Evidence suggests that a flexible, task-dependent neuronal coupling of the upper and lower limbs exists, and this allows for coordinated rhythmic movement (e.g., locomotion). To further understand this coupling, muscle activity and reflex patterns can be examined by stimulating peripheral nerves during various tasks. In particular, cutaneous reflexes demonstrate task- and phase-dependent modulation, making them highly sensitive probes into neural activity during rhythmic movement. The purpose of this research was to use reflex modulation to probe the neuronal coupling between the arms and legs. This was done using a cycling paradigm that allowed for the separation of arm and leg movement, which is difficult to do in most forms of locomotion (i.e., walking). Participants (N=14) performed three cycling tasks: 1)arm cycling with stationary legs (ARM); 2)leg cycling with stationary arms (LEG); and 3)combined arm and leg cycling (ARM&LEG). The relative contributions from the arms and legs to reflex modulation in the legs were then determined throughout the movement cycle. It was hypothesized that the individual contributions from arm and leg movement to reflex amplitudes in the legs would summate during the combined arm and leg task. This hypothesis was tested explicitly by comparing the reflex amplitudes expressed during the combined arm and leg task to the algebraic summation of the reflex amplitudes expressed during the arm cycling and leg cycling tasks alone. Static trials were also collected at 4 positions within each task. Tasks were performed under two different cycling conditions: 1) Focused tibialis anterior (TA) contraction (FCC) (N=14); and 2) normal cycling (NC) (n=8). During all trials, stimulation was delivered pseudorandomly throughout the movement cycle to the superficial peroneal nerve at the ankle. EMG was recorded bilaterally from muscles in the arms and legs, and kinematic data were obtained from the elbow and knee joints. Results focused on the middle latency reflex amplitudes in TA (ipsilateral to the site of stimulation) during the FCC condition because the focused contraction did not significantly alter EMG or reflex activity in the other leg muscles studied. This also allowed for comparisons among tasks at comparable EMG levels. The main finding from this study was that reflex amplitudes expressed during the ARM&LEG task agreed with the predicted algebraic summation of reflex amplitudes expressed during the ARM and LEG tasks separately. Examination of the relative contributions from the arms and legs to the reflexes expressed during the combined task revealed that across all movement phases the legs accounted for 33% (p < .05) of the variance observed during the ARM&LEG task, while the arms accounted for an additional 5% (p < .05). The relative contributions from the arms and legs were also found to be phase dependent. That is, the relative contribution from the arms was dominant during the power phase of leg cycling while the leg contribution was dominant during the recovery phase. More specifically, the greatest contribution from the arms accounted for 57% of the variance in the ARM&LEG task when the leg was at 11 o'clock (p < .05) and the greatest contribution from the legs was 71% of the variance accounted for when the legs were at 9 o'clock (p < .05). Additionally, characteristic patterns of reflex amplitude modulation (i.e., phase- and task-dependent modulation) were observed during most of the cycling tasks. In conclusion, these findings suggest evidence for a neuronal coupling between the rhythm generators responsible for arm and leg movement which is functionally gated throughout the movement cycle of a combined arm and leg task.

Rhythmic locomotor activity involving the arms or the legs results in task and phase specific Hoffmann (H)-reflex modulation between the two arms or between the two legs. As well, specific ipsilateral and contralateral movement effects are observed. Recently it has been found that there is also interlimb (between arms and legs) task modulation of the H-reflex, using a rhythmic arm cycling paradigm. That is, the stationary Soleus H-reflex amplitude during arm cycling was attenuated when compared to a static condition (Frigon et al. 2004). The specific parameters of the arm cycling movement which may contribute to this attenuation however are unknown. The purpose of this research was to examine whether the interlimb Soleus H-reflex suppression is specific to: the phase of the arm movement; the movement of both arms; arm excursion; and, rate of arm cycling. Participants sat in a custom designed chair to prevent leg and trunk movement and performed bilateral arm cycling at frequencies of 1 and 2 Hz and with short and long crank lengths (to alter arm range of motion; ROM). As well. ipsilateral (relative to leg stimulated) and contralateral single arm cycling were performed at 1Hz with a long crank length. The Tibial nerve at the popliteal fossa was stimulated psuedorandomly at four phases of the arm cycle and changes in the Soleus H-reflex were recorded while maintaining a small, but stable motor (M)-wave for all trials. EMG was recorded from the Soleus, Tibialis Anterior. Vastus Lateralis and the Anterior Deltoid muscles. Peak to peak amplitudes of the H-reflex from each participant were determined off line and normalized to the M-max determined from individual M-H recruitment curves. Results indicate comparable suppressive effects in all phases of the arm movement, and with bilateral or unilateral cycling. The large ROM and the 2 Hz frequency of movement resulted in a stronger inhibition than with the small ROM and the 1 Hz arm cycling. This suggests that neural processes associated with generating both the rhythmic arm cycling pattern and the peripheral feedback from the arms, have an effect on the H-reflex modulation in the legs. We conclude that a general, rather than a specific, signal related to rhythmic arm muscle activity mediates the suppression of Soleus H-reflex during arm cycling.

