibly due to rapid loss of active muscle fibers and chronic loss of oxidative muscle fibers with no change in muscle metabolism.

O objetivo deste estudo foi de analisar a confiabilidade teste reteste do posicionamento dos eletrodos na aquisição do sinal eletromiográfico dos músculos do antebraço na tarefa de preensão palmar, por meio de dois posicionamentos. O primeiro posicionamento proposto por Cram; Durie e o segundo proposto por Mogk; Keir. Foram recrutados 30 voluntários sendo divididos em 2 grupos com 15 indivíduos cada. O primeiro grupo era formado por indivíduos saudáveis, isto é, que não apresentavam qualquer patologia, trauma ou dor no membro superior. Este grupo era composto por 13 mulheres e 2 homens com idade média de 23,4 anos, sendo 13 destros e 2 canhotos. O segundo grupo era formado por indivíduos que apresentavam algum trauma no antebraço, punho ou mão, recrutados no centro de reabilitação e no ambulatório de cirurgia do membro superior do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo. A amostra era composta por 13 homens e 2 mulheres com idade média de 34,6 anos, sendo 14 destros e 1 canhoto. Todos os participantes assinaram o Termo de Consentimento Livre e Esclarecido. O procedimento foi realizado em dois dias com diferença de 24h entre as avaliações. A avaliação consistia em realizar a tarefa de preensão palmar com o dinamômetro analógico da marca Jamar® , realizando a máxima contração voluntária pelo período de 10 segundos com repouso de 3 minutos entre cada preensão, sendo coletados o sinal eletromiográfico de sete canais dos músculos do antebraço volar e dorsal, segundo cada método. Foi analisada a confiabilidade pelo índice de ICC e o SEM (Standard Error of Measurement). Os resultados obtidos mostram excelente correlação entre os dois posicionamentos em ambos os grupos. Quando verificado o valor de ICC do grupo de saudáveis verificou valores acima de 0.75 em todos os canais, o que demonstrou uma alta correlação entre as medidas em ambos os posicionamentos, com pequeno SEM. No grupo pacientes foi observado que nos músculos FUC, FSD e ERC uma correlação moderada para o posicionamento Mogk; Keir e somente no músculo FRC apresentou correlação moderada no posicionamento Cram; Durie. Os gráficos de Bland e Altman mostraram alta concordância entre as medidas, visto que, em ambos os posicionamentos, os valores ficaram entre o intervalo de confiança de 95% e próximos da linha média. Como conclusão pode-se inferir que ambos os posicionamentos apresentaram alta confiabilidade e alta correlação quando avaliado por meio do teste e re-teste, podendo ser utilizados para medida eletromiográfica dos músculos do antebraço / The objective of this study was to analyze test retest reliability of the electrodes placement in the acquisition of electromyography forearm muscles during a isometric hand grip task, through two different methods. The first method was proposed by Cram; Durie and the second by Mogk; Keir. We recruited 30 volunteers divided into 2 groups with 15 subjects each. The first group consisted of healthy subjects, who did not show any pathology, trauma or pain in the upper extremity. This group consisted of 13 women and 2 men with a mean age of 23.4 years, and 13 right-handed and 2 left-handed. The second group consisted of individuals who had previous trauma on the forearm, wrist or hand. They were recruited from the rehabilitation center and upper limb surgery clinic of the Medical School of Ribeirão Preto Clinical Hospital. The sample consisted of 13 men and 2 women with a mean age of 34.6 years, 14 right-handed and left-handed one. All participants signed the consent form. The procedure was performed in two days with 24 hours difference between assessments. The evaluation was to carry by a isometric handgrip task with a analog dynamometer Jamar®, with maximum voluntary contraction for 10 seconds with 3 minutes of rest and analised by CCI and SEM (Standard Error of Measurement) . The results obtained have a high correlation between the two methods in both groups. Analyzing the ICC value of the healthy group value noted above 0.75 in all channels, demonstrating a excelent correlation between the measurements in both positions and low SEM. Checking in group patients realize that the FUC, FSD and ERC muscles has a moderate correlation for Mogk; Keir positioning and only on FRC showed moderate correlation in Cram; Durie electrode placement method. Analyzing Bland and Altman method a high concordance was found between the measures, since in both positions, the values were between the confidence interval of 95% and close to the midline. Through this we can infer that both positions have high reliability and high correlation when measured by the test and retest

O objetivo deste estudo foi avaliar a confiabilidade intradia e interdias dos valores de amplitude da eletromiografia de superfície, dos músculos da cintura escapular e membro superior, durante a realização de 3 exercícios isométrico com a extremidade distal do segmento fixa em uma superfície estável e outra superfície instável, com descarga de peso axial controlada para o membro superior. Para tanto, 20 adultos saudáveis realizaram os exercícios push-up, bench-press e wall-press em diferentes níveis de carga (80 e 100% da carga máxima). Os valores de carga produzida por cada um dos exercícios foram registrados de maneira simultânea à eletromiografia. Os sujeitos realizaram três contrações voluntárias máximas (CVM) na posição de prova de função muscular de cada músculo, para obtenção do valor de referência para normalização dos valores de root mean square (RMS) e da integral do envoltório linear (?env). Os sujeitos foram instruídos, a realizarem de forma aleatória, 3 séries de contrações isométricas por 6 segundos em cada exercício, com intervalo de 2 minutos entre as séries e exercícios.Os sinais eletromiográficos dos músculos deltóide porção anterior e posterior, trapézio fibras superiores, serrátil anterior, peitoral maior porção clavicular, bíceps braquial porção longa e tríceps braquial porção longa foram captados por eletrodos de superfície ativos simples diferenciais, realizados em dois testes com intervalo de sete dias. Os dados foram coletados com freqüência de amostragem de 4000Hz e aplicados filtros digitais de passa baixa de 500Hz e passa alta de 20Hz. Os valores de RMS e ?env foram normalizados pelo valor máximo da amplitude eletromiográfica obtida em 1 das 3 CVM do músculo correspondente. As confiabilidades intradia e interdias foram calculadas através do coeficiente de correlação intraclasse (ICC), erro padrão da medida (SEM) e coeficiente de variação (CV). Os resultados indicaram excelente confiabilidade intradia dos valores de amplitude eletromiográfica (ICC ?0,75). A confiabilidade interdias dos valores normalizados de RMS apresentou valores variando entre bom e excelente (ICC 0,52-0,98), já os valores normalizados de ?env apresentaram valores pobres a excelente de confiabilidade (ICC 0,06-0,93). Os valores de carga produzidos durante os exercícios apresentaram excelente confiabilidade intradia e interdias (ICC ?0,97). Por fim, os resultados do presente estudo sugerem que a confiabilidade dos valores normalizados de amplitude eletromiográfica dos músculos analisados apresentam valores mais confiáveis durante os exercícios realizados com superfície estável. Já os níveis de carga empregados (80 e 100%) durante os exercícios parecem não ter influenciado nos níveis de variabilidade, talvez por serem cargas muito próximas. / The objective of the present study was to evaluate the intra and interday reliability of surface electromyography amplitude values of the scapular girdle muscles and upper limbs during the performance of 3 isometric exercises of closed kinetic chain regarding the upper limbs with the fix distal segment extremity on one stable surface and the other one on one unstable surface. In this regard, 20 healthy adults realized the exercises push-up, bench-press and wall-press with different load levels (80 and 100% maximal load). The load values produced for each exercise were recorded simultaneously to the electromyography. The individuals performed three maximal voluntary contractions (MVC) in the muscular testing position of each muscle for the obtainment of the reference value for the root mean square (RMS) normalization values and for the integrated of the linear envelope (?env). The individuals were instructed to realize at random, 3 isometric contraction series taking each exercise 6 seconds with a rest of 2 minutes between the series and the exercises. The electromyographic signals of the anterior and posterior deltoid, upper trapezius, anterior serratus, pectoralis major, biceps and triceps brachial muscle were captured by simple active differential surface electrodes, in two tests with a 7-day interval. Data were collected with a sampling frequency of 4000Hz and 500Hz low and 20Hz high passage digital filters. The RMS and ?env values were normalized by the maximal electromyographic amplitude value obtained in 1 of the 3 MVC of the corresponding muscle. The intra and interday reliabilities were calculated