In common with animal species, evidence in humans suggests that similar neural mechanisms (e.g. locomotor central pattern generator (CPG)) regulate rhythmic movements in both arm and leg and that interlimb neural connections coordinate movement between upper and lower limbs ; however, by comparison the evidence in humans is limited. This thesis focused upon exploring the neural control of rhythmic arm cycling and the influence of the neural control of arm cycling on the neural circuits controlling the legs. Specifically, the effect of five different arm cycling paradigms on EMG and reflex responses in arm and leg muscles were explored. First, the pattern of muscle activity and cutaneous reflex modulation evoked with electrical stimulation to the superficial radial (SR) nerve were evaluated during forward and backward arm cycling. Irrespective of the cycling direction, background electromyographic (bEMG) and cutaneous reflex patterns were similarly modulated suggesting similar neural control mechanisms for both forward and backward cycling. These bEMG and reflex findings provide further evidence of contributions from CPG activity to the neural regulation of rhythmic arm movement. Second, bEMG and cutaneous reflex (SR nerve) modulation were evaluated during three dissimilar bilateral rhythmic arm cycling tasks created by unilaterally manipulating crank length (CL). The neural regulation of arm cycling was shown to be insensitive to asymmetrical changes in arm crank length suggesting that the neural control was equivalent across the three dissimilar rhythmic arm cycling tasks and that differences in peripherally generated inputs between the dissimilar rhythmic tasks had limited effect on the neural control. Third, the neural control of arm movements was evaluated between those with unstable shoulders and control participants. The alterations of bEMG and the cutaneous reflex patterns suggest that the neural control is compromised in those with shoulder instabilities during rhythmic arm movement. Fourth, inhibition of the soleus H-reflex in stationary legs induced by rhythmic arm cycling was shown to be graded with arm cycling frequency. A minimum threshold arm cycling frequency of .8Hz was required to produce a significant interlimb effect. Fifth, the degree of the soleus H-reflex suppression induced by arm cycling was independent of afferent feedback associated with arm cycling at different crank loads. In combination the latter two studies suggest that central motor commands related to the frequency of arm cycling is the major signal responsible for the soleus H-reflex suppression in stationary legs, while afferent feedback related to upper limb loading during arm cycling is not. Collectively, the data contained in this thesis contribute to the evidence suggesting that CPG activity contributes to neural regulation of rhythmic arm movement, alterations in sensory feedback associated with arm cycling have limited influence on the observed reflex modulation and that the neural control can be disrupted in the presence of prolonged orthopaedic injury. Taken together with our previous findings, the current results also suggests that central motor command (e.g. CPGs) for rhythm generation of the rhythmic arm movement is the primary source of the signal responsible for the observed interlimb neural communication.

Two experiments were undertaken. The objective of Experiment One was to identify the lower limb muscles that were most frequently active during the early period of a step turning task for further testing in Experiment Two. In Experiment Two participants undertook multiple trials of a step-turning task, 30 and 60° to the left and right of midline, at a self-selected pace in response to a visual cue. There were five objectives to Experiment Two. Firstly, to identify the predominant order in the onset of foot movement so that anticipatory muscle activity could be defined for this task. Secondly, to identify whether there is a consistent temporal order in movement onset between the head and the feet. Thirdly, to identify whether and how consistently anticipatory lower limb muscle activity is present bilaterally. Fourthly, to assess whether there is a consistent sequence in the onset of anticipatory muscle activity among muscles active in at least 80% of trials. The final objective was to identity whether there was a consistent temporal relationship in the onset of the anticipatory muscle activity present in at least 80% of trials, with the onset of head and foot movement. Study Design: A repeated measures design was used. Background: Anticipatory lower limb muscle activity in gait initiation and forward stepping studies has been reported to be consistently present, and associated with initial and important balance responses. Falls during turning are associated with a high incidence of hip fractures in the elderly population. The presence of anticipatory lower limb muscle activity turning has not been previously reported. Participants: There were five participants in Experiment One, and ten in Experiment Two. All were between 18 and 40 years of age and did not have neurological or musculoskeletal disorders, or severe visual loss. Results: In Experiment One, four muscles were consistently active bilaterally, during the early period of step-turning and were: tibialis anterior, gastrocnemius, biceps femoris and gluteus medius. In Experiment Two the ipsilateral foot moved before the contralateral foot in 68% of trials towards the left, and 79% of trials towards the right. The onset of head movement consistently occurred before the onset of foot movement during turns towards both directions. The percentage of trials in which the four muscles were active in an anticipatory manner was low bilaterally, ranging from 12 to 38% of trials. Objectives that involved the further analysis of muscles active in at least 80% of trials were unable to be completed. Conclusions: During a step-turning task young healthy adults predominantly move their ipsilateral foot before their contralateral foot. The consistent onset of head movement prior to that of the feet, indirectly suggests that the visual system might influence the temporal onset of the feet. The low levels of anticipatory muscle activity during step-turning suggest that the lower limbs are not involved with the initial balance responses for this task thus making it inherently different to gait initiation and forward stepping.

Thesis (M.S.)--Rochester Institute of Technology, 2008. / Typescript. Includes bibliographical references (leaves 69-70).

Thesis (M. Phil.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 254-261).

Introdução: A dor lombar gera alterações motoras que podem comprometer a caminhada. Contudo, pouco se sabe sobre suas repercussões sobre a cinemática e energética da caminhada. Objetivo: Verificar: a) a correlação entre variáveis cinemáticas da caminhada (intensidade do deslocamento e velocidade horizontal) e variáveis neurofisiológicas e psicossociais da dor lombar (intensidade da dor e nível de incapacidade, respectivamente); b) o efeito da dor lombar crônica sobre parâmetros cinemáticos e metabólicos da caminhada. Métodos: A amostra foi composta por voluntários com dor lombar crônica inespecífica, (GL/ n=6) e indivíduos saudáveis (GC/ n-7). O nível de incapacidade foi obtido pelo Índice de Incapacidade de Oswestry e a intensidade da dor pela escala visual analógica (EVA). As variáveis cinemáticas foram determinadas por cinemetria, e as variáveis metabólicas por análise de gases enquanto os sujeitos caminharam em esteira rolante. A bateria de teste foi dividida em três blocos de acordo com a intensidade do esforço (preferida, abaixo e acima da preferida). Resultados: Não foram observadas correlações entre as variáveis cinemáticas da caminhada e as variáveis neurofisiológicas e psicossocias da dor. Também não se observou efeito da dor lombar sobre os parâmetros cinemáticos. Embora não houvesse diferença entre os grupos nos parâmetros metabólicos, os lombálgicos foram mais econômicos nas velocidades mais baixas. Conclusão: Embora a dor lombar crônica não tenha influenciado os parâmetros mecânicos da caminhada, e não se tenha observado diferenças nos parâmetros metabólicos entre os grupos, a velocidade ótima de caminhada nos lombálgicos parece estar nas baixas velocidades. / Introduction: Low back pain causes motor abnormalities that may impair walking. However, little is known about its effects on the kinematics and energetics of walking. Objectives: To check: a) the correlation between kinematic variables of walking (intensity of displacement and horizontal velocity) and neurophysiological and psychosocial variables of low back pain (pain intensity and disability level, respectively), b) the effect of chronic low back pain on kinematic and metabolic parameters walk. Methods: The sample consisted of patients with chronic nonspecific low back pain, (GL / n=6) and healthy subjects (GC / n=7). The level of disability was obtained by the Oswestry Disability Index and pain intensity by visual analog scale (VAS). The kinematic variables were determined by kinematics, and metabolic variables for gases analysis while the subjects walked on a treadmill. The battery test was divided into three blocks according to the intensity of the effort (preferably above and below the preferred). Results: There were no correlations between the kinematic variables of the walk and the neurophysiological and psychosocial variables of low back pain. Also there was no effect of back pain on the kinematic parameters. Although there was no difference between the groups in metabolic parameters, the lumbar group were more economical in lower speeds. Conclusion: Although chronic back pain did not influence the mechanical parameters of the walk, and has not been seen differences in metabolic parameters between groups, the optimal speed of walking on person with low back pain seems low speeds.