through the intraclass correlation coefficient (ICC), standard error measure (SEM) and coefficient of variation (CV). The results indicated an excellent intraday reliability of the electromyographic amplitude values (ICC ?0.75). The interday reliability of the RMS normalized values presented values varying between good and excellent (ICC 0.52-0.98), whereas the ?env normalized values presented poor to excellent reliability values (ICC 0.06-0.93). The load values produced during the exercises presented excellent intra and interdays reliability. Finally, the results of the present study suggest that the reliability of the electromyographic amplitude normalized values of the analyzed muscles present better values during the performance of the exercises with stable surface. However the load levels utilized during the exercises do not seem to have influenced the variability levels, eventually in view of being very close levels

Orientador: Mônica Fernandes Gomes / Banca: José Elias Matieli / Banca: José Benedito Oliveira Amorim / Resumo: Esta pesquisa avaliou por meio de análise eletromiográfica de superfície (EMGs)os efeitos terapêuticos de um dispositivo intrabucalsobre as atividades elétricas dos músculos masseter (porção superficial) e temporal (porção anterior), bilateralmente, em pacientes com síndrome de Down. A amplitude de abertura bucal, a intensidade de força mastigatória total (FMT) foram, também, investigadas por meio de paquímetro e transdutor de força. Adicionalmente, medidas antropométricas, incluindo índice de massa corporal (IMC), circunferências do pescoço (P) e abdominal (A) e relação cintura e quadril (RCQ) foram analisadas antes e após dois meses de terapia com DM. Dez pacientes com síndrome de Down, adultos, de ambos os gêneros, foram submetidos a uma terapia com um dispositivo mastigatório (DM). Os registros eletromiográficos foram realizados para avaliar a atividade elétrica dos músculos masseter e temporal, antes e após a terapia preconizada.Diante dos resultados obtidos, conclui-se que o DM promoveu diminuição das atividades elétricas do músculo temporal em condição de repouso da mandíbula e aumento da abertura bucal, conferindo um possível equilíbrio no sistema muscular mastigatório. A atividade elétrica na contração isométrica do músculo masseter e temporal foi aumentada, sugerindo uma maximização nas unidades motoras. A discreta redução do IMC e da RCQ indica, provavelmente, uma melhoria na distribuição de gordura corporal dos pacientes.Portanto, o DM colaborou para a melhoria do... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This research evaluated the therapeutic effects of an intrabuccal device on the electrical activities of the masseter (superficial portion) and temporal (anterior portion) muscles, bilaterally, in patients with Down syndrome by means of surface electromyographic analysis (EMGs). The mouth opening amplitude and the total masticatory force intensity (FMT) were also investigated by means of a pachymeter and force transducer. In addition, anthropometric measurements, including body mass index (BMI), neck (P) and abdominal (A) circumference and waist and hip ratio (WHR) were analyzed before and after two months of DM therapy. Ten patients with Down syndrome, adults of both genders, underwent masticatory (DM) therapy. The electromyographic records were performed to evaluate the electrical activity of the masseter and temporal muscles, before and after the recommended therapy. In view of the obtained results, it was concluded that DM promoted a decrease in the electrical activities of the temporal muscle in a condition of rest of the mandible and increase of the buccal opening, conferring a possible balance in the muscular masticatory system. The electrical activity in the isometric contraction of the masseter and temporal muscle was increased, suggesting a maximization in the motor units. The discrete reduction in BMI and WHR probably indicates an improvement in patients' body fat distribution. Therefore, DM collaborated to improve the biomechanical performance of mastication / Mestre