Introdução: A dor lombar gera alterações motoras que podem comprometer a caminhada. Contudo, pouco se sabe sobre suas repercussões sobre a cinemática e energética da caminhada. Objetivo: Verificar: a) a correlação entre variáveis cinemáticas da caminhada (intensidade do deslocamento e velocidade horizontal) e variáveis neurofisiológicas e psicossociais da dor lombar (intensidade da dor e nível de incapacidade, respectivamente); b) o efeito da dor lombar crônica sobre parâmetros cinemáticos e metabólicos da caminhada. Métodos: A amostra foi composta por voluntários com dor lombar crônica inespecífica, (GL/ n=6) e indivíduos saudáveis (GC/ n-7). O nível de incapacidade foi obtido pelo Índice de Incapacidade de Oswestry e a intensidade da dor pela escala visual analógica (EVA). As variáveis cinemáticas foram determinadas por cinemetria, e as variáveis metabólicas por análise de gases enquanto os sujeitos caminharam em esteira rolante. A bateria de teste foi dividida em três blocos de acordo com a intensidade do esforço (preferida, abaixo e acima da preferida). Resultados: Não foram observadas correlações entre as variáveis cinemáticas da caminhada e as variáveis neurofisiológicas e psicossocias da dor. Também não se observou efeito da dor lombar sobre os parâmetros cinemáticos. Embora não houvesse diferença entre os grupos nos parâmetros metabólicos, os lombálgicos foram mais econômicos nas velocidades mais baixas. Conclusão: Embora a dor lombar crônica não tenha influenciado os parâmetros mecânicos da caminhada, e não se tenha observado diferenças nos parâmetros metabólicos entre os grupos, a velocidade ótima de caminhada nos lombálgicos parece estar nas baixas velocidades. / Introduction: Low back pain causes motor abnormalities that may impair walking. However, little is known about its effects on the kinematics and energetics of walking. Objectives: To check: a) the correlation between kinematic variables of walking (intensity of displacement and horizontal velocity) and neurophysiological and psychosocial variables of low back pain (pain intensity and disability level, respectively), b) the effect of chronic low back pain on kinematic and metabolic parameters walk. Methods: The sample consisted of patients with chronic nonspecific low back pain, (GL / n=6) and healthy subjects (GC / n=7). The level of disability was obtained by the Oswestry Disability Index and pain intensity by visual analog scale (VAS). The kinematic variables were determined by kinematics, and metabolic variables for gases analysis while the subjects walked on a treadmill. The battery test was divided into three blocks according to the intensity of the effort (preferably above and below the preferred). Results: There were no correlations between the kinematic variables of the walk and the neurophysiological and psychosocial variables of low back pain. Also there was no effect of back pain on the kinematic parameters. Although there was no difference between the groups in metabolic parameters, the lumbar group were more economical in lower speeds. Conclusion: Although chronic back pain did not influence the mechanical parameters of the walk, and has not been seen differences in metabolic parameters between groups, the optimal speed of walking on person with low back pain seems low speeds.

Introdução: A dor lombar gera alterações motoras que podem comprometer a caminhada. Contudo, pouco se sabe sobre suas repercussões sobre a cinemática e energética da caminhada. Objetivo: Verificar: a) a correlação entre variáveis cinemáticas da caminhada (intensidade do deslocamento e velocidade horizontal) e variáveis neurofisiológicas e psicossociais da dor lombar (intensidade da dor e nível de incapacidade, respectivamente); b) o efeito da dor lombar crônica sobre parâmetros cinemáticos e metabólicos da caminhada. Métodos: A amostra foi composta por voluntários com dor lombar crônica inespecífica, (GL/ n=6) e indivíduos saudáveis (GC/ n-7). O nível de incapacidade foi obtido pelo Índice de Incapacidade de Oswestry e a intensidade da dor pela escala visual analógica (EVA). As variáveis cinemáticas foram determinadas por cinemetria, e as variáveis metabólicas por análise de gases enquanto os sujeitos caminharam em esteira rolante. A bateria de teste foi dividida em três blocos de acordo com a intensidade do esforço (preferida, abaixo e acima da preferida). Resultados: Não foram observadas correlações entre as variáveis cinemáticas da caminhada e as variáveis neurofisiológicas e psicossocias da dor. Também não se observou efeito da dor lombar sobre os parâmetros cinemáticos. Embora não houvesse diferença entre os grupos nos parâmetros metabólicos, os lombálgicos foram mais econômicos nas velocidades mais baixas. Conclusão: Embora a dor lombar crônica não tenha influenciado os parâmetros mecânicos da caminhada, e não se tenha observado diferenças nos parâmetros metabólicos entre os grupos, a velocidade ótima de caminhada nos lombálgicos parece estar nas baixas velocidades. / Introduction: Low back pain causes motor abnormalities that may impair walking. However, little is known about its effects on the kinematics and energetics of walking. Objectives: To check: a) the correlation between kinematic variables of walking (intensity of displacement and horizontal velocity) and neurophysiological and psychosocial variables of low back pain (pain intensity and disability level, respectively), b) the effect of chronic low back pain on kinematic and metabolic parameters walk. Methods: The sample consisted of patients with chronic nonspecific low back pain, (GL / n=6) and healthy subjects (GC / n=7). The level of disability was obtained by the Oswestry Disability Index and pain intensity by visual analog scale (VAS). The kinematic variables were determined by kinematics, and metabolic variables for gases analysis while the subjects walked on a treadmill. The battery test was divided into three blocks according to the intensity of the effort (preferably above and below the preferred). Results: There were no correlations between the kinematic variables of the walk and the neurophysiological and psychosocial variables of low back pain. Also there was no effect of back pain on the kinematic parameters. Although there was no difference between the groups in metabolic parameters, the lumbar group were more economical in lower speeds. Conclusion: Although chronic back pain did not influence the mechanical parameters of the walk, and has not been seen differences in metabolic parameters between groups, the optimal speed of walking on person with low back pain seems low speeds.

O pé torto congênito idiopático é a deformidade congênita de maior prevalência na ortopedia. Estudos da locomoção podem favorecer condutas na reabilitação de crianças com tal disfunção. Neste trabalho foram analisados parâmetros biomecânicos da marcha e do salto vertical com contra-movimento, além do estudo do limiar de percepção plantar de crianças com pé torto congênito, tratadas cirurgicamente. Para análise dos resultados, foram utilizados testes estatísticos não paramétricos. Não foram identificadas alterações na sensibilidade plantar. Apesar da semelhança das curvas médias de força, variação angular e eletromiografia, as variáveis biomecânicas mostraram diferenças. Na marcha, as crianças com pé torto mostraram maior taxa de crescimento para o primeiro pico da força vertical; no apoio médio, maiores flexão do joelho e dorsiflexão do tornozelo, e menor força vertical; na fase de propulsão, menores força ântero-posterior, segundo pico da força vertical e flexão plantar. Enquanto que as mesmas crianças mostraram na fase de preparação do salto vertical, menor dorsiflexão; na impulsão, maior flexão do joelho e menores flexão plantar, força vertical e atividade do músculo gastrocnêmio medial; e na aterrissagem, maior taxa de crescimento da força vertical, menor flexão plantar e maior flexão do joelho. O entendimento de como o sistema locomotor opera durante as atividades analisadas pode contribuir para direcionamentos relacionados com os estímulos adequados de atividades físicas para essas crianças / Idiopathic clubfoot is the most prevalent congenital deformity in orthopedics. Locomotion studies in children with such a deformity can help towards better rehabilitation. The aim of this study was to analyze the gait and countermovement jump biomechanics, and to describe the perception threshold in children with congenital clubfoot who have been surgically treated. For data analysis, non-parametric statistical tests were applied. Changes in plantar sensitivity were not found. Despite similar force, kinematics, and electromyography curves along groups, it was found differences for some biomechanical variables. For gait, children with clubfoot showed higher vertical force increase to the first peak. At midstance, they showed higher knee flexion and ankle dorsiflexion, and lower vertical force. At toe off, they presented lower anterior-posterior force, second vertical force peak, and plantar flexion. For jump, during the preparation phase, they presented smaller dorsiflexion; during propulsion, they showed larger knee flexion and smaller plantar flexion, vertical force and m medial gastrocnemius activity. In landing, there was a higher vertical force growth rate, less plantar flexion, and larger knee flexion. The understanding of how the locomotion system work contributes to choose the best stimuli to be applied during physical activity for those children