Despite the higher incidence of anterior cruciate ligament injuries in pediatric female populations, limited research has investigated sex-differences in youth biomechanics. Furthermore, research involving jump mechanics typically requires participant to follow a set protocol, such as sticking the landing. To reduce variability and improve reliability, trails where participants fail to meet the required protocol are discarded; however, significant clinical findings may be elucidated from these trials. The purpose of this thesis was to provide a complete biomechanical analysis of unanticipated single-leg drop-jump landings in youth athletes. Thirty-two healthy youth athletes completed unanticipated single-leg drop-jump landings on their dominant limb. Trials where participants shifted foot position or touched the ground with the contralateral leg were categorized as failed. Drop-jump landings were time-normalized using landmarks within the drop-jump task. Statistical parametric mapping (SPM) determined time-varying sex-differences in muscle onset time, co-activation, kinematics and kinetics. Wilcoxon signed-rank tests and paired sample t-tests compared lower-limb kinematics, centre-of-mass excursion and muscle activation amplitudes during the successful and failed landings. A logistic regression model was also fit to predict the likelihood of a successful landing. SPM identified significantly greater trunk flexion angle in males during the deceleration, flight, and landing phase of the drop-jump. Greater quadriceps-gastrocnemius co-activation was identified during the flight phase in female participants and independent sample t-test identified longer muscle onset time in the vastus lateralis of male participants. When comparing failed and successful landings greater hip abduction and less external rotation angles were observed during the successful trials. In addition, greater preparatory muscle activation was observed in the rectus femoris and semitendinosus during the flight phase of the failed landings. A logistic regression model, which included eight kinematic and neuromuscular variables, offered a training classification accuracy of 70% and a leave-one-out cross-validation accuracy of 65%. In conclusion, females land in a more erect posture and may be less effective at dissipating landing forces. In addition, greater co-activation and shorter pre-activations of the lower limb musculature may indicate a less effective muscle activation strategy in females. Furthermore, hip kinematics and the surrounding musculature play an important role in controlling successful and failed unanticipated landings. The variables included in the logistic regression model indicate which key factors are linked to landing a jump successfully. Training modalities aimed at improving landing mechanics should therefore focus on modifying these variables.

Made available in DSpace on 2014-06-11T19:30:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-09-15Bitstream added on 2014-06-13T20:21:20Z : No. of bitstreams: 1 melo_sg_dr_rcla.pdf: 609577 bytes, checksum: a9d51fbcdf884c8d8bd0fca73bb98fef (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A fadiga muscular é definida como a incapacidade que o músculo esquelético tem de gerar ou manter elevados níveis de força e potência muscular durante determinado tempo. Ela pode está associada a exercícios submáximos e/ou máximos, respondendo com diminuição da velocidade de contração das fibras musculares e aumento do tempo de relaxamento da musculatura trabalhada. Muitos estudos têm utilizado a eletromiografia de superfície (EMGs) para caracterizar a fadiga pelo aumento induzido da amplitude do sinal EMG, assim como investigar os mecanismos fisiológicos e biomecânicos associados ao processo de instalação da fadiga neuromuscular. O objetivo desse estudo foi analisar metodologias empregadas na determinação do limiar eletromiográfico na fadiga muscular (LFEMG), visando a comparação entre os métodos quanto a capacidade de determinar um índice de limiar anaeróbio eletromiográfico fidedigno. Participaram da pesquisa 10 jogadores amadores de futsal com médias de idade 20,8 anos, massa corpórea de 67,3kg e estatura de 1,75m. Executaram um protocolo incremental de corrida em esteira para análise do LFEMG. Foi utilizada a eletromiografia de superfície para músculos do membro inferior e coletados dados como amplitude do sinal e frequência mediana. Posteriormente os dados relativos à eletromiografia foram verificados quanto à normalidade (Shapiro-Wilk) e analisados (ANOVA) através do software SPSS. Os resultados confirmam a proposta de que o limiar de fadiga neuromuscular pode ser identificado por meio da análise do comportamento do sinal eletromiográfico durante o protocolo incremental de corrida, como observado em estudos anteriores, e que os métodos pesquisados não apresentam diferenças estatisticamente significativas entre eles, contudo necessitam-se padrões metodológicos mais confiáveis e reprodutíveis para determinação de índices de fadiga neuromuscular através da análise do sinal EMG / Muscle fatigue is defined as the inability the skeletal muscle has to generate or maintain high levels of muscle strength and power during a given time. It can submaximal exercise be associated with and / or maximum response with a decrease in speed of contraction of muscle fibers and increased time of relaxation of the muscles worked. Many studies have used surface electromyography (EMG) to characterize the fatigue induced by the increase of the amplitude of the EMG signal as well as investigate the physiological and biomechanical mechanisms associated with the installation process of neuromuscular fatigue. The aim of this study was to analyze the methodologies used in determining the electromyographic fatigue threshold (FTEMG) in order to compare the methods for their ability to determine an reliable index of anaerobic threshold electromyographic. 10 players of amateur soccer participated in the research with average age 20.8 years, body mass index of 67.3 kg and height 1.75 m. They performed an incremental protocol of treadmill running for FTEMG analysis. We used surface electromyography to lower limb muscles and collected as signal amplitude and median frequency. Subsequently, data were normalized relative to the electromyography (Shapiro-Wilk) analyzed (ANOVA) by SPSS software. The results confirm the proposal that the neuromuscular fatigue threshold can be identified by analyzing the behavior of electromyographic signals during incremental running protocol, as observed in previous studies, and that the methods surveyed have no statistically significant differences between them, however, more reliable and methodological standards for reproducible determination of indices of neuromuscular fatigue by EMG signal analysis are required

Osteoarthritis (OA) of the knee is a common condition. The condition causes pain and swelling in the knee joint and as a consequence knee range of motion, particularly knee extension, can be decreased. While a number of studies have indicated increases in knee extension range of motion (ROM) can be achieved following stretching interventions, these studies have been undertaken in young healthy populations mostly. To date, there have been no investigations of stretching as a single intervention in people with OA knee. Review of Literature: To gain an appreciation of the literature in this area, three structured literature reviews were undertaken. The first examined the efficacy of acute stretching interventions on lower limb joint ROM in young and elderly subjects, the second examined the efficacy of periodic muscle stretching interventions on lower limb joint ROM in elderly subjects and the third examined the efficacy of periodic muscle stretching interventions on ROM in subjects with OA of the knee joint. The results of the first review indicated that there is strong evidence for acute stretching interventions to increase joint ROM in the lower limb of young and elderly subjects. The results of the second review indicated that there is strong evidence for periodic stretching interventions to increase joint ROM in the lower limb of elderly subjects. The result of the third review indicated that there is limited evidence for stretching interventions alone to improve ROM in the lower limb in subjects with OA of the knee joint. As consequence of these findings two studies were designed to investigate the effects of acute and periodic stretching in people with OA of the knee joint. Study 1 Objective: The objective of this study was to investigate the effects of an acute hamstring-stretching programme on knee extension range of motion in individuals with osteoarthritis (OA) of the knee and compare them to individuals of a similar age without OA of the knee. Study Design: A cross sectional study design was used. Participants: Thirty one subjects (16 male and 15 female) with OA of the knee were recruited from the local population (mean age 67.8 yrs SD: 5.0, mass 81.4 kg, SD: 15.2, height 168.5 cm, SD 11.1). Thirty one subjects of a similar age (9 male and 23 female) were also recruited who were otherwise fit and healthy and did not have OA of the knee (mean age 68.8 yrs SD: 5.2, mass 71.4 kg, SD: 13.2, height 163.8 cm, SD 8.1). Method: Hamstring extensibility was assessed by a passive knee extension test using a Kincom® isokinetic dynamometer. Subjects undertook two trials of maximum knee extension. The Kincom® then stretched the hamstrings to a point determined as 80% of the initial maximum knee extension test. Three sets of 60 seconds stretching were undertaken with 60 seconds rest between sets. Two further maximal knee extension tests were performed after the stretching intervention. The variables of interests were maximal knee extension, peak passive torque and stiffness. Analysis: A 2-factor repeated measures ANOVA model was utilised. The alpha level was set at 0.05. Results: There was a significant main effect by time for knee extension ROM, peak passive torque and stiffness (p<0.05). There was no interaction effect between groups across time (p>0.05). Knee extension range of motion (ROM) in the OA group increased significantly from 75.6 (SD: 17.2) degrees to 80.5 (SD: 22.3) degrees after the intervention (p<0.05). Subjects in the non OA group increased significantly from 77.5 (SD: 15.5) degrees to 81.9 (SD: 18.2) degrees after the intervention (p<0.05). The knee extension ROM recorded at 50% of the peak torque level pre intervention for the OA group was 60.3 (SD: 18.7) degrees and this increased significantly to 67.2 (SD 16.7) degrees post intervention (p<0.05). For the non OA group, knee extension ROM at 50% of peak torque increased significantly from 60.1 (SD: 15.2) degrees to 65.8 (SD 16.0) degrees (p<0.05). Peak passive torque in the OA group increased significantly from 18.1 (SD: 9.6) Nm to 22.5 (SD: 12.9) Nm after the intervention (p<0.05). Subjects in the non OA group increased significantly from 21.05 (SD: 11.6) Nm to 22.05 (SD: 12.8) Nm after the intervention (p<0.05). For stiffness, there was a significant interaction effect (p <0.05) between groups across time. The OA group increased significantly from 0.70 (SD: 0.35) Nm/deg to 0.89 (SD: 0.5) Nm/deg after the intervention (p<0.05). Subjects in the non OA group increased significantly 0.78 (SD: 0.36) Nm/deg to 0.82 (SD: 0.42) Nm/deg after the intervention (p<0.05). Conclusions: The study demonstrated that knee extension ROM, passive resistive torque and stiffness increased with a single bout of stretching. These results indicate that both elderly subjects and those with degenerative joint disease are able to demonstrate immediate tissue adaptations with acute stretching interventions. This is important as clinicians often prescribe acute stretching exercises in the preparation for other activities such as strengthening and walking programmes. Improving joint range of motion prior to other subsequent activities may be beneficial to those people with OA in particular, as management guidelines for these populations recommend regular exercise to reduce the deterioration of the condition. Study 2 Objective: The purpose of this study was to investigate the effects of a six week stretching intervention to the key muscles of the lower limb, in people with osteoarthritis (OA) of the knee joint and compare them to individuals of a similar age without OA of the knee. A 12 week follow up was undertaken to see if these effects were maintained following the intervention. This study builds on the effects of an acute stretching intervention as demonstrated in Study 1. Study Design: A randomised control trial design was used. Participants: Forty three subjects (24 OA and 19 non OA) were recruited from the local population (mean age 68.8 yrs SD: 5.0, mass 79.5 kg, SD: 14.6, height 166 cm, SD 9.8). Subjects were randomly allocated by condition to either a stretch group or a control group. Methods: Hamstring extensibility was assessed by a passive knee extension test using a Kincom® isokinetic dynamometer at baseline, following the intervention and at a 12 week follow-up. Subjects in the intervention groups stretched the main lower limb muscles 3 x 60 seconds, 5 days a week for 6 weeks. The control groups did not stretch but received a placebo intervention of interferential current. The variables of interest were maximal knee extension, peak passive torque and stiffness. The following outcome measures were also used to assess activity levels: the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Lower Limb Task Questionnaire (LLTQ) and the Aggregated Locomotor Functional (ALF) score. Analysis: A 3-factor (group x condition x time) repeated measures ANOVA model was utilised. The alpha level was set at 0.05. Results: There was a significant main effect for time and a significant interaction effect for group (stretch and control) by time for knee extension ROM, peak passive torque and stiffness (p<0.05). There was no significant interaction for condition (OA vs non OA) (p>0.05). Subjects in the stretch group had 68.9 (SD: 15.5) degrees of knee extension before the intervention and this increased significantly to 76.8 (SD: 14.4) degrees after the intervention (p<0.05). At the 12 week follow up assessment, subjects had a mean of 72.5 (SD: 20.51) degrees. This difference was not significant when compared to the post intervention assessment (p>0.05). Subjects in the control group were not significantly different for knee extension ROM following the intervention or at the 12 week follow up (p>0.05). For the knee extension ROM at 50% of the maximum torque level, there was a significant main effect for time (p<0.05) but no significant interaction effect between groups across time (p >0.05). The mean knee extension ROM recorded at 50% of the peak torque level for the stretch group pre intervention was 55.9 (SD: 15.0) degrees and this decreased significantly to 50.8 (SD 12.3) degrees post intervention (p<0.05). The mean knee extension ROM recorded at 50% of the peak torque level pre intervention for the control group was 60.2 (SD: 11.4) degrees and this decreased significantly to 57.1 (SD 11.0) degrees post intervention (p<0.05). With respect to peak passive torque subjects in the stretch group were 13.2 (SD: 7.7) Nm before the intervention and increased significantly to 19.7 (SD: 9.5) Nm after the intervention (p<0.05). At the 12 week follow up assessment, the subjects in the stretch group generated a mean peak torque of 20.2 (SD: 11.5) Nm. This difference was not significant when compared to the post intervention assessment (p>0.05). With respect to stiffness, subjects in the stretch group were 0.62 (SD: 0.3) Nm/deg before the intervention and this increased significantly to 0.84 (SD: 0.3) Nm/deg after the intervention (p<0.05). At the 12 week follow up time point, the subjects in the stretch group had a mean stiffness of 0.88 (SD: 11.5) Nm/deg. This increase was not significant when compared to the post intervention assessment (p>0.05). Subjects in the control group were not significantly different for peak passive torque or stiffness following the intervention or at the 12 week follow up. There was no significant difference for time or condition for the WOMAC or LLTQ scores. There was a significant main effect for time for both groups for the ALF score (p<0.05), however there was no significant interaction for time by condition (p>0.05). Subjects in the stretch group had a mean ALF score of 23.1 (SD: 3.9) seconds pre intervention and this reduced significantly to 19.8 (SD: 5.4) seconds post intervention (p<0.05). Subjects in the control group had a mean AFL score of 24.8 (SD: 3.1) seconds pre intervention and this reduced significantly to 22.3 (SD: 3.0) seconds post intervention (p<0.05). Conclusions: The study demonstrated that knee extension range of motion, peak passive torque and stiffness increased in those subjects who undertook the six week stretching programme. Knee extension ROM was not maintained at the 12 week follow up assessment, however peak passive torque and stiffness were. These results indicate that both elderly subjects and those with degenerative joint disease are able to demonstrate long term adaptations with periodic stretching interventions. Functional improvements were also observed following the intervention in the stretch groups and the control groups. As previous studies investigating exercise interventions in subjects with OA of the knee joint have combined stretching and strengthening exercises, this study has provided a clear picture of the effects of stretching alone in this population. However, to gain a more obvious change in function in subjects with OA of the knee joint, the combination of stretching with other exercises such as strengthening, may be required in future studies.

The aim of the study was to examine the muscle activities of fifteen male participants (23.44 ±2.63 years) during unilateral hockey bag load carrying of different weights (10%, 20%, and 30% bodyweight) and sizes (small and large). Walking without a hockey bag was the control condition. The results showed that increased peak and integrated EMG occurred with an increased load weight in the semitendinosus, gastrocnemius, rectus abdominis, and vastus medialis. The left rectus femoris and left semitendinosus were both significantly greater than the right corresponding muscle. Carrying the large hockey bag produced greater peak EMG in the right rectus abdominis and the right rectus femoris, whereas the right vastus medialis showed a larger peak EMG in the small hockey bag. It was concluded that the posterior-lateral carrying style of hockey bag load carriage explained the results being similar to both backpack and side pack load carriage studies.